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oldtiffie
01-24-2008, 02:06 AM
As it seems to be a "slow day" I thought I'd lighten things up a bit and post a couple of pics (one came by email and the other from today's paper) that could have had their origin/concept in a HSM shop.

Very little carbon foot-print or just a lot of wind!

I must say I liked the the thought behind them!!

Any others in a somewhat lighter vein than some recent posts regarding "energy"?

http://i200.photobucket.com/albums/aa294/oldtiffie/Under_sail1.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Biker_and_babe1.jpg

darryl
01-24-2008, 03:17 AM
At first glance it seems like the sail doesn't have enough area to catch that much wind. A fuel savings of up to 35% doesn't seem possible, but who am I to say how much push (or pull) it takes to make a loaded freighter get up to speed. I suppose with the size of the freighter that kite looks too small, but really at 160 sq meters it's only the size of my house. Either A- I'm underestimating the power of the wind, or B- I'm overestimating the fuel consumption of the cargo ship.

Glad to see another manifestation of wind energy again, though.

I like the lil red wagon hauler. Does that cart have the towing package? :)

interiorpainter
01-24-2008, 06:03 AM
Your fuelsavings will rise even further going dead slow.:D
I really like that scooter idea. How about a roof.

Your Old Dog
01-24-2008, 06:36 AM
I like the lil red wagon hauler. Does that cart have the towing package? :)

I have that exact scooter from my Fathers estate. I used it when my ankle was crushed and yes, it seems to have the towing package! I used it to load the garbage into a garden wagon and it was surprisingly powerful :D

I think the sail on the tanker is a hot of huey perpretrated on a willing new media. But that's not to say the tanker industry shouldn't be concerned. Put this pic in a few more newspapers around the world and they'll be on everything that floats.....including turds!

J Tiers
01-24-2008, 09:02 AM
Hooey.......... yep, there has to be a LOT of stuff not mentioned..

Apparently nobody thinks the old time clipper ships were a good model. Very efficient, made for the best usage of the wind possible at the time, maximum speed, with the best "lines" and a huge amount of sail relative to the hull.

I suspect that "sail" is smaller than the sail area of a clipper, which is a VERY much smaller ship.

That can't "sail" at all except with the wind, the type of "sail" has no significant capability to vector the wind into a forward force if the wind isn't nearly dead aft.

I'd be surprised if the savings were even measureable over a whole trip.

Evan
01-24-2008, 09:09 AM
I have a small collection of stunt kites including one of the very first 4 line double diamond kites ever made. I have a six foot standard swept back "hang glider" type kite too. It probably has an area of about 1/2 to 3/4 sq meter or so. In a decent breeze it will almost lift me off the ground. In a good wind it will take off with me attached.

I would guess that parasail would produce at least a couple of thousand pounds of thrust (pull) in a good breeze and maybe 10 to 20,000 in a stiff wind. It doesn't take a lot of power to make a long ship go slow. A quick check on the power plants fitted to the narrow canal boats shows numbers such as 43 hp for a 55 foot 18 ton vessel. That's the same power as my Land Rover.

[edit]

Also, my stunt kite can be flown from nearly 90 degrees to either side and almost directly overhead. The force vector downwind is proportional to the cosine of the angle.

Lew Hartswick
01-24-2008, 09:25 AM
Hooey.......... yep, there has to be a LOT of stuff not mentioned..

That can't "sail" at all except with the wind, the type of "sail" has no significant capability to vector the wind into a forward force if the wind isn't nearly dead aft.

I'd be surprised if the savings were even measureable over a whole trip.
Yep. Thar was my first statement when I saw the picture in the news.
What a farce. As if the wind was always from behind. The solid airfoils
that were in the news a few years ago (mounted vertically) look a
lot more promising.
BUT you never know, how many remember when the first
"winglets" were invented ? It was on sailplanes and it took many
years to finally show up on big planes. Now they all have them.
...lew...

davidh
01-24-2008, 09:39 AM
this website may explain it. . .
http://www.greencarcongress.com/2006/01/beluga_shipping.html

hitnmiss
01-24-2008, 11:14 AM
Like Evan I was going to mention stunt kites. Mine was about the size of a medium TV and in a stiff (20mph) wind it felt like it would almost lift me (I'm not small!)

When I was a kid I hauled my 2 man raft to the local pond on the handle bars of my Stingray bike. Wind was blowing pretty good and suddenly I was moving way faster than I was comfortable with. I stopped but just barely.

Funny, it never crossed my mind to let go of my boat... Took a lot of mowing to buy that boat.

Prokop
01-24-2008, 11:42 AM
wind power? That reminds me of this interesting project:

http://www.otherpower.com/bartmil.html

If it was already posted here, my apologies:)

A.K. Boomer
01-24-2008, 11:54 AM
Keep in mind that about half the surface area of that sail is useless -------- look to where its mounted, its not attached to that black mast, its attached to the deck, In order to calculate the vector simply follow the chutes main lines, (close to 45 degree) Aprox. half of the sails energies are actually going to lifting the Bow rather than towing it, while this may be ever so slightly beneficial (due to having .0000001% less bow in the water) it pales in comparison to the lost effort in direct pull, also note that this reduces the area of the sail itself as it has to put in in an indirect angle to the power source, _----------- so -- that already out of proportion picture that everyones talking about, think aprox. 1/3rd less, now with the remaining 2/3rds think about 1/2 of that pulling skyward:rolleyes: Gotta admit its great advertising though, although the back of the ship and top cargo with gaps is creating much much more effective work... (granted you dont get to fold them up and put em away in a head wind Knuck, knuck knuck :) )


The Old bird on the rascal however is a lesson of direct efficiency, he's getting twice the amount of effective work done for little expenditure (she cant weigh over 45 lbs soaking wet), He's got the 6.2 volt because thats a box stock tow package --- he's obviously got it "sprung" -- there are to many modifications to list, Also -- the old birds no stranger to towing as you can see from his hitch angle, could stop on a pair of soiled depends and still not have the queen pass him by in a jackknife --- Dudes the real deal....:p

Evan
01-24-2008, 12:18 PM
Keep in mind that about half the surface area of that sail is useless

Not at all. All of the sail plays a part in generating lift. You can't cut away half of the sail and still have the same sail. The force being generated isn't made by "catching" the wind like a flat plate. It's produced by generating lift the same as a wing. That also means the force vectors aren't quite what you think. For instance, the fastest point of sail for a sailboat is not running downwind. It's a beam reach going directly across the wind or slightly "off" the wind. As the boat moves it also generates a different wind direction due to it's motion called the relative wind. This actually increases the apparent velocity of the wind on reaches. The thrust is produced by the action of the sail not just making lift but by doing so by changing the direction of the wind. The entire area of the sail is responsible for doing that.

Also, a simple square sail is not limited to just running down wind. I have sailed many miles with a square sail and it can reach to either side about 45 degrees course made good, even further with a keelboard.

This is the square rig I would use when I didn't feel like putting up the full sloop rig on my canoe.

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

jkilroy
01-24-2008, 12:31 PM
Most of the ships entering San Francisco Bay do so at pretty high speed, 16+ knots under the bridge. You would have to have some stiff wind to not over-run the sail.

Evan
01-24-2008, 04:27 PM
That's because the tidal current under the Golden Gate approaches 12 knots at times, if I recall correctly. I was born in Berkeley. I would think they would reel in the assist kite before making port.

jkilroy
01-24-2008, 05:34 PM
Evan, I just wanted to point out that these big ships are making some serious speed in the open ocean, 18 knots is no problem. Those tankers coming into SF are hitting on 16 knots AGAINST the tide! So in my mind you would have to have consistent wind speeds faster than the ships speed for it to work no?

I have no doubt that with a nice surface area and a good breeze that you could get plenty of pull. The web site says they got 5 tons of force out of the prototype in less than ideal conditions. You could probably use three or four of these things in monster size on a big tanker (1000+feet) or container ship (Approaching 2000 feet now) That would have to be worth a lot of power.

Peter S
01-24-2008, 06:19 PM
A few days back I listened to an interview on the BBC Worldservice radio, talking about a sail system for ships. I didn't take must notice, but seem to remember the most important point of the system was that the sail keeps moving around, it is not just fixed in the breeze. Apparently this movement improves its efficiency, this is what made the idea distinctive apparently. Does that make any sense? I don't think the guy was claiming any huge reduction in fuel, but some savings.

BTW, the fast ships (with huge engines) tend to be the container ships, there are plenty of slower vessels with bulk cargo, they have much smaller engines and run at only moderate speeds.

hdj80
01-24-2008, 06:41 PM
I have a small collection of stunt kites including one of the very first 4 line double diamond kites ever made. I have a six foot standard swept back "hang glider" type kite too. It probably has an area of about 1/2 to 3/4 sq meter or so. In a decent breeze it will almost lift me off the ground. In a good wind it will take off with me attached.

I would guess that parasail would produce at least a couple of thousand pounds of thrust (pull) in a good breeze and maybe 10 to 20,000 in a stiff wind. It doesn't take a lot of power to make a long ship go slow. A quick check on the power plants fitted to the narrow canal boats shows numbers such as 43 hp for a 55 foot 18 ton vessel. That's the same power as my Land Rover.

