Author Topic: Dream Chaser Q&A (including suggestions and improvements)  (Read 592332 times)

Offline douglas100

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Re: Dream Chaser Q&A (including suggestions and improvements)
« Reply #940 on: 03/21/2012 07:57 pm »
Yes, I was going to comment on that. The DC is also "clocked" at 90 degrees to its configuration in the picture where crew access is via the umbilical mast.

Would the tower be a NASA requirement or an initiative from Sierra Nevada?
Douglas Clark

Offline adrianwyard

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Re: Dream Chaser Q&A (including suggestions and improvements)
« Reply #941 on: 03/21/2012 11:10 pm »
DC008.jpg includes what I'm guessing is an older CGI model of the Dream Chaser with white tiles on the underside of the fins, i.e. facing into the re-entry airstream. In DC010 they are black which makes more armchair sense. DC007 shows a covered walkway which seems like a reasonable addition. So could it be the crew access tower/arm config depicted in DC007 is more current than that shown in DC008?

Offline Lurker Steve

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Re: Dream Chaser Q&A (including suggestions and improvements)
« Reply #942 on: 03/21/2012 11:20 pm »
Yes, I was going to comment on that. The DC is also "clocked" at 90 degrees to its configuration in the picture where crew access is via the umbilical mast.

Would the tower be a NASA requirement or an initiative from Sierra Nevada?

That was one of several different crew access options proposed by ULA.
I suppose all commerical crew users launching from a Atlas 402 might be able to share the tower since all the vehicles will probably have their access hatches at about the same height.

Offline douglas100

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Re: Dream Chaser Q&A (including suggestions and improvements)
« Reply #943 on: 03/22/2012 08:27 am »
That's assuming both DC and CST-100 reach launch status, which is far from certain.

You could imagine a swing arm on the north and south sides of the tower each with a dedicated white room on its end, serving both spacecraft. But how easy that would be from an operational standpoint I have no idea.

There has been criticism of the "universal launch pad" idea on this forum in the past and this would be a small step in that direction.
« Last Edit: 03/22/2012 08:29 am by douglas100 »
Douglas Clark

Offline A_M_Swallow

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Re: Dream Chaser Q&A (including suggestions and improvements)
« Reply #944 on: 03/22/2012 10:43 am »
That's assuming both DC and CST-100 reach launch status, which is far from certain.

You could imagine a swing arm on the north and south sides of the tower each with a dedicated white room on its end, serving both spacecraft. But how easy that would be from an operational standpoint I have no idea.
{snip}

Use an exchangeable swing arm.  Insert it into the tower's lift.

Offline yg1968

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Offline Lurker Steve

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Re: Dream Chaser Q&A (including suggestions and improvements)
« Reply #946 on: 03/23/2012 04:01 pm »
Sounds like the captive carry test is coming up next month. They are really making great progress on their milestones.

Offline lucspace

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Re: Dream Chaser Q&A (including suggestions and improvements)
« Reply #947 on: 03/25/2012 10:21 am »
The new artist impressions of the DC vehicle show refinements; looks like it has lost the nosewheel, replaced by a 'SpaceshipTwo-like' skid. Any thoughts about the reason for this?

Offline docmordrid

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Re: Dream Chaser Q&A (including suggestions and improvements)
« Reply #948 on: 03/25/2012 11:54 am »
First blush: weight & simplicity.
« Last Edit: 03/25/2012 11:57 am by docmordrid »
DM

Offline douglas100

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Re: Dream Chaser Q&A (including suggestions and improvements)
« Reply #949 on: 03/25/2012 12:31 pm »
Extra free braking as well.

EDIT: fixed spelling.
« Last Edit: 03/26/2012 07:46 am by douglas100 »
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Offline Rocket Science

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Re: Dream Chaser Q&A (including suggestions and improvements)
« Reply #950 on: 03/25/2012 12:41 pm »
Yea, why not… KISS. Since this is not a conventional aircraft, no need for nose gear steering because it does not taxi for takeoff. You really only need differential braking on the mains during landing when necessary. I would add that the nose skid would also create drag with a “speed brake effect” at touchdown reducing rollout and required runway length ;)
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Offline Ronsmytheiii

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Re: Dream Chaser Q&A (including suggestions and improvements)
« Reply #951 on: 03/26/2012 02:52 am »
Yea, why not… KISS. Since this is not a conventional aircraft, no need for nose gear steering because it does not taxi for takeoff. You really only need differential braking on the mains during landing when necessary. I would add that the nose skid would also create drag with a “speed brake effect” at touchdown reducing rollout and required runway length ;)

The orbiter initially only used differential braking, but nose wheel steering was added:


Quote
The first landing at KSC was Mission 41-B on Feb. 11, 1984. KSC was the landing site for four of the next six missions. Extensive brake damage and a blown tire at the conclusion of the 51-D mission in April 1985 prompted officials to postpone further KSC landings until nose wheel steering and improved brakes were installed in the orbiters.

http://www-pao.ksc.nasa.gov/kscpao/release/1992/1-92.htm
« Last Edit: 03/26/2012 02:55 am by Ronsmytheiii »

Online simonbp

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Re: Dream Chaser Q&A (including suggestions and improvements)
« Reply #952 on: 03/26/2012 04:29 am »
One might call it the reverse X-15 landing technique...

http://www.dfrc.nasa.gov/gallery/photo/X-15/HTML/E-7469.html

Offline Namechange User

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Re: Dream Chaser Q&A (including suggestions and improvements)
« Reply #953 on: 03/29/2012 11:36 pm »
The new artist impressions of the DC vehicle show refinements; looks like it has lost the nosewheel, replaced by a 'SpaceshipTwo-like' skid. Any thoughts about the reason for this?

