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gld
09-06-2006, 09:15 AM
I have a 3/4 square of alum stock labeled 6061-T6511. Could someone explain that T number. Never seen one that large.

Evan
09-06-2006, 09:27 AM
T6 Solution heat-treated, and artificially aged.

T_511 Applies to extruded products and to drawn tube when stress-relieved by stretching 1 to 3 % permanent set. Stretching is performed after solution heat treatment or after cooling from an elevated temperature shaping process. These products may receive minor straightening after stretching to comply with standard tolerances.



http://shopswarf.orcon.net.nz/alalloy.html

DR
09-06-2006, 12:31 PM
6061-T6511 is pretty much "garden" variety aluminum.

Interesting to note some of the bike makers have taken to listing their tubing with the complete "-T6511" heat treat spec. The implication being that they use exotic alloy in their frames.

J Tiers
09-06-2006, 01:16 PM
Wrth noting that the stretch is commonly done just for straightening extruded products.... it ain't very special.

YankeeMetallic
09-06-2006, 03:06 PM
Additionally the "T6511" is what is generally referred to by its first two digits "T6" by manufacturers who don't know any better. I'm sure you've heard that several times, "T6 aluminum,T6 aluminum, T6 aluminum..." It's the same people who are pushing their product, "...And now the new RONCO Apple-peeler-corer-slicer. Made from T6 aircraft aluminum" & then it says somewhere else "T6 6061 aluminum". It's just the run of the mill, most common 6061 aluminum, and generally the best priced aluminum you come across as a machinist. However it is NOT the strongest aluminum.

A.K. Boomer
09-06-2006, 03:16 PM
Not the strongest but i also wouldnt call 6061 T6 "garden variety" either, its still tough stuff, garden variety aluminum wont even take a heat treat.

7000 series is suposed to be the bomb for bike frames now --- my cannondale is 6061 and is doing just fine (so far)

Evan
09-06-2006, 04:36 PM
T6 isn't a particular alloy of aluminum, it's a heat treat identifier that is used to designate the condition of any heat treatable alloy. You can have 2024-T6, 6061-T6, 7075-T6 and any of the other members of those alloy families as well as the 4000 and 8000 series.

If somebody is refering to aluminum as "T6" thinking that it means a specific alloy it simply shows that they have no idea what it means.

motorworks
09-06-2006, 05:03 PM
Just a side note
I see a lot of the term "6061 T6 aircraft aluminum" and the the phrase "billet aluminum" used on ebay.
Items mainly for motorcycles,ATV's, etc.
When I last checked aircraft aluminum was 7075, and billet means a semifinished section...

Stupid people selling stupid things to people with an even lower IQ.

Evan
09-06-2006, 05:48 PM
Aircraft aluminum is usually 2XXX series and most commonly 2024-T4 for all the outer skins and most fabricated structural members like ribs and spars. It is a lot stronger than 6061-T6 which is used for some things but not nearly as much as 2024. Again, anybody referring to 6061-T6 as aircraft aluminum doesn't know much about aircraft and probably not aluminum either.

7075 is also used in aircraft but not much as it is too prone to stress corrosion cracking. When it is used it is normally for parts that don't undergo heavy cyclical loading but still need to be very strong. Seat belt brackets and seat frames are a good example.

All aluminum is made from billets so that makes all aluminum billet aluminum to start with.

topct
09-06-2006, 05:50 PM
And the numbers behind the T6 are neccasary to take the wrinkles out of it.

You will not find any just "6061 T6". It is unusable, as the heat treat process warps it. You should see sheet and or plate as it leaves the solution furnace. And it gets worse as it cools. Yes it's T6 but it is ugly.

Stretching or leveling is the finale step to make it into a presentable and usable product. And is that finale "kiss" to further align its chemistry. Not it's hardness.

Whether you see it as the complete designator or not depends on the customers specifications for said designator.

Boeing has to have all the numbers on thier metal. Thus "aircraft" grade. Even the numbers of a labratory test are tracable in thier case.

"All aluminum is made from billets so that makes all aluminum billet aluminum to start with."

Extrusions are made from billets, the rest is made from ingots.

BadDog
09-06-2006, 06:00 PM
And the term "billet" in those contexts is simply and indicator that it is machined to shape rather than extruded, pressed, or cast.

Evan
09-06-2006, 06:05 PM
There isn't any difference between billet and ingot except perhaps shape.

smagovic
09-06-2006, 07:02 PM
A billet is simply a solid piece of material that is shaped into it's finished form by machining.
Most finished products are either cast or molded into shape. A billet is a raw block of material.

Ingot-A bar or wedge of steel, gold, or other malleable metal, cast in a mold; a mass of unwrought cast metal.
Vic

topct
09-06-2006, 07:19 PM
As a fork lift, crane, and machine operator for Kaiser Aluminum I cannot ever remember making "billets". The other plants had "billet" making machinery.

From the bottom, it started, hens, chicks, pigs, and ingots, all ingots. Any alloy on the list. Just different sizes. We did not make billets.

We made sheet and plate out of ingots.

There were billet makers however. They would take our ingots and make billets out of them.

They then could extrude or forge, from them. Thats what we were taught.

Machining is not done from billet. It is done from an extrusion or forging or a casting. The other is from plate. And that plate can be ten inches thick. But it was still called "plate", not billet.

And castings are not made from billet either.

Did we do this once before?

mochinist
09-06-2006, 07:27 PM
When a new customer tosses around the word billet, I see dollar signs$$$$$$

motorworks
09-06-2006, 07:52 PM
I must bring up this old post by Forest because it is sooo true:
Forest:


"Billet" is a classic example of common usage in a group noted for invincible ignorance triumphing over precise technical language.

A "billet" is the term used to describe the material in its first stages of a hot rolling process. "The billets are heated then run through the first stand of rolls..." Before the billet was a billet it was a "bloom" and before that it was a "cast ingot." "Billet" is the material form in an intermediate step in the rolling process.

In the machine shop parts can be made from hot roll, cold roll, plate, welded fabrications, castings, or forgings. But never "billet". Billets never get to the machine shop because they're an intermediate product in the rolling mill. Strictly speaking it's impossible to make stuff from a "billet" unless the material was purchased in the billet form from a rolling mill. I dare say the mill would be entirely be justified in removing all the material's identifying marks and requireing the purchaser to sign a waiver of warranty acknowledging the purchased material's properties were incertifiable and its processing to commercial standards were incomplete.

In short actual "billet" material can very possibly be substandard compared to material that's fully processed and heat treated.

"Billet" is strictly a hot-rodder's term used to cover parts machined to net shape and detail from solid stock. "Billet" as a material identifier does not signify superior quality. Quite the opposite: in fact, "billet" rocker arms, connecting rods etc might be inferior in ultimate strength and reliability to identical products made from net shape forgings where the materials grain structure is directed to maximize its resistance to stress.

So when you see "billet" proudly printed on a colorful box of hot-rod goodies think "bull****." There's hardly a segment of the market place so bamboozled and led by fad and hysteria as hot-rodders unless it's buyers of cosmetics and male enhancement products. Ignorance and folly among purchasers is actively fostered by makers of hot rod products - purchasers who spend mountains of money to secure the last iota of performance from their favorite overweight, unreliable, unstreamlined, obsolete POS.

People who build hot-rods and race cars are building nothing more than high performance parade floats. They're made for glamour and to excite envy among the cannaille. The apotheoses of fast cars are Formula 1, Indy cars, and unlimited dragsters. Anything less is the province of wannbes and dreamers.

So use "billet" as a general material descriptor if you wish but by doing so you flaunt your ignorance of materials and their designation in the industry. If you're working in a machine shop such usage will brand you as a dunce, a wannabe, and if a customer as someone to relentlessly fleece by making them "billet" parts from plate and barstock and charging them extortionate prices.

[This message has been edited by Forrest Addy (edited 04-23-2005).]

Evan
09-06-2006, 07:57 PM
Yep.


And castings are not made from billet either.
Of course not. Billet is made by casting. All aluminum starts as a casting.

gld
09-06-2006, 08:28 PM
I buy mostly scrap, so never saw a 4 digit T number. I am now enlightened the the alum numbering system.

Thanks

Millman
09-06-2006, 08:38 PM
{{If you're working in a machine shop such usage will brand you as a dunce, a wannabe, and if a customer as someone to relentlessly fleece by making them "billet" parts from plate and barstock and charging the...}} Damn Forrest...that impressed me. Too bad more people don't realize what you stated. Maybe some will not throw their wannabee status around so bad.

dicks42000
09-06-2006, 09:42 PM
Here on the North Shore we have a new shop that caters to the Hotrod & Chopper set...(Sorry David et al, just the unknowing ones...) He calls his shop "North Shore Billet" of course....Seems to be busy enough, though. Guess he's better at marketing than I am. Seen some cool stuff in his shop.
The other small manual machine & Fab. shops around here ( me included, but I'm just a part-timer machinist & full-time HVAC guy.) are surviving doing what ever we do. CNC shops & bigger places are busy.
Have fun making chips. I gotta get back to some marine work on the 13 in. South Bend.
Rick

HTRN
09-07-2006, 02:58 AM
Again, anybody referring to 6061-T6 as aircraft aluminum doesn't know much about aircraft and probably not aluminum either.

I used to make alot of Microwave components that ultimately went to the military. A good deal of it was 6061, and I know that some of indeed wound up in Aircraft. So, yeah, the stuff we made from 6061 was indeed "aircraft aluminum" ;)


HTRN

DR
09-07-2006, 08:30 AM
Meanings change.....

In the hot rod and motorcycle world "billet" implies a chunk of metal, usually aluminum, that will be used to machine a part from. There's an implication that the part is well made and costly because of the machining processes. Nothing at all incorrect or wrong about the useage, it's become a quite common part of the language of aftermarket parts.

Millman
09-07-2006, 09:57 AM
Now tell the truth....how many times do you have to know the EXACT alloy for any part? That's only necessary if someone hands you a print and demands you use that alloy because they are a paying customer. Do you walk around your shop, pick up a piece of aluminum, and think, I could never use that for my project because it's not the right alloy? If it's aluminum, just use it. Same with other mats. Just use it and make something! The" mystery metal" thing is a myth, just take a test cut and then determine what you can use it for, no big deal!

Evan
09-07-2006, 11:29 AM
Ingot, Billet

Ingot and billet play an integral part in the production of almost all other aluminum products. Plate, sheet, foil, wire, rod, and bar products are all produced by pressing or rolling ingot and billet.
Ingot and billet are cast from molten aluminum. In the cast house, crucibles of molten aluminum empty their silvery liquid either directly into molds or into a holding furnace where the metal is kept molten at temperatures between 1200 and 1500 degrees F. Alloying elements are then added.
Before the alloyed metal can be cast, it must be purified by forcing mixtures of gases through the hot metal. Impurities (dross) come to the surface and are skimmed off. http://www.aluminum.org/Images/aaluminum_industry_images/aluminum_products/ingot_billet_sow/Billets3.jpg
Most metal is cast by the direct-chill (DC) process, which produces huge sheet ingot for rolling mills, round log like billet for extrusion presses, or square billet for production of wire, rod, and bar.
In DC casting, alloyed aluminum flows from the furnace through troughs to the casting station and into molds. For sheet ingot, weighing several thousand pounds each, three or four molds or a dozen or so billet molds may be poured simultaneously. The mold itself is only a few inches deep and forms the cross-sectional shape of the ingot. In the mold, sprays of cool water rapidly solidify the metal, which is gradually lowered into the casting pit. The process continues until the desired length is achieved and the process can be done either vertically or horizontally.


http://www.aluminum.org/Content/NavigationMenu/The_Industry/-Ingot,_Billet/-Ingot,_Billet.htm


According to that there is no difference between ingot and billet except shape.

Millman
09-07-2006, 11:36 AM
{{no difference between ingot and billet except shape.}} Yep, that's the ticket. Another one of those open-ended terms meant to impress somebody.

Evan
09-07-2006, 11:46 AM
It also means that if the guy making stuff "directly from billet" doesn't have some 20" logs of aluminum lying around someplace then he is either clueless or lying.

Evan
09-07-2006, 11:57 AM
Alcan has a major facility north of here in BC. They have a site just for ingot products alone although they make just about anything. One of the ingot products they make is extrusion billet.

http://www.ingot.alcan.com/Ingot/AlcanAluIngot.nsf/APMGen/Welcome_Home

BadDog
09-07-2006, 01:08 PM
It also means that if the guy making stuff "directly from billet" doesn't have some 20" logs of aluminum lying around someplace then he is either clueless or lying.

round log like billet for extrusion presses, or square billet for production of wire, rod, and bar.

The term billet as you use it doesn't have to be in round logs, but generally implies aluminum in a sort of "source material" or “bulk” form to be fed into some other process. That might be an extrusion press or other forming process, including machining. If the result of that machining is a pulley for a V8, then the producer of the part would say it is “machined from billet”. Then the common usage shortens that to say simply “it is a billet pulley”.

