NASA's X-43A Vehicle Ready for Flight

Aielman writes "NASA has set March 27 as the date for testing the X-43A vehicle over a Navy range in the Pacific. It will be testing a non-rocket air breathing scramjet engine at approximately 5,000 mph. This is the second attempt, the first ending in intentional destruction due to course deviations shortly after launch."

Comments

I got to wondering what the fastest flight was...

[dukarukus]

(all from guinnessworldrecords.com)

Fastest Winged Aircraft
On October 3, 1967, an X-15A-2 piloted by USAF Major William J. "Pete" Knight, was released from its B-52 mother plane at 10,668 m. (35,000 ft.) above the Mojave Desert where it achieved an absolute speed record of Mach 6.7. (4,520 mph)

Fastest Airliner
The Tupolev Tu-144, first flown on December 31, 1968, was reported to have reached Mach 2.4, or 2,587 km/h (1,600 mph), but normal cruising speed was Mach 2.2. The Tupolev TU-144, which Nato codenamed 'Charger', was built as a competitor to the British and French Concorde supersonic jetliner, however one of the aircraft crashed during a presentation at the Paris Air Show in 1973.

Fastest Biplane
The fastest biplane was the Italian Fiat CR42B. The plane had a 1,100-hp (753-kw) Daimler-Benz DB601A engine, which propelled the craft to speeds of 520 km/h (323 mph) in 1941. Although only a single CR42B prototype was built, 1,780 of the CR42B Falco were produced. It proved invaluable to the Italian Air Force in World War II.

I realize this last one isn't about speed, i just thought it was cool :)
Longest Paper Airplane Flight
The level flight duration record for a hand-launched paper airplane is 27.6 sec., by Ken Blackburn of the USA, at the Georgia Dome, Atlanta, Georgia, USA, on October 8, 1998.

I don't mean to sound bitter ...

[Daniel Dvorkin]

... but why weren't we doing this 40+ years ago? The X-43 seems to me like a logical evolution of the X-15, which is the kind of thing we should have been working on all this time. Big dumb one-shot boosters to get heavy materials that we never intend to bring back down into space, combined with winged air-launched reusable vehicles for carrying people, instead of hybrids like the Saturn V and the Shuttle ... it seems so obvious, now that we've had decades of a space program which now can't even reliably get people into and out of LEO.

I'd like to think that we will, in the next decade, see a manned descendant of the X-43 which will use scramjets to achieve orbital velocities and rockets for maneuvering in orbit, and will provide human transportation to/from LEO orders of magnitude cheaper than the Shuttle. It's certainly technically possible. But I'm not holding my breath.

Re:I don't mean to sound bitter ...

[delibes]

Although ramjets have been around for decades, they've generally been used at speeds of around Mach 1-3. The BOMARC webpage gives a good example, with a speed of just under 2000 mph. Scramjets might one day be developed to work well at around Mach 5-10, but it's been a tricky problem for engineers to solve.

Scramjet combustion is tricky because the fast air flow can easily blow out the flame. Imagine blowing gently on a small match flame to increase the flame versus blowing strongly on a candle flame to put it out.

Also the shape of the scramjet generally favours a "sweet-spot" in air pressure (altitude) and speed. This makes them OK for cruise missiles, but not so good for orbital launch rockets. You can try variable geometry (change the shape of the inlet/nozzle) but that means some machinery, which adds weight to the system.

That brings me onto another problem - thrust/weight ratio. Rocket engines get much higher thrust/weight ratios than air breathing engines. The best air-breathing thrust-weight design that I've seen is Skylon's SABRE (not a ramjet) which will be nice if they can ever build it.