[edit]

Also, my stunt kite can be flown from nearly 90 degrees to either side and almost directly overhead. The force vector downwind is proportional to the cosine of the angle.

Say this is a small container ship of 40,000 metric tonnes displacement.
The average speed for a merchie of that displacement is @ 20 knots.
To do this it has an engine output of over 20000hp. Now granted it won't use max power to maintain cruise speed but you would think the parasail would only have a limited effect.
If you have 20knots of wind and you are travelling at 20knots what thrust will the parasail produce then? (serious question I know that it will work but what is the effect).

Evan
01-24-2008, 09:34 PM
If you have 20knots of wind and you are travelling at 20knots what thrust will the parasail produce then? (serious question I know that it will work but what is the effect).

If you are going down wind then the assist is almost nil. Running with the wind is one of the least efficient points of sail as the faster you go the less relative wind there is. You can not even maintain half the speed of the wind in the best of boats. The best is to have the wind from either beam. As with an aircraft, the lift vector is approximately 90 degrees to the movement of the air relative to the wing. The parasail is a wing. In all, there would be about 180 degrees, 90 on either side of upwind/downwind where the parasail would provide a significant benefit. The most efficient sailboats can easily exceed the speed of the wind by a large margin when running on a beam reach.


As for the horesepower required to move a vessel, it is extremely non-linear. A displacement vessel is limited by the length of it hull, that limit is known as the hull speed. To travel at a small fraction of the hull speed, perhaps 20 percent, may take 1/100 the power it takes to go 90% of hull speed. On military ships such as the HMCS Algonquin, a Canadian missle destroyer, they use two relatively small diesel engines for cruise power which will move the ship at about 24 knots. For full military power they fire up two turbines of 25000 hp that are geared into both propellor shafts. For maximum speed "without regard for man or machine" they run all engines at full power. The top speed is classified but then it is between 30 and 40 knots. I know what it is but really shouldn't reveal it.

The diesel engines are only about 6000 hp each and that is all they use for normal cruising. The diesels will maintain the ship at over 20 knots. It's only when you wish to push a ship close to hull speed that a lot of power is needed.

gellfex
01-24-2008, 09:49 PM
Here's the way to set sail in the 21st century.
The coolest part is the sails furl into the masts. No doubt about it, being a billionaire can be fun!
Details: http://www.theengineer.co.uk/Articles/293074/Ship%20shape.htm

http://i.n.com.com/i/ne/p/2006/trial1_550x366.jpg

aboard_epsilon
01-24-2008, 10:08 PM
Say this is a small container ship of 40,000 metric tonnes displacement.
The average speed for a merchie of that displacement is @ 20 knots.
To do this it has an engine output of over 20000hp. Now granted it won't use max power to maintain cruise speed but you would think the parasail would only have a limited effect.
If you have 20knots of wind and you are travelling at 20knots what thrust will the parasail produce then? (serious question I know that it will work but what is the effect).

you would use the engine to go up to 15 knots ..and the other extra 5 knots would be from the wind.

so in that case your engine would be working 25 percent less harder .......and using less fuel.

if that sounds right

all the best.markj

LastOldDog
01-24-2008, 10:19 PM
I too have competed with stunt kites (Team Hawaiian for one) for many years. Do not underestimate the 'pull' on the lines when the sail is in 'undisturbed air' at altitude. Consider it a sail with all the aerodynamic engineering available to surface bound vehicles. Ponder 100MPH+++ ice racers. As a result of my experience, we have experimented with a group featuring 'Kite Ship' for our racing yacht. Although the class immediately outlawed the kite as 'Not in the spirit of the class as a spinnaker . . .', the trials were breathtaking.

Evan, as you know, one of the convenient schemes for 'parking' delta kites is bring it around to nearly 90*, stall it, drop the two ends in the grass and fix the controls to the ground with a big screwdriver. Following an adult beverage, grasp the handles, step back and you are airborne again.

Watch videos of the kite surfers, you may find entertainment in the airborne antics.

As to the pull, many times I have been towed across the field when the foot boards let loose, or, barefooted along the beach just to see how far we could go without stopping or falling. In a blow, one cannot stand unless tethered to a tree or ground anchor. Too much fun.

Lloyd

wierdscience
01-24-2008, 11:06 PM
I have that exact scooter from my Fathers estate. I used it when my ankle was crushed and yes, it seems to have the towing package! I used it to load the garbage into a garden wagon and it was surprisingly powerful :D

I think the sail on the tanker is a hot of huey perpretrated on a willing new media. But that's not to say the tanker industry shouldn't be concerned. Put this pic in a few more newspapers around the world and they'll be on everything that floats.....including turds!

And you were wondering how to get that new mill home:rolleyes:

oldtiffie
01-24-2008, 11:52 PM
I really didn't expect this topic to be taken seriously - perhaps I should have known better.

Anyway, I thought I'd go to the web and see what it had to offer.

http://www.google.com.au/search?hl=en&q=skysails&btnG=Search&meta=

The principles of adjusting sail has been known and practiced since when-ever.

Nelson with his adjustable sails defeated the Spanish who did not have this facility (French either).


http://en.wikipedia.org/wiki/SkySails

http://www.youtube.com/watch?v=2umdKznDkfA
(in German? - perhaps our European members can help/advise/translate). TIA.

http://www.youtube.com/watch?v=a8qeKslrqeY&feature=related

I thought that Evan had it nicely.

Arab dhows and Polynesian and Micronesian people have been using adjustable sails for millenia (known as laktoi craft).


http://en.wikipedia.org/wiki/Dhow
http://www.google.com.au/search?hl=en&q=dhow&btnG=Search&meta=


http://www.anthropologising.ca/papua/hanuabada/photos/lakatoi.htm
http://www.google.com.au/search?q=lakatoi&hl=en&start=0&sa=N


The Chinese Junk is in a class of its own - amazing!

http://en.wikipedia.org/wiki/Junk_%28ship%29
http://library.thinkquest.org/04oct/00450/chinesejunk.htm
http://web.cecs.pdx.edu/~trent/junk.html
http://www.google.com.au/search?hl=en&q=chinese+junk&btnG=Search&meta=

Mad Scientist
01-25-2008, 12:00 AM
If it works for ships why not airplanes?

http://i68.photobucket.com/albums/i17/mscientist/sailplane.jpg




I really didn't expect this topic to be taken seriously - perhaps I should have known better.
:):):)

J Tiers
01-25-2008, 12:49 AM
Evan, there is some differnce of a square-rigger from a parasail....

The square-rigger can effectively use the vectors, because they can FORCE the sails to any angle.

The parasail shown seems to have ONE line back to the deck. That means it WILL be effectively "downwind" for almost any wind direction, and a lot of its force will be sideways or up.

The square-rigger ( or sloop rig) can vector that side force into a forward directed force because it's rig is more rigid, having a mast etc which forms a framework for the sail.

With some more lines, they might be able to get better efficiency of propulsion.

LastOldDog
01-25-2008, 02:15 AM
The sails we tried had three lines, one at each lower corner and one at the head, so it could be steered both in altitude and direction. This control is constantly monitored to respond to minor changes in 'apparent' wind direction and 'operant' wind velocity, not to be confused with 'true' wind velocity and direction. Further it is 'pumped' as in any spinnaker on a large boat, allowed to inflate, move slightly off wind, then the clew is trimmed to get a slight additional effort. Then it is allowed to fall off a little, thence to be trimmed again.

Computers can control these lines and provide unassisted management. With a sail (kite) 100 metres + in the air, it sees the winds as far more stable and predictable. For our purposes, while on a run, or actually tacking DDW we could fly white sails or douse everything for evaluation of the various test kites. Youse guys with inquiring minds would have been fascinated.

Lloyd

Lloyd

sconisbee
01-25-2008, 02:56 AM
The sky sails idea is a very promising one, my brother is in marine logistics and a fair few shipping companies like the idea. the main thing being it can be retrofitted to any vessel regardless of deisng and age pretty much as its a "towing" device more than anything. and once one of those cargo ships are moving a large enough sail area can have a significant effect on reducing engine load and thus economy....will it catch on? well only time will tell. Also dont forget that the picture does not depict the sail fully deployed, in actual use its tether is much longer extending the sail into higher wind levels, there are some better pictures on http://www.skysails.info/

wierdscience
01-25-2008, 10:26 AM
Only problem I see with the sails is if it were to blow out or colapse then it would run under and into the screws,oh well that's what divers are for right?

batt-man
01-25-2008, 11:00 AM
Here's a link to the bbc news website about this ship - apparently they can save upto £800 a day !!!

http://news.bbc.co.uk/1/hi/world/europe/7205217.stm

Cheers

Evan
01-25-2008, 11:18 AM
I am curious what effect it will have on maneuvering ability, especially in a maximum effort turn or stop. It depends a lot on how quickly the system can be redeployed or stowed. I would also like to know what happens if a squall blows through with winds of 40 or 50 knots.

Another major issue is what happens in a sudden reversal of wind. I was once flying a military antenna box kite from the deck of a power cruiser in the middle of San Francisco Bay. The captain had to make a sudden turn to avoid another vessel and my kite lost the wind. It headed for the bay. This was a very well made kite with aluminum spars and canvas sails intended to take just about anything. It turns out that a kite will fly underwater just fine if it is strong enough. The problem is that it wants to go down and with a lot more authority. It very quickly became apparent that A: I couldn't reel it back up without drifting the boat and B: drifting the boat in the traffic lanes in San Franciso Bay was a non starter.

