View Full Version : OT - NASA's Scramjet...

Mike Burdick
11-14-2004, 01:22 AM
Scramjet, now this is pretty neat!


Some more info:


11-14-2004, 02:32 AM
Yes very intersting but NASA weren't the first to get supersonic combustion to work.

The University of Queensland flew a scramjet two years ago on a shoestring budget.


Google is your friend for more info.

11-14-2004, 04:58 AM
'Scuse me, but the SR71 used supersonic ramjet engines good to somewhere above mach three. Circa 1950's. Not exactly new...

Yes, I know, the flow in the engine was dropped to below sonic speed, but the engine was a miracle of engineering done with slide rules. Also, the maximum altitude of the SR71 has never been revealed.

[This message has been edited by Evan (edited 11-14-2004).]

11-14-2004, 05:03 AM
"Yes very intersting but NASA weren't the first to get supersonic combustion to work."

I'm sure the drawing is over simplified but the drawing looks like a pulsejet engine. The German V2 rockets went supersonic with the pulsejet engine during WWII. That's a little longer than 2 years ago. http://bbs.homeshopmachinist.net//biggrin.gif

Correction: The V1 rockets used pulsejet but the V2 didn't. It used liquid O2 but it did go supersonic. I thought they both ran pulsejet engines.

[This message has been edited by pgmrdan (edited 11-14-2004).]

11-14-2004, 10:28 AM
<font face="Verdana, Arial" size="2">Originally posted by pgmrdan:
"Yes very intersting but NASA weren't the first to get supersonic combustion to work."

I'm sure the drawing is over simplified but the drawing looks like a pulsejet engine. The German V2 rockets went supersonic with the pulsejet engine during WWII. That's a little longer than 2 years ago. http://bbs.homeshopmachinist.net//biggrin.gif

[This message has been edited by pgmrdan (edited 11-14-2004).]</font>

Those engines may have been cpable of supersonic flight, but those V1s never went that fast. A lightly loaded supermarine spitfire(the sexyest single engine fighter ever) could push one out of the sky.
My late father had the job of testing captured enemy power plant at Wright Paterson airforce base during WW2, and tested V1 motors.

11-14-2004, 11:40 AM
Yep, V1's couldn't cut it but I referred to the V2's, not the V1's. See my correction above where I mistakenly thought the V2 used pulsejet to achieve supersonic speeds.

"The V-2 was first used in September, 1944. Like the V-1 Flying Bomb it carried a one ton warhead. However, this 14 metres (47 feet) long, liquid-fuelled rocket was capable of supersonic speed and could fly at an altitude of over 50 miles. As a result it could not be effectively stopped once launched.

Over 5,000 V-2s were fired on Britain. However, only 1,100 reached Britain. These rockets killed 2,724 people and badly injured 6,000. After the D-Day landings, Allied troops were on mainland Europe and they were able to capture the launch sites and by March, 1945, the attacks came to an end. "

[This message has been edited by pgmrdan (edited 11-14-2004).]

11-14-2004, 12:21 PM
The U. Queensland folks were the first to get a SCRAM jet to work. But, this was a benchtop test setup only. The NASA project actually flies a craft.

While the SR-71 is jet powered and travels faster than sound, it has conventional jet engines.

The sailient difference between a conventional jet and a SCRAM jet is the speed of the airflow through the engine. In a conventional jet, the airflow through the engine is subsonic until it reaches the tailpipe. What this means is that for a plane in supersonic flight the air flowing into the engine must first be slowwed down to subsonic speed before it can be consumed by the engine. The air is energized in the engine and then reaccelerated to supersonic speed in the tailpipe nozzel. This need to slow the airflow leads to great inefficiency.

Hence the desire for the SCRAM jet where the airflow stays supersonic while it travels through the engine. This is the goal for the mentioned projects, to achieve efficient high supersonic flight by means of a SCRAM jet.

Mike Burdick
11-14-2004, 03:17 PM
A couple of more links:



11-14-2004, 04:17 PM
When Ringer mentioned supersonic combustion I thought he meant using some form of combustion engine to exceed supersonic speed but it appears he meant supersonic speed air being used for combustion. Looks like the SR71 doesn't fit this category nor does the V2.

11-14-2004, 05:19 PM
I seem to recall reading somewhere that at altitude the SR71s engines acted like ram jets engines.

11-14-2004, 06:59 PM
They do. Their engines are considered a hybrid turbojet/ramjet.

The air inside the engine is slowed down below supersonic.

[This message has been edited by pgmrdan (edited 11-14-2004).]

11-14-2004, 08:06 PM
How high can the SR71 go? the pilots have astronaut wings.. I talked to one guy in Huntsville after a tournament over there.

I pushed one on a simulator up and it went black with most beautiful star cloud.