There are only two minor problems here as far as I can see.

1) To be totally correct, this ignores the intermediate process of forming the billet by extrusion, press, or roll (including heat treat and finishing) into the final material that was machined. But when you need a short and simple term for common use description of a material, “billet” works well enough and appropriately invokes the accurate mental image of “I started with a chunk of material and machined this part from it.”

2) The term “billet” has come to invoke a Pavlovian irrational response in many humans. It somehow imbues the product with magical properties far beyond having simply been machined/cut from a metal blank, perhaps alluding to some assumed high accuracy.

And to be totally fair with the language police efforts, lets clarify the term “hot rodders”. A true hot rodder wouldn’t be caught dead wasting money or time with “billet” parts. This term is more appropriately used for the guys doing what ever it takes to make a car go faster, generally on a budget. “Street rodders” are the morph often more interested in show than “go”. And the culmination of that is the current “tuner” crowd, often given the derogatory “ricer” moniker by hot rodders and other gear heads. There are some real gear heads among the tuners, and they do some amazing things with those cars, but the ratio of posers and wanna-bes to those “keeping it real” is terribly high in that arena.

In the automotive world, it is primarily this “tuner” crowd as well as the posers from the street/hot rod community that give the billet parts so much worship and foolish adoration, not even really understanding WHY those parts originally became valued. They just know that “the cool kids have them on cars that work” so obviously their’s needs them. This includes the people who replace a 2 bbl Rochester on a stock base model 350 with a “750 double pumper” and no other mods other than “big-n-littles” before proclaiming themselves “hot rodders”. Or “tuners” who bolt on a contrasting body kit, big wing, fart pipe extension, and to really show they are serious; Pep Boys “graphite look” shifter handle with fake NOS button, matching steering wheel, and a PVC “cage” from Home Depot...

LarryinLV
09-07-2006, 03:00 PM
BadDog,

Don't be shy. Tell us how you really feel :cool:

I think you summed up what us "Hot Rodders" think; good job.

The language police and other purists will tell us our "motors" ain't really motors, they're engines, etc. Now we will probably see the avalanche of internet snippets telling us that "billit" ain't really billit, it's something else.

Well.....fine....I suppose many of us know that already. It's marketing.

But, still.....the word "billit" is now part of the new culture of enthusiasts vocabulary and, just like many other words each year, isn't going to go away. And marketers will continue to add "6061 T-6", and "aircraft aluminum" because as has been said, it appeals to the new culture.

No conspiracy by Hot Rodders though, it just means that the part was machined out of a chunk of aluminum. If you know more than that, great, you're more knowledgable than some. If not; do you really need to know more? I doubt it.

Evan
09-07-2006, 03:14 PM
The problem is that most people have no idea what the term billet means. If they come in to your shop and ask that something be made from billet do you get a 6" dia piece of extruded aluminum stock off the rack and tell them it's billet?

Or, do you try and explain that they can't get something machined directly from real billets of aluminum? Of course they won't believe that and will think you are an idiot because everyone knows the best stuff is made from billet.

I'm glad I'm not running a job shop catering to those customers.

kap pullen
09-07-2006, 03:16 PM
[QUOTE=Evan] Again, anybody referring to 6061-T6 as aircraft aluminum doesn't know much about aircraft and probably not aluminum either.

Guess I have a lot to learn. You go thru life and everyone has something they can teach you.

No one knows everything unless they have time on their hands, and a computer these days.

Kap

Todd Tolhurst
09-07-2006, 03:38 PM
It also means that if the guy making stuff "directly from billet" doesn't have some 20" logs of aluminum lying around someplace then he is either clueless or lying.

Are astronomers clueless or lying when they call nitrogen or oxygen "metals"? Of course not; they simply use a different terminology from chemists (or machinists) because it suits their work.

Evan
09-07-2006, 03:53 PM
I worked in the aircraft repair business for a number of years. When repairing aircraft it is common practice, especially in Canada, to fabricate replacement parts from raw material instead of odering factory made replacements. I have made parts for nearly every part of an aircraft ranging from gas welding control column assemblies to replacing all skins to removing and installing new wing spars on C-130s.

When doing repairs by fabricating replacement parts the replacement must be made from the exact same alloy as the original. I do not recall ever making a part from 6061 alloy, not even once. That was considered a commercial alloy and wasn't suitable for aircraft use because of the much lower strength to weight compared to 2000 series aluminum. 6061-T6 has an ultimate tensile yield strength of about 45,000 psi whereas 2024-T4 is around 68,000 psi. Even more important is the difference in ultimate bearing strength which for 6061-T6 is 88,000 and for 2024-T4 is 118,000 psi. The fracture strength of 2024-T4 under cyclical load is nearly double that of 6061-T6.

There are few areas in which structural strength vs weight is important that 6061 would be a better material. The only property that it has that is superior to 2024 is the ability to be anodized well. This isn't often a criteria as anodizing isn't a common method of protecting large components and adequate alternatives exist.

6000 series alloys are used in aircraft for parts where high strength to weight isn't critical. That is not a lot in an aircraft as aircraft are designed to make every part count. Non-structural parts are considered dead weight and are minimized as much as possible.

LarryinLV
09-07-2006, 04:02 PM
6061 T-6 aluminum is used extensively in the aerospce industry for fittings, hydraulics, and other components where a high degree of corrosion resistance is desired, good machinibility is desired, and the component is not expected to undergo a high level of stress.

20xx is used a lot in skins and rivets and screws. 7079-T6 or X7080-T7where high stress forces are expected in relatively thick parts

Evan
09-07-2006, 04:06 PM
Are astronomers clueless or lying when they call nitrogen or oxygen "metals"? Of course not; they simply use a different terminology from chemists (or machinists) because it suits their work.

No, it's not because it suits their work. "Metallic" nitrogen exists only at extremes of temperature and pressure and is called that because it assumes a face centered cubic crystal structure which is the same as metals. That doesn't make it a metal. Nobody calls nitrogen a metal. There is a big difference between having a metallic like structure and being a metal.

Evan
09-07-2006, 04:12 PM
6061 T-6 aluminum is used extensively in the aerospce industry for fittings, hydraulics, and other components where a high degree of corrosion resistance is desired, good machinibility is desired, and the component is not expected to undergo a high level of stress.

Exactly. Also, those components are anodized for corrosion resistance. It's not because 6061 is inherently greatly superior to 2XXX alloys in corrosion resistance, it's because it can be anodized a lot easier. Those are all non structural components and make up only a small percentage of the total aluminum in an aircraft. As for machinability, 2024 is much more machinable than 6061. 6061 machinability rating is 50%, 2024 is 70%.

Todd Tolhurst
09-07-2006, 04:33 PM
Nobody calls nitrogen a metal.

Whoa, Evan. Better check your references!
I'm afraid they do, and not because of any crystal structure.

Don't believe me, believe WikiPedia (http://en.wikipedia.org/wiki/Metal#Astronomy).

Or perhaps the sci.astro Stars FAQ:

In astronomy, "heavy elements" or "metals" refers
to all elements heavier than helium. Since heavy elements are created
in stars, stars formed later in the life of the galaxy have more heavy
elements than found in older stars.

How about NASA? They must know about this sort of thing:

These advances enabled more accurate study of the nearby galaxies that comprise the "Local Group" of galaxies. Astronomers observed Cepheids in both the metal rich inner region of the Andromeda galaxy and its metal poor outer region. (To an astronomer, a "metal" is any element heavier than helium - the second lightest element in the periodic table. Such elements are produced in stars and are ultimately released into the interstellar medium as the stars evolve.)
[http://map.gsfc.nasa.gov/m_uni/uni_101expand.html]

Evan
09-07-2006, 04:47 PM
Strange. I have been involved in astronomy since I was a child and have never heard of "anything heavier than helium" being called a metal. I don't think that is a very common usage. I have never seen it used that way in any article or paper I have read.

Evan
09-07-2006, 04:51 PM
I also note that in the description of "metal rich" stars wiki has this disclaimer:



To meet Wikipedia's quality standards (http://en.wikipedia.org/wiki/Category:Wikipedia_style_guidelines), this article or section may require cleanup (http://en.wikipedia.org/wiki/Wikipedia:Cleanup).

J Tiers
09-07-2006, 05:04 PM
Gosh, when I see that term "billet" on automotive stuff, there is a little list of things that come up in my mind.....

1) That's gonna take a lot of machining time.... and leave a lot of chips.

2) it's gonna be expensive for what it is.

3) it's gonna be inferior to a forging because the grain won't follow the shape.

4 I sure hope the guy who made that isn't an OCC guy moonlighting! ;)

5) I wonder if those bozos did any NDT on that part..... prob'ly not.... :rolleyes:

5) That sucker might just break because it's "billet"...... either from a hidden defect, or a stress riser left from machining. :eek:

Evan
09-07-2006, 05:05 PM
Here is a quote from a paper discussing the metallicity of stars.


It is worth recalling that metallicity is determined as the content of heavy metals relative to the hydrogen content. All the elements heavier than hydrogen (Z > 2) are assumed to be “metals” or “heavy elements,” having in mind that metals give a large fraction of electrons in a stellar interior, and Ca, Na, and Fe produce the strongest lines in the stellar spectra. The metallicity [Fe/H] of stars is defined relative to the Sun, which itself is an order of magnitude (or even more) more strongly enriched with metals relative to the mean composition of halo objects. The metallicity [Fe/H] is the difference between the logarithms of ratios of the atom concentration of iron NFe to that of hydrogen NH for the star and for the Sun:
http://exoplanet.eu/papers/SSR372_Metallicity.pdf#search=%22star%20metallicit y%22

The quote marks in the quote are as written.

Note that they make a distinction between "metals" and "heavy elements" and the description of metal content does actually refer to metals. When discussing the metals present they refer only to actual metals. Ca, Na, and Fe are all metals. Metallicity is defined as the ratio of iron to hydrogen.

Todd Tolhurst
09-07-2006, 05:11 PM
Strange. I have been involved in astronomy since I was a child and have never heard of "anything heavier than helium" being called a metal. I don't think that is a very common usage. I have never seen it used that way in any article or paper I have read.

I've been considerably less involved in astronomy than you have, but it's a usage that I have heard many times (usually among the stellar evolution and cosmology folks). It's because it is such an unconventional use of the term that I thought it was a good example of how jargon in one area can mean something quite different in another area.

Evan
09-07-2006, 05:14 PM
I added a slight edit to point out what they really mean as stated in the quote.

"Metallicity is defined as the ratio of iron to hydrogen."

As I said, I haven't heard anyone actually refer to non metals as metals in stellar evolution.

Todd Tolhurst
09-07-2006, 05:21 PM
As I said, I haven't heard anyone actually refer to non metals as metals in stellar evolution.

You mean, other than the sources I quoted?

kap pullen
09-07-2006, 05:24 PM
Evan,

You must be a hundred years old to do all you have done.

Maybe you can tell what you do to live such a long life.

Kap

DR
09-07-2006, 05:37 PM
"When doing repairs by fabricating replacement parts the replacement must be made from the exact same alloy as the original. "

Not arguing with this point, just thought some might be interested....while in college I worked summers at Boeing in flight test while the Dash 80, the original 707, was still being used as a test bed for the later generation of planes.

It wasn't unusual to see a plywood panel replacing the skin in areas where they needed temporary access to the internal structure of the plane. It was so common I didn't really give it a second thought, now I'm curious about the thickness and type, etc. Undoubtedly, aircraft plywood, huh?

LarryinLV
09-07-2006, 06:02 PM
DR,

I find it funny (and timely) that you bring up "aircraft plywood".

I spent a few years in Alaska during the "70s and we had an air carrier there, I think it was Reeve Aleutian, that was one of the true pioneers of aviation.

They used to tie a plumb off the nose and tail and load it so they both went down the same amount to maintain weight and balance, but I digress.

One day they were loading a DC-3 at Anchorage for a delivery to Ketchican, and the forklift driver ran the forks into the side in front of the load door. They brought out some "aviation plywood" and repaired the hole and off they went. The following season I noticed the same DC-3 loading and it appeared they had fixed the hole. Closer examination showed that they just painted the plywood to match the rest of the aircraft paint.

I think it was 2024-T4 birch..

Evan
09-07-2006, 06:10 PM
Wood is used sometimes in metal aircraft. The Swiss Pilatus Heli Porter has floor panels made of .020 aluminum sandwiched over 3/4" balsa. I had to make a replacement panel once. The performance of the turbo version is amazing. It can take off and do a 360 and land where it started in about 500 feet. They use them for mountain rescue.

Anything goes in flight test. You aren't carrying passengers other than techs.



Maybe you can tell what you do to live such a long life.
I don't sleep much. Maybe 4 to 5 hours max per day. Even when I sleep I am mostly awake. It's why I have FMS. Or maybe it's because I have FMS. They don't know. My brain never shuts down.

