Author Topic: Dream Chaser suffers landing failure after first flight  (Read 130645 times)

Offline Jester

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Re: Dream Chaser suffers landing failure after first flight
« Reply #220 on: 10/29/2013 05:31 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 Were a pilot on board, both gear would have been retracted, if possible,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.
« Last Edit: 10/29/2013 05:34 pm by Jester »

Offline Go4TLI

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Re: Dream Chaser suffers landing failure after first flight
« Reply #221 on: 10/29/2013 05:41 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 Were a pilot on board, both gear would have been retracted, if possible,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.

What's the point of having a retract option?  It's a gliding lifting body, not like it can power up the engines, swing around and make another pass. 

The orbiter did not have a retract capability.  It did have pneumatic thrusters to push the gear down and out the doors in the event of a hydraulic actuator failure. 

Offline Kim Keller

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Re: Dream Chaser suffers landing failure after first flight
« Reply #222 on: 10/29/2013 05:44 pm »
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.

There is no point in having a gear retraction mechanism on a vehicle which only gets one attempt at landing. Including one adds weight, complexity and failure points.

As for deviating off runway, the lakebed is adjacent to the concrete runway used for this landing. The lakebed MAY provide a slightly softer surface, but remember that Edwards was chosen as a test facility because of the hard-baked surface. Setting down on it would likely result in just as great a level of damage. At any rate, landing a vehicle with the dimensions, stance and touchdown speed like DC with one strut up is a recipe for a flip regardless of surface.

Offline Jester

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Re: Dream Chaser suffers landing failure after first flight
« Reply #223 on: 10/29/2013 05:53 pm »
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.

There is no point in having a gear retraction mechanism on a vehicle which only gets one attempt at landing. Including one adds weight, complexity and failure points.

As for deviating off runway, the lakebed is adjacent to the concrete runway used for this landing. The lakebed MAY provide a slightly softer surface, but remember that Edwards was chosen as a test facility because of the hard-baked surface. Setting down on it would likely result in just as great a level of damage. At any rate, landing a vehicle with the dimensions, stance and touchdown speed like DC with one strut up is a recipe for a flip regardless of surface.

Understood, i'm thinking more of an aircraft, the navy flyboy in me came out, id still like to have the retract option to minimize damage doing a belly flop and have a better chance of walking away in one piece, but I can understand the tradeoff on vehicles like this.
« Last Edit: 10/29/2013 05:54 pm by Jester »

Offline notsorandom

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Re: Dream Chaser suffers landing failure after first flight
« Reply #224 on: 10/29/2013 06:14 pm »
Would the propulsion system on the real thing allow it to make another landing attempt? I seem to recall that at least being talked about a long time ago. Perhaps due to its start as a suborbital vehicle.

Offline Lars_J

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Re: Dream Chaser suffers landing failure after first flight
« Reply #225 on: 10/29/2013 06:20 pm »
Someone made these three screen-caps in sequence, showing the gear deploy (and lack of it):

Offline neilh

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Re: Dream Chaser suffers landing failure after first flight
« Reply #226 on: 10/29/2013 06:25 pm »
I would call this a successful test flight with an unsuccessful landing gear deploy and roll-out.  The flight itself was fine.  Better than fine, even.

Likewise, well said.
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Offline Chris Bergin

Right, so because all the media are writing up and publishing their articles on the media event, I'm taking my time and will go for a long article on the details. 1,000 words in and only after 15 percent of the recording, so going to take me hours, but hopefully it will stand out a bit with a full overview. There will also be a second article based on the long-term future.

Not attempting to pat myself on the back (;D), just want to get something out there that wouldn't look too much like a repeat of other articles already out there.
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Offline Lar

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Re: Dream Chaser suffers landing failure after first flight
« Reply #228 on: 10/29/2013 06:33 pm »
Not attempting to pat myself on the back (;D), just want to get something out there that wouldn't look too much like a repeat of other articles already out there.
Oh go on then, pat yourself on the back, you know you deserve it.
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Offline dcporter

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Re: Dream Chaser suffers landing failure after first flight
« Reply #229 on: 10/29/2013 07:04 pm »
Not attempting to pat myself on the back (;D)

that's what you got us for.

Offline Pheogh

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Re: Dream Chaser suffers landing failure after first flight
« Reply #230 on: 10/29/2013 07:12 pm »
Someone made these three screen-caps in sequence, showing the gear deploy (and lack of it):

Absolutely beautiful was my reaction to the video. Go Dream Chaser!!! Nothing against Orion, but a hundred years from now the "Capsule design" is going to look primitive.