SUpermarine was my favorite simulator warbird. I think the cannon on it was tops. It was designed to drop the bombers out of the sky.
Get up close and walk the rudder back and forth washing the engines one at a time with cannon fire and soon you are flying in a debris field..
WITH the hot-rod computer I had just built with voodoo 3 board, you could see the shadows of your own airplane on the debris as it went past.
I became a addict. Not sure where that version Combat simulator went. I played online, played offline, the bullets when they whacked the aircraft made the same sound as they do when they hit a car you are riding in.. Make your palms sweat.

AND them kids, the ten and eleven year olds would splash US old guys in a matter of minutes. No sparring, fighting for a shooting position.. But I had a stock list of aircraft.. no mods..

That is the future of combat, remote intelligence.. where you lose machinery and not qualified pilots.


11-14-2004, 09:44 PM
I will post some stuff tomorrow....

11-15-2004, 12:28 AM
Here's a photo of the SR71 engine on a test stand running.


Ivy McNeil

11-15-2004, 12:31 AM
That's an impressive picture. I wouldn't like to be paying the fuel bill http://bbs.homeshopmachinist.net//biggrin.gif

And also the University of Queensland did fly a scram jet in the atmosphere except because of lack of money it had to fly downwards to get the necessary speed. Supersonic combustion did happen before it hit the ground.

[This message has been edited by Ringer (edited 11-14-2004).]

Mike Burdick
11-15-2004, 12:55 AM
Here's a link that discusses the "Blackbird's" specifications and history. Scroll down a bit to find out how it’s engine functioned.


11-15-2004, 03:04 PM
You will note that the service ceiling spec only says 85,000+ as well as the maximum speed spec says mach 3.2+. The actual numbers are still classified.

An interesting thing happened a few years ago. It isn't likely that you will find any reference to it online as it has been supressed. A couple of months after the air force stood down the SR71 the seismic network that covers southern California recorded a sonic boom that traveled across the state from San Diego to Nevada, headed for Groom Lake. It was traveling at mach 3.5

Also, several years ago an item made the news here in BC. It was shown once on the evening news and never seen again. That in itself is highly unusual especially considering the nature of the item. A person with a high quality camcorder took footage of something flying from north to south over the Fraser River delta just east from Vancouver. The something displayed a contrail that can only be formed at extremely high altitude where the air pressure is low enough. This means well above 100,000 feet, more likely around 200,000 or so. At that altitude the contrail from an engine spreads out at about a 45 degree angle as there is no pressure to constrict it. I have personally seen this my self when watching an ICBM test launch at Vandenberg. The third stage contrail spreads out in a wide vee shape.

The "something" that flew over the Vancouver area was being "escorted" by two F-16s at far lower altitude. They were all headed towards Groom Lake. The story was killed immediately and is not in the archives.

Also, an experienced plane spotter who was working on a north sea oil platform saw a black triangular aircraft at extreme altitude heading towards England. He was extremely certain that it wasn't any aircraft known to exist.

I have to be careful how much I say here because there are some serious security issues involved. What I have said is all in the public domain although it has been supressed.

[This message has been edited by Evan (edited 11-15-2004).]

11-15-2004, 04:12 PM
There is both an SR-71 and a German V-1 on display at Lackland AFB in San Antonio. Have not seen them for about 5 years, but when my daughter was younger, we went right up to the SR-71 - no fence around it - but I recall that the engines were removed. The V-1 still had the primitive pulse jet engine in it with plywood plugs over each end. I saw it in detail in the early 70's when a friend of mine did a Master's thesis on pulse jet engines - I held the fire extinguisher when he ran his engine - the experiment was to examine the flame front inside the engine which was made of GLASS!! He took 1,000 frame/second 35mm film of the flame pattern through the glass - made a Schleering diagram on a sheet in front of the camera. Scary at the time, and only done ONCE!! A.T.

11-15-2004, 04:18 PM
At such high altitudes how does the engine get enough oxygen to suppport combustion????

11-15-2004, 04:31 PM

Several possibilities exist. A hypersonic ramjet will possibly function as high as 200,000 feet, certainly up to 150,000. Ramjets will operate at much lower air density than conventional jets. Also it is thought that the plane in question, usually referred to as Aurora, is a hydrogen ramjet. Hydrogen has the property of being able to burn very lean. It has a very wide volume range that it will burn in, notably at the lean end. It can burn at mixture ratios with oxygen as low as 4% to as high as 75%.

Also, the engine may be a hybrid, ramjet/rocket. It wouldn't be much more of a trick to inject oxidiser along with fuel.

This is a frame from the video that aired on BCTV news only the one time. It is clearly not a known aircraft type. The extent of the contrail spread is not as obvious as it is watching the video but is still clearly not what one would expect. I just happened to snag the image off the TV station web site before it was taken down the next day.