Todd,

Those are examples of very loose usage of the term and aren't correct. "Real" astronomers don't use it that way. They refer to metallicity as I quoted above. When I said I hadn't heard of all lighter elements being called "metal" it's because I haven't. Metallicity is a different matter and is commonly used. As the quote points out it is a measure of iron content.

Evan
09-07-2006, 06:12 PM
I think it was 2024-T4 birch..

Heh. Duct tape is handy too and comes in aluminum. It won't pass an annual inspection though. :eek:

Todd Tolhurst
09-07-2006, 07:56 PM
Those are examples of very loose usage of the term and aren't correct. "Real" astronomers don't use it that way.

I would think a professor of astronomy like Fred Walter of the University of Stony Brook might know how real astronomers use the term:


F stars are slightly hotter than the Sun. Absorption lines of metals appear (to an astronomer, anything that is neither Hydrogen nor Helium is a metal). Procyon is an F star.

Linky (http://www.ess.sunysb.edu/fwalter/AST443/cen511_week2.html)

LastOldDog
09-07-2006, 08:42 PM
Wood is used sometimes in metal aircraft. The Swiss Pilatus Heli Porter has floor panels made of .020 aluminum sandwiched over 3/4" balsa.

Evan, curious you should mention that adaptation of a recognized composite construction. For a few years we made laminates just as you described, aluminum skins over end-grain blocks of balsa for; ribs, frames, cockpit floors, deck sections, and stringers for our throw-away test hulls (sail boats), and also for single use tank testing hull models. Vacuum bagging was the accepted clamping methodology as long as 'print through' was not a problem. In the interest of expediency we did use 6061 T6 because of cost/availability before fabbinbg with carbon fibre for beta testing. Evan, you have a broad base of knowledge accompanied with field experience, my kind of guy. Lloyd

Evan
09-07-2006, 09:20 PM
F stars are slightly hotter than the Sun. Absorption lines of metals appear (to an astronomer, anything that is neither Hydrogen nor Helium is a metal). Procyon is an F star.
That's because virtually all the spectral lines detected in the sun are metals. Fluorine, Chlorine, bromine, iodine and all the inert gases (except helium) were not detectable to astronomers in the first half of the 20th century. This is when the term "metallicity" was coined to describe the observed emission lines of metals in stars. Nearly all the gases radiate in the extreme ultraviolet and were not detected until the advent of space observatories.

Nobody actually directly refers to nonmetals as metals. You will never see the statement: "The emission lines of the metal oxygen..."

bob_s
09-07-2006, 09:25 PM
Number 263 (Story #1), March 22, 1996 by Phillip F. Schewe and Ben Stein
http://www.aip.org/pnu/1996/split/pnu263-1.htm

The planet Jupiter, which didn't quite attain sufficient mass to become a star, is composed of metallic hydrogen.

Todd Tolhurst
09-07-2006, 09:44 PM
Nobody actually directly refers to nonmetals as metals.

So when a professor of astronomy explicitly writes that astronomers refer to all elements heavier than helium as "metals", he is incorrect?

Note the definition of metallicity (http://en.wikipedia.org/wiki/Metallicity):

In astronomy, the metallicity of an object is the proportion of its matter made up of chemical elements other than hydrogen and helium. All heavier elements are described in astronomy as "metals".

You are mistaken, Evan.

Evan
09-07-2006, 09:53 PM
Metallic hydrogen.

As I explained, it is considered metallic in nature because of a change in character. In the case of hydrogen it isn't even a crystalline phase but only an increase in conductivity accompanied by a phase change to a more closely ordered arrangement of protons. The band gap drops to near zero because of the atomic spacing. I did a little looking and Lawrence Livermore first produced it in 1996 at a pressure of 1.4 million bar and a temp of 3000K. It lasted one millionth of a second.

Evan
09-07-2006, 10:24 PM
In astronomy, the metallicity of an object is the proportion of its matter made up of chemical elements other than hydrogen and helium. All heavier elements are described in astronomy as "metals".


You are mistaken, Evan.

Don't believe everything you read on Wiki. I use it too but I usually check other sources if I have any doubt.

The symbol for metallicity in stars is Fe/H.
It's a measure of the iron/hydrogen ratio.

Example:


Of the ten stars currently known to host extrasolar transiting planets, the star XO-1 is the most similar to the Sun in its physical characteristics: its radius is 1.0+-0.08 R_Sun, its mass is 1.0+-0.03 M_Sun, V sini < 3 km/s, and its metallicity [Fe/H] is 0.015+-0.04.

http://www.spaceref.com/news/viewsr.html?pid=20665

Todd Tolhurst
09-07-2006, 11:01 PM
Don't believe everything you read on Wiki. I use it too but I usually check other sources if I have any doubt.

How many other sources do you require? Other than WikiPedia, I have provided a sci.astro FAQ, a NASA web site, and an astronomy professor's web site.

How about an article (http://www.astrobio.net/news/article1241.html) from Astrobiology Magazine, regarding work done by Greg Laughlin, an assistant professor of astronomy and astrophysics at UC Santa Cruz on steller metallicity:


Laughlin's prediction comes from studying a characteristic of stars that, until a few years ago, few paid much attention to: metallicity. New stars form when vast clouds of interstellar dust and gas collapse. This dust and gas is mostly primordial hydrogen and helium, but it also contains a smattering of heavier elements, which astronomers call "metals" (even though non-astronomers don't normally think of all of these elements as metals). The metallicity of a star tells you what portion of its material is made of metals.

And here's a web page (http://www.astronomy.ohio-state.edu/~pogge/Ast161/Beyond/newworlds.html) by Prof. Richard Pogge from Ohio State, which contains the statement:

Astronomers call all elements heavier than Hydrogen and Helium "metals".

And here's a letter to Nature (http://www.astro.wisc.edu/wham/papers-dir/nature.pdf#search=%22metallicity%20metal%20site%3A .edu%20heavier%22) from ten assorted astronomers and physicists:


Models of the chemical evolution of the Milky Way suggest that
the observed abundances of elements heavier than helium
(‘metals’) require a continuous infall of gas with metallicity
(metal abundance) about 0.1 times the solar value.

So, that's one Usenet FAQ, thirteen astronomers and physicists, two WikiPedia articles, and NASA all in agreement. Are you saying they are all wrong and you are right?

Evan
09-07-2006, 11:18 PM
Nope. I'm saying the astronomers are right. Metallicity is measured by the iron/hydrogen ratio. Not the oxygen or nitrogen or other nonmetal but by iron. As I said, the idea of heavier elements in stars being all metals was formed when all they knew were metals. The term has stuck since it doesn't make any difference. There isn't a single astronomer out there that really considers a nonmetal to be a metal. Since the light elements heavier than helium are the first to be synthesized describing the metallicity in terms of iron ratio also gives an indication of all the lighter elements. If an unusual distribution is found it is made clear and they don't use the term "metal" to describe a nonmetal when doing do.

Evan
09-07-2006, 11:23 PM
Incidentally, there is a very good reason that iron is the measure of heavy element formation in star. That's where fusion stops.

Todd Tolhurst
09-07-2006, 11:52 PM
Nope. I'm saying the astronomers are right.

Then we are agreed. In astronomy, all elements heavier than helium are termed 'metals', even though that meaning of the term is quite odd when used in non-astronomical contexts. Kinda like the meanings of the term 'billet'.

Evan
09-08-2006, 12:05 AM
Nope, not agreed.

darryl
09-08-2006, 12:57 AM
Imagine the size of a 'billet' if it happened to be made inside a star. Imagine the size of the pile of chips if that billet could be made into something- like a planet/spacecraft. 'Course those aren't made of aluminum, they're probably zamacalalloyium. Actually, the pile of chips might just weld itself into another billet because of the intense gravity-

Having been introduced to the concept of warpage in a part during and because of machining operations, it's a wonder to me that any part produced from a solid block could have any real degree of accuracy unless it's machined close to finished shape first, then stress relieved, re-mounted without being distorted, then trued up. Maybe this process would have to be done more than once to get a truly accurate result. No wonder it's called billet- billet to the customer.

Todd Tolhurst
09-08-2006, 08:46 AM
Nope, not agreed.

I didn't think so.

Look, those silly "real astronomers" with the Sloan Digital Sky Survey (http://www.sdss.org/news/releases/20030818.metalpoor.html) also think metals are any element heavier than helium:


After the Big Bang 14 billion years ago, the only atoms in the Universe were hydrogen and helium. All heavier elements, known as metals in astronomical terms, were produced in the superheated hearts of emerging stars. As galaxies aged, the stars continued to be born and to evolve, increasing the amount of metal-rich material in the galaxies. Therefore galaxies in the present-day Universe tend to be metal-rich.

You should really set them straight.

Evan
09-08-2006, 08:49 AM
Example of how real astronomers deal with it:


"We will show in section 8.4 that our galaxy metallicities
appear quite accurate. Could the missing metals be hiding
in the galaxies, or possibly in the halo reservoir? We have
done the same analysis as in Fig. 6, but added to the ICM all
the metals contained in the halo reservoir, and all the metals
locked up in the cold gas inside galaxies. This thus represents
the maximum metallicity we can attain without somehow
lowering the mass of non-metals in the ICM. Although this
has a large effect for small halos, there is little change in the
metallicity of the largest clusters. We conclude that we are
not simply ‘misplacing’ the heavy elements

http://arxiv.org/PS_cache/astro-ph/pdf/0309/0309186.pdf




Hale Observatories, Carnegie Institution of Washington

Title Carbon and nitrogen abundances on the first giant branch of NGC 6752
Subject640102 -- Astrophysics & Cosmology-- Stars & Quasi-Stellar, Radio & X-Ray Sources; ;CARBON-- ABUNDANCE;NITROGEN-- ABUNDANCE;RED GIANT STARS-- CARBON;RED GIANT STARS-- NITROGEN;RED GIANT STARS-- STAR CLUSTERS; STAR EVOLUTION;STELLAR ATMOSPHERES Related SubjectATMOSPHERES;CRYOGENIC FLUIDS;ELEMENTS;FLUIDS;GIANT STARS;NONMETALS;STARS Description/
Abstract Spectrum synthesis techniques have been used to derive quantitative carbon and nitrogen abundances for two stars with M/sub v/approx.^=0.0 in the globular cluster NGC 6752.^The stars CL 25 and CL 166 have similar effective temperature and gravity but different lambda3883 CN band strength.^The abundance ratios derived, relative to the other elements for which (A/H)=-1.5, are ((C/A),(N/A))+0.1, -0.2for CL 25 and (-0.2, +0.6) for CL 166.^The abundance ratios for CL 166, and presumably those of the other CN-strong stars in this cluster, can be explained by the mixing of processed material into the atmosphere of the star.

Todd Tolhurst
09-08-2006, 09:00 AM
Example of how real astronomers deal with it:

From the same paper:


Using these models, we are able to use the tree to track
the metals ejected by stars at each time step, over the whole
merging history of the galaxy, and let new stars form out
of the enriched gas, assuming instantaneous mixing in the
ISM. This is in contrast to the assumption of instantaneous
recycling, the approach generally used in semi-analytic modelling
(CLBF, KCDW, SP99). Correct modelling of the ejection
is likely to be especially important for elements such as
iron, nitrogen and possibly carbon, for which the production
delay can be significant (eg. 1 Gyr for Fe produced by SN
Ia).

Note the "metals" specifically mentioned here: Iron, Nitrogen and Carbon.

Evan
09-08-2006, 09:23 AM
This shows how the concept of metallicity arose. As explained in this paper from 1929 the metals produce thousands of spectral lines while the known nonmetals at the time produce only a very few. As a result they are mainly ignored since they are almost entirely overwhelmed by the true metals in stellar spectra. Most spectral lines for gases are not detectable at all from earth based telescopes. The concept of metallicity represents the content of actual metals as detected by a spectrograph, not nonmetals.

http://vts.bc.ca/pics/nonmetal1.gif

http://www.pubmedcentral.gov/picrender.fcgi?artid=522558&blobtype=pdf

ERBenoit
09-08-2006, 09:41 AM
The simple question of what does the "T-6511" mean has apparently morphed into an astromy tug-of-war. Apparently astronomers have a different idea of what "metal" is compared to the rest of us.

About all I can find in common with where the post started and where it is now is that aluminum and astronomy can be found, in that order, under "A" entries in the dictionary.

Astronomy/astrophysics has nothing to do with the original inquiry. I, for one, do not even understand astrophysics. I might be, though I doubt it, alone on that.

I wonder if "gld" is still following this? Looks like he got the answer he was looking for long ago.

Millman
09-08-2006, 05:05 PM
[QUOTE=kap pullen]Evan,

You must be a hundred years old to do all you have done.

Maybe you can tell what you do to live such a long life.

