#SpaceShipTwo has experienced an in-flight anomaly. rumor parachutes seen, Confirmed Loss of vehicle

a reply to: roadgravel

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


Should it have feathered anyway? Of course not. But, according to NTSB copilot disengaged one of the 2 failsafes . Perhaps combo of design flaw and pilot error, but part 1 of this event is very clearly pilot error. Part 2 more than likely wouldn't have happened without part 1.

a reply to: Vdogg

Pilot error contributed, yes. But even with them unlocked the system should have been able to keep them closed.

a reply to: Zaphod58

In your opinion is the problem fixable or does VG have to go back to the drawing board?

a reply to: crazyewok

Oh it's fixable. Shouldn't be incredibly hard to do either. I can think of both software and hardware ways to do it that should work.

a reply to: Zaphod58

It's my understanding that the new plastic-based propellant was being used in an effort to reduce vibration problems that had been previously experienced immediately following engine start and just prior to engine shutdown when using the rubber-based propellant. Even so, I initially thought that the new propellant was a likely cause of the mishap since it was the only new variable in the flight parameters.

Now, it seems likely that there were significant human factors involved. Obvious design factors include the human-machine interface (the lock/unlock lever can be actuated prematurely) and the feathering mechanism (once unlocked it can apparently move uncommanded). There may also be organizational factors involving training and supervision, safety culture, etc., all of which will be explored by the NTSB investigators. This will be a long and intensive effort.

a reply to: Zaphod58

That vibration MAY have helped lead to early deployment

Sure that's possible. I figure the fuel though didn't overwhelm the whole airframe. But vibrations would be something looked at by engineers though. Hopefully higher vibration wouldn't move levers. Of course there are latching systems, etc.

Maybe the cause will be found.

a reply to: Shadowhawk

I am mostly convinced that the fuel played at MOST a very minor role now. The fact that the feathers can move uncommanded surprises me. That HAD to be something they tested for early on, as it's an obvious failure mechanism. If the best they could come up with was "Wait until Mach 1.4 to unlock them", that stuns me.

a reply to: roadgravel

It didn't move the lever to unlock them. That was clearly moved manually. What it MIGHT have done was set up a vibration in the feathers themselves, allowing them to move uncommanded.

From what I understand it's supposed to take both pilots to unlock the feathering mechanism, but when the co-pilot unlocked it prematurely, the feathering mechansim still unlocked and the failsafe failed. In a strange way, if it wasn't for the co-pilot releasing the mechanism early, they might not have learned about the design flaw until having it happen at an even worse time.

It didn't move the lever to unlock them. That was clearly moved manually.

It was written as two steps. Eenable and deploy were separate. I wasn't referring to the first step.

a reply to: roadgravel

Once they're unlocked they don't need the second lever to be moved under some conditions. It's not SUPPOSED to happen but there are some conditions that can cause it in the current design.

a reply to: Junkheap
Well, yes and no. I feel that this could've been found out on the ground without the loss of life. That's why what these test pilots do is so dangerous. You can test these things for thousands of hours and still not find all the kinks. Or, to get Rumsfeldian a bit, it's impossible to know the unknown unknowns. What this does do is put egg on the face of those in the media who claimed this was an explosion due to faulty engine design. I always wait at least 24 hours b4 attempting to draw conclusions about this stuff because initial media info is almost always wrong.

originally posted by: Zaphod58
a reply to: roadgravel

Once they're unlocked they don't need the second lever to be moved under some conditions. It's not SUPPOSED to happen but there are some conditions that can cause it in the current design.

If that is true that was known design flaw.

"they can move but are not supposed to move"

a reply to: roadgravel

Not necessarily a flaw from the sound of it, but a known issue that they chose to overcome by procedure. We'll find out more as the investigation goes on.

a reply to: Zaphod58

The investigation will be interesting and important, for sure.

I dont get it...At Mach 1 the airframe fell apart, yet those flimsy tail pieces were supposed to function better at Mach 1.4...


Sounds to me like they couldn't handle half the speed of sound.

originally posted by: Soloprotocol
I dont get it...At Mach 1 the airframe fell apart, yet those flimsy tail pieces were supposed to function better at Mach 1.4...

Sounds to me like they couldn't handle half the speed of sound.

isn't the point that this is the configuration for descent? not ascent.

sounds to me like you hit that booster and those tail fins go back to landing mode , surely this would tear the thing apart?

Q

a reply to: Soloprotocol

No, they weren't supposed to be unlocked until Mach 1.4. Below that and airflow turbulence could cause exactly this to happen. Once you reach 1.4 and above things smooth out some. Going through the sound barrier is when most stress is on the airframe.

originally posted by: Zaphod58
a reply to: Soloprotocol

No, they weren't supposed to be unlocked until Mach 1.4. Below that and airflow turbulence could cause exactly this to happen. Once you reach 1.4 and above things smooth out some. Going through the sound barrier is when most stress is on the airframe.

Sounds to me like a major school boy error in the design of the back section of the craft. The more i learn about how the machine failed the more scratch my head asking HOW.?

a reply to: Soloprotocol

The same design has worked perfectly until now. Even the shuttle had to throttle down when going supersonic. It puts a lot of stress on a vehicle and can cause problems in many areas.