The problem with a hydrocarbon fuel for a scramjet is that under those conditions it tends to fall apart into carbon and hydrogen.

Hydrogen is fine as it can combust with oxygen and make water, but the carbon bits tend to go all sooty and clog up your engine. You might as well power your jet with coal. (As the USAF intends to indirectly do. See http://www.af.mil/news/story.asp?id=123026906 )

A much better choice for a scramjet is anhydrous ammonia, last seen on the X-15 rocket plane, which oddly enough operated at the speeds needed.

-HJC

DARPA may want hypersonic aircraft for observation despite having ICBMs and satellites so they have options. I think we have seen (repeatedly, now) that satellites are not guaranteed to be around long if the right kind of hostilities break out.

yeah, the plane that could only take off with an almost empty fuel tank, and had to be refueled in air because otherwise the skin would leak fuel on takeoff and could only store enough fuel for a single high speed fly over of the USSR.

Less than barely practical... On the other hand, the Vulcan, now that was a plane!

Hardly inspires confidence, does it? All it means is that the pilot doesn't have to land with the thing on top of him. Meanwhile gossip says the Russians have cracked flight control mechanisms at Mach 6...

SR-71 will be a tough act to follow. Wot a beast - on the runway it would drip fuel cos it had no fuel tanks and its panels only closed up once it got going. Thank goodness Chavs only have rottweillers.

A barrel roll cannot be done in *any* aircraft by sole use of ailerons.

A barrel roll requires positive g throughout, including when the aircraft is inverted. This is accomplished by pulling back on the stick to generate increased g, and also needs a higher than normal entry speed to the maneouver.

Long-chain hydrocarbons might conceivably have a sooting problem, but not, I think, propane. Chilled propane is the best stuff ever; it can be as dense as gasoline but is 18 mass percent hydrogen!

--- G.R.L. Cowan

http://www.eagle.ca/~gcowan/boron_blast.html --

let the baby play with matches in the fuel storage room!

That's going to be one touchy maneuver... almost a shame there won't be a pilot in it to experience it, though the ground bods will probably be wetting themselves...

I know, right? Don't most modern aircraft need to be able to -turn-?

Otherwise, it's just a launch vehicle.

Lewis, you know better than this..

There are three separate types of 360 longitudinal axis rolls on conventional aircraft;

1) Aileron roll - where the stick is just pushed sideways. Zero Gee

Ailerons are not used at speed as their application results in the wing twisting away from it and apparent control reversal. Usually a spoiler is popped up on the opposite wing root to achieve the effect. Check this on your next holiday flight. Fighters have elevons too.

2) Slow roll - An extremely difficult exercise in pilot co-ordination. +1 & -1 Gee.

Where the a/c rolls on a constant track and altitude. The a/c nose follows a complex attitude change.

3) Barrel Roll - A combination of pitch up and roll. Results in +1 gee added onto a/c. Any a/c can barrel roll

I'm amazed to see the words "barely practical" used to describe the SR-71. If you want to fly that high and that fast, the SR-71 is the ONLY way to date it was ever achievable. The SR-71 had plenty of quirks and foibles, but whenever you are at the absolute bleeding edge of the state of the art, no, it is not going to be as ho-hum as a trip to the chemists in a dented Mondeo. The Blackbird was shot at (guns, missiles, interceptors, you name it) something like 4,000 times during the years it flew, NONE were ever brought down by hostile action. If that's "barely practical", I'll have three, please.

The need for non-satellite based surveillance is because satellite orbits are well known and totally predictable. If someone has something they don't want seen from orbit, they just cover it up when the satellite is due overhead. This is kind of a nuisance because there are a lot of satellites orbiting out there, and a lot of imagery (including Google earth, etc.) but when you are talking military secrets, the price of tarpaulins and labor to deploy them isn't an issue. The advantage of the Blackbird was that it was stealthy (to some extent) and was so fast that by the time you realized it had taken your picture, it was long gone.

I like it! Everyone should have one!

Hmmm , still having engine problems I see !

Quote: "If it works, that is - which not very many DARPA projects ever do."

Well, the agency's work during the 1960s on packet-switched redundant networks (first inspired by JCR Licklider and carried through by many others including Bob Kahn and Larry Roberts) seems to work after a fashion.

But I bet when Lick first mused about inter-active computerised communications he didn't foresee Facebook (bitch!), YouPorn, Larry 'n' Brin or phucking Phorm.

... for epic lulz.

If you believe Wikipedia, ( http://en.wikipedia.org/wiki/SR-71#Second_retirement ), and NASA. Like the man said, I'll have three, please.

This looks like a kid's Christmas prezzy wishlist, not specs for something achievable.

It is easy to ask for a computerised watch that fits on your wrist and has a 17 inch screen, wifi and 200W speakers but a lot harder to actually make one.

@Sceptical Bastard:

Well so much for the military and all their security-think. How come the internet has such poxy security? But, I guess you do have a point. DARPA do occasionally throw a double-six. If they always achieved their goals they'd hardly be doing advanced research.

