News Virgin Galactic SpaceShipTwo accident during powered test flight

[C3PO]

This "prototype", as you call it, was meant to take on passengers within a year. When it comes to lifes, you add the complexity you need to add to keep those lifes safe... and twice as true when you are flying passengers that have some expecrations of making it back home in one piece and healthy. Point final!

In that case space tourism ends today. I don't think you've grasped how dangerous space flight really is. Nobody is going to be able to offer airline-grade safety on space travel in the next 10-20 years, not even on suborbital trips. The captured V2s reached space in the mid 1940s, but it took a decade more to reach orbit and that was with cold-war budgets. Private space flight is presently barely past the Wright-flyer stage.

Safety wise base jumping is a walk in the park compared to even "just" a sub-orbital hop. Climbing Everest might be a bit closer, and nobody expects guaranteed safety on a trip up there. But it's that level of danger we're talking about. The only difference is that good physical condition doesn't mean squat if something goes wrong with your space craft if you're a passenger.

 

[Evil_Onyx]

According to this (linked from Wikipedia) B.A.S.E Jumping has a fatality every 2,317 jumps

According to This the Everest Summit to Fatality rate is 1.82% but is lower for failed assents (i.e. they don't make it to the top) K2 is a far more scary stats wise, of the 300 summits 31 died on the way down, 71 people have died making an attempt on K2. Statistics for the number of attempts at Mt Everest is not clear.

Statistically Sub Orbital flight still safer than climbing K2, but how many manned sub orbital flights has there been? Mecury (two flights), X-15(two recognised by FAI), SpaceShipOne(Three flights over 100km), SpaceShipTwo?

 

[C3PO]

Soyuz 18a: At least one injured, perhaps one minor and one serious. The reports vary quite a bit. But that went accidentally sub-orbital, so does it count?

But yeah, the cohort in sub-orbital flight is way too small to draw any meaningful statistical conclusion. And I'm afraid that once the number of flights increases, we are going to have some fatalities if history is anything to go by. The amount of energy involved makes it almost inevitable.

But IMHO that is not a good reason to stop.

 

[Evil_Onyx]

I did not include Spyuz 18a as it was not meant to be sub orbital.

I think Sub orbital Transportation (Intercontinental passenger flights) is some thing we should be striving for, but this incident is not going to help getting there.

 

[statickid]

sorry :shifty:

 

[llarian]

What really gets me is the rush to judgement about causes before any assessment is done. Must be rubber-necker syndrome. Also there is the numerous prognostications from so-called experts (all of whom seem to be employed in competing areas or are otherwise self-serving) that private or commercial space flight is now suddenly dead.

Delayed perhaps. Anyone consider the number of ships and lives that were lost while mankind was just exploring this planet ... without leaving the ground?

And does anyone remember Lieutenant Thomas E. Selfridge? He was the passenger who was killed in the first fatal airplane crash. The pilot? Wilbur Wright. Wright was injured but survived. Considering that the crash occurred in September 1908, what was the accuracy of statements that powered flight was at an end as it was too unsafe?

They will find the cause. Be patient. Try to simulate the incident. And carry on supporting the efforts to get us off this rock.

 

[Urwumpe]

Also there is the numerous prognostications from so-called experts (all of whom seem to be employed in competing areas or are otherwise self-serving) that private or commercial space flight is now suddenly dead.

"The report of my death was an exaggeration."

 

[SHADO]

Latest news from Virgin Galactic but nothing new.

http://www.virgingalactic.com/statement-from-virgin-galactic/

 

[RGClark]

I saw this video mentioned on Rand Simberg's blog, Transterrestrial, of an earlier powered SS2 flight.

The video is from the outside facing towards the rear of the vehicle. But it's accompanied by an audio and you can hear that the pilots state that they are unlocking the feather when the motor is still burning. The feather doesn't deploy until it is commanded to do so later after the rocket has ceased burning:

SpaceShipTwo's Intense Rocket Ride - Tail View and Cockpit Recording | Video.
Published on Sep 6, 2013

A camera was strapped to the rear of the Virgin Galactic vehicle to capture footage of the rocket engines and feather system at work. The vehicles 2nd powered flight occurred on September 5th, 2013.

Bob Clark

 

[statickid]

however there may be a critical difference in the actual timing that has nothing to do with the engine being on or off, such as a transient turbulence or pressure wave passing over the feathers in a certain way that is no longer an issue at mach 1.4

 

[C3PO]

How many Gs are they pulling during that pitch-up maneuver? The voices/breathing sound like people in a centrifuge or during hard aerobatic maneuvers, especially the very sharp exhaling. This doesn't sound like child's play.

 

[Urwumpe]

How many Gs are they pulling during that pitch-up maneuver? The voices/breathing sound like people in a centrifuge or during hard aerobatic maneuvers, especially the very sharp exhaling. This doesn't sound like child's play.

Peak acceleration during reentry should again be +5 g, that is still within Space Shuttle and rollercoaster ride limits.

 

[pattersonlee]

From an interview with the Scaled production head:

"Pivoting the tail section for descent increases the ship's surface area so that it can safely and effortlessly re-enter Earth's atmosphere, 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, Mike Moses, Virgin Galactic vice president of operations, explained in an interview with Reuters.

