Virgin Galatic Spaceship Two down in the Mojave.

[robdean]

First quotes from surviving pilot, via his father:

Space pilot: I came to on the way down ...and gave thumbs up to a passing aircraft to say: 'I'm OK!'* | Daily Mail Online (http://www.dailymail.co.uk/sciencetech/article-2826931/Space-pilot-came-way-gave-thumbs-say-m-OK.html)

‘He doesn’t remember anything from the actual crash. He came to during the descent. He must have woken up about halfway down. When he was on the way down the chase plane was circling him and he was waving and giving the thumbs-up to indicate he was all right while he was dangling from the parachute.
‘He’s recovering at home. He broke the head of the humerus bone that sits in the right shoulder. He’s got a rib and lung contusion and there is an issue with his eyes because of the cold. It was around minus 60 degrees up there.'

[Dogma]

Their experience might make them qualified Engineers but not Test Pilots as we would know it? These lessons on the right experience and qualifications for the task have been learnt before in areas ranging from UAVs to NASA programs.

[West Coast]

And you know this how?

[Rob Bamber]

But I'd rather see these flamboyant salesmen Billionaires spending their money on something that pushes boundaries and provides employment for innovators. I'm as envious of their wealth as the next guy, but get a good feeling from seeing their money go to something that captures the public imagination and perhaps boosts the human spirit of endeavor just a little bit.Whilst I agree with your sentiment, the real world is not that simple. We, in the West, live in a highly financialised economy. People make money trading derivatives and ideas: profit without production. IMHO, the crazy schemes for sending people to Mars are a perfect example of this: ideas for investment, profit today. Nobody will ever actually build anything in the future, but the money will turn around nonetheless.

VG's project sprang off from genius Burt Rutan, and his Scaled Composites. Now that he's retired, I don't see there being sufficient impetus to push forward the practical side of the project; after all, it's difficult and expensive, and the financial types prefer easy money.

Also, I've learned from reading this thread just how far this technology is from orbital flight. It simply won't be scalable to orbital launches, and so any comments about a stepping stone towards private orbiting hotels are misinformation. Yes to "capturing the public imagination" and "boosting human endeavor". But using misinformation to do so would be counter-productive IMHO.

[westhawk]

the real world is not that simple.

Rob Bamber:

I don't think so either. I was just expressing a personal sentiment. I'd rather see the Bigshots put their money into these kind of projects than keep their money out of circulation or invested in boring ventures I care nothing about!

I live in the real world myself. (most of the time)

[Volume]

Such a critical operational requirement seems like an inherently unsafe design.At least it looks like a single failure cause resulting in catastrophic failure...
headed by the expert (genius?) Mr Rutan. I would neither doubt that he is an expert, nor a genius. But is he an expert for supersonic flight and spacecraft ?

[172driver]

Pressing a button at the wrong time should not result in instant death.....

While I agree that it shouldn't result in instant death, getting speeds wrong is inherently dangerous in any aircraft. Extending gear, flaps at the vastly wrong speed will also ruin your day.

From a design POV, this feathering mechanism is a tricky circle to square. You want as few failure modes as possible, yet have to safeguard against unintended / uncommanded deployment.

[jimjim1]

As far as I can see he retired in 2011. He is now 71 years of age.

I doubt he is much involved with Spaceshiptwo but of course who knows what is going on inside a private company.

[joema]

There has been some discussion in this thread if a supersonic ejection (or bail) is survivable.

Yes, some encapsulated ejection systems were survivable at very high altitudes or lower altitudes at high speed, e.g,

B-58: http://www.ejectionsite.com/eb58caps.htm

XB-70: http://www.ejectionsite.com/xb70caps.htm

FB-111A: FB-111A.net (http://www.fb-111a.net/Module.html)

B-1A: http://www.ejectionsite.com/b1amodule.htm

A cabin ejection system requires a many different pyrotechnics, separators, sequencers, aero-stabilization under various conditions, air bags, etc. Yet it's used when the surrounding vehicle is torquing, disintegrating, maybe even exploding. All those complex separation systems have to work in that environment. This probably explains the limited success rate of the above systems.

Also suborbital spacecraft have an even greater problem because the flight envelope is much larger. So the tradeoff is having a conventional ejection system that covers only a fraction of the envelope (e.g, first four Space Shuttle missions), or a heavy, complex ejection system that covers more of the envelope but still not 100%.