I had to cut the kite loose. Sniff.

I will assume that the parasail has some sort of emergency jettison system that will instantly cut the lines if need be. It better.

topct
01-25-2008, 12:09 PM
Actually what they are doing is just testing the para sail. The ship is just being used as an anchor to hold it down. I suspect they have a scale on it to measure the amount of pull it is making.

That thing would make a terrible sail for a ship. It would be useless in a crosswind or a headwind.

dicks42000
01-25-2008, 02:10 PM
Further to what others have said, the savings on fuel will be small.
The thing to remember is in the shipping business, margins are said to be small, so shipping companies persue cost reduction opportunities them like a crack addict. Even to the point of abandoning marginal ships and crews that go on strike....
If the labour to set and furl this kind of rig is small and it produces 2 to 5 % savings, it could be attractive.
Rick

Evan
01-25-2008, 05:31 PM
It would be useless in a crosswind or a headwind.

Useless in a headwind, yes. A crosswind is where it works best. As I have been saying, the fastest point of sail is when the wind in on your beam. That means a crosswind from either side. The sail, including the parasail, converts that energy of motion of the wind into lift. The sail will be forced to one side of the ship but will not be blown directly to the lee side. Instead, it will try to fly ahead of the ship towing the ship with it. This is exactly the same as what happens when you fly a kite and the kite climbs overhead. You can be sure there isn't a wind blowing up from the ground to make it do that.

Peter S
01-25-2008, 05:45 PM
batt-man,

Thanks for the BBC link, that sounds like the one I heard the interview on. It explains what I was trying to say in my earlier post about it being a more than a sail, it is the "figure eight" motion that seemed to be the main point of the idea:

"One computer helps it to fly in figures of eight in the sky"

A.K. Boomer
01-25-2008, 06:14 PM
[QUOTE evan]Not at all. All of the sail plays a part in generating lift. You can't cut away half of the sail and still have the same sail. The force being generated isn't made by "catching" the wind like a flat plate. It's produced by generating lift the same as a wing. That also means the force vectors aren't quite what you think. For instance, the fastest point of sail for a sailboat is not running downwind. It's a beam reach going directly across the wind or slightly "off" the wind. As the boat moves it also generates a different wind direction due to it's motion called the relative wind. This actually increases the apparent velocity of the wind on reaches. The thrust is produced by the action of the sail not just making lift but by doing so by changing the direction of the wind. The entire area of the sail is responsible for doing that.

[QUOTE/]


Nope, not talking about the sails ability to adjust from side to side or such, re-read my post, I stated that it looks like its taking off from the deck to a 45 degree to the sky, this is a fuque no matter how you cut it, and the parasail load lines are direct proof of the vectors involved, ----- so -- Like I said (and you said in the begining of this quoted post about "generating lift")

About half of the energies from the parasail are being wasted, lifting does not push the barge, 45 degree's would be the perfect angel to deduct 50% of the workload , thats the best that it gets, as the barge picks up speed it does NOT have the vector force advantage as if wind was coming from the side (also read JT's post about solid rigging) Further note; sailboats can go faster than the wind not because the sails work better, its because the vectors allow for a transsimission of sorts, a full blown sail and boat will take off faster from a dead stop every single time facing downwind as compared to a boat 90 degree's , but the advantage of the latter is it gets to utilize higher speed gearing --- even though its sail is turned in a less efficient manner its still able to get a bite as its not leaving the winds power,------------- think speed skaters skate, the most powerful transition is from a dead stop where he can push directly behind him, as the speed increases his vector angle adapts accordingly, hes not making more power, hes simply changed his gears, and I might add gives up a little power in whatever hes using to "pry" against the medium hes going through, in this case the stable skate on the ice and the one thats "prying against it" --- taking off neither skate has to "pry" against the other, its direct propulsion , in a sailboats case the keel fin in the water is one vector medium and the wind on the sail the other...

So--- No -- the barges sail is already at a huge disadvantage, It IS aprox. half its effective size because aprox. half its effort is being wasted,and it never gets better for if the wind changes then its not only trying to still pull the boat skyward, its giving up other powers in the horizontal angel of attack, (unless of course the pig gets moving fast enough) follow the parasails lines to the deck Evan, this is where its eating its lunch.... these lines do not lie --- these particular lines are a direct correlation of the vector forces that be.
Its important to recognize that drastic vertical deviation is a no win -- unlike horizontal deviation which can still give you purchase even at speeds exceeding the wind vertical does not work this way, unless of course your goal is to catch a jetstream up in the clouds

Weston Bye
01-25-2008, 09:39 PM
...when you fly a kite and the kite climbs overhead. You can be sure there isn't a wind blowing up from the ground to make it do that.

Not unless there is a group of idle machinists standing around on the ground looking up at the kite and talking about wind power.:D

oldtiffie
01-25-2008, 11:23 PM
There has been some comment regarding the height of the sail and wind direction.

FWIW, wind can, and often does, have different speed and directions at different layers at different heights. The sail lead may well be controlling the sail to act as a kite an search for the best wind at varying heights. Watch the smoke from a big fire and sometimes different wind-speed and directions at different layers will show up in the way the smoke plume is blown.

Any aircraft pilot can tell you of that phenomenon!!!.

It also seemed to me that the sails can be controlled as a para-glider does - by pulling/controlling the parachute/canopy by use of control chords/wires.

Evan has it right as regards wind direction and reactions to and with it as regards directions and vectoring.

Evan made mention of the braking effect and effort if the "kite" gets into the water and is kept "inflated" under water. The resistance is huge. That is the principle of the sea anchor!! which will keep a vessel "head to wind" and assist it to not "broatch".

http://en.wikipedia.org/wiki/Sea_anchor

A.K. Boomer
01-26-2008, 12:44 AM
Tiffer, like I stated in my first post, if the sail were at a lesser vert angle but attached to the top of the steel mast It would indeed be at the same hight yet have a lesser angle than what they have to utilize for the deck mount, All that would be needed is to adjust the parasails control lines to achieve this, Walla --- the sail is high enough to get over all the deck drag yet its angle of attack is less vertical so most of its effort is being used for what it was intended for -- pulling the barge (instead of trying to lift the front of the boat out of the water) The sail itself can also be kept at a larger surface area to the wind --------- Once again, follow the main lines for a good view of the vector, they suck --- its good advertising, but those guys are hillbilly's when it comes to efficiency, absolute hillbilly's.

Keep in mind having a vert. hight can be a good thing, but having a vert. angle of tow is bad, its an absolute waste of power, and unlike a horizontal angle it cannot help the boat "change gears" It simply gets overrun the faster the boat goes ---- so the force will always decrease with the speed of the vessel...
A parasail can be set up to drag a larger blunt sail to proper hight, and if the line from parasail to the lower sail is long enough you can do some pretty amazing things and actually make a total rope sail apparatus mimmick solid rigging in some ways due to the leverage manipulation of the smaller more controllable sails effect over the larger one, once again, to find the vector forces simply look at the two different angles that each tow line has, The lines dont lie, they cant --- they are the sails vector force.

Evan
01-26-2008, 01:22 AM
its good advertising, but those guys are hillbilly's when it comes to efficiency, absolute hillbilly's.

Nope. The parasail as shown is operating at it's most efficient for several reasons. There is clean air (not turbulent) higher up and the wind speed is higher once out of the boundary layer near the surface. Also, it wouldn't have room to maneuver if it were near the surface. Also, and this is the reverse of what is desirable in an aircraft, induced drag helps the efficiency because it produces more effort. When an airfoil operates near the surface the boundary layer effect reduces induced drag. This is very noticeable within one wingspan height from the surface and operates up to about two spans altitude. It's because the surface helps to prevent the formation of tip vortices.

Furthermore, the sail must operate on the lee side of the ship, naturally. It needs to be high enough to be out of the wind shadow of the vessel and above the turbulence it causes.

oldtiffie
01-26-2008, 02:23 AM
Evan is right again.

The length of cable that can be streamed (let out) from the cable drums is limited only by their capacity.

I could imagine a Kilometer (0.6 mile) or a mile or more of cables being streamed.

The last place I would attach the sail and its cables to would be the top of the mast. I would imagine that the best attachment would be directly to the ship's hull. It would not only be better mechanically and as regards efficiency but would be cheaper and easier to retro-fit to an(y?) existing ship.

When I was in the Navy we had air-craft towing target drogues (like wind-socks) on a cable well over a Kilometer. It was used as anti-aircraft firing practice which uses proximity fuses in the nose of the shells. I've seen the shells "get" the drogue and then explode on the wire and march up toward the aircraft. Pilots were NOT amused - and the Language over the Communications systems!! Air-craft were also fitted with "scissor-gear" to cut the cable in an emergency. Pilots told me that streaming the drogues put a huge load on the planes and the when the drogue was streamed the plane was pulled up with a real jerk (NOT the pilot) and when/if cut or the drogue was shot out the aircraft just leaped forward.

