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Virgin Galatic Spaceship Two down in the Mojave.

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Virgin Galatic Spaceship Two down in the Mojave.

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Old 3rd Nov 2014, 07:13
  #81 (permalink)  
 
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I accept NTSB released the information, I just dont think it is helpful to drip feed facts. The press are already claiming pilot error and "Initial indications are, that this was not equipment failire".
Initial indications mean nothing, facts mean nothing in isolation, the only thing that matters is the result of a full and proper investigation. That is the stage when NTSB should be briefing.
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Old 3rd Nov 2014, 07:46
  #82 (permalink)  
 
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A few facts:

1) Video evidence showed the co-pilot manually unlocking the feathering system early (Mach 1) and against normal procedures. (Mach 1.4)

2) The pilots did not manually deploy the feathers, but the feathers deployed anyway after being unlocked.

3) The rocket motor and propellant tanks were recovered with no signs of burn-through or breaching.

Source:
Virgin Galactic rocket plane deployed braking system prematurely | Spaceflight Now
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Old 3rd Nov 2014, 08:35
  #83 (permalink)  
 
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Thanks for the award. It's a very serious point, were these poor Pilots qualified? If they were, please direct me to their credentials and experience. I agree that the drip feeding of information from the NTSB is unhelpful. Who knows, the unlock of the empennage for auto feather might have become the normal variation to procedure?

I think their families deserve answers to understand if these Pilots were adequately trained and qualified.
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Old 3rd Nov 2014, 08:58
  #84 (permalink)  
 
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OK- some published stuff-
Michael Alsbury, 39, was an experienced flier who co-piloted the same craft when it first broke the sound barrier last year. He worked for Scaled Composites — which built and operates SpaceShipTwo — for more than a decade, according to his biography.

Alsbury held the titles of project engineer and test pilot, and was also sitting in the co-pilot's seat when the craft was first dropped in 2010 from its carrier aircraft several miles above the Earth for an unpowered glide test. According to test logs, Alsbury flew primarily as the craft's co-pilot, logging at least seven trips from 2010 to early 2014.

Alsbury's official bio says he held a B.S. in Aeronautical Engineering from California Polytechnic State University-San Luis Obispo and was a member of the Society of Experimental Test Pilots and Society of Flight Test Engineers. The undated bio said he had 15 years and more than 1,800 hours of flight experience, and held his single and multiengine instrument commercial, glider commercial and single and multiengine instrument flight instructor certificates.

Peter Siebold obtained his pilot's license at age 16.[4] Siebold has been a design engineer at Scaled Composites since 1996.
Siebold holds a degree in aerospace engineering from California Polytechnic University at San Luis Obispo, from 2001.[4]
Siebold was responsible for the simulator, navigation system, and ground control system for the SpaceShipOne project at Scaled.
Although he was one of four qualified pilots for SpaceShipOne, Siebold did not pilot the craft during the flights later in 2004 to meet the requirements of the Ansari X Prize.[5] Although Siebold flew SpaceShipOne to an altitude of 32 km (just under 20 miles), he did not cross the 100 km Kármán line -- the international standard for reaching space.
For his contribution to the SpaceShipOne project, Siebold, along with Mike Melvill and Brian Binnie, received the 2004 Iven C. Kincheloe Award presented by the Society of Experimental Test Pilots.
Siebold became the Director of Flight Operations at Scaled.[2]
He was the pilot who flew the White Knight Two on its maiden flight on the 21st of December 2008.[6] He won the Iven C. Kincheloe Award a second time in 2009, this time individually, for his work on the first WhiteKnightTwo, VMS Eve, as chief test pilot.[4]


Mixed sources.
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Old 3rd Nov 2014, 09:13
  #85 (permalink)  
 
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It seems quite strange to me that their procedures called for unlocking the tail feathers at M1.4. I would have thought that you wouldn't want to unlock the feathers until you were at a point in the flight profile that an uncommanded feather would not create a hazard. M1.4 is early in the motor burn, so even if the feathers had been unlocked per procedure, an uncommanded feather would have had the same catastrophic consequence.

It will be very interesting to learn why their procedures called for unlocking the feathers so early.
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Old 3rd Nov 2014, 09:17
  #86 (permalink)  
 
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The NSTB are not "drip-feeding" - they are reporting facts as they gather them in accordance with their procedures. Each accident will be different and require different actions. This accident is unusual in that there is so much recording equipment on board, thus hard evidence will come quicker and faster. There will still need to be a full analysis which will take time and the NSTB have clearly pointed this out.

There is an excellent article in the Financial Times regarding the commercial, marketing and PR motivations and issues - I won't post the link because it won't work if you don't have an FT account, but it sums up the situation very well indeed.
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Old 3rd Nov 2014, 09:33
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Feathering time line

The NTSB briefing seemed to posit two distinct accounts of the assumed feathering application.
The first, early in the resume, seemed to say that all communication and recording got lost two seconds after the feathering has been unlocked. Implying the possibility that feathering would have occurred two seconds later resulting in catastrophic failure.
The second account, during questioning, seemed to state that after unlocking, the feathering was (immediately?) activated, and two seconds later, all communication got lost, due to catastrophic failure.
Which of the accounts is the correct one?
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Old 3rd Nov 2014, 09:40
  #88 (permalink)  
 
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Originally posted by khorton:
It will be very interesting to learn why their procedures called for unlocking the feathers so early.
Probably to ensure reasonable confidence in feather capability before committing to the ballistic pull-up. SS1 and 2 cannot safely re-enter unfeathered.