Once the flight test phase is over, yet another problem in vehicles like SS2 or the shuttle is handling passenger escape. It's difficult to envision a workable practical system, hence the vehicle itself is the only escape system for much of the envelope.

[hoodie]

... who knows what is going on inside a private company.

Scaled Composites has been wholly owned by Northrop Grumman since 2007.

At least it looks like a single failure cause resulting in catastrophic failure...

Making any technical judgement only on early reports filtered through the media is rarely worthwhile.

[donotdespisethesnake]

I see your point wrt media, but judgements can be made on statements directly from NTSB https://www.ntsb.gov/investigations/2014/mojave_ca/mojave_ca.html.

[WingNut60]

Once the flight test phase is over, yet another problem in vehicles like SS2 or the shuttle is handling passenger escape


Once the flight test phase is over doesn't the vehicle become "just another commercial aircraft" - albeit somewhat specialised?
Why would inflight escape be any more of a consideration, for crew or passengers on this aircraft, than on any other commercial aircraft?


Though it may be a bit more practical than floor lighting and slides :rolleyes:

[RF4]

There has been much speculation and questioning about the locking system and feathering system architecture. I would have no reason to presume that the SS2 architecture of these system is significantly different than the Architecture of the same systems in SS1. It is presumed that the changes that were instituted from SS1 to SS2 were driven primarily by the need for increased size. This meant that the cockpit and cabin size needed considerable up sizing, necessitating changes such as the escape system ( no more ejectible nose cone), dual controls and an enlarged rocket motor. SS1 was a tested/proven system within its design context - no reason to change it.
The only facts that we know about the architecture to-date, is that both systems were pneumatic and the locks have been described as "hooks". This fits completely with SS1 architecture. I suspect that the SS2 architecture was an enlarged and more robust version of the SS1, which is shown and described in detail in Scale Composite's patent application for same:

http://www.spacepatents.com/patented_inventions/pat7195207.pdf

Fig. 7-9

[Radix]

Thanks for that link. Answers a lot of questions!


Ps. I needed to search in Bing to find the patent number as the direct link didn't work.

[ORAC]

This link (http://www.google.co.uk/patents/US7195207) leads to a copy.

[deanm]

Same here, dead link.

Googled "USPTO 7195207"

Interesting!

[Jwscud]

I think anyone expecting this craft to be fully certified would be making a similar mistake to NASA made after 4 flights of the Shuttle. They will never make enough powered flights in the test program to certify it to the same standards as the well understood tropospheric sub Mcrit areas most of us operate in.

DARPA regularly have in-flight breakups of their experimental high Mach number vehicles. This is not an area that is well understood. Most space vehicles brute force their way through it with massive amounts of thrust rather than what Scaled are trying.

[RF4]

Sorry about that ! The link for the SS1 architecture patent should be;

http://www.spacepatents.com/patented_inventions/pat7195207.pdf

[RichardC10]

I wonder if when the design was scaled up from SS1 to SS2, the locks went from a nice to have/safety feature to being absolutely vital to control the feathers in the critical Mach region. It’s clearly marginal, since the locks are not needed when the vehicle is slowing down through the same speeds after engine shut-down.

[thcrozier]

I'd be very interested to know the altitude at which it goes subsonic on descent.

[PrivtPilotRadarTech]

Wall St Journal reports:
The pilot was unaware the co-pilot had prematurely unlocked its movable tail surfaces, recalled falling out of the space plane as it was coming apart, then managing to unbuckle his seat belt before his parachute opened automatically.

[Flash2001]

Interesting that the patent application has what seems to be a typo that would alter the meaning if taken literally!

[peekay4]

From Bloomberg news:

"The (surviving pilot's) last memory before passing out was the realization that the water on his tongue was boiling, according to NASA. Water boils at lower temperatures as pressure decreases." :ooh:

Pilot Who Survived Space Crash Says Parachute Opened Itself - Bloomberg (http://www.bloomberg.com/news/2014-11-12/pilot-who-survived-spacecraft-crash-says-parachute-opened-itself.html)

[Airbubba]

"The (surviving pilot's) last memory before passing out was the realization that the water on his tongue was boiling, according to NASA. Water boils at lower temperatures as pressure decreases."