A sea-anchor has a huge pulling power. Just throw a bucket (with or without holes in the bottom) on a rope over the back of a small boat under power and see what the effect is. Box-kites (and a lot of Chinese kites) can have huge lift in mild breezes - even from relatively small kites. My FAIL had a canvas sea-anchor in the bottom of his boat as insurance in case of an engine break-down in heavy seas. We needed it twice - that was more than enough.

tattoomike68
01-26-2008, 03:41 AM
Useless in a headwind, yes. A crosswind is where it works best. As I have been saying, the fastest point of sail is when the wind in on your beam. That means a crosswind from either side. The sail, including the parasail, converts that energy of motion of the wind into lift. The sail will be forced to one side of the ship but will not be blown directly to the lee side. Instead, it will try to fly ahead of the ship towing the ship with it. This is exactly the same as what happens when you fly a kite and the kite climbs overhead. You can be sure there isn't a wind blowing up from the ground to make it do that.

thats right, on average it would help 50% of the time so thats better than a swift kick in the pants.

I sail and have gone many miles without a drop of gasoline. I learned to sail from some yacht racers running hobi cats. we get a 2 man crew hanging from trapezes wires and fly a hull so we have one pontoon in the water and are going very fast in rough waters.The fancy jet boat ski boat boys would never go out into the stuff we play in. The cables are howling in the wind and we are layong back hanging from a wire with a beer in our hands. :)

I have crashed 2 sail boats but have never sunk one so I am batting 1,000. :D

Sailing is very old technology that I love much like steam. I built a land sailer once but never did get it out on the road.

The place I sail is called "Port Kelly" at wallula junction right at the Washington/Oregon boarder on the Columbia river. It is about 10 miles from one of the largest wind power farms in the world. A little west of that is a place called wind river (hood river area) that place is so windy that if the wind stooped blowing all at once everyone would fall over.

There are fools who dont like wind power but its as close to free energy as it gets. We should exploit it at all windy places on earth.

;)

A.K. Boomer
01-26-2008, 11:03 AM
Nope. The parasail as shown is operating at it's most efficient for several reasons. There is clean air (not turbulent) higher up and the wind speed is higher once out of the boundary layer near the surface. Also, it wouldn't have room to maneuver if it were near the surface. Also, and this is the reverse of what is desirable in an aircraft, induced drag helps the efficiency because it produces more effort. When an airfoil operates near the surface the boundary layer effect reduces induced drag. This is very noticeable within one wingspan height from the surface and operates up to about two spans altitude. It's because the surface helps to prevent the formation of tip vortices.

Furthermore, the sail must operate on the lee side of the ship, naturally. It needs to be high enough to be out of the wind shadow of the vessel and above the turbulence it causes.



Im changing my Gig, Im going to have patience no matter what, Im biting my tongue and I will redirect you and Tiff to re-read my post, with all due respect your both incorrect,,, Once again --- by attaching the sail to the top of the mast you can actually be higher than where the sail is right now even if you change the sails control lines for a far lesser angle of vert. pull on the boat, this is as simple as it gets folks --- its called a win-win, The sail is therefore kept in the upper non-turbulent air yet its line of pull is more direct on the boat ------- it also has all the manuverability and even more so as the lower lines that are attached to the deck are not catching on the decks lower obsticles ---------- I feel it important to bring this up, Can either of you guys see the main tow lines of the parasail? Im not trying to sound insulting but they are hard to pick out, Also --- have either of you guys ever gone parasailing, I have --- and I can tell you that with a tweek of the control lines I can "fan out" the chutes angle of attack to that its more direct, in fact this is what you do just before landing, the drag is immense as compared to the aprox. 45 degree angle when flying,

So --- one more time, higher than where they are right now with a sail thats more broad side to the wind AND a pull line thats at far far less of a vert. angle = win -win-win, what could I do with the efficiency of that parasail you ask? I could increase its effective towing values by aprox. 2/3rds.

sorry Tiff, This is how stuff works;)

A.K. Boomer
01-26-2008, 11:55 AM
http://i146.photobucket.com/albums/r249/AK_Boomer/DSC00116.jpg



http://i146.photobucket.com/albums/r249/AK_Boomer/DSC00114.jpg






Its important to recognize the angle of the tow line and where the boat is (i go for the big ride) its at aprox. a 45 degree angle,,, in fact, this is actually where a parasail works best for the amount it can lift for the LEAST amount of effort, increase the angle and whatever your towing with has to increase its speed against the wind, decrease the angle and you have to come up with some major H.P's to overcome the extra induced drag to lift ratio, results --- you dont have to go faster, but you have to have more torque because your optimal lift angle is decreased,

Actually -- a parasail is not an Ideal sail to use for the barge but it can be made to work much better than how they installed theirs, they kept it in the form for what a parasail was designed for --- big mistake, parasails are designed to produce optimal lift with minimal drag, its exactly the opposite of what you really want for towing a barge --------- forget the lift, its a waste -- mount it high so you get it in the fresh and then run it in a fanned out high drag position --- now you have something that might be worth attaching to the barge... The way they have it mounted on the barge is actually producing maximum lift for least amount of effort, this is the exact opposite of what you want, lift is useless, and it also puts the sail in a position to create little drag.......:cool:

One last time ---- follow the tow lines of the parasail to the barge, they dont lie, If you see an aprox. 45 degree angle then half your already lame ass reduced effort is being wasted trying to pull the barge into the air - not forward --- HALF.

A.K. Boomer
01-26-2008, 12:16 PM
Tattoomike thats actually one of my biggest dreams is to have a nice sailboat with a couple of sea kayaks on board, maybe a bunch of limes so I dont get scurvy --- take off for god only knows:)


I cant imagine a better way to travel, dont long for too many material goodies but I have to admit that that one has got me...

Evan
01-26-2008, 12:44 PM
Boomer,

How are you going to install a track on the top of a mast that allows the cable drum to move around the perimeter of the ship in order to control the parasail?

You are focused on only one aspect, the angle of the tow line and are ignoring all the other factors that govern the efficiency and even the practicality of the concept. Don't you think that they gave at least a few minutes thought to this concept?

Evan
01-26-2008, 12:50 PM
forget the lift, its a waste --

Surely you can't be serious. You don't mind if I call you Surely, do you? Without lift you can't even fly the sail, never mind control it. Try it some time. Tie a few lines to the edge of a garbage bag with a soda straw hoop to keep it open like a wind sock. See just how far you can get it off the ground.

A.K. Boomer
01-26-2008, 01:42 PM
Boomer,

How are you going to install a track on the top of a mast that allows the cable drum to move around the perimeter of the ship in order to control the parasail?
[quote/]

Haaaa! How are they doing that with it attached to the deck? dont you think the sail lines would run directly into the mast thats right behind it? the answer is they dont have to, all there using it for is in the bows lead direction, as soon as the wind changes its reeled in, But if you want to get fancy having it on a ball swivel on top of the mast will get around everything and maintain good hight --- however, this would suck the fuel right out of the barge in a headwind... (duh) [quote]


You are focused on only one aspect, the angle of the tow line and are ignoring all the other factors that govern the efficiency and even the practicality of the concept. Don't you think that they gave at least a few minutes thought to this concept? Why no, no i dont think they did, Its the very reason i called them "hillbilly's" next question.

A.K. Boomer
01-26-2008, 02:16 PM
Surely you can't be serious. You don't mind if I call you Surely, do you? Without lift you can't even fly the sail, never mind control it. Try it some time. Tie a few lines to the edge of a garbage bag with a soda straw hoop to keep it open like a wind sock. See just how far you can get it off the ground.






One of the really cool things about my Pops was he taught all of us kids how to fly a kite, It doesnt take a 45 degree angle for stability Evan, In fact you can get by with far less than half that angle IF you know what your doing, we built massive structures that would literally drag us off our 1 acre property and across the neighbors yards, We didnt use kite string -- we used clothes line, Having 6 older brothers my Dad thought he'd seen it all until i started using 2by4rs in the construction, we would snap the mainspars and have to start all over --- we would also change the tow angles to fly low --- unstable at first --- until my Dad taught me to put more of a pre-curve into the mainspar --------- this effectively controlled the vortexes and radical shifting eddy currents on the backside side edge of the kite with the kite still keeping most all of its surface area, The results were a stable kite that needed very little tail, and put much of its energies into tow rather than lift, the other result was bloody hands form the kites tow line, stability can be had --- and it dont take throwing half of your energies away to produce it, when the kites flew higher this was difficult simply for the fact that it effectively reduced my body weight and had some tow effect, but there were no bloody hands from the rope,,, Fact --- I can create huge drag and have good stability with aprox. 15 to 20 degree's, other fact-- Lift is a waste, (unless thats what your trying to achieve) even in that 15 degree's, but its so much better than throwing half your energy away with a 45, the guys on the barge are hillbilly's,,, any other questions be "surely" to let me know K...

One last note to further embarrass you ----- If there were no stability within low angles I would never have gotton off the ground Evan, Keep in mind i started off at 0 degree's to the boat ------ and very slowly I might add, stability can be had simply by design...

Guido
01-26-2008, 03:46 PM
Whutever happened to this guy Flettner and his working ship sails?
http://i126.photobucket.com/albums/p86/Guido_album/flettnerrotorship.jpg
Not too long ago, someone in LA built a prototype device like Flattner's, located atop a windy hill just off I-5. Stood there for several months, experimental data obtained, glowing reports for use as a power source for electrical generation versus the 'ugly' windfarms we know today.