Offline BrightLight

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Re: Dream Chaser suffers landing failure after first flight
« Reply #231 on: 10/29/2013 07:14 pm »
Right, so because all the media are writing up and publishing their articles on the media event, I'm taking my time and will go for a long article on the details. 1,000 words in and only after 15 percent of the recording, so going to take me hours, but hopefully it will stand out a bit with a full overview. There will also be a second article based on the long-term future.

Not attempting to pat myself on the back (;D), just want to get something out there that wouldn't look too much like a repeat of other articles already out there.
As I don't have the time to listen to an hour long briefing, I'm going to rely on you to get to the salient points, as I feel you are the most reliable source on the net (hows that for a pat on the back!)

Offline Elmar Moelzer

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Re: Dream Chaser suffers landing failure after first flight
« Reply #232 on: 10/29/2013 07:22 pm »
Nothing against Orion, but a hundred years from now the "Capsule design" is going to look primitive.
Well, a capsule doing powered landing, like the Dragon will, still looks scifi to me ;)

Offline clongton

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Re: Dream Chaser suffers landing failure after first flight
« Reply #233 on: 10/29/2013 07:30 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. That’s 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.
« Last Edit: 10/29/2013 07:32 pm by clongton »
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Offline Rocket Science

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Re: Dream Chaser suffers landing failure after first flight
« Reply #234 on: 10/29/2013 07:35 pm »
It was fortunate that the concrete runway was selected for the test instead of the lake bed. The dry lakes offer a greater chance that an appendage will dig in and cause it to roll multiple times as it was with the M2F2... Better to have it scrub off speed on the solid concrete.
« Last Edit: 10/29/2013 07:37 pm by Rocket Science »
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Offline rayleighscatter

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Re: Dream Chaser suffers landing failure after first flight
« Reply #235 on: 10/29/2013 07:45 pm »
Not sure if it's been mentioned but in the video there was an anomaly with the right gear as well. The tire catches briefly on the inboard landing gear door.

Offline Todd Martin

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Re: Dream Chaser suffers landing failure after first flight
« Reply #236 on: 10/29/2013 07:48 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?

Offline Oersted

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Re: Dream Chaser suffers landing failure after first flight
« Reply #237 on: 10/29/2013 08:18 pm »
Don’t call it a successful test? Just what do you think a “test” flight is for, to show off perfection? No it is not. A test flight is to use the developed hardware and software in real world conditions specifically to find the bugs (that EVERYBODY knows are there) that slipped thru pre-release testing. That’s what it’s for, and it found a few. Most test flights of anything will have something show up that’s not right. Very few are a picture perfect event. So just to be absolutely clear: This was a successful TEST flight. Yes it was and extreme congratulations to SNC for it. It was a GREAT test flight and they learned some valuable lessons that will be applied to the next TEST flight.

Go DreamChaser! Go SNC!

...Don't think you will find may test pilots who would say that flipping over on landing constitutes a succesful test flight. Your test article is supposed to be able to go up again.

Anyway, I see you are emotionally involved from your "Go Dreamchaser! Go SNC!" salute, so I guess discussing things won't really make a difference. I'm just sad that SNC goes for pulling wool over people's eyes... They're showing that you can rely on them to cover up stuff, which is not a good reputation for a company to get. Especially not if they want investors to trust them as they develop cutting-edge technology.

Online woods170

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Re: Dream Chaser suffers landing failure after first flight
« Reply #238 on: 10/29/2013 08:24 pm »
Not sure if it's been mentioned but in the video there was an anomaly with the right gear as well. The tire catches briefly on the inboard landing gear door.

That's not an anomaly. I've seen that happen on F-5's a number of times. The inboard door sometimes is slow in opening with the main strut coming out faster. The wheel than very briefly catches the still opening inboard door. Nothing unusual about it. As I understand it, the main landing gear on the DC ETA is basically a modified F-5 main landing gear. It would probably display similar behaviour.

One difference I did notice was that on DC the inner door remained open after deployment of the main landing gear. On an F-5, once the main gear is down and locked, the inner door closes again.
« Last Edit: 10/29/2013 08:38 pm by woods170 »

Offline rcoppola

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Re: Dream Chaser suffers landing failure after first flight
« Reply #239 on: 10/29/2013 08:38 pm »
Most excellent flight. I'm really not concerned about the landing gear. The validation of flight characteristics, mold lines, etc. was mission critical and can only be throughly validated in flight, which DC appears on-track to doing. This bodes extremely well for the program.

This is indeed a very good day for commercial crew.
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