Slashdot Mirror
Hypersonic Test Aircraft Peeled Apart After 3 Minutes of Sustained Mach 20 Speed
coondoggie writes "DARPA's experimental Hypersonic Technology Vehicle (HTV-2), lost significant portions of its outer skin and became uncontrollable after three minutes of sustained Mach 20 speed last August. That was the conclusion of an independent engineering review board investigating the cause of what DARPA calls a 'flight anomaly' in the second test flight of the HTV-2. Quoting the report: 'The resulting gaps created strong, impulsive shock waves around the vehicle as it traveled nearly 13,000 miles per hour, causing the vehicle to roll abruptly. Based on knowledge gained from the first flight in 2010 and incorporated into the second flight, the vehicle's aerodynamic stability allowed it to right itself successfully after several shockwave-induced rolls. Eventually, however, the severity of the continued disturbances finally exceeded the vehicle's ability to recover.'"
The technology exhibited here is completely independent of the fuel source on which it runs. Your comment misses the point.
And scientifically, it went around 750 miles in 3 minutes. In an atmosphere. That's a pretty damn awesome piece of engineering.
"Little does he know, but there is no 'I' in 'Idiot'!"
Isn't that close to reentry speed? What did they expect? If we had a cheap, durable, stable material that could stand up to that for any length of time we would have used it on the Space Shuttles and maybe kept them flying for another 10 years.
That's the point of DARPA. To figure out how to answer these sorts of questions.
Yes. Science and engineering are often advanced by never doing anything you are not absolutely certain will work perfectly.
Why yes, I AM a rocket scientist!
So what the fuck is the alternative, then? Do you really want it to be nuclear-powered? Is that really what you want? Because I know you'd be among the first to bitch and moan when the same thing happens during the next trial, and then there's goddamn uranium or plutonium raining down all over the place.
No, solar power won't work in this case. No, wind power won't work in this case. No, hydro power won't work in this case. No, tidal power won't work in this case. No, burning hydrogen won't work in this case. No, burning coal won't work in this case. No, burning wood won't work in this case. No, you peddling your ass off on a bicycle won't work in this case. None of these other energy sources will work.
So I'll ask you again, WHAT THE FUCK IS THE ALTERNATIVE?
IMHO, this was not a failure, just another step forward. We learned something useful, to be explored/applied next.
Good job, folks! Keep moving forward....
Down With Slashdot BETA!!! I've been around the corner and seen the oliphant; you can only abuse me from your perspecti
Because it can teach you how to build a plane that goes that fast and *doesn't* burn itself to pieces. This is the closest we've ever gotten to that.
Science and engineering are often advanced by never doing anything you are not absolutely certain will work perfectly.
/. articles should have this as the first comment.
Many, many
It seems we have completely forgotten the words 'trial and error', and 'that's interesting...'
But Mach 20? Really? Does it really serve a purpose other than finding out that we can push the limits of things?
Purpose? Probably to build a long-range bomber that can hit a target anywhere on Earth a few minutes after it's been identified. Or to build a vehicle that can reach low Earth orbit and return. Or maybe just to see what's humanly possible.
The fact that they corrected the problems found in the first test, and have a clear idea about why the second test failed, speaks very well to this program. I look forward to reading more about it.
The English word fart is one of the oldest words in the English vocabulary.
several points (not all covered here, these are just a few that immediately popped into my head):
-from the telemetry they can determine how exactly the materials and structure failed. From this better material and structure design for slower aircraft making them more survivable;
-from the telemetry they can determine the high stress points on a craft travelling at such a speed (I can imagine, the leading edges of the control surfaces, the wingtips and the nose will get stupendously hot and massive vortices spilling from the trailing edges may have had something to do with the failure of the superstructure). Again, this leads to improvements in aircraft design;
-from observation and telemetry they can determine the aerodynamic stresses at the moment of failure.
As lessons previously learned: in reinforced carbon composite skinning, it is known that several thin and continuous layers are far stronger than a single thick, segmented layer. This principle is used in hulls on sporting boats, as hull integrity at speed is kinda important. When we learn how to spin alloys into a contiguous undulating skin we'll be doing well.
Consider also that without such pioneers as Chuck Yeager we would not have transsonic or supersonic airliners. We would not know how to compensate for TS turbulence, or how differently control surfaces behave across the sound barrier, or how baffles slow intake air enough so as not to shatter fan blades, or most importantly, how the human body reacts to such unnatural velocities.
Operation Guillotine is in effect.
This close to the bleeding edge, definitely. We have better models and more teraflops to run them than ever before, but real breakthroughs come from unexpected, unintuitive results. Remember how hard it was for most engineers to believe that mere foam could bash in a shuttle wing - until they fired an actual piece of foam at an actual leading-edge panel?
Flying real hardware is still the only way to conclusively
1. Learn Something (if it has problems) or
2. Silence the critics (if it works fine).
IMHO, while a good number of aerospace contracts can be criticized for either being pork or thinly veiled airliner-maker subsidies, that should be focused on those never producing an instrumented flight.
It already happens -- even today you sometimes spend more time in the airport at each end than you spent in the air.
I wonder if a hypersonic passenger craft would have to be cleared for landing before they even took off?
Oliver's law of assumed responsibility: If you're seen fixing it, you will be blamed for breaking it.