Looks like it still has the nosewheel to me, see 11:57 on the video. 
Enjoying viewing the forum a little better now by filtering certain users.

Offline Rocket Science

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Re: Dream Chaser Q&A (including suggestions and improvements)
« Reply #954 on: 03/30/2012 12:16 am »
Yea, why not… KISS. Since this is not a conventional aircraft, no need for nose gear steering because it does not taxi for takeoff. You really only need differential braking on the mains during landing when necessary. I would add that the nose skid would also create drag with a “speed brake effect” at touchdown reducing rollout and required runway length ;)

The orbiter initially only used differential braking, but nose wheel steering was added:


Quote
The first landing at KSC was Mission 41-B on Feb. 11, 1984. KSC was the landing site for four of the next six missions. Extensive brake damage and a blown tire at the conclusion of the 51-D mission in April 1985 prompted officials to postpone further KSC landings until nose wheel steering and improved brakes were installed in the orbiters.

http://www-pao.ksc.nasa.gov/kscpao/release/1992/1-92.htm

Hey Ron,

Thanks for the link and for refreshing my memory, it’s been a while.  :) Given my preferences, I would like nose wheel steering especially for a concrete runway (a lot less margin for error deviating off the center line). If indeed they do use a skid it would be better suited to a dry lake bed. The Dream Chaser gears are close coupled in distance compared to the Orbiter with less inherent stability and thus more susceptible to a ground loop. The X-24A used the nose gear from an T-39 (F-11F-1F on X-24B) and T-38 main gear and DC may be very similar in handing… The nose gear steering was deleleted and deemed too sensitive.

Regards
Robert

Wingless Flight: The Lifting Body Story
 By R. Dale Reed, Darlene Lister

http://www.vskylabs.com/vsl-techreports/martin-marietta-x-24a-reports/x-24-approach-flare-and-landing

P.S. Perhaps they are considering a nose skid for the initial drop and landing tests and reevaluate after the test results.

« Last Edit: 03/31/2012 12:35 am by Rocket Science »
"The laws of physics are unforgiving"
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Offline Rocket Science

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Re: Dream Chaser Q&A (including suggestions and improvements)
« Reply #955 on: 03/30/2012 12:20 am »
The new artist impressions of the DC vehicle show refinements; looks like it has lost the nosewheel, replaced by a 'SpaceshipTwo-like' skid. Any thoughts about the reason for this?

Looks like it still has the nosewheel to me, see 11:57 on the video. 
It might be an angle-illusion OV, I looked at a larger still and I only see two main gears. Anyone else??

~Robert
"The laws of physics are unforgiving"
~Rob: Physics instructor, Aviator

Offline manboy

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Re: Dream Chaser Q&A (including suggestions and improvements)
« Reply #956 on: 03/30/2012 01:10 am »
The new artist impressions of the DC vehicle show refinements; looks like it has lost the nosewheel, replaced by a 'SpaceshipTwo-like' skid. Any thoughts about the reason for this?

Looks like it still has the nosewheel to me, see 11:57 on the video. 
It might be an angle-illusion OV, I looked at a larger still and I only see two main gears. Anyone else??

~Robert
After relooking over the the pictures from the video it still looks like the nosewheel was removed. Compare it with these older images that still showed the nosewheel.
« Last Edit: 03/30/2012 01:14 am by manboy »
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Offline Namechange User

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Re: Dream Chaser Q&A (including suggestions and improvements)
« Reply #957 on: 03/30/2012 01:33 am »
The new artist impressions of the DC vehicle show refinements; looks like it has lost the nosewheel, replaced by a 'SpaceshipTwo-like' skid. Any thoughts about the reason for this?

Looks like it still has the nosewheel to me, see 11:57 on the video. 
It might be an angle-illusion OV, I looked at a larger still and I only see two main gears. Anyone else??

~Robert

I think you may be right about the angle.

So if I had to guess why there is a skid now in place of the nose gear, it may have something to do with thermal issues. 

Since this is a tire, it has to be managed and conditioned in order to maintain pressure, etc.  Obviously, there is still the main gear but deleting the nose wheel may have offered a mitigation to a thermal/life-cycle issue. 
Enjoying viewing the forum a little better now by filtering certain users.

Offline clongton

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Re: Dream Chaser Q&A (including suggestions and improvements)
« Reply #958 on: 03/30/2012 01:41 am »
Most likely the skid is for Edwards. The skid would be better on the flat than a wheel.
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Offline ChefPat

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Re: Dream Chaser Q&A (including suggestions and improvements)
« Reply #959 on: 04/04/2012 09:42 pm »
In this presentation, it states SNC is "Investigating other options (ATK Booster)", for Dream Chaser.
Could DC handle the acoustic enviroment of a solid rocket? How fast would it have to go on LES Engines to get away from a solid rocket in case of an abort?
Playing Politics with Commercial Crew is Un-American!!!

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