Virgin Galactic spaceship crashes

[island911]

Originally Posted by flipper35

From NTSB
Hart: Review of cockpit forward looking camera shows that the feather was unlocked by the copilot. #SpaceShipTwo
Hart: Normal procedures are to unlock feathers after Mach 1.4 so aerodynamic forces do not extend feathers prematurely. #SpaceShipTwo
Hart: Engine burn was nominal up until feather extension. #SpaceShipTwo

but earlier, you were insisting that it was pulled minutes earlier.

Originally Posted by flipper35

Perhaps if you don't understand the dynamics of the situation you should go read up on aerodynamics. Plus, he didn't pull the release a couple seconds early. He pulled it a couple minutes early.

Read: it doesn't take minutes to go from 600mph to 1.4_M under 3G rocket power.

[flipper35]

It is carried by WK2 and dropped at those altitudes already. Look at some of the other videos, you can see the altimeter at 56k on one of them when it is dropped.

That said, they are looking at more efficient fuels. The original rubber was quick, dirty and effective on SS1.

[flipper35]

Originally Posted by island911

but earlier, you were insisting that it was pulled minutes earlier.



Read: it doesn't take minutes to go from 600mph to 1.4_M under 3G rocket power.

I said minutes thinking they were pulling it for re-entry.

[island911]

Originally Posted by flipper35

It is carried by WK2 and dropped at those altitudes already. Look at some of the other videos, you can see the altimeter at 56k on one of them when it is dropped.

So much conflicting information floating about.

I suppose there is the likelihood that they can exceed 50k under light testing conditions; but loaded with 1200_lb of passengers would be a problem. ..safety factor to stall and all. (dunno)

Originally Posted by flipper35

That said, they are looking at more efficient fuels. The original rubber was quick, dirty and effective on SS1.

Rubber is the material that the early rocket scientists found to do the best job of controlling the burn. It's well proven/understood. Non-uniform chemical kinetics can really ruin your day/rocket.

[flipper35]

Originally Posted by island911

So much conflicting information floating about.

That is for sure.

On the Scaled web site it said they were having issues with the rubber fuel on engine burns longer than 20 second.

[red-beard]

Virgin Galactic crash: worried passengers ask for refunds - Telegraph

[island911]

Thanks RB

it supports my speculation.
- the unlock happens during rocket accel
- the tail remains pinned back by aerodynamic forces (it's not like pulling a hood release)
- transonic shockwaves dancing unsympathetic waves

Pivoting the tail section for descent increases the ship's surface area so
that it can float down to Earth, flying like a badminton shuttlecock. It had
been used dozens of times during SpaceShipTwo's atmospheric test flights,
including two rocket-powered flights.

As the ship is rocketing upward, the tail is held fast by a large hook that is
supposed to remain engaged until the craft reaches supersonic speed,

At that point, the pilots release the hook, though the tail remains pinned
back by aerodynamic pressures. The command to actually move the tail into
descent position comes after the rocket motor burns out, near the apex of
the ship's altitude. Unlocking the tail is done well before then so that if
the mechanism fails, the pilots can abort the flight.

"It's a great safety feature, but if you use your safety feature in a
regime that it's not designed to handle, bad things are going to happen,"
Mike Moses, Virgin Galactic vice president of operations, told Reuters. "It's
like your car airbag going off at 65 miles per hour."

[red-beard]

Has anyone pointed out that the change in fuel for the engine had to do with higher than expected weight and a lower than expected launched altitude?