Author Topic: Dream Chaser suffers landing failure after first flight  (Read 69351 times)

Offline Rocket Science

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Re: Dream Chaser suffers landing failure after first flight
« Reply #40 on: 10/27/2013 01:28 AM »
Iíll give you an engineering upside... We are going to learn about the integrity of an all composite spacecraft in a non-nominal landing... Good data there...
"The laws of physics are unforgiving"

Offline Chris Bergin

NASA Statement:

Commercial Crew Program Updates
NASA Statement Regarding SNC Dream Chaser Free-Flight Test
Sat, 26 Oct 2013 10:31:22 PM EDT
During today's free-flight approach-and-landing test of Sierra Nevada Corporation's Dream Chaser spacecraft, the vehicle experienced an anomaly as it touched down on the Runway 22L at Edwards Air Force Base, Calif.
No personnel were injured. Damage to property is being assessed. Edwards Air Force Base emergency personnel responded to scene as a precaution. Support personnel are preparing the vehicle for transport to a hangar.
Sierra Nevada Corporation engineers, NASA Dryden Flight Research Center and U.S. Air Force representatives are looking into the anomaly that occurred. Sierra Nevada Corporation will release information as it becomes available at www.SNCDreamChaser.com.

Offline yg1968

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Re: Dream Chaser suffers landing failure after first flight
« Reply #42 on: 10/27/2013 02:00 AM »
Because the flight mechanism wasn't ready when this vehicle was built.  So they borrowed an existing system.

Is the flight mechanism ready now? I suppose that there is no point building a new ETA. They might as well start working on the FTA.

Offline Lee Jay

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Re: Dream Chaser suffers landing failure after first flight
« Reply #43 on: 10/27/2013 02:14 AM »
They've been working on the FTA for quite a while.

Offline yg1968

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Re: Dream Chaser suffers landing failure after first flight
« Reply #44 on: 10/27/2013 02:51 AM »
The FTA will only be ready in a couple of years assuming further funding.

Offline john smith 19

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Re: Dream Chaser suffers landing failure after first flight
« Reply #45 on: 10/27/2013 08:45 AM »
First let me remind people Jeff Greasons's comments on the the WK2/SS2 tests. Roughly

"It's a flight test programme. It's purpose is to find problems and it will take as long as it takes."

All comments that apply here.  I'll note that AFAIK this is the 1st time ever a US full sized composite crew rated lifting body design has completed this set of (automated) manouvres. And it seems to have done very well.  :)  :)

I'll also note that historically the general rule of X programmes was "If we didn't get break at least one vehicle once we probably weren't testing them hard enough."

Like a lot of Skunk Works projects its not core functions were re-used from other vehicles and landing gear was one of those.  But note at this point there are at least 2 possible failure scenarios.

1) Landing gear fails to deploy, due to failure  of control system to release it, sticking of actuators, door, whatever.  Especially bad as other side is rolling forward when wing tip is likely to go into the ground. Sever structural damage but (depending on cause) not that bad from a design PoV, as the lessons learned can feed the FTA detail design and sub systems installation. OTOH repairing  it is a whole different matter. NASA did some tests on composite pressure vessels subject to impact damage. They found that strength could be reduced 30% without visible damage. AFAIK this has driven various NDE developments, which hopefully are ready to use.
[edit IRC Shuttle had 4 separate systems to drop the landing gear. Maybe DC needs more backups, maybe not  :( I think it's too early to say]
2)Landing gear deploys but suffers structural failure. Given the design came from another vehicle it could be either a design fault (IE no copies of that landing gear would have held up (serious if you don't have a solid handle on the landing forces that you under spece'd the gear) , or something specific to that particular copy of the gear (hairline crack, fatigue limits etc) . IOW it's basically bad luck.  :(

Dream Chasers goals are ambitious but that is in line with NASA's charter and in an ideal world should have received full funding, but that's another topic.

I wish SNC's team a prompt resolution of the causes and (reasonably) fast resumption of testing.
« Last Edit: 10/27/2013 12:02 PM by john smith 19 »
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Offline Rocket Science

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Re: Dream Chaser suffers landing failure after first flight
« Reply #46 on: 10/27/2013 11:06 AM »
The X-15 had a rear skid collapse while landing overweight and the vehicle rolled. Even a simple system can fail... It can happen to a program with big players such as NASA, USAF and North American.  It was rebuilt to fly again and set a hypersonic speed record.  You can go visit her in Ohio at W.P.A.F.B.
 
http://www.thisdayinaviation.com/9-november-1962/
« Last Edit: 10/27/2013 11:18 AM by Rocket Science »
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Offline eriblo

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Re: Dream Chaser suffers landing failure after first flight
« Reply #47 on: 10/27/2013 01:12 PM »
Indeed not the best outcome, although it seems to have gone more or less as well as it could except for the end :( - with a (hopefully) irrelevant cause.