I believe you misread the Bloomberg article. The water boiling on the tongue was from the 1965 NASA vacuum chamber incident:

At NASA's Manned Spacecraft Center (now renamed Johnson Space Center) we had a test subject accidentally exposed to a near vacuum (less than 1 psi) in an incident involving a leaking space suit in a vacuum chamber back in '65. He remained conscious for about 14 seconds, which is about the time it takes for O2 deprived blood to go from the lungs to the brain. The suit probably did not reach a hard vacuum, and we began repressurizing the chamber within 15 seconds. The subject regained consciousness at around 15,000 feet equivalent altitude. The subject later reported that he could feel and hear the air leaking out, and his last conscious memory was of the water on his tongue beginning to boil.

Human Body in a Vacuum (http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970603.html)

[peekay4]

Ah, right, what a frightful experience that would be!

[jimjim1]

RichardC10
since the locks are not needed when the vehicle is slowing down through the same speeds after engine shut-down.thcrozier
I'd be very interested to know the altitude at which it goes subsonic on descent. It may well be that during the descent the aircraft is subsonic before the feather is lowered and gliding begins.

The idea of the feather is that the aircraft is both stable and has high drag. (I am almost sure that everyone will know this already but not quite:-)


SpaceShipOne Pilot Report (http://www.airbum.com/pireps/PirepSS1.html)

SS1 simulator ride

"As we approached apogee, as indicated by the rate of climb, Jim Siebold, one of the SCALED test pilots who had taken over coaching me, called for feather deployment. I pulled a large lever under my left arm up to unlock the feather, waited until the TONU told me it was unlocked, then pulled the feather lever.
...
In the SS1, once in feather, the airplane is so stable and self-aligning that the pilot doesn’t have a thing to do but wait until it’s down to around 60,000 feet, when he puts it back in glider mode and he starts worrying about finding the airport.

The foregoing is a brilliant concept. It removes the single most terrifying and critical part of space flight. The SS1 never sees indicated re-entry speeds higher than about 130 knots even though mach numbers are approaching 3.2 so it never gets hot."So if an indicated airspeed of 130 was assumed someone could work out the altitude that the aircraft passed below mach one. That would set a lower bound to the altitude since the actual IAS might be lower.

I could root around for a while and get some numbers but there is likely someone here who knows what they are about and I propose to leave that to them.

Ah, coffin corner! Possibly an easy way to get some decent data.

According to the diagram on Coffin corner (aerodynamics) - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Coffin_corner_%28aerodynamics%29) the U2's "mach limit" (pretty sure this is under mach 1) is 125 KIAS at 65,000 ft and 145 KIAS at 60,000 ft. In the case of SS1 then 130 KIAS therefore seems comfortably subsonic at 60,000 ft when the feather is unfeathered. Does anyone have any idea what the stall speed might be? That is, is there any need to go faster again?

If it is the case that the stall speed at 60,000ft is above 145 KIAS then the transonic flight regime could be avoided entirely during the feather stowed portion of the gliding descent to the landing.

[RichardC10]

In the SS2 powered flight video below, the feather deployment (not unlock) command is given at very low speed.

Virgin Galactic's Second Rocket Powered Flight Tail Footage - YouTube

It's interesting that the SS1 simulation has the unlock command very close to the feather command (which seems natural), while the as-flown SS2 sequence moved the feather unlock much earlier (at speed of Mach 1.4). This has been stated to be because they were concerned that an unlock failure would result in a dangerous situation later in the nominal, high-altitude (300,000ft) flight when the mission could not be aborted. So they removed a single-point failure (unlock failure) by moving it to earlier in the flight, but consequently added a new single-point failure of incorrect unlock actuation (at high speed).

[joema]

So they removed a single-point failure (unlock failure) by moving it to earlier in the flight, but consequently added a new single-point failure of incorrect unlock actuation (at high speed).

It's interesting the feathering system is to provide "care-free reentry". The design goal was to eliminate "risky" active control and requirement for precise AOA during reentry. Rutan conceptually modeled it on the self-stabilizing badminton shuttlecock.

