Ordinary-fuel scramjet prototype suffers test failure An innovative hypersonics programme has suffered a failure, with a prototype scramjet missile failing to perform properly and crashing into the Pacific after less than a minute in the air. HyFly dual-combustion ramjet in windtunnel tests It works well here... Aviation Week reports that a "HyFly" test airframe was launched …
"The scramjet engine did not operate as expected and after approximately 58 seconds of flight, the vehicle impacted the ocean."
So...given the likely altitude at which the poor unsuspecting little blighter was released, is the "flight" in question akin to the "flight" demonstrated by a brick released from a block of flats...?
"As an example, the proposed A2 hydrogen hypersonic airliner is bigger than an Airbus A380 superjumbo, yet it can carry barely a third as many passengers because it is mainly a vast cylindrical hydrogen tank"
So it's basically a hypersonic zeppelin? Hindenburg we go again...
Blew up because a static spark set fire to the fabric covering the airship. Though that is a matter of debate, and I guess the static spark could have set fire to the hydrogen cells themselves.
Airships are making a comeback, certainly they are more efficient and greener than a scramjet, which is a waste of damn time for commercial use. The ability to get a few rich f**ks from London to New York an hour or so quicker is hardly a goal worth pursuing. Ditto Branson and his useless spaceship program.
Hypersonic wind tunnels tend to be very small cross section tunnels (about 100cm2) attached to extremely large pressure vessels. The pressure vessel is filled with very high pressure air which is then allowed to rapidly vent through the wind tunnel. This produces hypersonic flows fro fractions of seconds or sometimes as much as a second. The airflows over the models are studied using high speed cameras and Schlieren photography.
High Supersonic speed tunnels do not use fans as a more conventional low speed tunnel would. Instead they work on a pressure difference between a very high pressure vessel and a very low pressure vessel. As a result you tend to have a system that will have a run time of say up to a minute (about as long as the contraption worked, co-incidence?) rather than continuously. Essentially the faster you want a wind tunnel the shorter time it is going to run for.
On the missile front, that is not too far beyond the performance MDBA get out of the throttle able solid rocket motor fitted to the Meteor (see your local Wikipedia for more [probably inaccurate] details).
I don't know what sort of wind tunnel they're actually using, but I've heard about hypersonic test chambers powered by a huge tank of compressed gas on one side and an even larger tank evacuated down to a near vaccuum. I didn't think that they had terribly large test chambers, however.
On a side note, how many articles a week feature a mention of DARPA? Seems like they've been productive recently. At producing news, at least.
This post has been deleted by its author
"It took Edison 100's of attempts before he got a working lightbulb."
And recent rumour is that he stole that design. What's documented is that Francis Upton was actually the "engineering lead" in the practical incandescent bulb design, not T.A. Edison.
http://www.unmuseum.org/lightbulb.htm
58 Seconds?
By Nick Palmer
Posted Thursday 7th February 2008 15:16 GMT
"The scramjet engine did not operate as expected and after approximately 58 seconds of flight, the vehicle impacted the ocean."
So...given the likely altitude at which the poor unsuspecting little blighter was released, is the "flight" in question akin to the "flight" demonstrated by a brick released from a block of flats...?
========
This is very unlikely - 60 seconds is about what it would take to drop 1.5 miles. (Keep in mind that terminal velocity is about 120 MPH.) That is not very high.
Terminal velocity of what? I'm pretty sure that the terminal velocity of a feather is much slower, and a feather would take much longer than 58 seconds to fall 1.5 miles. This scramjet thingy looks quite streamlined and so could have a terminal velocity greater than 120 MPH.
I've seen paper aeroplanes fly for longer than 58 seconds!
@george I would suggest you read a good book on Hypersonic Compression Ram Air jet engines and come back and rephrase your answer !
The main rocket booster appears to be of the same size and shape as that of a surplus Hercules Rocket Motor as was used in the now out of service AIM54C Phoenix missile which had a burn time of 90 seconds to reach a peak altitude of 90,000 ft and hit a Mach 5 terminal velocity !
Enough of this dumb and stupid lecture , I'll get my coat .
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