Kap, you are getting as bad, {or good} as me! You are right, NOBODY knows it all or EVER will. That's the cool thing about this trade. People just THINK they do, I admit my arrogance; I've had guys I was training turn and ask a question that I knew yrs. before...and actually had to tell them, I can look it up. That's what it's all about.

Evan
09-08-2006, 06:14 PM
Sometimes when I get up in the morning from "sleeping" I am so exhausted I can barely remember my name. It takes several hours to recover from a nights "sleep".

Most people don't make anywhere close to full use of their brain. It has a storage capacity of something like 10 to 100 terabytes, something like the Library of Congress. Some estimates are much higher. It also depends on your individual brain, something that cannot be identified by any objective physical means. Einstein willed his brain to science and upon study nothing unusual was found.

The brain has incredible capabilities and severe limitations. It can process some information faster than the fastest computers on earth. A human can recognize a complex shape like a face with high accuracy in less than 100 milleseconds but cannot recall more than about 4 items from short term memory after 20 seconds. How often do you look up a telephone number and by the time you are ready to dial you have to look it up again?

I have always had a severe disability in one specific area. I cannot remember faces. I can remember nearly anything else including nearly photographic images of things I have seen but not faces. I can however remember voices with extreme reliability.

Everybody has different capabilities. My memory for facts and figures is exceptional although not as good as it once was. My ability at math is not very good and although I know quite a bit about math it is always a chore to work things out. It doesn't come naturally as it does for some people.

Kap wanted to know how I have lived so long to learn so much. For me learning is what I live for. Other kids would be out playing and I would be studying or experimenting with something. I also have experienced a lot. I have traveled and lived many places. Not all the experiences have been good. I have seen all sides of human existence. I have watched someone die with the side of their head torn off and I have seen my children born. I watched a friend die as he collapsed on the pool table after OD'ing on speed. I know where the junkies live. I have seen how the very wealthy live.
I have no idea how many different "official" jobs I have had but they have ranged from picking fruit to military service to working with radioactive isotopes.

Somehow I seem to have done rather a lot compared to many. I have no explanation why that may be other than I am not content to sit and vegetate. I am not hyperactive in the least but would rather do anything than spend my time watching somebody else play a game. I invest as little time as possible in keeping track of what anybody else is doing unless it has a direct impact on me. I have no phobias that I know of and am willing to try almost anything once. At least, that used to be so. I have slowed down a great deal in the past 10 years and part of that is my health.

Todd Tolhurst
10-22-2006, 07:22 PM
I have been involved in astronomy since I was a child and have never heard of "anything heavier than helium" being called a metal. I don't think that is a very common usage. I have never seen it used that way in any article or paper I have read.

Since you rejected the umpteen references I provided earlier, I decided to simply ask my friendly neighborhood astronomer. Not the backyard-with-a-homebuilt-scope sort of astronomer, but one of the "real astronomers" you claimed do not refer to anything heavier than helium as a metal. I contacted Gerald J. LaSala, Chairman of the Physics Department of the University of Southern Maine, Director of the Southworth Planertarium, and representative to the International Astronomical Union 2006 General Assembly.

Here is our email exchange:

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Date: Tue, 17 Oct 2006 18:10:48 -0400
From: "Gerald Lasala" <lasala@usm.maine.edu>
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Hi Todd,

To astronomers, "metals" are any elements heavier than helium, in other
words, everything but hydrogen and helium. This is obviously quite
different from a chemist's use of the word!

Cheers,
Jerry LaSala

>>> Todd Tolhurst <todd@toddtolhurst.com> 10/17/06 5:23 PM >>>
Dear Professor LaSala:

I wonder if I might trouble you with a quick astronomy-related
question. As the Director of the University of Southern Maine's
Southworth Planetarium and the chair of the USM Physics Department, I
believe you are very well qualified to provide an authoritative answer.

The question is simply this: What is the meaning of the term "metal", as
used by astronomers?

Thank you for your time.

--
Todd Tolhurst
todd@toddtolhurst.com


I trust this settles the matter of the meaning of "metals" in astronomy, unless you'd like me to check with MIT or Cambridge.

Millman
10-22-2006, 08:47 PM
Evan, nobody has the balls to tell you this. You are so full of useless info, you would be kicked out of any normal machine working environment. I tried to like you, all you can do do is puke up useless **** that any good machinist would smack you upside the face with. Grow up , these guys are not as stupid as you would like to believe in. You have a snotty little kid's need to educate, bad news, you're not that intelligent either. You're lucky we are not neighbors. Have a good day, ****head.

Millman
10-22-2006, 08:59 PM
I will bump this one till you admit you are a worthless piece of $%$%. For once, try being a machinist, instead of a cartoon Tutor Turtle.

BillH
10-22-2006, 09:36 PM
Thank you Millman for reminding all of us of how poor your people skills are.
I think I should go ask the Astronomy professor I had in College about this metal thing... Oh snap I just lost the urge to.

Evan, I find it extremely interesting when you talk about how your brain functions, quite different from most. I find the discussion on human brains by far the more interesting topic discussed in this thread thus far. I think we have some things in common, like a broad knowledge in many things, just you've been alive far longer to deepen the knowledge you have. I feel as if I know a lot about a lot of things but not enough to specialize in any one thing.

John Stevenson
10-23-2006, 03:44 AM
Sometimes when I get up in the morning from "sleeping" I am so exhausted I can barely remember my name. It takes several hours to recover from a nights "sleep".



What about just going to bed, going to sleep and not arguing with yourself ? :rolleyes:
That way you get twice the sleep.

.

Joel
10-23-2006, 05:09 PM
Millman, Evan is NOT a machinist by profession. He is just a curious Renaissance man who happens to be pretty good at the trade. Being incorrect or somewhat argumentative is not exactly parallel to being a “worthless piece of $%$%” IMHO.

"Useless information", as you so deftly stated, is a matter of opinion and approaches oxymoronic (or perhaps Millmanmoronic) by my way of thinking. A broad interest and particular amount of expertise in many different areas is found to be desirable, useful, and beneficial by a majority of us. It also makes one interesting, as opposed to say – pointlessly inflammatory.

You give every appearance of being a rather narrow person who posses a crude and one-track mind. Please do not make the mistaken assumption that all of us share your viewpoints.
I would suggest that once in awhile you might consider learning something which lies beyond your small span of interests (Sociology comes to mind for some reason), but this is a semi-free country and you can certainly do as you please. But, since you devote so great an amount of time to this board, why not at least put forth a tiny bit of effort and assist other members in areas where you perhaps posses greater level of skill? Taking the time to contribute and help others is always appreciated, but please note that a little humility goes a long way.

CaptainEqs
02-14-2008, 02:47 PM
Aircraft aluminum is usually 2XXX series and most commonly 2024-T4 for all the outer skins and most fabricated structural members like ribs and spars. It is a lot stronger than 6061-T6 which is used for some things but not nearly as much as 2024. Again, anybody referring to 6061-T6 as aircraft aluminum doesn't know much about aircraft and probably not aluminum either.


Hmmmm . . .well, if you say so.

I guess I'll have to write off 42 years around planes, including my Songbird, which I designed and which first flew in 1989, and which now has over 2500 flight hours (TTAF). The structure is composed of roughly 300 feet of 6061-T6 tubing and about 10 feet of 4130 tubing, with fabric covering. Not a gram of 2024-T4 was used.

Here, all this time I thought I was pretty conversant with aircraft and not too stupid when it comes to aluminum . . .

;)

The moral of this story is that ALL materials have their place, and sometimes the best choice isn't the one you expected it to be.

smiller6912
02-14-2008, 03:12 PM
In 10 years of class 2 airframe design and modification for the Air force, by far, our most used aluminum is 2024.

pcarpenter
02-14-2008, 03:59 PM
Boy...this is a blast from the past....a 1-1/2 year old thread suddenly rising to the top of the list???

I don't know that the fact that someone built a home built aircraft out of 6061 refutes the notion that most of what is used in aircraft may be 2024-T4

Paul

DR
02-14-2008, 05:21 PM
Yeah, 2024-Tx, 7075 and 7050 are what I would say are most used.

boslab
02-14-2008, 06:24 PM
over here its extruded, then aged at 175 degrees c for 8 hours, air quenched, tf temper is percipitation treated in water after extrusion, virtually all extrusions are stretched by up to 5 % prior to ageing or annealing as required as you cannot anneal any metal that has not been cold worked due to disslocation energy required for recrystalisation, duralamin or Cu bearing exepted.
mark

CaptainEqs
02-14-2008, 08:20 PM
I don't know that the fact that someone built a home built aircraft out of 6061 refutes the notion that most of what is used in aircraft may be 2024-T4


Tens of thousands of aircraft have been built with 6061-T6. I didn't just pull the spec out of a hat. It is the most common aluminum used in light planes, whether experimental or cookie-cutter factory production, and there are more light planes in the US alone than all other aircraft in the world combined.

Thus, the idea that "anybody referring to 6061-T6 as aircraft aluminum doesn't know much about aircraft and probably not aluminum either" just doesn't fly. So to speak.

Would I have liked to get a 70K aluminum instead of a 45K aluminum? You bet! But it wasn't cost-effective. Anyhow, if I could have my pick for material at the same cost as 6061, I'd have built it out of titanium.

Evan
02-14-2008, 09:31 PM
Tens of thousands of aircraft have been built with 6061-T6... It is the most common aluminum used in light planes, whether experimental or cookie-cutter factory production, and there are more light planes in the US alone than all other aircraft in the world combined.

Total nonsense. I worked on aircraft from the smallest such as my Cessna 140 up to and including C130 transports, helicopters and jet aircraft. I was trained by the US military in airframe repair. I don't recall ever using 6061 to repair any aircraft structure, not even once.

CaptainEqs
02-14-2008, 10:10 PM
Total nonsense. I worked on aircraft from the smallest such as my Cessna 140 up to and including C130 transports, helicopters and jet aircraft. I was trained by the US military in airframe repair. I don't recall ever using 6061 to repair any aircraft structure, not even once.

If you say so.

IIRC, Cessna specified that if I metalized the wings on my 1947 Cessna 140, the approved material was 6061-T6, matching the wing ribs.

Likewise, the tail feathers on the wrecked 150 and the wing on the groundlooped L-19 that I bought at Oshkosh and rebuilt. My Ercoupe was monocoque built with 6061, as were the aluminum parts of the Bellanca Cruisemaster, Taylorcraft and most of the Navion that I was part owner of. The Mooney Mite and AeroCommander Shrike Commander that I sold in 1990. The Bensen Gyrocopter plans that I never used specified 6061-T6 throughout, and there were a few thousand of those (and their offspring) built. The SeaBee that I rebuilt, and the floats on my Super Cub.

Most of the small metal homebuilts of the 1950s through 1980s used 6061-T6, such as my Thorpe T-18 and the BD-4. The metalized control surfaces mod on the F4U called for 6061, as were at least some parts of the P-38 (but I guess Kelly Johnson didn't know anything about airplanes or aluminum), because I bought a bunch of it from Lockheed in 1978, some of which had been formed back in WWII and still had the spec markings. My Reno racer was largely built from P38 metal (though it didn't seem to help it go any faster).

When I prototyped the Songbird, I used 6061-T6 and -T6511 because it was readily available, relatively inexpensive, and I didn't need 70,000-lb rated alloy. This is probably why Cessna used so much of the same stuff. And Piper. And Mooney. And tens of thousands of homebuilders.

But then, we didn't have you to ask.



These are just the ones which I've owned or worked on, but they pretty much answer the question, at least as far as I'm concerned.

I've been using 6061-T6 on aircraft since the 1960s.

smiller6912
02-14-2008, 10:16 PM
Tens of thousands of aircraft have been built with 6061-T6. I didn't just pull the spec out of a hat. It is the most common aluminum used in light planes


Please sight references. As your first post seamed to indicate that you have a superior knowledge of airframe structure this should be simple enough. I need to see the specifications for the use of 6061 in commercial and military airframes, as suggested in the original thread discussions.

CaptainEqs
02-14-2008, 10:50 PM
Please sight references. As your first post seamed to indicate that you have a superior knowledge of airframe structure this should be simple enough. I need to see the specifications for the use of 6061 in commercial and military airframes, as suggested in the original thread discussions.

Actually, the original contention was that "anybody referring to 6061-T6 as aircraft aluminum doesn't know much about aircraft and probably not aluminum either."

All I need to do to refute that is to note that I have owned, repaired and built a number of planes, most of which had 6061, and designed and built my own plane, again using 6061.

Then I can just suggest that you check with Cessna, who have been building planes using 6061-T6 for over 50 years. Do a search on "Cessna" and "6061" and you will find references to the guys in Canada who "cloned" the 182, and discovered that the 2024 that they used instead of the original 6061 was LESS durable -- it didn't have the elasticity needed.