I don't remember whether the landing gear was retractable or not, but does anyone care to speculate on how feasible a (completely) gear-up landing is with a lifting body like this? Higher landing speed, more friction but also a nice flat surface with no protruding engines or wingtips?
« Last Edit: 10/27/2013 01:20 PM by eriblo »

Offline Rocket Science

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Re: Dream Chaser suffers landing failure after first flight
« Reply #48 on: 10/27/2013 02:40 PM »
They've been working on the FTA for quite a while.
Lee Jay,

Do you recall seeing any other wing sets or stabilizers aleady fabricated or in the state of fabrication during your visit?

Thanks
Rob
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Offline rcoppola

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Re: Dream Chaser suffers landing failure after first flight
« Reply #49 on: 10/27/2013 03:23 PM »
Congratulations to SNC. This was a remarkable achievement. A tremendous amount of hard work and dedication went into it. And I for one look forward to the next flight. After all, for goodness sakes, it's a test program.

They will analyze, determine, fix/replace, fly and land again. You test to fail, in order to succeed. They will succeed, eventually.

SNC always had the least funding and most complicated system with the most risk to mitigate.

Under a down select, they were not going to make this round anyway.  Timing was never on their side. But I do believe they will eventually be selected as a follow on to the initial 6 flights that will be split between Boeing and SpaceX.

Anyway, great flight! And best of luck moving forward. Dream Chaser will keep chasing the dream and its' day will come. Yes, dreams really do come true.
« Last Edit: 10/27/2013 03:24 PM by rcoppola »
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Offline HIP2BSQRE

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Re: Dream Chaser suffers landing failure after first flight
« Reply #50 on: 10/27/2013 03:24 PM »
People love SNC but do people really think that the another test article is going to fly within the next 3 -6 months?  No.  There will be an investigation  1 -2 months.  Then it will take time to build another test device.  Unless they have another waiting in the wings that is going to take another 3-6 months.  I do not see them flying again till at least Q2\Q3 2014.  Unless SpaceX and Boeing both have large failures they will too far behind the leaders.  Sorry to say it - Spacex can afford to have the abort test in the spring to be a complete failure and still will be ahead of SNC.  SNC can do Dreamchaser on their own dime but if I was them I would not expect them to win.  Sorry - it sounds hard but those are the facts as I see them.  Please explain to me why I am wrong if you have different facts.

Offline HIP2BSQRE

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Re: Dream Chaser suffers landing failure after first flight
« Reply #51 on: 10/27/2013 03:39 PM »
The X-15 had a rear skid collapse while landing overweight and the vehicle rolled. Even a simple system can fail... It can happen to a program with big players such as NASA, USAF and North American.  It was rebuilt to fly again and set a hypersonic speed record.  You can go visit her in Ohio at W.P.A.F.B.
 
http://www.thisdayinaviation.com/9-november-1962/


Yes and it was 18 months before she flew again.  Think what a gap of only 6-9 months will do to SNC?

Offline Jason1701

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Re: Dream Chaser suffers landing failure after first flight
« Reply #52 on: 10/27/2013 03:40 PM »
Are there any pictures or videos of the damage to SS1 after its landing gear collapse?

Offline rcoppola

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Re: Dream Chaser suffers landing failure after first flight
« Reply #53 on: 10/27/2013 03:40 PM »
People love SNC but do people really think that the another test article is going to fly within the next 3 -6 months?  No.  There will be an investigation  1 -2 months.  Then it will take time to build another test device.  Unless they have another waiting in the wings that is going to take another 3-6 months.  I do not see them flying again till at least Q2\Q3 2014.  Unless SpaceX and Boeing both have large failures they will too far behind the leaders.  Sorry to say it - Spacex can afford to have the abort test in the spring to be a complete failure and still will be ahead of SNC.  SNC can do Dreamchaser on their own dime but if I was them I would not expect them to win.  Sorry - it sounds hard but those are the facts as I see them.  Please explain to me why I am wrong if you have different facts.
Well, for reasons I stated above, there was very little chance they were going to make this down select anyways. As for you being wrong, I can't say. But unless you work for SNC, what you've stated are not facts, they are reasonable assumptions.
« Last Edit: 10/27/2013 03:41 PM by rcoppola »
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Offline antiquark

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Re: Dream Chaser suffers landing failure after first flight
« Reply #54 on: 10/27/2013 03:44 PM »
A landing gear failure is a pretty bad, basic mistake.  Lots of companies develop aircraft and test fly them without having landing gear failures.  It calls into question SNC's management and oversight practices.