Device generates energy similar to energy needed to make a baseball 'curve' in flight? I dunno-----Looked good to me.

G

Evan
01-26-2008, 05:25 PM
[quote]Fact --- I can create huge drag and have good stability with aprox. 15 to 20 degree's, other fact-- Lift is a waste, (unless thats what your trying to achieve) even in that 15 degree's, but its so much better than throwing half your energy away with a 45, the guys on the barge are hillbilly's,,, any other questions be "surely" to let me know [.quote]

Making drag isn't anywhere near as efficient a use of the wind energy as lift is. With drag the majority of the energy of the wind isn't transfered to the object producing the drag but is wasted in creating turbulent air. Also pay attention to the other reasons I gave why they cannot do as you suggest and why it wouldn't work.

topct
01-26-2008, 07:02 PM
A parasail that was computer controlled, could be used to drop heavy cargo from a high altitude, very precisely.

We've seen how these work with a person steering them.

They are not trying to assist the propulsion of a ship. They are testing the mechanisms needed to steer a parasail of that size.

The sails design is not radical.

So has someone got a picture of one propelling even a boat?

Evan
01-27-2008, 09:35 AM
So has someone got a picture of one propelling even a boat?

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

http://www.kiteboat.com/

J Tiers
01-27-2008, 11:57 AM
I don't think anyone doubts that such a sail CAN move a boat.

I do notice that the size of the sail in the kiteboat picture and the size of the sail in the original picture are in a proportion that is completely different than the proportion of mass or other dimensions between that kiteboat and the container ship.

Of course THAT has absolutely NO relevance..................... Hmmmmmmmm.

A.K. Boomer
01-27-2008, 12:01 PM
Now your talking Ev, Far better design and exactly what i was talking about, they kept the tow angle to a minimum, they put the parasail sideways to be able to take advantage of two things ---- one; they no longer are at the mercy of releasing their exhaust air vertically, so this keeps the sail low to the tow line and does not waste precious energies in trying to lift the boat skyward, Two; now they have the advantage of excepting crosswinds --- in fact, if the control lines are designed properly they can be adapted on a cammed hub, the adjustments to the sails leading and lagging edges can then be automatic ----- It would be possible to actually make this boat Tack --- although nowhere near the angles that can be achieved with solid rigging....

These guys arent hillbilly's, they put some thought into the rig, cammed hubs might not even be necessary if you follow the tow lines, i believe the lower is to the front and the higher to that little pole on the rear, if they have their geometry correct the parasail could self adapt to the changeover quite nicely, laying down the high part of the sail at an angle towards the rear in a crosswind but still keeping it higher than the front,

At their very worst position of tow they approach a 45 degree like the barge, but at their best position they are at aprox. 15 degree's --- do the math to calculate what their effective tow angle is -- way better than the hillbilly's...

You know what im thinking, encoder cable reals inside the hull so that you can let out much more line, get the sail up a little higher while at the same time drastically reducing your tow angle, Like I stated earlier -- a Win win, that could prove to be one fast ride, God -- I swear I got a hankering to sell everything I own and go out and be an ocean bum, stop posting stuff like this...:)

Damn --- now i wanna build one...

A.K. Boomer
01-27-2008, 12:36 PM
[quote]

Making drag isn't anywhere near as efficient a use of the wind energy as lift is. With drag the majority of the energy of the wind isn't transfered to the object producing the drag but is wasted in creating turbulent air. Also pay attention to the other reasons I gave why they cannot do as you suggest and why it wouldn't work.



Unacceptisissio, non-corecto, missdiagnosio, and non-complieassiso, all at the risko of starting to sounda ignorameosio....

Your not listening again, The bloody hands from kite flying, the way I come in for a landing when parasailing , when i say i create drag I mean I CREATE DRAG, that is I create more pressure on the tow line, Im not trying to piece the air back together in the apparatus like its a ferrari, in fact its about the opposite with a little measure for control, Fluid dynamics are very similar --- My kayak paddle was state of the art when I purchased it, as skill levels increase and the whitewater turns to nothing but foam many paddle companies were racing to achieve a very broad blade that gets a massive purchase on the water yet still behaves acceptable in flatwater paddleing --- anotherwords -- it doesnt "flutter" in the thick stuff, AT did just this, aprox. 20 percent more surface area AND stability to boot, The fact is Evan be it fluid or air, all it takes to have huge drag and acceptable control is good design, You can have both -- I do it and use it all the time...:D

sconisbee
01-27-2008, 01:24 PM
im surprised its got this far without being mentioned, however... that "black mast" that keeps being refered to is simply a hydraulic vertical lift for launching and recovering the parasail, the last place you would want to attach the cables for a parasail. Now anyone who has actually read the SkySails site and details on the system will know that they expect 10 to 35% savings, not always the 35% saving that the media advertised, as usual the media has focused on the more generous side of things. Secondly some of the skysails info actually goes into detail on why they chose a deck and not a mast mount, and for the most part its about stability...read for yourself...
http://www.skysails.info/fileadmin/user_upload/Pressedownload/Dokumente/EN_Turn_Wind_into_Profit.pdf
as its been said even a saving of a few percent is alot better than a kick in the teeth.

Why is it that there are soo many people ready to jump on new technology and slate it as useless, i mean really there was a time when people thought computers would never catch on. So instead of arguing that it *wont* work how about thinking more along the lines of *what if* it works and the good things that might come from it.

Now shall we all agree to disagree?

Evan
01-27-2008, 03:46 PM
Now shall we all agree to disagree?

No. Boomer doesn't have a clue about aerodynamics or hydrodynamics, sorry to say. He has no argument since it is based solely on fallacies and incorrect thinking.

Points:

If all you have is drag then you have zero control.

Lift works more efficiently than drag to extract energy from moving fluids. Aircraft prove that.

Flying a kite near the surface is less efficient than flying it higher up. Personal experience has shown me that and many others too.

Note that the parasails are NOT flying long axis horizontal. The lift being generated is being vectored horizontally, not vertically.

The size of the parasail in the picture is no indication of the size required for a larger vessel. The power extracted from the moving air goes up as the square of area of the wing as well as the square of the velocity. That means that if the wind speed a few feet higher is double what it is near the surface then the power generated is 4 times greater. That totally wipes out any vector inefficiencies. If the sail is also twice as large then the effort is 16 times greater. It doesn't take a much larger sail to tow a very much larger vessel. This is especially so if the vessel is long and narrow since the drag is not directly proportional to the wetted area of the hull but mainly to the cross section of the wetted hull and half wavelength of the bow wave.

Rich Carlstedt
01-27-2008, 08:09 PM
This whole episode is phoney.
You folks are making so many variences to prove the worth of such "Green Brain" delieriums, that it is hysterical.
First , The proof will be in the pudding. Lets see how many rush to the order desk on this.!
but lets review some of it
The proof of ignorance on this is shown when no one, absolutely no one here mentioned the "criteria" that ocean carriers must meet.
They are on strick schedules folks.. they do not lolygag around in the water.
The only time they deviate from the shortest line between two points is if a major storm demands such. They cannot zig-zag to keep the sail on the lee, or whatever...Time is Money !
Next,
They do in excess of 20 knots, this is not your WW II trawler !
Last, if energy was king, why don't we still have 1850 Clipper ships running cargo ? (eliminate the diesels 100 % right)
Oh, by the way, those sleek clippers averaged about 12 knots, far too slow for modern logistics to even be considered except for those stuck in the past and lacking engineering logic.
Rich

Evan
01-27-2008, 09:50 PM
Who says they will ziz zag to find the right wind? They will take the same course as usual and use the sail when it is possible. The winds tend to be in the same direction for long periods of time over the ocean as there is nothing to disrupt the flow of air of the weather systems. It also won't affect their schedules which aren't nearly as strict as you may think. The only thing it will do is to get them there faster so they can wait in line for a pilot and a berth. It isn't unusual for freighters in Vancouver having to wait several days or longer before they can get a berth. The worst that can happen is they don't have a chance to use it at all and then just arrive as per usual.



Last, if energy was king, why don't we still have 1850 Clipper ships running cargo ?

They were too small and require too many crew. Also, 20 knots cruising speed is at the high end of the range and is not representative of the commercial fleet. Most freighters cruise between 14 to 18 knots in good conditions.

toastydeath
01-27-2008, 10:09 PM
Those kites can also be had for extreme sports - people do skateboarding, kitesurfing, and have little buggies powered by those things. They can get pretty darn high up in the air. Youtube has videos.

Also, those kites have maneuvering and power options not available to traditional sails. That's why they're making a comeback, and traditional sails are not.

aostling
01-28-2008, 01:18 AM
The place I sail is called "Port Kelly" at wallula junction right at the Washington/Oregon boarder on the Columbia river.

Are you a member of the Walla Walla Yacht Club? Your moniker is more in keeping with being a biker from Pasco.

A.K. Boomer
01-28-2008, 10:10 AM
No. Boomer doesn't have a clue about aerodynamics or hydrodynamics, sorry to say. He has no argument since it is based solely on fallacies and incorrect thinking.

Points:

If all you have is drag then you have zero control.

