Author Topic: Dream Chaser suffers landing failure after first flight  (Read 76174 times)

Offline Kim Keller

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Re: Dream Chaser suffers landing failure after first flight
« Reply #240 on: 10/29/2013 08:41 PM »
There is no point in having a gear retraction mechanism on a vehicle which only gets one attempt at landing.

That depends. There does need to be some contingency for this type of vehicle. Shuttle had an auxiliary pneumatic system to force the gear down and lock. Thatís one approach. Another would be an emergency retract option. The former is well understood and tested. The latter is unknown, but would also work provided the decision point was far enough prior to touchdown to execute a full emergency retract because there is no go-around for any gliding vehicle which is essentially low enough to be experiencing ground-effect. The choice comes down to complexity, mass and expense. But there obviously does need to be a contingency mechanism of some kind included in the design. Leaving the vehicle with no option is not an option - as demonstrated by this test flight. A controlled hard landing is preferable to an uncontrolled roll-flip-stop. That's one of the lessons learned. And better learned and addressed early before the vehicle becomes operational with crew and passengers.

I think a retract circuit is out of the question. Gear deploy comes very late in the approach, leaving very little time for crew assessment of the situation and reaction. What if the talkback fails, not the deploy? There's no time to sort it out.  And, they have a final-approach workload to deal with on a vehicle with a high approach speed, high sink rate and less than awesome roll/yaw characteristics (typical of lifting bodies). They need to be focused on the runway and not have to even think about the gear position. The appropriate design choice would be a positive deployment mechanism that ensures gear down every time.

Offline Rocket Science

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Re: Dream Chaser suffers landing failure after first flight
« Reply #241 on: 10/29/2013 08:42 PM »
I'll be keen to learn more about SNC's options.  It is easy to lose track of how many mock-ups they have made so far of Dreamchaser and which could be upgraded to serve for further testing or be completed as an operational vehicle.  There's an ETA (Engineering Test Article) which we're discussing now.  There's a FTA (Flight Test Article) which is under construction and I believe an Orbital Vehicle that is only planned?  Weren't there previous mock-ups as well?
There was the original HL-20 mock-up acquired by SNC as well from Langley...
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Offline spectre9

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Re: Dream Chaser suffers landing failure after first flight
« Reply #242 on: 10/29/2013 08:54 PM »
This is landing gear.

I can't help but feel it's a simple component in use for nearly a century and a company getting millions-billions of government money should have never got it wrong.

Video or not DC has dug their own grave here and will not move forward after CCiCap.

I was a supporter.

Unfortunately due to the economics of the situation 100% success was required here.

Offline Eric Hedman

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Re: Dream Chaser suffers landing failure after first flight
« Reply #243 on: 10/29/2013 08:58 PM »
I haven't read the entire thread so I don't know if this was covered here, but I'll ask the question anyways.

I'm curious if a crew would have survived the landing.  SNC said the cabin was intact.  If it tumbled a few times at 200 mph, would the forces be too great on a crew.  Drivers of race cars that crash at that speed usually survive.  What do people think the outcome on a crew would be if this happened on a real mission?

Offline clongton

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Re: Dream Chaser suffers landing failure after first flight
« Reply #244 on: 10/29/2013 08:59 PM »
Anyway, I see you are emotionally involved from your "Go Dreamchaser! Go SNC!" salute,

I am not emotionally involved in any way. I am excited to watch another commercial spacecraft take flight. I was just as excited by Dragon and will be just as excited by the CST-100 if it ever actually flies.
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I started my career on the Saturn-V F-1A engine

Offline clongton

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Re: Dream Chaser suffers landing failure after first flight
« Reply #245 on: 10/29/2013 09:04 PM »
... and a company getting millions-billions of government money should have never got it wrong.

billions???
You need to do some serious reading about how much SNC actually got.
You are off by an order of magnitude.
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I started my career on the Saturn-V F-1A engine

Offline Rocket Science

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Re: Dream Chaser suffers landing failure after first flight
« Reply #246 on: 10/29/2013 09:08 PM »
There is no point in having a gear retraction mechanism on a vehicle which only gets one attempt at landing.

That depends. There does need to be some contingency for this type of vehicle. Shuttle had an auxiliary pneumatic system to force the gear down and lock. Thatís one approach. Another would be an emergency retract option. The former is well understood and tested. The latter is unknown, but would also work provided the decision point was far enough prior to touchdown to execute a full emergency retract because there is no go-around for any gliding vehicle which is essentially low enough to be experiencing ground-effect. The choice comes down to complexity, mass and expense. But there obviously does need to be a contingency mechanism of some kind included in the design. Leaving the vehicle with no option is not an option - as demonstrated by this test flight. A controlled hard landing is preferable to an uncontrolled roll-flip-stop. That's one of the lessons learned. And better learned and addressed early before the vehicle becomes operational with crew and passengers.

I think a retract circuit is out of the question. Gear deploy comes very late in the approach, leaving very little time for crew assessment of the situation and reaction. What if the talkback fails, not the deploy? There's no time to sort it out.  And, they have a final-approach workload to deal with on a vehicle with a high approach speed, high sink rate and less than awesome roll/yaw characteristics (typical of lifting bodies). They need to be focused on the runway and not have to even think about the gear position. The appropriate design choice would be a positive deployment mechanism that ensures gear down every time.
Here you "3 green" no waiting...

http://www.nasa.gov/centers/dryden/history/Speeches/lifting_bodies/lifting-2.html
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Offline rcoppola

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Re: Dream Chaser suffers landing failure after first flight
« Reply #247 on: 10/29/2013 09:12 PM »
This is landing gear.