You can also check the aircraft material supply houses, such as Aircraft Spruce and Specialty, Wicks, etc. -- not only will you find 6061 by the truckload, you will also find replacement parts for Cessnas, Beechcraft, Pipers, etc made from 6061 and carrying factory part numbers (which they couldn't do if they used different materials).

Evan
02-15-2008, 01:12 AM
You can also check the aircraft material supply houses, such as Aircraft Spruce and Specialty, Wicks, etc. -- not only will you find 6061 by the truckload, you will also find replacement parts for Cessnas, Beechcraft, Pipers, etc made from 6061 and carrying factory part numbers (which they couldn't do if they used different materials).
Still utter nonsense. No place I ever worked even stocked any 6061 let alone used it. 2024 t3 alclad aluminum is the standard. It must be alclad to prevent corrosion. No designer in his right mind would use a material 30% weaker when the correct material is just as readily available. Using 6061 would necessitate making the airframe about 30% heavier. That then imposes a further strength penalty which requires making it heavier yet.


The (Cessna)180 and 185 are very similar in appearance, but the 185 has a larger dorsal fin attached to its vertical surface (although some 180s were produced with the larger fins and others have been modified to its specifications). Both aircraft are constructed of 2024-T3 Alcad aluminum using a semi-monocoque design with rivet fasteners.

http://www.bush-planes.com/Cessna-180-185.html
Of course, all other models are also constructed of 2024.

From the Kaiser Aluminum Sheet and Plate Handbook:

http://vts.bc.ca/pics3/kasp.jpg

http://vts.bc.ca/pics3/kasp2.jpg


You have managed to give ironclad proof of the verity of my previous statement. Either that or you are simply trolling.

CaptainEqs
02-15-2008, 02:37 AM
Still utter nonsense. No place I ever worked even stocked any 6061 let alone used it.

Then you didn't work too many places, did you?



From the Kaiser Aluminum Sheet and Plate Handbook:


You mean "Sheet and Plate Product Information" -- that 1953 museum piece is certainly a valid reference in 2008. Or do you have the "recent" version (1978)?

It might surprise you to know that the Kaiser Aluminum website's "Aerospace and High Strength" pages, list 6xxx-series alloys as "Kaiser Aluminum Hi-Form Aircraft Sheet Product," which are "Best for difficult forming applications."

They go on to note that "Kaiser Aluminum offers tube products tailored for the aerospace and high-strength market. Tube can be created from the following alloy selections: 2024, 7075, 7050, 7068, 6061."

I guess Kaiser "doesn't know much about aircraft and probably not aluminum either."

Okay, let's see what NASA has to say about 6061:

In the NASA Small Self-Contained Payload Program, Package G-056 (GAMCIT Gamma-ray detection) used a ring made of 6061-T6 to hold the optical quartz window in place, through which the the experiment camera watched the package. 6061 was also used for portions of the package structure. GAMCIT flew on Endeavor in 1996. See http://www.its.caltech.edu/~gas/reportfinal.html for more information.

I'll wait while you look in your "Sheet and Plate" book to see which alloy it recommends for "orbiting spacecraft payload package" -- because "No designer in his right mind would use a material 30% weaker when the correct material is just as readily available."

I also want to be there when you tell the "Caltech faculty and staff, JPL scientists and engineers, Caltech alumni, and even an astronaut," what idiots they must have been to use 6061.

But then, NASA must not be in their right minds anyhow, because 6061 has been on every Table of Flight Hardware Materials from 1958 (the first edition) through the current edition, in which it is rated for use in (among others) the Structural, Radiator, Impact Protective, Pressure Component, Milled Component/Assembly and Milled Pressurized Actuator/Valve categories. The only ones it's not rated for are those requiring titanium, rubber, glass, non-conductivity, 100% non-flammability or controlled ablation. Several of the Moonbuggy design teams are using 6061 extensively in their offerings.

So, maybe your collector's-item stone tablets don't say much about 6061 in aviation and aerospace, but the people who are doing aviation and aerospace seem to find plenty of uses for the stuff. Go look, all of these references are online.

So, who is trolling whom . . ?

Evan
02-15-2008, 06:17 AM
that 1953 museum piece is certainly a valid reference in 2008. Or do you have the "recent" version (1978)?
My Cessna 140 was built in 1947. The Cessna 150 a few years later. The specification and the uses of the alloys in question haven't changed.


In the NASA Small Self-Contained Payload Program, Package G-056 (GAMCIT Gamma-ray detection) used a ring made of 6061-T6 to hold the optical quartz window in place
So what? Not relevant to the discussion or the contention made. The large format camera mounts I built for the British Columbia government high altitude survey are made from 2024 t3. Also not relevant.


They go on to note that "Kaiser Aluminum offers tube products tailored for the aerospace and high-strength market. Tube can be created from the following alloy selections: 2024, 7075, 7050, 7068, 6061."
I can make tubing from pasta too. Again so what? The high-strength market is a reference to tractor trailers and related applications.


...in which it is rated for use in (among others) the Structural, Radiator, Impact Protective, Pressure Component, Milled Component/Assembly and Milled Pressurized Actuator/Valve categories.
What does that have to do with "...Cessna, who have been building planes using 6061-T6 for over 50 years"?

Stainless steels are also rated for the listed applications. That doesn't prove it's used to build aircraft structures.

You aren't going to find a reference that shows the general use of 6000 series alloys in aircraft construction since it has not been and is not used for that. The primary preferred attribute of the 6000 series alloys that distinguishes it from the 2000 series is weldability. Aircraft aluminum structural elements aren't welded as it destroys the heat treat properties of the alloy, among other reasons.

As to the age of the reference material I provided it is contemporary with the aircraft designs in question.

[edit to add]


It might surprise you to know that the Kaiser Aluminum website's "Aerospace and High Strength" pages, list 6xxx-series alloys as "Kaiser Aluminum Hi-Form Aircraft Sheet Product," which are "Best for difficult forming applications."
That is/was for non structural applications such as deep compound curved sections like wheel pants for fixed gear aircraft. These applications are now almost entirely made from composite materials. Incidentally, the reason for using 6061 or alloys other than 2024 alclad in that sort of deep die forming is because the alclad layer on 2024 would be compromised by the forming operation. There are very few if any such applications on most aluminum aircraft.

CaptainEqs
02-15-2008, 11:00 AM
My Cessna 140 was built in 1947. The Cessna 150 a few years later. The specification and the uses of the alloys in question haven't changed.

True. I'm just trying to figure out where you got the idea that one short paragraph in a specifications book covers all uses of 6061 -- especially when the people who WROTE the book list 6061 as an aircraft aluminum.



So what? Not relevant to the discussion or the contention made. The large format camera mounts I built for the British Columbia government high altitude survey are made from 2024 t3. Also not relevant.


I can make tubing from pasta too. Again so what? The high-strength market is a reference to tractor trailers and related applications.

The aircraft market is a reference to AIRCRAFT and related applications.



What does that have to do with "...Cessna, who have been building planes using 6061-T6 for over 50 years"?

Planes and aircraft are so closely related that even YOU should see the connection.



Stainless steels are also rated for the listed applications. That doesn't prove it's used to build aircraft structures.

I didn't see your absurd statement that stainless steel isn't used for aircraft, just your absurd statement that aluminum isn't.



You aren't going to find a reference that shows the general use of 6000 series alloys in aircraft construction since it has not been and is not used for that.

I've already proven you wrong on this one. You are getting a little obsessive about this, aren't you? Admit that you were wrong.



The primary preferred attribute of the 6000 series alloys that distinguishes it from the 2000 series is weldability. Aircraft aluminum structural elements aren't welded as it destroys the heat treat properties of the alloy, among other reasons.


Gee, I would have thought that an end-all expert such as yourself would know that you can RE-treat parts which have been welded.

However, the PRIMARY reason that 6061 is used so much in aviation is COST. That's the same reason that you're not driving a Rolls-Royce or living in a house that covers an acre. When a 45K alloy will do the job, using a 70K alloy is a waste of money. Airplane companies hate to waste money.



As to the age of the reference material I provided it is contemporary with the aircraft designs in question.

Hmmmm . . . .you said "anybody referring to 6061-T6 as aircraft aluminum doesn't know much about aircraft and probably not aluminum either."

I don't see a list of aircraft designs in that statement. Perhaps it was in disappearing ink?



That is/was for non structural applications such as deep compound curved sections like wheel pants for fixed gear aircraft. These applications are now almost entirely made from composite materials. Incidentally, the reason for using 6061 or alloys other than 2024 alclad in that sort of deep die forming is because the alclad layer on 2024 would be compromised by the forming operation. There are very few if any such applications on most aluminum aircraft.

"Very few if any" . . ? Even "very few" makes a lie of your absurd statements.

Evan, I'm obviously wasting my time trying to get you to admit that you were wrong when you claimed that "anybody referring to 6061-T6 as aircraft aluminum doesn't know much about aircraft and probably not aluminum either."

I have shown you that Kaiser -- the people you are quoting for "proof" -- DISAGREE with you. But you want us to believe that you know more about metal than they do.

I have shown you that NASA DISAGREES with you. But you want us to believe that you know more about aerospace than they do.

I have shown you that Caltech DISAGREES with you.

I have shown you that the people who sell Cessna parts DISAGREE with you. But you want us to believe that you know more about Cessnas than they do.

I have no way to show you the parts which I've bought for Cessnas which were marked "6061," but those parts and I DISAGREE with you.

Likewise, I have no way to show you the P38 parts which were marked "6061." The P38 predates your book, and Kelly Johnson DISAGREED with you. But you want us to believe that you know more about aircraft and METALS USED IN AIRCRAFT than the guy who built the P-38, the U-2/TR-1 and the SR-71.

Gee, I'll bet that if you had a 1953 book on titanium, it wouldn't say anything about aircraft being built from it, so I guess all of those -71s don't exist. Not to mention the F-117s, F-15, F-16, F-22 and all of the other aircraft which make extensive use of titanium for structure and surfaces.

You are welcome to ignore all of that real-world proof, to continue ducking and weaving to avoid having to admit that you were wrong, but you look really stupid when you take one small paragraph from one 55-year-old book as all-inclusive of every use EVEN AT THE TIME, much less in the decades since then.

I can show you a book from IBM which is merely 30 years old, which has an even longer list of things that computers are used for. It doesn't mention "calculating weight and balance of aircraft," but this was being done long before the book was written -- with the very same model of computer that the book used as an example for that description!

. . .nor does it say anything about using computers for communications, though the computer that the book came from was the Caltech ARPANET server for several years. ARPANET was the communications system which evolved into the Internet.

You're making the same mistake that cultists do when they claim that the Bible is word-for-work perfect, inerrant and complete -- but can't show me anywhere in the Bible where that claim is made -- so they use it to "prove" things that God never intended it to mean. You have "seized on jots and tittles," and rank your brain lower than your pride.

If I had realized that this was a religious issue for you, I wouldn't have tried to help you understand the truth.

Maybe if you close your eyes, plug your ears and hum REAL LOUD, you can avoid having to learn about anything which has happened in aviation in the 55 years since your book was published.

Now, I will continue on my way, leaving you to claim the victory in the same way as does a Chihuahua when a Great Dane walks past its yard. The people sitting on the porch watching us knows what really happened, and are amused by your barking and strutting.

Ken_Shea
02-15-2008, 11:42 AM
Putting aside Evans opinion for a moment, since he is wrong anyway, lets just put a logical positional twist to this.

What would be the chances of an Aircraft manufacturer ignoring the use of an Aluminum alloy that is known to be the most versatile and least expensive of all the heat treatable aluminum alloys ???

I say, not much ;)

CaptainEqs
02-15-2008, 12:53 PM
Putting aside Evans opinion for a moment, since he is wrong anyway, lets just put a logical positional twist to this.

What would be the chances of an Aircraft manufacturer ignoring the use of an Aluminum alloy that is known to be the most versatile and least expensive of all the heat treatable aluminum alloys ???


According to Evan, about 100% -- which makes it about 100% probable that Evan doesn't know as much as he wants you to think that he knows.

JCHannum
02-15-2008, 01:19 PM
CaptainEqs, welcome to the forum. It looks like you will fit in here.

I, for one, would be more than interested in seeing some of your work and hearing of your experiences with the aircraft you have built.

One bit of warning though, citing publications and information from manufacturers in a discussion with Evan is misguided. These are merely opinion and carry no weight if they are counter to his Experience. Evan's Experience trumps anything you foolishly believe to be factual. You will come to accept this after a while and your life will become much simpler.

Ken_Shea
02-15-2008, 01:38 PM
Evan does seem to exhibit a small stubborn streak from time to time :D
I thought he was Irish at first :D

Don't think for one minute though that he is not one extremely knowledgeable individual in many areas.

Ken_Shea
02-15-2008, 01:41 PM
Quote from JCHannum
I, for one, would be more than interested in seeing some of your work and hearing of your experiences with the aircraft you have built.


