Actually, the stuff that has caught my eye is the Pulse-Detonation Engine which is even cooler than Hypersonic Scramjets. The thing that caught my eye "Supersonic for a Subsonic Price".

The highest official speed record I could find for the SR-71A is 2193.167 mph. The story you reference talks about 3700 mph for the X43A.

That said, I have heard rumors that the SR-71A could do Mach 6*.

So, how fast was the SR-71A Blackbird? The Air Force Museum only says, "Maximum speed: Plus 2,000 mph".

Would that be 2,193.167 mph "Plus 2,000 mph"?

8-)

Doug Sundseth

*An interesting thing to remember, though, is that there is no easy way to canonically compare Mach number to speed without knowing the temperature, which varies with altitude.

You see, the Mach number of an object is the multiple of the local speed of sound at which the object is traveling. The speed of sound drops as the square root of the temperature. According to NASA, "temperature changes with altitude in a very complex way".

It is possible that an object traveling at Mach 7 could be slower than an object traveling at Mach 6, if the Mach number is measured at temperatures that vary sufficiently.

The first "test" flight of the X43A is tomorrow, March 27, 2004.

http://www.nasa.gov/home/hqnews/2004/mar/HQ_04098_x43_flight.html

(sorry, I don't know how to make the link work. my html is rusty)

Doug: As I recall, when they set the top speed "record" in the Blackbird, they actually intentionally just set for a speed they knew would break the last record to a significant degree, and just sought to hit that speed. They intentionally throttled the bird down in order to make that number, and refuse to allow the machine's true top speed to be recorded. Speculation is that it may be a great deal faster than that officially recorded top speed.

Note that the Blackbird is so fast that you could light a cigarette off its skin after it's been at hypersonic speeds. The temperature and other stresses actually cause the machine other problems: in order to hold fuel at cruising altitude, the fuel tanks actually leak when they're on the ground. They only seal up properly once the plane is in the air and moving fast--something about the material heating up and stretching actually closes off the leaks. When she's on the ground, the Blackbird constantly oozes fuel, and typically she has to be refueled in the air within a few minutes of takeoff. Then when the tanks are all warmed up, she can go for a skip across the globe.

It is, truly, the most amazing airplane ever put into production. To date, anyway. And as I say, her top speed is classified, and the military claims that they significantly slowed her down on the day they set that speed record.

Note that the top altitude of the Blackbird is top secret--the Blackbird holds the record for top altitude, mind you, but again, the military says they intentionally flew her lower than they needed to on the day they set that record.

There is a rumor out there that at least one Blackbird actually went too high, wound up drifting out of the atmosphere and extinguishing its engines as a result, then burning up when it re-entered the atmosphere.

This is, of course, a totally uncomfirmed rumor.

Still. It is an amazing machine, truly amazing. More or less obsoleted by spy satellites, although last I heard there's one or two still in operation for special missions.

Dean,
What is even more amazing is the technology or lack of it to build Blackbird. It first flew in 1964 and that was only about 12 months after the contract was let. By today's standards the computer technology was very crude and yet the aircraft's performance has never been matched and we have never lost one to enemy action.

It drove the Russians crazy trying to figure out how to shoot it down.

The aircraft would get about one foot longer when hot do to expansion. The designers figured the airframe would last forever. That's because each flight got hot enough to stress relieve the airframe. That made each flight as if the airframe had just rolled out of the factory.

Ted, I'm with you. The more I learn about the Blackbird, the more agog I am at what a stupendous achievement it was for the Skunkworks.

By the way, here's an interesting bit of trivia I'll bet you don't know:

There were three planes planned for this series from Lockheed: The Reconnaissance Bomber, the Reconnaissance Fighter, and the Reconnaissance Scout. All were supposed to be very fast, very high-flying. The Scout would be the fastest and highest flying of all, but the other two were still supposed to be amazing in their own right, and quite deadly.

Thus the Blackbird was originally dubbed the RS-71.

So how did it become the SR-71? Well as it turns out, it's Lyndon Johnson's fault. In a speech where he advocated the funding to finish development and purchase of this line of airplanes, he flubbed his lines and repeatedly referred to it as the "SR-71 Blackbird" instead of its proper designation of "RS-71 Blackbird."

In order to avoid embarassing the President, the good folks at Lockheed and the Pentagon decided to quietly change the designation.

No foolin'.

You know, I'd give almost anything to fly in one of those birds, I really would.

Ted: um, no. ;)

Kelly Johnson was called to Washington in 1958, when they started the competition to replace the U-2. Lockheed won the contract in 1959.

The first A-12 flew April 28, 1962. The first public showing of the YF-12A was the fall of '64. Supposedly the YF-12A was the follow-on to the F-108 Rapier.

But still, three years is very respectable, compared to today's development times. What really trips me out about the Blackbird is that it was designed with nothing more than slide rules. None of this namby-pamby, "let the computer do all the grunt work" stuff!!