However -- to my knowledge there has been only one reentry fatality related to flight control -- the Mike Adams X-15 flight on 15 Nov 1967: https://en.wikipedia.org/wiki/X-15_Flight_3-65-97

Although not widely reported at the time, Scott Carpenter's Mercury mission was a near fatality due to reentry control problems: Mercury Astronaut Scott Carpenter and the Controversy Surrounding Aurora 7 | Popular Science (http://www.popsci.com/blog-network/vintage-space/mercury-astronaut-scott-carpenter-and-controversy-surrounding-aurora-7?dom=PSC&loc=recent&lnk=3&con=mercury-astronaut-scott-carpenter-and-the-controversy-surrounding-aurora-7)

However those are the only two. In retrospect it seems odd to make "care free" reentry such a fundamental design priority. Reentry is critical but it's just one phase. Flight control is always critical, whether inside or outside the atmosphere, or at reentry interface. SS1/SS2 have cold-jet RCS to provide active attitude control above the atmosphere, so it's not like the feather system eliminates that.

Furthermore VG's ultimate goal is using follow-on vehicles for point-to-point suborbital transport. However that requires nearly the same engines, velocity and thermal protection as orbital flight. It is unclear if the feathering system would work at orbital reentry speeds or whether VG has even done preliminary testing on this. If the experience gained on SS2 can't be used on that, it's a technological dead end.

There is an obvious attraction to passively safe systems. Engineers learn early that "complexity breeds failure". But as we see from this incident, even passively safe systems introduce their own complexity and tradeoffs.

[cwatters]

Rutan conceptually modeled it on the self-stabilizing badminton shuttlecock.

Interesting. I'd assumed it was based on the pop-up tail used in free flight model aircraft to bring them down out of thermals.

[MG23]

However -- to my knowledge there has been only one reentry fatality related to flight control -- the Mike Adams X-15 flight on 15 Nov 1967: https://en.wikipedia.org/wiki/X-15_Flight_3-65-97

However, there have been a number of issues with spacecraft with active controls not pointing the right direction during re-entry.

Off the top of my head, Columbia's first flight might well have burned up if they'd let the computer fly the re-entry, because the computer's aerodynamic model was wrong. Columbia's final flight was doing OK despite losing parts of the wing, until the drag exceeded the ability of the RCS to keep it pointed in the right direction. Not sure if you can count the Soyuz that re-entered backwards, since that was due to the service module failing to detach... but Soyuz, like Apollo was built to be aerodynamically stable with the heat shield pointing in the right direction, and could survive an uncontrolled re-entry that way, even if the crew might not be happy about the 10+g deceleration.

I would guess that 'feathering' was used on SS1 because it was much cheaper and faster to develop than an active system. I presume they did a similar cost/benefit analysis before deciding to use it on SS2.

[janrein]

Columbia's first flight might well have burned up ...

From http://www.nasa.gov/centers/dryden/pdf/88290main_H-1894.pdf

Space Shuttle Hypersonic Aerodynamic and Aerothermodynamic Flight Research and the Comparison to Ground Test Results

[...]

Center of Pressure Location

The STS-1 showed that significantly more body-flap deflection was required to trim the vehicle hypersonically at an alpha of 40 degrees than was presicted [...].

See a.o. Page 5 and Figure 5.

[khorton]

So if an indicated airspeed of 130 was assumed someone could work out the altitude that the aircraft passed below mach one. That would set a lower bound to the altitude since the actual IAS might be lower.
130 kt CAS is Mach 1 at 77,565 ft. 130 kt CAS at 60,000 ft would be Mach 0.70.

[donotdespisethesnake]

NTSB reports posted here http://www.ntsb.gov/news/events/Pages/2015_spaceship2_BMG.aspx

[Peter H]

This submission by Virgin for the executive summary is interesting reading.

NTSB Executive Summary of SpaceShipTwo Accident at Parabolic Arc (http://www.parabolicarc.com/2015/07/28/ntsb-executive-summary-spaceshiptwo-accident/)

[deefer dog]

The last post sheds far more light than the NTSB preliminary report (slide show of all things!) from which I learn't nothing - other than detail related to permits which may, or may not, have been applied for.

Is it me, or are NTSB reports of late turning into a devalued product?

[Radix]

Yep the good old investigation from all angles is no more. Particularly GA reports are often so poorly written and jump to conclusions with some cheap 'learning points'.

[Less Hair]

What is the current status of SS2 "dash two" please?

[henry_crun]

http://www.ntsb.gov/news/press-releases/Pages/PR20150728.aspx

dash two
http://www.flightglobal.com/news/articles/analysis-where-next-virgin-galactic-407537/