Me too !

Evan
02-15-2008, 01:44 PM
Evan, I'm obviously wasting my time trying to get you to admit that you were wrong when you claimed that "anybody referring to 6061-T6 as aircraft aluminum doesn't know much about aircraft and probably not aluminum either."

I have shown you that Kaiser -- the people you are quoting for "proof" -- DISAGREE with you. But you want us to believe that you know more about metal than they do.

I have shown you that NASA DISAGREES with you. But you want us to believe that you know more about aerospace than they do.

I have shown you that Caltech DISAGREES with you.

No, you haven't, not even close. You have shown that 6061 is approved for flight. Apparently you don't know what that means.

Kaiser agrees with me. The Sheet and Plate handbook is still perfectly valid even though what we are talking about is aircraft designed when the book was printed.


What would be the chances of an Aircraft manufacturer ignoring the use of an Aluminum alloy that is known to be the most versatile and least expensive of all the heat treatable aluminum alloys ???
The simple fact that there are better alloys. Alloys with better strength to weight ratios.

Here are some facts:




http://www.tpub.com/air/1-24.htm

Greater strength is obtainable in the heat-treatable alloys. They are often used in aircraft in preference tothe nonheat-treatable alloys.


Heat-treatable alloys commonly used in aircraft construction (in order ofincreasing strength) are 6061, 6062, 6063, 2017, 2024, 2014,7075, and 7178.


Alloys 6061, 6062, and 6063 are sometimes used for oxygen and hydraulic lines and in some applications as extrusions and sheet metal.

(My note: Anodized trim strips, instrument panels, luggage bins and similar are examples. The uses of 6061 in sheet metal form are generally limited to non-structural applications due to the relatively low strength. It is used for formability. )


Alloy 2017 is used for rivets, stressed-skin covering, and other structural members.


Alloy 2024 is used for airfoil covering and fittings. It may be used wherever 2017 is specified, since it is stronger.

Alloy 2014 is used for extruded shapes and forgings. This alloy is similar to 2017 and 2024 in that it contains a high percentage of copper. It is used where more strength is required than that obtainable from 2017 or 2024.


Alloy 7178 is used where highest strength is necessary, Alloy 7178 contains a small amount of chromium as a stabilizing agent, as does alloy 7075.

So, not only do you not want to admit you are wrong about the use of 6061 in aircraft, it is obvious that my statement you take issue with is so far perfectly accurate.

More to the point, if you had ever worked with 2024 alloys you would realize why 6061 isn't used in structural components. It's like cheese compared to 2024.

CaptainEqs
02-15-2008, 02:31 PM
More to the point, if you had ever worked with 2024 alloys you would realize why 6061 isn't used in structural components. It's like cheese compared to 2024.

Evan, you have obviously never had to work within a budget, or you would realize why 6061 is EXTENSIVELY used in structural components.

I'm through arguing with you. You have proven to have NO CLUE what you are talking about in this matter, and I'm not interested in seeing all the hairs you can split in the vain (pick your definition) attempt to prove yourself right.

CaptainEqs
02-15-2008, 02:50 PM
CaptainEqs, welcome to the forum. It looks like you will fit in here.

I, for one, would be more than interested in seeing some of your work and hearing of your experiences with the aircraft you have built.


I don't know how much I can tell you. A lot of what I've done really isn't all that interesting. Most experimental aviation is unremarkable (that's the way we LIKE it!) . . .but to give you a little info on my background, I grew up in a flying family. Where most people had cars or household stuff in the garage, we usually had an airplane in various stages of upgrade or rebuild. This is a tradition that I have carried on.

My Songbird is a playtoy -- my single-seat Happy Wings -- but my own garages (and yards) have, since the 1970s, been home to MiGs, racing planes, remnants from a dozen wrecks, a few homebuilt planes and warbirds from an L-3 to half of a P-38 and 3/4 of an F4U Corsair. The U-Bird restoration had to be moved to the airport (you can believe we got LOOKS), then after a hundred or so hours I sold it -- it was fun to fly, but EXPENSIVE!!!!!!!!!!!!!! (Hmmm . . .that may not be enough "!"s).

I worked in aerospace for a while, and still get dragged in off and on. Some of my stuff is still out there, where no man has gone before (Go Beavers!).

During that process, I have used truckloads of various alloys, much of which was the 6061 that Evan has Officially Proclaimed Unfit for Aircraft.



One bit of warning though, citing publications and information from manufacturers in a discussion with Evan is misguided. These are merely opinion and carry no weight if they are counter to his Experience. Evan's Experience trumps anything you foolishly believe to be factual. You will come to accept this after a while and your life will become much simpler.

I had discovered the problem. Actually, I find it fun to loudly proclaim that the Emperor has no clothes (and not much to hide), but it gets time-consuming. "Never try to teach a pig to sing -- it wastes your time and it annoys the pig."

Speaking of time, I have to be wheels-up in about two hours, so I'll talk to you folks another time. You're fun, but I have a lovely lady waiting for our Valentine's Day dinner, and I'm not getting any closer to her with the keyboard in my lap.

CaptainEqs
02-15-2008, 02:53 PM
Evan does seem to exhibit a small stubborn streak from time to time :D
I thought he was Irish at first :D

Don't think for one minute though that he is not one extremely knowledgeable individual in many areas.

He may be, but what I've seen so far doesn't impress me. Not FAVORABLY, anyhow. He's the kind of guy who builds bridges that fall down, rather than admit that there really WAS a mistake on Sheet 94.

He reminds me of my ex-wife.

Evan
02-15-2008, 05:50 PM
Mr. Eqs

You can go on as long as you want proclaiming how 6061 is the prefered alloy of aircraft construction but it won't make it so. Don't ask me to fly in anything that you have had a hand in. When it comes to designing aircraft (other than experimental class homebuilts) budget is not the first consideration.

Try to find me just one quote that specifically says that the airframe and skin of a commercially produced aircraft were constructed of 6061 alloy.

I have no problem finding all the references I want specifically saying that 2024 alloy is used.

For example:



Generally DC-10 uses 2024-T3 aluminum for tension structure such as lower wing skins, pressure critical fuselage skins and minimum gage applications. This material has excellent fatigue strength, fracture toughness and notch sensitivity. 7075-T6 aluminum has the highest strength with acceptable toughness. It is used for strength critical structures such as fuselage floor beams, stabilizers and spar caps in control surfaces. It is also used for upper wing skins.
http://adg.stanford.edu/aa241/structures/structuraldesign.html

and,



Also, according to Mayo, For safety and performances sake we made selected improvements. Alclad 2024-T3 aluminum was used throughout instead of the Dural of the 1930s because the modern alloy is 20 percent stronger.

http://www.mayocraft.com/projects.html

And a wooden aircraft except for the use of 2024 aluminum:



All leading edges are made from 0.020 gauge 2024-T3 sheet aluminum that extends back to the main spars. Ailerons are Frise type and are installed on all four panels. Construction is similar to that of the wings except have leading and trailing edge spars.

http://www.steenaero.com/articles_detail.cfm?ArticleID=4

A Ryan ST-R restoration




He spent about a year making formers, ribs and other parts out of 2024-0 aluminum, then began searching for a shop where he could get them heat treated.

http://www.sportsmanpilot.com/AL/articles/sum2000/Summer2000.htm

Then there is this quote from Department of Mechanical Engineering, College of Engineering , Witchita.



This work was funded by the State of Kansas and the Federal Aviation Administration to investigate the applicability of friction stir welding (FSW) for aerospace structures. Two of the most common aerospace aluminum alloys, 2024 and 7075, were investigated. ...
http://webs.wichita.edu/depttools/depttoolsmemberfiles/gradschool/Abstract_book_final0706.pdf

I have to go to town. Later.

boslab
02-15-2008, 06:29 PM
okay, theres no such thing as aircraft ali, there is however ali that has been approved for aircraft use via its QA process, you can pritty much use any alloy you like provided that tracability an manufacturing integrity is provable.
from memory 6061 t, tf or whatever temper asr aluminium silicon magnesium alloys suitable for hot forming by extrusion for example.
Extrusion billots are round to fit the cannisters of the extrusion press [direct pushes the tool onto the ali, indirect shoves the ali through the tool]
extrusion or round billot are vertically continuously cast normally 12 at a time via lauders [refractory troughs] the casting pit is usualy 4000/5000mm deep.
after casting they get homogonised in a furnace and water quenched.
square billot is fo rolling, both are suitable for forging if required.
some alloys are not recomended for certain apps due to fatigue/creep etc
the British Standard is bs 1474 so you can find the appropriate iso or whatever
billots=regular section w=d or a diameter normally up to 10"
slabs = irregular ie rectangular
theres also blooms and slooms but dont worry
also kaiser and reynolds made some of the best billot iv ever used
mark
slab

darryl
02-15-2008, 07:53 PM
Well, I haven't heard of a sloom, but no matter. The way I understood it is that unless the application is specified up front, the molten metal is poured into molds and called ingots. If there's a specific destination for the metal, and it needs to be a certain size and shape to fit the processing machine, the cast metal is called billets. There may be a stage in there somewhere where alloying elements are added, maybe before the first pour, but I don't know enough about all that to make sense of it all. I can see that if an ingot is workable at some factory as poured, they would be buying ingots from the foundry and not billets, unless of course the foundry has to process an ingot of metal to prepare a certain alloy- this is just what I have understood it all to mean.

For me to buy some part that has been machined from billet would probably mean that the part is quite large and is not more economical to make by re-melting either an ingot or a billet. For the most part, extruded and rolled products would satisfy the material needs of manufacturers who produce those parts that are commonly called billet. What can those parts be- say a bracket for the front of an engine to hold the alternator, power steering pump, some other things- that part is going to be produced from possibly 4inch thick sheet or something, if not cast. The metal may have been in billet form previously, but it lost that designation as soon as it passed the first stage in the rolling or forming process.

I said it before- billet as the guy off the street calls it is bill-it- to the customer. They should be calling it 'stick-it' :)

The other issue I would like to have some answers to is this one of 'aircraft alloy'. I've never heard of this material called 'aircraft' :rolleyes:I don't want to stir up the pot, but my question about it is in another vein- what are the actual legal requirements when it comes to selecting the alloy for an aircraft? I'm talking about the structure here, not the bushings and knobs. I can imagine that certain aircraft would fail the inspection process if it was discovered that, for instance, 6061 had been used instead of 2024. When you think of the requirements for bolts and fasteners, and then see some of the scandals surrounding sub-standard parts, you would wonder where else a minimum specification would have to be met, whether it's the covering for seat cushions or wing spars.

I don't know, but I would think that any military craft would be rejected if 6061 was found in the structure where 2024 was spec'd, and I honestly can't see the weaker alloy being spec'd where a stronger one was available, and actually designed around. Probably the same goes for commercial aircraft, but I can imagine it getting pretty complicated to define what part can be made of what, or must be made of what-. There must be some regulations in regard to what structural material a manufacturer is allowed to use- this should help to settle this contoversy. What are the actual rules- government, faa, etc?

CaptainEqs
02-16-2008, 10:12 AM
I don't know, but I would think that any military craft would be rejected if 6061 was found in the structure where 2024 was spec'd,


Well, of course!



and I honestly can't see the weaker alloy being spec'd where a stronger one was available, and actually designed around.

Think about it. Each alloy has specific characteristics. It is far easier to make compound curves with 6061 than with 2024.

More important is the fact that 2024 is significantly more expensive than 6061, and if 6061 will work, using 2024 is a waste of money. That's not what a company is in business to do -- every penny wasted is a penny that would have gone to something more important, and too many wasted pennies will mean pricing yourself out of the order.

Do you buy a brand new car every year? Do you drive a Mazda RX-8? Do you live in a mansion on 50 acres of parkland? Probably not -- even though those things are more desirable than driving your same Chevy for 8 years and living in a condo, they just are not COST-EFFECTIVE for most people.

Same for using 2024 where 6061 is good enough.



Probably the same goes for commercial aircraft, but I can imagine it getting pretty complicated to define what part can be made of what, or must be made of what-. There must be some regulations in regard to what structural material a manufacturer is allowed to use- this should help to settle this contoversy. What are the actual rules- government, faa, etc?

The FAA doesn't specify materials, just construction and maintenance methods. Generally, this is the same for the military and commercial markets. They just want an airplane that won't fall out of the sky. I will note that, as designer, builder and pilot of my own plane, I'm kind of interested in the same thing. And in 2500+ hours TTAF, I haven't had a single problem with the 6061 that I used -- and I got to spend a couple of thousand dollars on other things, instead of giving that money to the metal supplier.

Materials are specified by the designer, who is constrained only by his imagination, the realm of physics, and the budget (not necessarily in that order, and not always).

