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Virgin Galactic SpaceShipTwo's Re-entry Tech: the Feather
Dutch Gun writes: When most people think about rocket science, they think of the challenge of getting a spacecraft into space. However, the problem of safely re-entering the atmosphere is a daunting challenge as well. Virgin Galactic introduces us to the concept of "the feather," their term for the combination of fixed-wing and capsule based solutions both used by spaceships in the past, and explain how they believe this hybrid approach to be a superior solution. SpaceShipTwo folds its wings in the initial decent, acting a bit like a badminton shuttlecock, when a capsule decent has the most advantages. In the latter part of the decent, the wings are extended, giving the vehicle the advantages of a glider-like landing.
How can someone misspell descent three times in two sentences?
you initiate the feather to soon and cause the spaceship to break up.
For those interested, the documentary Black Sky is a must-see on explaining how this concept (and SpaceShipOne in general) works.
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Branson and Virgin did nothing at all except provide funding after the fact to the actual, certified genius aerodynamist and visionary Burt Rutan. /., I will just introduce Rutan to the crowd who might be attracted to the silly clickbait article: Burt has for about
Since it is far outside the knowledge domain of
40 years years been designing outstanding aircraft, some large, most small. He designed for NASA, for Jim Bede, and for thousands of home builders. He pioneered the modern use of canard winds and composite construction. He designed many famous aircraft including SpaceShipOne and its unique tail feathering.
I have serious doubts that a feathered reentry would work for anything that has orbital reentry speed. There's a reason we have capsules with heat shields, and it's still tricky. We lost a shuttle over damaged heat shields. I suspect there would be strong vibration issues at orbital reentry speed as well that they haven't had to face yet since all of their flights so far (as well as those actually scheduled) have been sub-orbital. That being said, I wish them luck and hope they continue to innovate.
The feathering mechanism is very clever and effective, and I'm sure that Richard Branson and Virgin Galactic love getting free advertising on Slashdot. But this concept - the mechanism, the shuttlecock behavior, the passive stabilization - was successfully demonstrated when SpaceShipOne won the X-Prize ... in 2004.
So please explain, Oh submitter and editors, why are you cluttering up our lives with old news?
What's the news in this? This has been Virgin's approach for many years now, and it's very interesting, but what brought this to the front page today? Did something change?
What kind of parachute are you going to deploy at several times the speed of sound? No chance.
3 "decent" fails actually.
First of all, this is really old news. SpaceShip One no longer flies and has been a museum piece for years, and Virgin's burned their bridges with Scaled Composites and thus made it a lot less likely that they will be able to mount a near space effort with the SpaceShip Two design.
Second, this is not an orbital re-entry system, because it's not well-suited for a heat shield and thus can't do the necessary atmospheric braking. It's just a system to get you back from high altitude suborbital flights.
Bruce Perens.
However, the problem of safely re-entering the atmosphere is a daunting challenge as well.
Yes this is especially true since they updated Kerbal Space Program manager to 1.02...
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Just under orbital speed, around 7000 metres per second?
Seven puppies were harmed during the making of this post.
I would still like to see a redundant parachute in case of the the mechanical failure of the the wing folding mechanism.
A redundant parachute would be worthless. Deploying a parachute at supersonic speeds from an spacecraft will simply make confetti. The unfeathered spacecraft likely would be torn to pieces before it could slow down to speeds where a parachute might be effective, hence the problem.
The feathering mechanism, like many things in engineering, simply must work without fail as there is no plausible backup option. Failure of the feathering mechanism means likely loss of crew and vehicle.
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The initial entry is in "shuttlecock" position, which is neat because it both has an easier surface to protect and can stay thermal-armor-down without a chute or thrusters.
The risk is that when it's time to "open" the wings and transform to plane mode, that complex mechanical stuff fails. At that point it seems useful to have a parachute. I'd wonder about the weight though - there's usually multiple chutes involved to cope with the speed, and that can get heavy (although the first chute is sometimes there just to orient the ship, which skipped here).
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There are no wings. Either the feathers rotate back to become a stabilizer, or the craft is torn to pieces (see video of the most recent failure).
The parachute is for if they don't reopen, after shuttlecock mode has done it's job.
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You know, you're correct in saying if they wings don't close, well then, you're proper fucked.
The parachute is for if they don't reopen, after shuttlecock mode has done it's job.
True, good point. Though, with a parachute, there needs to be some clear abort envelopes and interlocks in place to prevent parachute deployment at an inappropriate time.
Adding backup systems increases the complexity of the system as a whole, and can sometimes introduce more failure modes, actually decreasing the overall safety of the system. Having a simple system with no backup can actually be the safest arrangement. It depends on whether you want to gamble with an 0.01% chance of a completely unsurvivable failure with no backup, or have a 1% chance of failure, with a backup that might save you 99% of the time, but the backup system may itself cause a unrecoverable failure in 0.5% of the flights.
It's complex, requires a lot of engineering analysis, and personal feelings about safety can actually lead to the most unsafe solution.
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It never gets anywhere close to orbital speed. SS2 is to max out at about 1 km/s. It also won't even reach the Karman line, they're aiming for the 50 mile/80 km altitude where Air Force pilots get astronaut wings via a purely bureaucratic definition.
It's a rocket plane. A rocket AIRplane. It's not a spacecraft, and the technology is not relevant to spacecraft.
It reminds me of Branson crowing about how environmentally friendly and efficient their hybrid motor is. "We have reduced the [carbon emission] cost of somebody going into space from something like two weeks of New York’s electricity supply to less than the cost of an economy round-trip from Singapore to London."
Never mind that spaceflight would have to scale up many orders of magnitude to be a meaningful contributor to carbon emissions, that there are few rockets that emit as much carbon for their performance as their hybrid, or that they produce fewer emissions simply because they aren't doing anywhere near as much.