I'll let Dean talk about the D-21 drones. Also, about the six A-12s flown by the CIA that have never been accounted for. :)

Some more information on the SR-71A and fueling.

1) When the Blackbird was sitting on the ground, the fuel leaked enough that the entire pad surrounding the plane was wet with fuel. (We're not talking about a few drips here.)

2) As I understand it, the normal procedure was to launch the bird, which would immediately rendezvous with a KC-135Q. If the first pass at the tanker was not successful, the Blackbird would declare a fuel emergency and immediately land. This was not, IIRC, primarily a result of the leaks, but a result of engines designed to be efficient at Mach (whatever), that were extraordinarily inefficient during takeoff.

In terms of the craft's materials, it depends on what altitudes we're talking about. Just as the air temp changes with altitude, so does the air pressure, and thus so does the drag on the airplane and thus the heat from the air resistance. This thing is meant to fly at a much higher altiutude than the blackbird, so to compare the two is more than a bit unfair. Let me put it this way, there's no way that the blackbird could fly at the altitude this thing is meant for, but there's also no way that the X-43 could fly at the speeds that the blackbird did at the altitude for which the blackbird was intended. These two birds really are apples and oranges.

Doug:

"I have heard rumors that the SR-71A could do Mach 6*."

Only rumors. The peak speed of Mach 3.2 is just about the upper limit of the aircraft, and happens to be the record speed.

At a little under Mach 3.3, shockwaves off the nose chines begin to move across and into the engine's intakes. The resulting heating and airflow disruption put a cap on the engine performance.

Ted:

Fantastic aircraft.

It began in 1956 with the Oxcart project for the CIA. The A12 first flew in 1962. (I remember when LBJ publicly announced it, as the A11, picture on the front page of the L.A. Times.)

The the YF-12 fighter project followed the A12 in 1963, and the SR-71 in 1964. The SR-71 contract was let in Feb. 1963, first flight Dec. 22, 1964.

Lockheed built 15 A-12s, three YF-12As and 31 SR-71s.

Dean:

"There is a rumor out there that at least one Blackbird actually went too high, wound up drifting out of the atmosphere and extinguishing its engines as a result, then burning up when it re-entered the atmosphere."

Lots of exciting times for the Blackbird crews, but not quite that "interesting".

The engines had a troubling habit of "unstarting" during cruise flight; one would just quit. They would have to descend a bit, maybe to the mid-60,00s to restart, and then back up to cruise height and motor on.

Sounds like no big deal, except that the pilots recalled that an unstart was easy to detect. One described it as being something like being t-boned by a locomotive.

If you haven't read it, look around for "Sled Driver" by Brian Shul, who flew the airplane for years. Fascinating book.

LBJ apparently malaprop'd several aircraft designations. He called the A12 A11, and the RS-71 SR-71.

The RS-71 was supposed to be next in line after the RS-70.

The what?

When it became clear that flying high wasn't going to be proof against Soviet SAMs, the B-70, with a radar return roughly the size of Idaho, was killed by the Air Force.

Of course, folks working on it didn't think that was right, and tried to figure a way to keep the airplane in the air. They came up with a post-nuclear strike recon (and if the target is twitching, hit it again) role and pitched it as the Recon/Strike RS-70. A few months after it got the go ahead, it got unstarted, and that was it for the B-70, except for two test articles.

Then the XB-70A2 crashed...

My high school physics class got to go to Edwards AFB for a field trip. The highlight was the part of the tour into the hangar where sat the XB-70, almost within our reach. Fantastic aircraft.

The Blackbird is most certainly a hot plane. So hot, the crew can heat their food tubes by holding them against the windows. Nevertheless, it's vulnerable to the SA-5, SA-10 and SA-12. That's why it's kinda-sorta retired and why the next generation SR plane will eschew the blazing comet approach in favor of low-observable and pilotless technology. Send a robot, not a man; and all that.

With regard to the X-43, let's cross our fingers in the hope it succeeds. But let's also remember that the X-15 flew these profiles almost forty years ago. Might we aim a bit higher?

A couple of minor nits:

The top speed for the SR-71 is no longer classified and, according to the NASA researcher who headed their SR-71 operations in 1994, is Mach 3.43. The X-43 Hyper-X, if successful, will just about double that.

Also, a correction to a comment above, this will be the second flight attempt of the X-43. The first failed three years ago shortly after its Pegasus boost stage ignited.

Mike

SR-71; The most awesome, beautiful, aircraft I have ever seen. One of the great engineering accomplishments of all time.
Kelly should be considered one of history's greats.

Hey guys: thanks for the updates, it's been years since I read anything about the Blackbird so I'm not surprised that stuff's been declassified!

You wait till they get the next gen launch vehicle plans out. Ram>Scram>Vasimr

Gee, that's fast. Simple, and clean. No boosters either.

Yeah, we're talking about what happens with the HyperX research, and these other project systems.

Vasimr is to space right now, what HyperX is to aeronautics. What's funny, the X34 successfully tested today. how's that?

but i can't wait till the RSV prototype rolls out for testing. goshdarned.