I once heard a song about a designer who sets out to spec a part to give the production shop a nervous breakdown: ". . .brass is too easy to machine, I feel / so I'll have them make it from TUNGSTEN STEEL!" The FAA would have no complaint about this, unless the part failed in flight and caused a reportable incident. The military or commercial buyer wouldn't even notice unless it boosted the price of the end product by an appreciable amount.

A.K. Boomer
02-16-2008, 11:25 AM
Im with you on that "Cappin" (quite the log book)

Like I stated in my original post --- It sticks in my craw a little when I hear people say that 6061 is "garden variety" aluminum, Its not, for one garden variety doesnt even take a heat treat, So be it T-6 or T-9 its testimonial to the fact that the stuff is much more versitile than the simple soft putty that you cant do anything with,
For years all aluminum bike frames worth a damn were 6061, Yes now we have better, but Iv seen enough of 200lb. guys going over brutal terrain for year after year in racing applications to have a great deal of respect for just how well .030" 6061 aluminum tubing can hold up,


That being said --- I know my bike eventually has its days numbered --- and I wish it was the newer 7,000 series although it would only postpone the inevitable --- but its also why my bike cost $850.00 instead of $1300.00

It's enough of a diff. between being able to ride with a bike thats made of 6061 or dreaming of a 7,000 series frame while sitting on the couch, That price difference was the next model up in the manufacturers line-up, Its not just the extra money that the frame and fork material costs, its all the other gadgets and componentry of the next higher end model...


6061 is more prone to stress cracks, (esp. the higher the T rating) but generally it takes many many cycles before this happens ------- Iv always ridden Cro-mo, I was leery of aluminum at first but my bikes now a 2003, and at least I can afford to find out how far she goes before I crack her, they all will crack -- its just a matter of time ---- but my cro-mo HooKoo-E-Koo (HKII)fisher took 45,000 miles of brutal punishment before the first crack appeared (rear dropout) and less than 5,000 more miles before the second.... Ohh and uhh, we are talking MT. bikes here, big diff...

Willy
02-16-2008, 11:30 AM
I'm not disputing the fact that 6061 T-6 is not a viable and cost effective alloy for aircraft use, but everything I have read seems to indicate that for most commercial applications it is not the material of choice.

I will admit that I personally have no direct involvement in the industry but do have several close friends that are, and all agree that 2024 T-3, T-4 alclad is much more prevalent in the industry than 6061 T-6.

Have a look at this link and please explain why you believe 6061 is still the alloy of choice.

http://www.key-to-metals.com/Article96.htm

Signed: confused

CaptainEqs
02-16-2008, 10:13 PM
Have a look at this link and please explain why you believe 6061 is still the alloy of choice.

http://www.key-to-metals.com/Article96.htm

Signed: confused

I believe that 6061-T6 is the alloy of choice because a lot of us who have designed, built and repaired airplanes chose 6061-T6.

That includes my mentor, Kelly Johnson, who probably knew more about aerospace metallurgy -- from directly working with so many different alloys -- than any other man who ever lived. Several alloys only exist because Kelly said "'Xa' doesn't work, but it's close. 'Xb' doesn't work, but it's close. Can you make me something that's halfway between 'Xa' and 'Xb'"?

If you spend a few minutes online, you can find references to 6061-T6 used in aircraft from homebuilts to the King Air to the P-38 to the F4U to the Cessna 140 and 150, not to mention satellites and Space Shuttle payload experiment packages.

Evan
02-16-2008, 10:26 PM
I believe that 6061-T6 is the alloy of choice because a lot of us who have designed, built and repaired airplanes chose 6061-T6.
Still spouting this BS? I am not going to waste my time explaining this to you since it is clear you aren't interested and should know better. You are Trolling here. Why else would somebody sign up and pick a post long dead to kick to the top in order to pick a fight with a ridiculous assertion that is obvious invalid while using as an excuse something posted by an established member of the forum?

That is probably the best example of trolling I have yet seen. I shall remember to use it as an example if the subject comes up again.

For the regular members of the forum, I would be happy to explain what the difference is between an experimental aircraft of the homebuilt variety and a commercially produced aircraft covered under the strict inspections and regulations of an FAA STC, Standard Type Certificate. However, right now I am going to finish my supper and retire to the shop.


Please, do not feed the troll. (of which I am also guilty).

[added]

Note also that so far Mr. Troll has not yet provided a single shred of evidence that 6061 is used as a structural alloy in commercially built aircraft under an STC.

CaptainEqs
02-17-2008, 12:27 AM
Still spouting this BS?


Oh, no, Evan, "spouting BS" is clearly YOUR role.

CaptainEqs
02-17-2008, 03:44 AM
Note also that so far Mr. Troll has not yet provided a single shred of evidence that 6061 is used as a structural alloy in commercially built aircraft under an STC.

Wow, you've certainly gotten specific, after your original global "anybody referring to 6061-T6 as aircraft aluminum doesn't know much about aircraft and probably not aluminum either" brainbarf.

And you mean Type Certificate, dummy. An STC is a SUPPLEMENTAL Type Certificate, issued when a Type Certified aircraft is being modified or operated outside of its Type Certificate. For instance, when Cessna sent out the specification that 6061-T6 was to be used when metalizing the wings of 120s and 140s, that was done under an STC.

YHEEEH, I hate it with the ignorant try to prove themselves by slinging jargon and acronyms that they don't understand.

I hereby present that "single shred of evidence" -- ask someone to read you the big words.

http://books.google.com/books?id=-6kznZF10mYC&pg=PA290&lpg=PA290&dq=lockheed+%226061+t6%22&source=web&ots=ReF9fwJ3_9&sig=xiMckZWRnwXaDVs14nkng_ACW-I#PPA290,M1

This is a portion of "Airplane Design, Part III," a book written by Dr Jan Roskam. At the time that this book was published (2002), Roskam had authored 11 books and over 160 papers on the subject of airplane flight dynamics and airplane design, and he taught aircraft design at the University of Kansas, Lawrence, where he is the emeritus Ackers Distinguished Professor of Aerospace Engineering. His bio is at http://en.wikipedia.org/wiki/Jan_Roskam -- and I think we can assume that he knows what he's talking about.

In the page that comes up when you go to that Google URL, note Figure 5.32 -- "Typical Empennage Skin Gages in a Beech King Air F90", where it notes that 6061T4 (.032) is used for the upper tailcone, and 6061T6 (.020) is used for the elevators and elevator trim tabs.

Even YOU have to admit that the King Air is a "commercially built aircraft under a TC" (though, since you like to split hairs, I'm sure that some of them are under STCs, too).

Now, will you PLEASE shut up, Mr Expert, before you embarrass yourself even more? I've shown how your reference book is outdated and anecdotal, while the people who published it list 6061 in the "Aerospace and High Strength" category, on a page titled "Aerospace Aluminum." I have shown how 6061 has been used in the structural fabrication of hardware sent into orbit, and how it is on the NASA Table of Flight Hardware Materials.

Now I have even jumped through your latest hoop, landed on both feet and thumbed my nose at you.

In other words, I have proven that your initial statement was WRONG. Pretend you're a man, take your lumps, and go on with your life.

Evan
02-17-2008, 05:56 AM
Granted that there is a very few parts made of 6061 in that tail section, they aren't structural (controls surfaces are NOT structural, that's why they have the name empennage). They are used for the very reasons I already pointed out, formability. The structural parts of the tail assembly are made from 2024.

You are correct about STC vs TC, but that changes nothing about the ridiculous statements you have made. You did note that the majority of the empennage is made of 2024 didn't you? In fact those trim tabs etc are likely the only parts made of 6061 on the aircraft. That probably adds up to a few pounds in all. Doesn't exactly support your claims, does it?

It also doesn't excuse misleading the members of this board regarding your claim to have designed your own aircraft. I too have doodled up designs for flying kites powered by glorified lawnmower engines. That is what you are talking about isn't it, an ultralight that doesn't even require a pilots license. Did you ever switch that Rotax to a Mazda rotary like you wanted to? You know, the engine that you claim has only three moving parts?

You are guilty as charged of at the very least misleading with hyperbole and more likely outright prevarication. You are what is known as a "poser".


In other words, I have proven that your initial statement was WRONG. Pretend you're a man, take your lumps, and go on with your life.

I would do that if I were wrong and if I were dealing with another man. I am not wrong and you are not as honorable as your self bestowed appellation suggests.

Peter N
02-17-2008, 06:41 AM
CaptainEqs, I have no idea who may be right or wrong here, and neither do I much care.
However I would like to point out that juvenile name calling and general rudeness will not get you far on this forum, and will most certainly lose any respect that your knowledge and experience may gain, particularly when coming from a new member.

I have had disagreements with Evan myself, as have others here, but in general and with very few exceptions this group has always managed to keep disagreements fairly civil.

Peter

CaptainEqs
02-17-2008, 12:15 PM
CaptainEqs, I have no idea who may be right or wrong here, and neither do I much care.
However I would like to point out that juvenile name calling and general rudeness will not get you far on this forum, and will most certainly lose any respect that your knowledge and experience may gain, particularly when coming from a new member.

I have had disagreements with Evan myself, as have others here, but in general and with very few exceptions this group has always managed to keep disagreements fairly civil.

Peter

Peter:
Evan has made sweeping statements -- from the beginning, before I even arrived -- which I have responded to. My first post here was intended as a means of letting him know that such global pronouncements are not accurate.

He has responded by calling me a troll, and implied that I am an idiot and a liar. It has always been my practice, when met by unthinking insult, to return in kind.

He has continued his ducking and weaving, to the accompaniment of more insult, rather than accept any loss of face which would come from admitting his error. He has split the hairs so finely that one needs a microscope to find them, and even now, when I have disproved his ultimate claim, he is trying to find ways to again call me an idiot.

I'm not here to make points or to prove my expertise. I and my employers have been satisfied with that expertise since the late 1970s. One of those employers was an unknown shop in a company that nobody's ever heard of, but that I'm sure will someday make, oh, I dunno, maybe the world's fastest production airplane, or maybe stick a jet engine on a glider and bebop along at 70,000+ feet, where the stall speed is a whole, whopping 8 knots slower than redline. Or build an airplane which has the radar cross-section of a pigeon. Or maybe roll out this country's first operational jet fighter. Inconsequential stuff like that.

His latest attempt to keep from admitting his error is the claim that the elevators on a King Air aren't "structural." This is a unique point of view, not shared by anyone who actually knows anything about aircraft.

Th rest of us (especially those of us who actually design aircraft) know that the control surfaces are "sections of lifting or stabilizing airfoils which can be manipulated to provide varying amounts of lift, for the purposes of increasing, reducing, reversing or canceling the rates of yaw, pitch or roll."

An airfoil is"A fluid interface structure having at least two fluid interface surfaces to provide lift in addition to lift resulting from fluid speed on said fluid interface structure, said fluid interface structure generally including a moving means for incrementing lift" -- in other words, a control surface. Like, say the elevator on a King Air, which is the rear half of the smaller horizontal lifting surface.

We also know that, when calculating wing area of an airfoil, we include integral control surfaces, such as elevators or ailerons.

That means that, even though Our Hero refuses to admit it, the elevators on a King Air are in fact structural.

HSS
02-17-2008, 04:36 PM
I don't know beans from butterflies, but I surely do like making hot chips out of 6061, and I have read all of the posts on this thread and honestly appreciate each and every argument presented. I only wish I was even closely as knowledgable as the respondents. Oh well, best wishes all.

John Stevenson
02-17-2008, 04:53 PM
Why does my 6061 keep flying off the sticky table on the surface grinder ?

.

small.planes
02-17-2008, 05:00 PM
Because your using the wrong sort of glue ;)

Dave

Evan
02-17-2008, 10:06 PM
Peter:
Evan has made sweeping statements -- from the beginning, before I even arrived -- which I have responded to.

Yes you did, with far more sweeping statments that are complete hogwash.

My first post here was intended as a means of letting him know that such global pronouncements are not accurate.

Something you are well practiced at. Just go back and review what YOU have posted. Incidentally, why are you on this forum?

He has responded by calling me a troll, and implied that I am an idiot and a liar. It has always been my practice, when met by unthinking insult, to return in kind.
'
My comments were carefully considered. If you feel them to be insults then perhaps you are somewhat insecure about the truthfulness of YOUR comments.

He has continued his ducking and weaving, to the accompaniment of more insult, rather than accept any loss of face which would come from admitting his error. He has split the hairs so finely that one needs a microscope to find them, and even now, when I have disproved his ultimate claim, he is trying to find ways to again call me an idiot.

Asking for actual evidence that 6061 is "the alloy of choice of the aircraft industry" might place you in an uncomfortable position but it certainly isn't splitting hairs. Those sorts of accusation are a classic technique of the person who no longer has a position that is supportable. You still haven't proven your contentions.

I'm not here to make points or to prove my expertise.

Then why are you here? So far all you have done is question my expertise and display your own ignorance.