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," Moses said. "It's like your car airbag going off at 65 miles per hour."


So the feathers are "hooked" until the "unhook" switch is flipped which essentially makes them free to move depending on what aero forces are on them? And they unhook them doing boost in case of an abort. It strikes me as incredibly bad to rely on when a pilot flips a switch during the burn of a rocket to ensure that aero structures aren't accidentally ripped from the vehicle.

there must be more to it than this.

 

[rhoude57]

In that case space tourism ends today. I don't think you've grasped how dangerous space flight really is. Nobody is going to be able to offer airline-grade safety on space travel in the next 10-20 years, not even on suborbital trips. The captured V2s reached space in the mid 1940s, but it took a decade more to reach orbit and that was with cold-war budgets. Private space flight is presently barely past the Wright-flyer stage.

Safety wise base jumping is a walk in the park compared to even "just" a sub-orbital hop. Climbing Everest might be a bit closer, and nobody expects guaranteed safety on a trip up there. But it's that level of danger we're talking about. The only difference is that good physical condition doesn't mean squat if something goes wrong with your space craft if you're a passenger.

Spend a little time going through VG's web site and you'll discover that "airline-grade safety on space travel" is exactly what they are pitching to their customer base. The challenge is tall, but not impossible, IMHO. Yes, we are dealing with Rocket Science and monster loads of energy expended at an astronomical rate... Yes, we are dealing with one of the most unforgiving environments for humans to evolve in. Yes, perhaps naïve civilians think they can do better and faster, cheaper than NASA could ever achieve. Perhaps, shortcuts are being taken on the belief "the NASA Way" was way overdoing things... Only time will tell... but I believe it will happen...

 

[Donamy]

Also, have to remember, there is something important when it comes to spaceflight, ... "The Right Stuff".

 

[Andy44]

Making this thing safe is an obvious no-brainer for this kind of program. You're not sending test pilots on daring missions anymore, you're trying to give sight-seeing rides to lay people.

Given that this is uncharted territory, it's not easy, but it does not seem insurmountable, certainly not by the standards of orbital flight.

Also, have to remember, there is something important when it comes to spaceflight, ... "The Right Stuff".

With commercial space tourism, "Right Stuff" is actually something you get out of your bank account to buy a ticket...

 

[dman]

It's true. Alsbury was the one who unlocked the feathering mechanism, but another command is required to actually initiate the feathering configuration change. The actual feather deploy, as what happened in the anomaly, was entirely uncommanded from what we currently know. 2 seconds after that, the vehicle disintegrated.

There ARE two levers to deploy the feathers. Only the unlock lever was hit. Pilot error is possible, but not confirmed, at this point.
__________________

Sounds little like Gus Grissom on 2nd Mercury flight

Grissom removed safety pin and the hatch blew , It took 40 lbs of pressure on plunger to fire it and other astronausts said recoil would leave welt

Believed stray voltage or short caused hatch to blow......

 

[PhantomCruiser]

Does anyone know if the command to feather is manual or automatically initiated due to a load change on the vehicle? Or it a matter of either/or?

 

[C3PO]

Making this thing safe is an obvious no-brainer for this kind of program. You're not sending test pilots on daring missions anymore, you're trying to give sight-seeing rides to lay people.

Given that this is uncharted territory, it's not easy, but it does not seem insurmountable, certainly not by the standards of orbital flight.



With commercial space tourism, "Right Stuff" is actually something you get out of your bank account to buy a ticket...

Well, safe is a relative term. I don't think space flight safety is going to catch up with airline safety, unless airlines start doing sub-orbital flights. But we are still at the beginning of the road to space tourism. We still don't know what space tourism will look like when it finally takes off. In the 60s everybody thought we'd be traveling supersonic by now, but the demand never materialized. But we still might get there. Predicting technical breakthroughs has not been very successful historically. But yeah, safety is a no-brainer. But as "safe as practical", not "safe as possible".

And I consider anyone that willingly straps in to a rocket powered vehicle to have a bit of "the right stuff". Either that or unbelievable ignorance.

 

[Urwumpe]

It's true. Alsbury was the one who unlocked the feathering mechanism, but another command is required to actually initiate the feathering configuration change. The actual feather deploy, as what happened in the anomaly, was entirely uncommanded from what we currently know. 2 seconds after that, the vehicle disintegrated.

There ARE two levers to deploy the feathers. Only the unlock lever was hit. Pilot error is possible, but not confirmed, at this point.

Thats not that easy. The important detail is in the Scaled statement: "Held back by aerodynamic forces". In transonic flight, these forces change quickly resulting in the aft part of the plane going from subsonic to supersonic airflow.

And Mach 1.4, where the lever is usually pulled, the wave drag effect is over and the airflow is "smoothly" supersonic around the plane, while in this accident, the plane was still in the transition at about Mach 1. Even a small change in the feathering would have big effects on the chaotic forces that act on the feathering actuator.

It is really possible that this early unlocking overpowered the feathering actuator and deployed the feather by different aerodynamic forces.