I never stated that all I would use is drag, once again re-read, its all there in front of you, what im stating to you is that if you think you need a 50% drag to 50% lift ratio to keep control then your outright smoking crack, Tell that to the people stopping our space shuttle and they will be the ones calling you a hillbilly... there totally round chute is approaching 100% of its surface area dedicated to one thing --- Drag, Sitdown Evan, it is you who does not have a clue (this is also verified from all the Private messages I get all the time from our debates when other members ask me "how can he not see this?) I dont mind being called out on something, in fact, I welcome it, But for one --- when you step into my realm you better have your act together, when it takes pages to re-direct you and cover what i already said in my first post its flat out annoying, when you refuse to grasp simple concepts its upsetting, But whats the worst to me is when you start misleading the board, I know youv been to debate school and if this is some kind of a strategy to "wear down your opponent" they forgot to prepare you for two important factors, One; logic rules, Two; Me ----

You can spout off false info --- but if you do it on my watch it aint going to go over --- period.




Lift works more efficiently than drag to extract energy from moving fluids. Aircraft prove that.


Ohh, I see, thats why people jump to the ground with two opposing vertical airplane wings, because they extract so much energy, No wait a minute, --- dont they use parachutes? Why dont you try your wing theory and let us all know how it turns out, try towing a barge with it -- better yet -- jump out of a plane with it:p
The only way you will stay alive is if you quickly flip the wings into a horizontal position, this means that you have to travel through the medium that your in horizontally, Its great for lift --- its piss poor for towing as it dictates a predetermined angle of attack that is not sutible for direct horizontal pull if kept in a horizontal wing position like the hillbillys on the barge, turn the wing to the side and its a sail --- sails have "lift" just like a wing but its useful to towing because it puts it into a horizontal vector, No price to pay with wasted energies being lifted skyward, and the welcomed bonus of side vectors ideal for tacking.



Flying a kite near the surface is less efficient than flying it higher up. Personal experience has shown me that and many others too.



flying a kite with a longer string and staying at the same hight as the kite with the shorter string decreases your tow angle, this in turn converts more energies for pulling horizontal than vertical, it also puts the kite more broad faced against the power source which in turn increases its force on the tow line --- this is something that everybody else learned by the time they were in fourth grade Evan, If the kite gets a little squirly from the extra pressure and broader angle of attack simply add a little more tail to it:D


Note that the parasails are NOT flying long axis horizontal. The lift being generated is being vectored horizontally, not vertically.

Once again, Re- read, I already made a comment on how that was an improvement over the barge set-up as it keeps the sail at a lower tow angle, I also stated that if you could let out more line your efficiency would increase even further with the ability of being able to take advantage of the side vectors of the sail in crosswinds... listen up bro


The power extracted from the moving air goes up as the square of area of the wing as well as the square of the velocity. That means that if the wind speed a few feet higher is double what it is near the surface then the power generated is 4 times greater. That totally wipes out any vector inefficiencies.

One last effort --------- NOBODY ever stated anything about ever compromising hight, in
fact im all about getting it higher than what their achieving in the pics --- its never EVER NEVER been a part of this debate, (you had that one all by yourself:confused: ) What im saying is increase the hight and decrease the Tow angle --- if your tow angle is 45 degree's then that means your throwing away apox. 50% of your useful work ( minus less hull in the water effect --- which is far less of an effect of just carrying 1 less of its cargo boxes, hardly a 30% saving in fuel ehh)
So if you get your chute up high enough for the speed to double which would then be force squared would you not want to take advantage of this --- or do you simply want to throw half of it away -- along with the added forces of putting your power source more broad to the wind -------- with control I might add...

Evan
01-28-2008, 10:38 AM
Ohh, I see, thats why people jump to the ground with two opposing vertical airplane wings, because they extract so much energy, No wait a minute, --- dont they use parachutes?

No, they don't use conventional parachutes anymore. They haven't for years. They use parafoils because they produce more lift than drag. Lift is much more controllable and more efficient. Wait, didn't I already say that?


I never stated that all I would use is drag, once again re-read, its all there in front of you,


when i say i create drag I mean I CREATE DRAG

Oh, you didn't really mean "I CREATE DRAG" then?


But for one --- when you step into my realm you better have your act together

I don't think this is your realm, in fact I am certain. I am a licensed pilot and also taught seamanship and sailing to the local sea cadets as a civilian instructor for five years. I also have designed and flown (successfully) several large model aircraft that were developed from my knowledge of the first principles of aerodynamics. Then of course there are my years of experience building and repairing REAL aircraft. I also designed, built and refined the sloop rig on my canoe which I sailed perhaps over 1000 miles. It includes a computer designed leeboard and suit of sails which outperform the rig available from Grumman. I've actually had the canoe on plane with it.


flying a kite with a longer string and staying at the same hight as the kite with the shorter string decreases your tow angle, this in turn converts more energies for pulling horizontal than vertical, it also puts the kite more broad faced against the power source which in turn increases its force on the tow line ---

You seem fixated on this idea that this is all that matters. Go back and read my posts as to why other factors outweigh it by a large amount. What is required is a device that actually works and as usual that involves weighing all the factors and not just concentrating on one to the exclusion of the rest.

A.K. Boomer
01-28-2008, 10:45 AM
impossible --- yeah thats why the shuttle is stopped with parafoils, what a mess in control that would be..

Pilot --- my arss, your the Guy who thought the airspeed indicator was actually air speed remember?;)

have a nice day -- gotta work

Evan
01-28-2008, 11:38 AM
impossible --- yeah thats why the shuttle is stopped with parafoils, what a mess in control that would be..
That has no bearing on the subject. I can't figure out why you even brought it up.

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


Pilot --- my arss, your the Guy who thought the airspeed indicator was actually air speed remember?

It is indicated airspeed. What do you think it means?

tattoomike68
01-28-2008, 03:00 PM
Are you a member of the Walla Walla Yacht Club? Your moniker is more in keeping with being a biker from Pasco.

No, I camp at the beach by the elevators scale house. The blessing of camping at a windy spot like that is we never get bit by mosquitoes.

speedsport
01-28-2008, 04:35 PM
Hey Boomer, do you really think you have the endurance to win a arguement with Evan?, if you do my hats off to you.

matador
01-28-2008, 05:19 PM
Geez,tiffie,see what you started?:D.From where I'm sitting,the only computer used was the one to photo-shop the sail onto the cargo ship.
There's one born every minute.

Evan
01-28-2008, 07:34 PM
From where I'm sitting,the only computer used was the one to photo-shop the sail onto the cargo ship.
There's one born every minute.
It seems to be a rather elaborate hoax, don't you think?



http://www.skysails.info/index.php?id=6&L=1

Address: Individually liable partner: SkySails GmbH & Co. KG SkySails Gründungs GmbH Veritaskai 3 Veritaskai 3 21079 Hamburg 21079 Hamburg Amtsgericht Hamburg HRA 100874 Amtsgericht Hamburg HRB 82712 (local court) (local court) Company registered at: Hamburg Company registered at: Hamburg VAT-ID-No.: DE814143833 Partners with statutory authority: Dipl.-Wirtschaftsing. Stephan Wrage Telefon: +49 (40) 702 99 0 Dipl.-Ing. Martin Lohss Telefax: +49 (40) 702 99 333 Dipl.-Ing. Stephan Brabeck Responsible person for the purpose of the press law: Dipl.-Wirtschaftsing. Stephan Wrage Internet Editorial: Dipl.-Wirtschaftsing. (FH) Henning Kühl Technical realisation: symbolic link - agency for digital communications Internet: www.symbolic-link.com (http://www.symbolic-link.com/) Design: Flameberry Internet: www.flameberry.com (http://www.flameberry.com/)


Watch the video. It must be a very elaboarate hoax. Or, it actually works.

http://s2.streamingfarm.tv/streamingfarm/skysails/20080120_Michael_A_Flugfilm_02_1000k.wmv

oldtiffie
01-28-2008, 07:57 PM
Geez,tiffie,see what you started?:D.From where I'm sitting,the only computer used was the one to photo-shop the sail onto the cargo ship.
There's one born every minute.

Thanks Hans.

Good points.

It isn't a "fudge" - check the original references.

But (do?) I detect a bit of "tongue in cheek" on your part!

If it was a fudge it would take the wind out of the sails of the discussion wouldn't it? (Soory for the pun - not).

I am enjoying the discussion - a bit of "heat" and "slamming" though - nothing of concern - its all part of the game.

But in case anyone has forgotten, there were 2 pics in my OP (original post).

The other (forgotten/over-looked/ignored?) one is/was?:
http://i200.photobucket.com/albums/aa294/oldtiffie/Biker_and_babe1.jpg

Not getting any traction at all is it - or is it getting more in the pic than it is in this thread?

Evan
01-28-2008, 08:04 PM
The video is very convincing, especially the part about 2 minutes 45 seconds in that clearly shows the wind blowing from the starboard side but the parasail is tracking directly in front of the ship where it is flying perfectly with the lift creating the towing force. The line, which looks to be at least an inch or more in diameter is stretched absolutely straight.

A.K. Boomer
01-28-2008, 09:56 PM
It is indicated airspeed. What do you think it means?