I and my employers have been satisfied with that expertise since the late 1970s. One of those employers was an unknown shop in a company that nobody's ever heard of, but that I'm sure will someday make, oh, I dunno, maybe the world's fastest production airplane, or maybe stick a jet engine on a glider and bebop along at 70,000+ feet, where the stall speed is a whole, whopping 8 knots slower than redline. Or build an airplane which has the radar cross-section of a pigeon. Or maybe roll out this country's first operational jet fighter. Inconsequential stuff like that.

Nope, no bragging. Now you want us to believe you work at the Skunk Works. :rolleyes:

His latest attempt to keep from admitting his error is the claim that the elevators on a King Air aren't "structural." This is a unique point of view, not shared by anyone who actually knows anything about aircraft.

Other than those who invented it, the French. That's why the tail control surfaces are called empennage, which translates to "arrow feathers". A structural component contributes strength to and ties together a structure. A control surface is flapping in the breeze on a hinge. While very important, it isn't a structural member.

Th rest of us (especially those of us who actually design aircraft) know that the control surfaces are "sections of lifting or stabilizing airfoils which can be manipulated to provide varying amounts of lift, for the purposes of increasing, reducing, reversing or canceling the rates of yaw, pitch or roll."

Once again you are implying that you are an aircraft designer. What designs do you have to your credit and where did you obtain your degree in aeronautical engineering?

An airfoil is"A fluid interface structure having at least two fluid interface surfaces to provide lift in addition to lift resulting from fluid speed on said fluid interface structure, said fluid interface structure generally including a moving means for incrementing lift" -- in other words, a control surface. Like, say the elevator on a King Air, which is the rear half of the smaller horizontal lifting surface.

Not relevant to anything being discussed.

We also know that, when calculating wing area of an airfoil, we include integral control surfaces, such as elevators or ailerons.

Still not relevant.


That means that, even though Our Hero refuses to admit it, the elevators on a King Air are in fact structural.

Sorry, no cigar. See above about what is and isn't a structural part.

JRouche
02-17-2008, 11:16 PM
Th rest of us (especially those of us who actually design aircraft)

Very cool Evan. I didnt know you had designed an aircraft... You really have some skills. Glad to have you here..

It always amazes me to see all the great wealth of knowledge we have here in this group. So many hidden professionals willing to spend time here helping out.... Great folks!!!!

What aircraft did you design?? Did you take it from the floor on up? I would like to see your design, hope it doesnt resemble a CNC mill.. J/K (cause that is a great design)..

Im sure its a great accomplishment. Were you working for a company when you laid it out. Whats the designation.. Any pics. Thats something to be proud of. I dont know of any aircraft designers.. JRouche

A.K. Boomer
02-18-2008, 01:25 AM
He has continued his ducking and weaving, to the accompaniment of more insult, rather than accept any loss of face which would come from admitting his error. .


Cappin, you hit what we call around here "the Evan-evan-van-an-n wall-all-ll"

ducking and weaving is a good description :p

Evan is missing some major links in aviation, but he by far makes up for it in many other topics,

For instance --- he thinks an airspeed indicator is actually true air speed, big No-No, but the guy can build a CNC mill from the ground up --- nuthin to sneeze at...

He thinks that the airspeed indicator (Or what I properly call a resistance indicator) will fly a plane for how a plane is needed to fly --- he's kinda right --- Till you have to take off or land it:D

Bottom line, a man with a brain almost twice the size of any of us --- but unfortunately -- he's also had a good sized lobotomy.

He's my bud, I also hate em sumtimes, Once in awhile he's fun to pick on --- but I do have to choose my topics, kinda like in "jeperty"

Generally, Evan dont need to choose topics, thats what makes him so damn dangerous :)

I know he hates me too sumtimes:o But He also says he dont hold grudges cuz they "git too heavy"

If you want some advice Cappin, line up all yer ducks in a row and let er rip...

You at least have me interested enough to read --- 6061 has been in the air since the git-go,(since 6061) But - My belief is it is getting faded out, Nobody has really mentioned time frame in this pissing contest ------- That would make all the diff. in the world in either of your arguements.

Evan
02-18-2008, 07:02 AM
Very cool Evan. I didnt know you had designed an aircraft... You really have some skills. Glad to have you here..

It always amazes me to see all the great wealth of knowledge we have here in this group. So many hidden professionals willing to spend time here helping out.... Great folks!!!!

What aircraft did you design?? Did you take it from the floor on up? I would like to see your design, hope it doesnt resemble a CNC mill.. J/K (cause that is a great design)..

Im sure its a great accomplishment. Were you working for a company when you laid it out. Whats the designation.. Any pics. Thats something to be proud of. I dont know of any aircraft designers.. JRouche
What the heck are you talking about? I have made no claims to designing aircraft other than doodling up some sketches of ultralight powered kites. It's the so called captain that is making that claim.

Boomer, Would you please stop repeating that nonsense about airspeed. You don't get it even though it has been explained to you by me and numerous others on this board. Also, don't misquote me. I have never said that indicated airspeed and true airspeed are the same thing.

As for aluminum, this is the claim that I take issue with.



Tens of thousands of aircraft have been built with 6061-T6... It is the most common aluminum used in light planes, whether experimental or cookie-cutter factory production, and there are more light planes in the US alone than all other aircraft in the world combined.
The fact that 6061 is used in aircraft in small amounts in non structural applications does not validate that claim. Nor has any evidence been offered to back this assertion.

Once again so nobody loses focus "It is the most common aluminum used in light planes". No it isn't, not even close.

Say for instance you wanted to buy some 6061 for an aircraft from Alcoa. They list the available products on their website. I have snapped page images of the offerings for aircraft structural components in the fuselage and wings. Note that the fuselage skin is a structural component as the fuselage in most metal aircraft is a stressed skin structure.

http://vts.bc.ca/pics3/alcoa1.jpg

http://vts.bc.ca/pics3/alcoa2.jpg

http://www.alcoa.com/aerospace/en/products/browse.asp?country_id=999&market_id=26&market_cat_id=347


Note that the only 6061 offering is tooling plate. You don't build aircraft out of tooling plate. It's used to make tooling (who would have guessed?). You pay extra to have it ground to an accurate thickness.

The reason that the "captain" hasn't provided any evidence that 6061 is the "most common aluminum alloy used in light planes" is because he can't. By the way, a light plane according to the FAA is any aircraft that weighs less than 12500 lbs.



light plane

light plane (plural light planes)

noun
Definition: U.S. small airplane: an aircraft with a takeoff weight that does not exceed 5,670 kg (12,500 lb), especially a privately operated one.http://encarta.msn.com/dictionary_1861698514/light_plane.html

Ken_Shea
02-18-2008, 08:13 AM
CaptainEqs, However I would like to point out that juvenile name calling and general rudeness will not get you far on this forum, and will most certainly lose any respect that your knowledge and experience may gain, particularly when coming from a new member.

Peter

particularly when coming from a new member

Peter, tell me, how many post, how long, how old, how experienced does one have to be to get to this mostly silent but otherwise obvious positional status to where we are worthy to utter an opinion with out a bowing of the head and having folded hands?

Ooops, maybe I am on the wrong site, this isn't the PM site is it ???








.

kendall
02-18-2008, 09:58 AM
I'm not involved in this, but since you ask, I just think it's odd that he has made 15 posts, and everyone of them has been in this ancient thread.
leads me to think the account was created for the simple purpose of the arguement.

actually think the debate has some interesting facts in it, never realy paid attention to the many varieties of aluminum.

ken

A.K. Boomer
02-18-2008, 10:01 AM
Boomer, Would you please stop repeating that nonsense about airspeed. You don't get it even though it has been explained to you by me and numerous others on this board. Also, don't misquote me. I have never said that indicated airspeed and true airspeed are the same thing.




We may finally be getting somewhere, I purposely threw that in there to separate things for you, You have to realize something Evan, some of your statements are so misleading they need to be dissected to find the truth, Its almost like you intentionally skip around the truth just to be able to argue --- Your starting to come around in this topic --- Only because Iv pinned you down on it and will never let up until its clear,
Youv come along way from post #23 of Higher mileage at higher altitude;

Quote:Boomer,
and its a good thing they can travel faster up thier

Quote; Evan, According to the airspeed indicator they don't.

So What --- Wrong answer
--- The airspeed indicator does not have anything to do with what airspeed is be it "true" Or "indicated" --- its a resistance gauge --- there is no such thing as "stall speed" thats all in your head -- the proper way to look at it is stall resistance. With some jets true airspeed values can be off 5 times the amount according to what's reading on the gauge that your calling an "airspeed indicator"
If you take your thinking one step further you now have the proper working theory's in place on things like how to take off and land planes at high altitude's and such --- Get it right -- for the most part you can get by without picking this apart --- but there are examples where its important to know as to why ---- improper working theory's are like Lying --- if you make a habit of it you will have to have a darn good memory on how to keep your story straight (something I dont recommend for air travel) ---
If you base your information on correct thinking you never have to try and compensate,
You can also be a smart ass to some of the best pilots you know and they will have to listen to you, Or take a severe spanking:)

One more time Ev --- its properly called "stall resistance" not "stall speed"
This is the gauge you use when you come in for a landing, you know -- the one with the buzzer hooked up to it...

Evan
02-18-2008, 10:05 AM
I'm not going to try and explain to you (again) what the device is and how it functions or how it is used. You didn't pay attention the last time so I don't see any point.

CaptainEqs
02-18-2008, 11:11 AM
I'm not involved in this, but since you ask, I just think it's odd that he has made 15 posts, and everyone of them has been in this ancient thread.
leads me to think the account was created for the simple purpose of the arguement.


Close. It was created after I read Evan's absurd comment that "anybody referring to 6061-T6 as aircraft aluminum doesn't know much about aircraft and probably not aluminum either."

Since there have been tens of thousands of aircraft built with 6060 components (and in some cases, complete airframes), I wanted to correct this false impression. I just didn't realize the lengths to which Evan will go to avoid admitting that he was wrong, and how sharp the razor with which he splits hairs.

Every hoop that he's put up, I've been able to go through, while he has desperately scrabbled for enough pieces to build a new hoop. He tries to prove his point with a book published in 1953 (a time when most aircraft then in the air were made with FABRIC and WOOD), then he disputes the very same company which wrote that book when they list 6061 as an "aerospace aluminum" on their website.

He says that I don't "a single shred of evidence that 6061 is used as a structural alloy in commercially built aircraft under an STC" -- a term which he doesn't understand, but offers to explain to everyone -- so when I show that one of the premier aircraft designs in the world uses 6061 for a key structure, he claims that lifting surfaces aren't "structural!"

He then does a Google search to find things that I've said elsewhere, not realizing that my whole life isn't involved with the Internet, and seizes on a few comments in other places (while ignoring numerous other posts and references). Some of those posts may even be mine, but I'm certainly not the only one who pays homage to the original "Captain Eqs." Evan doesn't even know who he was, or he would understand why there are a number of us keeping his nickname alive!

Interestingly, he ridicules "my claim" that the Wankel rotary engine has only three moving parts -- without actually looking up the information that it in fact DOES have only three moving parts (two rotors and an eccentric shaft).

Most amusing is his assertion that all I've designed was an ultralight (or, as he puts it, a "kite powered by [a] glorified lawnmower engine."

Nope. Sorry. I have had ultralights in the past, and may have in the future, but I don't own one right now and that's far from the ONLY kind of plane I've had or built. The plane that I designed isn't an ultralight. I also ride bicycles, but that doesn't mean that I ONLY ride bicycles. After all, Chuck Yeager has owned ultralights since the early 1980s, but that didn't keep him from flying P-51s and jets.

But, gee, now that he's mentioned it, there are another few thousand ultralights out there, and they are nearly ALL built from 6061. They are aircraft. So thanks, Evan, for reminding me about all of those other aircraft which use 6061 for their structure.

Oh, but wait, Evan Hath Spoken, and 6061 isn't an "aircraft aluminum," so I guess that all of those ultralights, the gliders, the gyroplanes, the Light Sport Aircraft, the experimental homebuilts, the P-38, the F4U, the Gooney Bird the Cessna 150 and the King Air just aren't "aircraft."

I'll try to crush my disappointment, and continue to pretend that I'm flying when I look down at the Sierra Nevada range this afternoon, from the cockpit of a plane which has held together much longer and much better than Evan's arguments and attacks.

CaptainEqs
02-18-2008, 11:16 AM
Evan, some of your statements are so misleading they need to be dissected to find the truth, Its almost like you intentionally skip around the truth just to be able to argue


Yes, I've noticed that also.

People here have said that Evan really is an expert in other areas. That may be so, but from what I've seen here, he stretches an inch of expertise into a yard of "I'm right and you're wrong" if anyone dares to disagree with his pronouncements.

To go so far as to Google my USER NAME to try to find grounds to ridicule me is really kind of overboard, especially when he pulls up stuff written by other "Captain Eqs's" to hammer me with.