Last edited by Case One; 3rd Nov 2014 at 14:14.
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Old 3rd Nov 2014, 09:57
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Enlighten me as to why the feathering of the tail would be more dangerous at mach 1 that at 1.4 ?
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Old 3rd Nov 2014, 09:57
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amateur "Test Pilots"?
100% of test pilots were amateur test pilots at one point in their career.
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Old 3rd Nov 2014, 10:05
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Enlighten me as to why the feathering of the tail would be more dangerous at mach 1 that at 1.4 ?
Feathering the tail is dangerous at any high speed in dense atmosphere.
Unlocking the feather, however, may well be more dangerous at around mach 1 than 1.4. Reason being that the airflow may be less stable at this speed as you're in the trans-sonic regime.
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Old 3rd Nov 2014, 10:08
  #92 (permalink)  
 
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Originally Posted by Fun fly
Enlighten me as to why the feathering of the tail would be more dangerous at mach 1 that at 1.4 ?
I'd guess it'd be to do with the way the shockwave is formed around the aircraft. Below M1.40 it may be impinging on parts of the airframe or control surfaces that aren't stressed for it.
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Old 3rd Nov 2014, 10:10
  #93 (permalink)  
 
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OFO - if you tell us the title of the FT piece and then type it into google - then you have it free of charge!
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Old 3rd Nov 2014, 10:16
  #94 (permalink)  
 
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Virgin Galatic Spaceship Two down in the Mojave.

Is the problem with deploying the feathering system due to the low Mach number or because the rocket motor was still producing thrust.In other words should the system only be deployed when it's a glider?
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Old 3rd Nov 2014, 10:20
  #95 (permalink)  
 
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Feathering and Tail Stalls

The second account, during questioning, seemed to state that after unlocking, the feathering was (immediately?) activated, and two seconds later, all communication got lost, due to catastrophic failure.
Which of the accounts is the correct one?
I think the NTSB report was fairly categoric that the system was unlocked but the deployment handle was not used.

But here is what is confusing me. We are told the feathering is for re-entry deceleration and never used at this stage in flight. Yet we already know about tail stalls in earlier test flights...

Virgin's SpaceShipTwo Stalls During Test Flight

Upon release, the Spaceship experienced a downward pitch rate that caused a stall of the tails. The crew followed procedure, selecting the feather mode to revert to a benign condition. The crew then defeathered and had a nominal return to base. Great flying by the team and good demo of feather system.
So we have some suggestion here that the feathering could be legitimately deployed at this early stage.
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Old 3rd Nov 2014, 10:36
  #96 (permalink)  
 
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Not sure you're comparing Apples with apples about the stage of flight though?

On release they're not ballistic and when they are ballistic and deploy the feather, it's in thin air.

Presumably the real criteria is below a certain aerodynamic loading, so fast and high in thin air, or slower down lower.
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Old 3rd Nov 2014, 11:09
  #97 (permalink)  
 
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Dynamic pressure, engine burn, feathering

Any drastic configuration change like feathering is not to be expected until well after q_max and most likely after motor burn-out (except perhaps for considerations as mentioned in Case One´s post, not sure if such considerations apply in the SS2 flight profile).

Could anyone enlighten about dynamic pressure vs time/altitude for SS2?

The video footage of the third powered flight shows feathering action just after motor burn-out.

p.s. Just read DontHangUps´s comment, it does seem there is multiple use of the feathering system, interesting.
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Old 3rd Nov 2014, 11:12
  #98 (permalink)  
 
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Isn't the point for discussion not so much the fact that the feather was enabled, which one would assume has some tolerance, but the fact that the feather subsequently deployed uncommanded?
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Old 3rd Nov 2014, 11:14
  #99 (permalink)  
 
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Procedure is to unlock the feather not to deploy or activate it. Initiating feathering at high q is a terminal no no.
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Old 3rd Nov 2014, 11:16
  #100 (permalink)  
 
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It's a very serious point, were these poor Pilots qualified? If they were, please direct me to their credentials and experience.
It's a serious question, yes, but what's the point of speculating. Do you have any indications that they were not qualified? How about you wait for the ntsb report, they'll figure it out. In the meantime, google is your friend. Here's a few hints. Just last year, the deceased pilot received the the "Ray Tenhoff award" for "the most outstanding technical paper presented at the annual Society of Experimental Test Pilots Symposium". He also received the Northrop Grumman’s President’s Award. He had 1600 hours of flight time in research aircraft, roughly 15 years of experience, and was not only an accomplished pilot, but also a highly qualified engineer.

Scaled is not a pay to fly program.
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