But don't it still look fantastic, even now.

Flames like afterburner

Fwhooooooooooooooooooooooooooooooooooooooooooooooooooooooosh

Any one remember the bad sun activity that pegged the meter and was at something like 40 on a scale of 1-15. One good hit from the sun having a even worse bad solar flare day can wipe out any and all satellites. It sure would be nice to have alternatives handy...

I really don't think that ARPA (as it was then) was spec'ing a worldwide commercial network.

It's research was in self-healing communication networks useful for military communications where many parts of the 'net might be taken out. This would be (and is) used on closed encrypted networks with no public access.

Also, don't tar the original research into packet switching with the poor implementation that plagues many applications now on the Internet.

Of course, there were weaknesses in the original design, such as the DoS SYN attacks or man-in-the-middle data capture attacks that are possible, but the security layers that leak so badly are definitly above the one provided by the basic ARPA design.

If you look at the original suite of applications that were demonstrations of the work (telnet, tenex, ftp, mail), they were useful, and people used them, even if they were basically insecure. The world was a more simple place, and generally the networks they were used on were internal to single organisations. Even then, firewalls were mooted (the first firewall I was aware of pre-dated the Web. by several years).

The concept of the World Wide Web (which is just a service running on the Internet) was NOT part of the ARPA research.

The fact that we are still using it, warts and all, justifies the strength of its original design, and it is only likely to be replaced by a derrivitive work (IPv6).

What's all this about needing to do a barrel roll before being a "real" plane?

Surely pressing R twice isn't That hard...

Alien because I can't see Peppy anywhere...

Please - the SR-71 was, and still is, in my opinion the greatest aviation achievement to date. As to it being retired 20 years ago, as someone has pointed out, it got reactivated in the early 90's and re-retired in 99. The reason for its reactivation is that it still has a place in today's satelite world - it can take 24 hours to reposition a satelite and the SR-71 could do it realistically in a quarter of that time.

I'll put my hands up and say I'm a glorified fanboy for the Blackbird. I'm not ashamed of that and will argue to the death about its use. The fact DARPA are calling the new plane "Blackswift" implies that they see it as a successor - to a cutting edge plane that stayed cutting edge during its 35 year life-span. It's habit of leaking jet fuel on the tarmac only endears me more to it. I'm sure by now we've got materials that can cope with the heat changes but it's easier to build a new version (Blackswift) than retrofit the Blackbird.

One thing I'm surprised at is that DARPA are actually admitting to building it. Don't these things stay classified for about 10 years or so? Or is this really Aurora in new clothes?

Nahhhh....

Karl Lattimer is right is right the Vulcan was by comparison a far greater achievement, bomber to nuclear deterrent back to bomber (scaring the crap out of the argies). The Vulcan was far more practical, the Vulcan kept the cold war cold, the RR engines served Concorde for years there's never been the same degree of mid air refueling than in the Falklands sortes.

The Blackbird was bleeding edge (literaly if you count the fuel leaking), basically the Blackbird was for show, tiny unmanned high altitude surveillance do the job much better (cheaper, no risk to life etc).

The Harrier, Jaguar, Concorde, F111 all were far more all round achievers, whereas the Blackbird just went fast, and lets face it the X-15 wins that particular accolade hands down (although it's not so much of an aircraft).

Oh and while we're at it, the Wright Bothers didn't fly powered aircraft first, they were beaten to it by many others (and their "first" needed a headwind to take off), it's just that the criteria for powered, controlled flight was made up to fit what they actually did (not that it was even proved what they did...) rant over.

PS. Blackbirds aint that fast, I've only had 185mph on the clock on mine and 173mph through the timing gate (stock tune).

"The original Blackbird was elbowed out of its job by spy satellites..."

Not really. It's more like the original Blackbird was killed off by the USAF, which didn't want civilian organisations like the CIA flying Mach 3 aircraft when the USAF's top-of-the-line fighter could only pull Mach 2. (Had the XB-70 entered service things might have been different.)

Karl: The SR-71 never took off with full tanks, and this was done on purpose. The tanks were left mostly empty to facilitate aborted takeoffs; if your plane is heavy, then it's harder to do an emergency landing. The air-refueling was standard safety procedure, not a design flaw.

it astounds me that one with your background misses this, or chooses to.

A missile cannot be recalled. Once launched, a ballistic weapon will hit it's target, it cannot be turned around. Self destruct doesn't quite cut it.

This is the same reason for manned bombers thruout the Cold War. It allows a country to scramble in the face of a threat but does not require a "point of no return" commitment that a missile does. Or in this case, a real flying hypersonic craft.

This thing gets the speed of a missile but can have it's mission aborted, instead of releasing it's payload in a terminal attack, it can turn around and come back some other time.

But then, you couldn't use politically clever stuff like "pork barrel" and other antagonistic terminology if you allowed common sense to take over. And here I dared believe the leopard could change his spots.