Sounds vaguely similar to the Delta Clipper X. One landing gear failed to extend, it tipped over, and that was it's last flight. (Ground crew forgot to connect a hydraulic hose).

But yeah, if your management process isn't resilient enough to ensure that landing gear will extend, then your corporate structure has big problems.

Offline Rocket Science

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Re: Dream Chaser suffers landing failure after first flight
« Reply #55 on: 10/27/2013 03:47 PM »
The X-15 had a rear skid collapse while landing overweight and the vehicle rolled. Even a simple system can fail... It can happen to a program with big players such as NASA, USAF and North American.  It was rebuilt to fly again and set a hypersonic speed record.  You can go visit her in Ohio at W.P.A.F.B.
 
http://www.thisdayinaviation.com/9-november-1962/


Yes and it was 18 months before she flew again.  Think what a gap of only 6-9 months will do to SNC?

Folks on here should know by now that as a rule I donít go too far down the rabbit hole when it comes to speculation...
"The laws of physics are unforgiving"

Offline rcoppola

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Re: Dream Chaser suffers landing failure after first flight
« Reply #56 on: 10/27/2013 04:03 PM »
A landing gear failure is a pretty bad, basic mistake.  Lots of companies develop aircraft and test fly them without having landing gear failures.  It calls into question SNC's management and oversight practices.

Sounds vaguely similar to the Delta Clipper X. One landing gear failed to extend, it tipped over, and that was it's last flight. (Ground crew forgot to connect a hydraulic hose).

But yeah, if your management process isn't resilient enough to ensure that landing gear will extend, then your corporate structure has big problems.
It was one failure point among thousands they got right. I think bringing management and processes into this is incredibly premature. I mean come on, one point of failure and we are questioning an entire corporate structure? Let's dial this back a bit and wait for word from SNC.
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Offline vt_hokie

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Re: Dream Chaser suffers landing failure after first flight
« Reply #57 on: 10/27/2013 04:07 PM »

Well, for reasons I stated above, there was very little chance they were going to make this down select anyways. As for you being wrong, I can't say. But unless you work for SNC, what you've stated are not facts, they are reasonable assumptions.

What will be interesting is to see the PR reaction to losing the pretty face of the commercial crew program.  Let's face it, Dream Chaser is simply sexier than any of the capsules and its imagery tended to find its way onto a lot of press releases.  I'm guessing the reason we weren't allowed to see live footage of the drop or video footage in the wake of the failure is that it is deemed too politically ugly to see Lori Garver's poster child turning into wreckage in an ugly crash.  But not sharing it when NASA used to be open about its failures just feels a little too Soviet-era Russia to me.
« Last Edit: 10/27/2013 04:07 PM by vt_hokie »

Offline rcoppola

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Re: Dream Chaser suffers landing failure after first flight
« Reply #58 on: 10/27/2013 04:26 PM »

Well, for reasons I stated above, there was very little chance they were going to make this down select anyways. As for you being wrong, I can't say. But unless you work for SNC, what you've stated are not facts, they are reasonable assumptions.

What will be interesting is to see the PR reaction to losing the pretty face of the commercial crew program.  Let's face it, Dream Chaser is simply sexier than any of the capsules and its imagery tended to find its way onto a lot of press releases.  I'm guessing the reason we weren't allowed to see live footage of the drop or video footage in the wake of the failure is that it is deemed too politically ugly to see Lori Garver's poster child turning into wreckage in an ugly crash.  But not sharing it when NASA used to be open about its failures just feels a little too Soviet-era Russia to me.
It's been 2 days.  Please give them some time. They deserve that.
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Offline JAFO

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Re: Dream Chaser suffers landing failure after first flight
« Reply #59 on: 10/27/2013 04:29 PM »
A landing gear failure is a pretty bad, basic mistake.  Lots of companies develop aircraft and test fly them without having landing gear failures.  It calls into question SNC's management and oversight practices.

Sounds vaguely similar to the Delta Clipper X. One landing gear failed to extend, it tipped over, and that was it's last flight. (Ground crew forgot to connect a hydraulic hose).

But yeah, if your management process isn't resilient enough to ensure that landing gear will extend, then your corporate structure has big problems.

Both the A-12 and F-117 program suffered "loss of vehicle"  mishaps when parts of the control system were incorrectly hooked up (SAS in the A-12, flight controls in the F-117). If something like that can happen to the Skunk Works (twice), then SNC is in good company.
« Last Edit: 10/27/2013 04:39 PM by JAFO »
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