I can't help but feel it's a simple component in use for nearly a century and a company getting millions-billions of government money should have never got it wrong.

Video or not DC has dug their own grave here and will not move forward after CCiCap.

I was a supporter.

Unfortunately due to the economics of the situation 100% success was required here.
Ok, hang on a minute. They are not getting billions of dollars. Neither does receiving said funds equate never getting anything wrong. Why are they being held to a standard not one defense contractor is held up against? Or any other Government contractor/partner for that matter.

Dug their own grave? I know it's close to Halloween but that's just....I don't even know.

NO. 100% success is not required for the FIRST flight test of a vehicle that has not even gone through a complete CDR.

And let me dispel the, "They screwed their chances for CCiCap because of this" nonsense. They were ALWAYs behind the schedule of Dragon and CST. Less funding, more risks to mitigate. SO the chance of them surviving THIS upcoming selection was always slim to none. BUT, they will continue and most likely be accepted for the next round in a few years time.

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Online Blackstar

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Re: Dream Chaser suffers landing failure after first flight
« Reply #248 on: 10/29/2013 09:35 PM »
I think you guys need to lighten up.

S#it happens in flight test. You pick yourself up, dust yourself off, and get back to work.
« Last Edit: 10/29/2013 09:35 PM by Blackstar »

Offline Paul Adams

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Re: Dream Chaser suffers landing failure after first flight
« Reply #249 on: 10/29/2013 09:49 PM »
There is no point in having a gear retraction mechanism on a vehicle which only gets one attempt at landing.

That depends. There does need to be some contingency for this type of vehicle. Shuttle had an auxiliary pneumatic system to force the gear down and lock. Thatís one approach. Another would be an emergency retract option. The former is well understood and tested. The latter is unknown, but would also work provided the decision point wasn't far enough prior to touchdown to execute a full emergency retract because there is no go-around for any gliding vehicle which is essentially low enough to be experiencing ground-effect. The choice comes down to complexity, mass and expense. But there obviously does need to be a contingency mechanism of some kind included in the design. Leaving the vehicle with no option is not an option - as demonstrated by this test flight. A controlled hard landing is preferable to an uncontrolled roll-flip-stop. That's one of the lessons learned. And better learned and addressed early before the vehicle becomes operational with crew and passengers.

I think a retract circuit is out of the question. Gear deploy comes very late in the approach, leaving very little time for crew assessment of the situation and reaction. What if the talkback fails, not the deploy? There's no time to sort it out.  And, they have a final-approach workload to deal with on a vehicle with a high approach speed, high sink rate and less than awesome roll/yaw characteristics (typical of lifting bodies). They need to be focused on the runway and not have to even think about the gear position. The appropriate design choice would be a positive deployment mechanism that ensures gear down every time.
Here you "3 green" no waiting...

http://www.nasa.gov/centers/dryden/history/Speeches/lifting_bodies/lifting-2.html

That's called 'down, locked and welded'.
It's all in the data.

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Re: Dream Chaser suffers landing failure after first flight
« Reply #250 on: 10/29/2013 09:51 PM »
I was a supporter.
I am not sure I buy that you're a supporter of anything... you always can be counted on for the most negative view. (which is goodness, mind, keep the fan bois on the straight and narrow) :)
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Online vt_hokie

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Re: Dream Chaser suffers landing failure after first flight
« Reply #251 on: 10/29/2013 09:57 PM »

No way.  You cannot just take a dump on an Air Force base.  Executives talk very seriously about jail if this stuff happens.  Rumored news that the NASA Commercial Crew guy quit:

http://nasawatch.com/archives/2013/10/management-chan-2.html

Does anyone know if there are linkage to the test anomaly/failure?

Wha?  Are you trying to imply a link between this news and the gear failure that occurred a couple of days into the future?

Offline QuantumG

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Re: Dream Chaser suffers landing failure after first flight
« Reply #252 on: 10/29/2013 10:02 PM »
Chris, I think you should put forward and center the statement that this was *NOT* a test of the landing gear.

Sheesh.
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Offline pathfinder_01

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Re: Dream Chaser suffers landing failure after first flight
« Reply #253 on: 10/29/2013 10:04 PM »
This has probably been said but I don't know how, other than searching all the posts in this thread to find it. Were a pilot on board, both gear would have been retracted, if possible,

Unlikely there would have been the capability to retract the gear.  It is unnecessary.

And what soft surface is nearby?

If a pilot was onboard, the outcome likely wouldn't have been any different

can you elaborate ?

Not having the option to retract the gear on a piloted vehicle seems strange to me.
I agree that the outcome would be the same, meaning a crashed vehicle, but the amount of damage is different when you belly flop or flip over, hard surface or not.

In the case of the shuttle the gear was deployed by gravity (it saved weight over hydrolics and the gear did not have to come back up since the shuttle would not be taking off like an regular plane).  If the gear did not deploy there was also a system of explosives that would blow the gear off and allow the shuttle to perform a belly landing like an aircraft whoís gears have failed. Unlike an aircraft there would be no time to foam up the runway.

Offline psloss

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Re: Dream Chaser suffers landing failure after first flight
« Reply #254 on: 10/29/2013 10:11 PM »
If the gear did not deploy there was also a system of explosives that would blow the gear off and allow the shuttle to perform a belly landing like an aircraft whoís gears have failed.
What?

Source for this?

Online Chris Bergin

Okay dokey, and I'm complete with the article.

I think we need a new thread, as there's a lot of silliness in this thread.


New thread:
http://forum.nasaspaceflight.com/index.php?topic=33174.0

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