You talking to me??? We already had this conversation Evan, remember when I spanked you silly on this? Its not "airspeed" Its a resistance meter your reading, its a measurement of air density, air temperature, air humidity and air speed, another words --- your airspeed can vary (in the air medium that your flying) and you can still have the same reading on your "airspeed indicator" if the other variables vary in opposing ways --- or if the other variables vary it can make your precious "air speed indicator" read more or less even though your going the same air speed.

You can call it an airspeed and fly by it and it will work perfectly for you --- but its an air friction meter that your viewing , an air resistance meter, Its actually way more critical than an "airspeed meter" -- for if we simply had real airspeed meters that we used for critical things like stall we could all turn on the news right now and hear about all the thousands of crashes, By the way, I have to re-write aviation here too (why stop now) The proper term is not called stall speed -- its stall resistance ------ thats what your airspeed indicator actually is, Big diff. Ev Going by stall speed alone we would all be dead right now ---- You see --- when you understand theory of operation you can buck decades of aviation --------- you can literally tell it like it is and NOBODY can touch you, And even people who consider themselves advanced pilots either have to adapt and listen, or put up a fight like you did -- and take a spanking on it,;)

Now --- We can do this the easy way -- or we can do it the hard way, It doesn't matter to me --- somebodys either going to learn something or their going to get embarrassed ---- its all good, Any questions:D

Why am i such a smartass to you? You keep forgetting when you call me out on something you better have your act together, and then you keep forgetting to get your act together... (plus --- I kinda like ya --- and i do respect much of what you have to say, but by no means everything esp. in my area's of know how, however --- iv learned many a thing in area's I didnt know a thing about --- so im not complaining) Your a blockhead Evan, But It takes one to know one... gimme your best rebuttal and take your spankin... you know your gonna, dont know why but you will....

sconisbee
01-28-2008, 10:41 PM
It is indicated airspeed. What do you think it means?

Evan is right, it doesnt matter that its measured by a friction meter or not...the entire aviation world knows it as IAS thats Indicated Air Speed... IAS is not measured by friction, its a measurment of the difference in pressure between the static pressure port and the pitot tube pressure, the only time IAS is the same as TAS is at 15°C and 29.92 in. Hg at sea level at all other times IAS is off by a certain degree however it can be corrected for to give Calibrated Airspeed CAS which inturn also has some small errors. Thus even though IAS is not "ground speed" it is still linked to groundspeed when you know the local conditions.

I'm glad Evan watched the video too i was quite impressed by just how much work they have put into this idea. and as stated before if its only 5% savings its worth it. And regarding *zigzaggin* as was mentioned earlier, evan is also correct as the ship just goes along its normal course and uses the skysail when it can, infact as part of the sky sails package the company provides the customer with a route optimisation service ontop of the skysails.

A.K. Boomer
01-28-2008, 11:07 PM
Dude you kill me!!!, He's not right at all, but because he has the masses behind him that makes you feel comfortable, Im the exact opposite my friend --- all I need is the truth and im very comfortable --- no matter who I butt heads with I have the comfort of knowing if push comes down to shove, I can give them and anybody else on the planet the spanking of their lives;)

Its an air resistance meter, and if you dont really look at it that way your theories of flight are very dangerous. but dont worry -- thats just your theories, you can use it for what its not and do just fine, just pay attention to it --- because even though you dont know what it means -- its still very very important K?

Back to Evans initial statement on the barge, Why are you so stoked about a 5% savings when U know who is completely content with throwing away 50% ??? Not trying to stir the pot, just curious I guess?

sconisbee
01-28-2008, 11:41 PM
Boomer, check your facts, an air friciton meter is an anemometer like so...

http://www.anemometers.co.uk/anemometer_01.jpg

Now this is *not* how an aircraft measures airspeed, an aircraft has a static pitot system, one closed tube one open ended, or one thats combined, this provides a ram air stream into the instruments including the IAS dial, which in its most basic terms measures the difference between the static pressure in the closed tube and the ram air pressure.. See below

http://www.aerospaceweb.org/question/instruments/airspeed/pitot-static-system.jpg


A key device you will see on the nose or wing of most aircraft is called a pitot tube. The purpose of this instrument is to measure the dynamic pressure, sometimes called the ram or impact pressure, the plane experiences as it moves through the air. Aircraft also take another measurement of the atmospheric pressure that is called the static pressure. The difference between the dynamic and static pressures is used to determine the indicated airspeed (IAS) that is displayed to the pilot on the airspeed indicator in the cockpit.
taken from http://www.aerospaceweb.org/question/instruments/q0251.shtml

there is not one single mention about air friction meters. The pitot tube system has its inacuracies and failings which is why its called IAS, because it is only an indication. because ram air pressure changes due to angle of attack amongst other things.

I remain neutral, i dont always believe evan and i dont care who the masses follow. Evan has been wrong in the past as im sure has everyone else infact the only one that seems to "never be wrong" is you boomer.

Before you assume anything or rant on perhaps you might want to check your facts next time. Air resistance meters and Pitot systems are so very different.

Moreover the *whole* argument is pointless as whether it gives 5% or 20% or 50% or 70% savings/improvment then surely its a good thing right? Or are you saying that all the research on polution is wrong? Marine logistics is a very complicated thing and believe me no company like skysails would even dare to produce something like this without doing their homework. I have seen the MS Beluga SkySails with my own eyes and have seen it with her skaysail flying and trust me there is alot of interest in this technology in the marine sector....how do i know? oh well 90% of my business comes from marine and i live less than 30 minutes from one of the worlds deepest harbours and my brother works and has degrees in Marine Logistics, so does this make me a hillbilly too?

A.K. Boomer
01-29-2008, 12:43 AM
Sconsibee, We can get even crazier than that unit but my point is is even the simple pitot tube (which like you state is whats on most planes) is way more than what people call an airspeed meter, Like I said -- airspeed is just one of the equations of many it uses to move its dial --- it really should not be called an airspeed meter any more than it should be called an air density meter as either of these factors will drastically change the final reading...

As far as you stating about looking for the little improvement being a good thing i could not agree more, and when i see massive amounts i say go after it tooth and nail, Research on pollution and minimizing it is awesome, but theres some obvious things we already know ------ Cut through the crap and make it count right? a tow angle of 45 degree's to the sky is a waste of 50%, its too much lift and lift is lift, were not trying to fly, We need tow to get from point A to point B -- tow is horizontal --- Idealy 100% tow, and then you start taking away what you will need for the proper hight above the water and control, It can be achieved with single digit figures, Not 50%...

100% lift and the boat goes nowhere, 100% tow and all energies are being utilized.

sconisbee
01-29-2008, 01:10 AM
a tow angle of 45 degree's to the sky is a waste of 50%, its too much lift and lift is lift.

If you had done your research you will have noted that the skysails system has its computer controling the angle of the sail, thus its not always at 45 degrees and its angle of attack is infact dynamicly adjusted by the computer system onboard ship, this means that when a sudden gust comes they can "park" the sail at 90 degrees and have no forward thrust, and in lighter winds sit it at say 20 degrees and get more pull. The computers also furl and unfurly the sail dynamicly to achieve the most efficient pull.

A.K. Boomer
01-29-2008, 01:33 AM
And if you had done your research you would find that the angle of attack arguement started with the barge --- what i was actually trying to tell Evan is it could be done up much better ---- thanks for bringing to light the skysails topic,
I just looked at the pics , Go re-read what i already wrote ------- just what my arguement was -------- let out a ton of tow line, keep it high but far away so that the tow angle is as low as possible, Also -- go take a look at what this has all been about -- the first pic of the barge, those guys are hillbilly's,--- if thats their sails position, Its all in print bro, its crazy, its like i can predict the future ----- no no no, no tricks, just know my theory's of operation thats all... By the way, look at how broad faced that vert. sail is in the skysails pics, like I also stated -- you can make a vert. work if you do this, and they appear to have kept their stability as the sails out of the water huh.... Im accepting the fact that the guys on the barge can maybe change their sail to do much more, if thats the case then their not hillbillys, but my entire arguement is if they cant then they are --- But Evan however was defending that first pic, This was his statement "The parasail as shown is operating at it's most efficient for several reasons." I could not listen to that bro, Thanks for bringing it up, anything else you want to add?

Evan
01-29-2008, 02:43 AM
Why do you keep trying to beat the truth Boomer? Indicated airspeed is a measure of the ram air pressure in the pitot tube compared to a vent that isn't under ram pressure. What it tells the pilot is how fast his plane is going based on the same factors that determine stall speed and Vne (never exceed velocity). Those two numbers are what matters.

It doesn't make the least bit of difference what the altitude, temperature or baro pressure is the stall speed doesn't change relative to the indicated airspeed. If you didn't have an airspeed indicator you wouldn't know how close you are to either stalling or ripping the tail off in a dive. It's rather important and is why it is one of the five non-electronic instruments that is still required to be present on the panel of every certified plane including a 747. Of all the possible instruments the airspeed indicator is the single most important for actually flying the aircraft. It's because it automatically takes into account variations in air density that it is used and is useful.