[This message has been edited by Evan (edited 11-15-2004).]

11-15-2004, 05:01 PM
Nasa was experimenting with a kerosene + hydrogen peroxide rocket.

The kerosene was self igniting at the pressures achieved. A pretty blue flame. Add this to a turbine and whoosh.

I was playing with the ideal to fuel a vehicle. I ran out of money before I got anywhere.

Hydrogen peroxide is the future fuel. Both in cells and propulsion.
I have been told it is too dangerous. BUT I see gasoline being dispensed everyday into vehicles by people who take it for granted, some smoking.. Others talking on cell phones..
I think that is why all the vehicles went to a poly gas tank.. that and crushing/fires like the pinto/chev truck was blamed with.

THE Nazi's had it first I think.. Thier catalyst was kinda fast thou. As Many pilots killed by accidents as shot down. One drop of each could shatter windows in a hangar they say.

Spin Doctor
11-15-2004, 07:03 PM
I wouldn't be suprised if the Air Scouts/NASA/DAPRA have some very unusual birds flying. A while back the Air Force/DAPRA was doing paper studies of a vehicle called Black Horse that would use either a set of conventional engines or a liquid fueled rocker engine to get to altitude with a partial load of fuel/oxidizer where it could tank from a KC-135/KC-10 and then head for orbit. From the information I found on the web and a couple of articles I read I seem to remember they were looking at some form of aviation kerosene with H2O2 as the oxidizer. The nice thing about the two is that they are both liquid at normal opertaing temperatures. The kerosene fuel while having less specific impulse than H2 does have the advantage that it is much more energy dense. As to whether the bird ever got built is of course unknown (probably not IMO). Its also possible that some sort of successor to the SR-71 got built and may or may not be flying.

11-15-2004, 07:52 PM
Used to see SR-71s at Kadena AB Okinawa nearly forty years ago. Where did the time go?
Here's an interesting site, maybe Evan saw them commuting between Groom Lake and Scotland....

11-15-2004, 09:13 PM
From having read about and finally seen a Blackbird on display I didn't quite grasp how the engines worked as ramjets until I got a closeup look.The nacelles have scavenging ports just aft of the afterburner sections on each engine.The thing reminded me of my forge burner,hot fast moving gas pulling in more air for combustion.

As for the future fuel,I think Burt Rutan has the ticket,Hydroxy-terminated polybutadiene(rubber)and nitrous oxide.The rubber is a solid and the nitrous is a liquid,both are stable and easy to store,until brought together and ignited with a high temperature then its up,up and away,plus unlike solid rockets you can shut them down just by turning off the nitrous.

[This message has been edited by wierdscience (edited 11-15-2004).]

Sandy H
11-15-2004, 09:37 PM
As a young guy, I find feats like the SR-71 almost unimaginable, especially given the understanding of the physics at the time. They did the cutting edge research to make it work, not just relying on completely understood phenomena. There were decades and decades of pioneering work done, financial support for the project and an infrastructure built to sustain their existence for decades more, for years without public knowledge.

I for one, really hope there is a true 'skunkworks' buried somewhere turning out this level of real science and engineering. Part of me fears that media scrutiny, financial detail and politics has killed this level of science without boundaries.

I can still hope. . .


11-15-2004, 11:29 PM
The SR71 is my absolute favorite airplane. As someone who has extensive aircraft metal working experience it just blows me away that they were able to design and build something like that in the late 1950's and early 60s using only slide rules.

It went from concept to first flight in 1 1/2 years. There are actually several models, the A12 and the SR71. There is also the SR-71C trainer, the only two seater produced. NASA now has it.

The sad thing is that this capability seems to have been lost. I'm not sure we could get to the moon within a couple of years if the planet depended on it.

11-15-2004, 11:45 PM
I dunno about them using slide rules now,but Lockheed is still pretty compitant,at least the skunk works is.
Did any of you see the Nova special on the X-plane compition? I think its the management style at the skunk works that makes it a success.Give a team a task and hands off from HQ.
During WWII many of their designs started out with tape measures and chalk lines on the shop floor,sound familiar?

11-15-2004, 11:52 PM
Dunno Wierd, in one of those infamous political decisions all the tooling and dies for the SR-71 were destroyed. We can't even build another SR-71.

11-16-2004, 12:07 AM
Im just going to assume that *we* have something much better than the Sr71 flying now that we won't find out about for many years to come.

11-16-2004, 04:11 PM
I saw the molds for this item built in my city a few years back, many of my former students and a fellow instructor did the programming and production. Many parts also made here im my town. Looks like the X-43 predecessor


Saw a Blackbird once, up close and personal at Bowling AFB. Amazing how truly big these were. Did not know at the time what it was exactly, I was a bit younger then.

[This message has been edited by spope14 (edited 11-16-2004).]