But Evan however was defending that first pic,

Nice try but no escape that easy. The first pic is merely a moment in time in the normal operation of the parasail. Watch the video.

dicks42000
01-29-2008, 06:28 AM
Well, of course Sconisbee & Evan have a good understanding of how it's measured.
Ask any seagull, ultra-light or hang glider pilot about IAS....Ever "taken off" in a breeze and once at altitude, throttled back abit while heading into the wind and not gone anywhere relative to the ground ?
It's funny to see the seagulls flying beside the bridge on a windy day and not going anywhere. They seem to be enjoying it, though.
Carriers turn into the wind and make max. speed to fly off aircraft....
It's all "relative"....
Rick

A.K. Boomer
01-29-2008, 12:31 PM
Why do you keep trying to beat the truth Boomer? Indicated airspeed is a measure of the ram air pressure in the pitot tube compared to a vent that isn't under ram pressure. What it tells the pilot is how fast his plane is going based on the same factors that determine stall speed and Vne (never exceed velocity). Those two numbers are what matters.

It doesn't make the least bit of difference what the altitude, temperature or baro pressure is the stall speed doesn't change relative to the indicated airspeed. If you didn't have an airspeed indicator you wouldn't know how close you are to either stalling or ripping the tail off in a dive. It's rather important and is why it is one of the five non-electronic instruments that is still required to be present on the panel of every certified plane including a 747. Of all the possible instruments the airspeed indicator is the single most important for actually flying the aircraft. It's because it automatically takes into account variations in air density that it is used and is useful.







Im all calmed down this morning, I ran out of 2% for my coffee and had to go to the store to pick some up --- i got a little upset about that --- but I chilled for awhile and waited before I posted as You guys were humane to me -- so i wanted to return the favor, Im done being a smart ass --- (unless my smartass button gets pushed again)


I really do want you guys to get this, I think it very important, and I promise I will keep an open mind for you to convince me, but please hear me out and try to forget for a second that Im such a butthead, :p

Now, For one, We are in agreement that this is the most important gauge/meter on the plane, and like Evan stated above its critical for stall and VNE, In fact --- You could be a pilot for a thousand years and If you use this gauge by its name "airspeed indicator" you most likely will not have a problem, however, thats not what the gauge is, the gauge is an airspeed density/temp/humidity/speed indicator with most of its emphasis on two things speed and density, and either of these two things can drastically change the outcome of the needle and what its pointing to,

We can go two directions with this, we can look at the plane going through the air or air going around the plane, since D42000 just used the seagulls as an example and was satisfied with Evans and Scons explanation lets take that one --------- we have two planes -------- one is in leadville colo. elevation 10,000 ft. one is at sea level, both planes are facing a direct headwind, a perfectly steady headwind, they are just above indicated stall speed yet 100 ft above the ground and holding dead even with the ground ------- there are state of the art air stations on the ground that are measuring the speed of the wind ----- why dont they match up with the indicated airspeed in the planes? Its because the plane in leadville has air that is very thin, the air has to travel much faster over the plane to keep it from falling out of the sky, the ground station is reporting steady wind in excess of 100mph yet the planes air speed indicator is 72 mph, its because the plane is using a resistance indicator, not a speed indicator -- its actually better than what the ground station is using because it compensates for air density AND speed, Its resistance that keeps your plane in the air, it is the single biggest factor in aviation,
The plane at sea level has 72mph indicated airspeed also, and the ground station is reading 72 mph, because the air is dense its creating the full effect on the pitot tube, the pitot tube is an ideal blend of BOTH speed and density...


So --- in summary, it does Not tell a pilot how fast his plane is going as Evan states above, it has no solid connection to ground speed or airspeed, Its a ram air devise that measures pressure/resistance, and the main contributors to the pressure/resistance are both speed AND density,
Evans last statement is right on the money --- "Of all the possible instruments the airspeed indicator is the single most important for actually flying the aircraft. It's because it automatically takes into account variations in air density that it is used and is useful."

but because he said it automatically takes into account the variations in air density he cooked his own goose ------- its because of this very factor that you cannot rightfully call it an "airspeed indicator" Its not, airspeed can be all over the place and the needle can be rock stable ---- I however can call it an air resistance gauge and nobody can argue with that, because thats exactly what it is,,, its the correct way of looking at it ---------- and its also the correct way of looking at flight,
Another quote;
"It doesn't make the least bit of difference what the altitude, temperature or baro pressure is the stall speed doesn't change relative to the indicated airspeed."
That statement is only true because your not looking at indicated airspeed Evan, your looking at indicated resistance, for if it was actually indicated airspeed most of us would be dead.



If you still dont get it read this quick example ----- dead calm, no wind, How come airplanes at altitude have to take off and land at such High ground speeds? (its a fact) Lets see, no wind means that thats higher airspeeds also, yet the airspeed indicator in the plane is reading the same, its because its not an airspeed indicator guys, its a resistance meter, its simple theory's of operation that separate people who just do it and dont ask any questions to the people who do because they know its important to understand Why,,,
WHY you ask? because if you dont understand the proper way of looking at what the meter really is - you could find yourself out of runway in leadville colorado thats why -------- cheers.

Evan
01-29-2008, 01:28 PM
the gauge is an airspeed density/temp/humidity/speed indicator
No it isn't. There is no way to determine those values from it's reading. You need other sources of information to deduce those values.


it does Not tell a pilot how fast his plane is going as Evan states above,
That isn't what I said. I said "What it tells the pilot is how fast his plane is going based on the same factors that determine stall speed and Vne (never exceed velocity)."

That is exactly what it does. It gives a velocity indication that is directly relative to those velocity limits because they are all influenced to the same degree by the same factors. You aren't understanding this here or in the last discussion. It's called AIRSPEED because it is the aircraft's aerodynamic velocity through the air. That number is what you need to know to fly a plane, first and foremost.


...its emphisis on two things speed and density, and either of these two things can drastically change the outcome of the needle and what its pointing to,
So what? That isn't relevant to it's intended purpose. As I said in the previous thread it isn't for calculating your ground speed. It's for flying the plane and for that knowing your ground speed is useless. You could be flying backward in a stiff headwind but that has exactly zero effect on the performance of the aircraft. It is ALL about indicated airspeed.



dead calm, no wind, How come airplanes at altitude have to take off and land at such High ground speeds? (its a fact) Lets see, no wind means that thats higher airspeeds also, yet the airspeed indicator in the plane is reading the same, its because its not an airspeed indicator guys, its a resistance meter,,

Of course it is reading the same. That's what you need to know and that is why it exists. It is measuring and indicating the effective aerodynamic speed (velocity) through the air to provide the required lift to fly the plane.

Get over the idea of ground speed. Until the aircraft touches the ground the ground speed has absolutely nothing to do with how the plane flys.

A.K. Boomer
01-29-2008, 03:59 PM
No it isn't. There is no way to determine those values from it's reading. You need other sources of information to deduce those values.
Not trying to separate them Evan, just an understanding that it IS those values that make up the reading, Yes you have to have better equipment to separate them, but they are the sum of all the value's --- not the sum of one -- big diff. Ev


It's called AIRSPEED because it is the aircraft's aerodynamic velocity through the air. That number is what you need to know to fly a plane, first and foremost.

It will get you by -- but its not what the number means -- its air resistance Ev, IT IS NOT THE AIRCRAFTS AERODYNAMIC VELOCITY THROUGH THE AIR,,,
If you were Chucky Y. and made that statement I would first off compliment you on the size of your balls maybe even offer you my wheelbarrow to push them around in and then call you a hillbilly and tell you whats been keeping your plane in the air all these years...



It's for flying the plane and for that knowing your ground speed is useless.

Thats where you get caught Ev,,, flying where im at its good to know the difference, altitude is where the resistance meter proves to be the proper term for the most important gauge we use, its also where calling it an airspeed indicator is flawed thinking, if you had a speedo hooked to your planes wheels upon landing and takeoffs you would imediatly see the flawed logic as the ground speed AND airspeed is much more at altitude for takeoffs and landings, (even though your air speed Indicator is showing identical, thats why its not really what its called) This is why you need to be prepared out here, If your landing or taking off at altitude its going to be much faster of a landing or takeoff, we got people from kansas overshooting the runways all the time, yes there are tons of other factors involved too, but first and foremost is your resistance has to be kept at the same value at altitude for stall/landing ---- at altitude this requires traveling at faster speed through the thin medium ------- period ----- Your meter isnt reading that, but it is accurately reading the resistance.
In keeping your theorys correct you dont have to manipulate anything, its kinda like telling the truth, if you never lie you never have to try to keep your story straight, When talking about how the most important instrument functions in an aircraft its good to tell the truth...




Of course it is reading the same. That's what you need to know and that is why it exists. It is measuring and indicating the effective aerodynamic speed (velocity) through the air to provide the required lift to fly the plane.

Nope, its indicating the effective resistance ------ period...


Get over the idea of ground speed. Until the aircraft touches the ground the ground speed has absolutely nothing to do with how the plane flys.

Well said --- you can call each increment a fannywaggle and if you know your marks and stick to them it will keep you out of trouble in flight wherever you go, until you have to take off or land at different altitudes, then you really should know what that gauge is actually telling you, Or I dont care who you are -- or who you think you are, you dont have a good understanding of your craft...

A.K. Boomer
01-29-2008, 04:04 PM
Hey -- how come I didnt get the darkend box quotes above? i did everything right...

never mind - i figured it out, yes --- im a computer hillbilly ;>}

speedsport
01-29-2008, 04:58 PM
Hey Boomer, If Burt Rutan sided with Evan in this arguement would you tell him hes a idiot as well?