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Thermal Protection Scaled Composites

Posted by: Klaus Schmidt - Mon Oct 31, 2005 4:22 pm
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Thermal Protection Scaled Composites 
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Post Thermal Protection Scaled Composites   Posted on: Mon Oct 31, 2005 4:22 pm
I don't know if it's already known. I think Scaled Composites at least had, perhaps still has access to the following heat shield technology:
http://www.flug-revue.rotor.com/FRheft/ ... R9812k.htm

Scaled built the X-38 test vehicle so they had to know about the exterior of the craft. As the X-38 program was quite advanced I think, they already made at least components with the corresponding heat shield.

As far as I remember (I searched but couldn't find the quote) Rutan once said he has four problem for orbital flight und two were solved. So what do you think, could the heat shield be one of the solved problems?


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Post    Posted on: Tue Nov 01, 2005 10:10 am
I'm actually wondering what the 2 remaining problems are.. any one wanne guess ? :)

One of them could be "flexibility" after entering earths atmosphere to fly easily to a nearby airfield or spaceport, cause current Soyuz or SpaceShuttle have as good as no "flying" capabilities.

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Post    Posted on: Tue Nov 01, 2005 1:54 pm
My guess is that one of the unsolved problems is funding.


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Post    Posted on: Wed Nov 02, 2005 7:15 am
Hello, Klaus.Schmidt,

regarding heat shielding Rutan is using the shuttle cock conspet in the design of the CXV. As far as I undertsnad it this is - basically or principially at least - the same concept used by the feather technique of SSO.

Under this aspect I think that heat shielding is one of the two solved problems.

Since Scaled Composites is part of t/Space and t/Space has said that they could have ready the CXV in 2008 The two remaining problems may be solved but perhaps

a) not by Scaled und additionally kept secret by that t/Space-partner who solved them,
b) the solution doesn't include sufficient reusability,
c) the solution still includes too much stresses for touristic passengers.

Could the unsolved problmes be

a) that the booster isn't reusable yet,
b) that the CXV is landing in th ocean instead of on land?
c) Rutan wnats a landing as soft as possible but the CXV isn't capable of that because it has no wings?



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Post    Posted on: Wed Nov 02, 2005 5:13 pm
C'mon, we're all fart smellers.... Uh, I mean smart fellers. Surely we can figure out what the four fundamental problems of spaceflight are from Rutan's viewpoint.

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Post    Posted on: Wed Nov 02, 2005 10:38 pm
In my opinion they are:

-some kind of booster.. in other words..enough energy to get to the orbit
-reentry (-> heat shield technology)
-life support in orbital flight, e.g. air, water, perhaps food and enough space
-attitude control in all aspects

I never thought of funding, but this could also be a major problem.


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Post    Posted on: Thu Nov 03, 2005 4:26 am
Okay, folks, I'm going to ramble a bit now, just so you know. If I miss anything, please let me know -- I'll be glad to hear it.

Four fundamental fources of flight are lift, drag, thrust, and weight.

Weight is a minor issue, to be dealt with in bits and pieces. Lift and drag are both nonexistant in a space vehicle (they're almost minor problems on this, since the goal is to get to space), so we can officially ditch this model, except for the rocket engineer's mantra: THRUST.

So we need an engine. We also need a way to get the people back on the ground, necessitating a set of landing gear of some sort (remember, SS1 used a nose skid), and a TPS.

So now we're up to an engine and some sort of thermal protection widget. What else can we use? Getting the thing airtight isn't that bad -- SS1 used a cork for cabin pressure control at altitude (although not in vacuum). Guidance doesn't seem to be that big of a problem, SS1 didn't have any trouble, except for a few minor wiring SNAFUs.

Maybe the mothership? He's going to have to build something bigger than he's ever done before: remember, Rutan likes light, fast, and maneuverable little birds, not the big, lumbering behemoth that the WK2 will have to be.

Life support shouldn't be a problem; nobody's going to be cooped up in the thing that long. For air, you shouldn't need anything spiffier than a compressed air can duct-taped to the back of the seat.

Control can be a problem -- remember, he liked that feathering re-entry configuration, and will likely try to implement it on SS2. He shouldn't need that well-developed of an RCS, though, as the ship will be oriented in roughly the right direction when it exits the atmosphere, and won't be out of atmosphere long enough to be doing any fancy maneuvers.

Ekkehard may have brought up a very good point, though: maybe his current launch/re-entry methods will put too much g forces on the craft for either passenger comfort or even structural integrity.

Okay, that's everything I can think of right now. Anybody got anything else to add?

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Post    Posted on: Thu Nov 03, 2005 10:13 am
spacecowboy wrote:
Okay, that's everything I can think of right now. Anybody got anything else to add?


If I may? :)

Quote:
Guidance doesn't seem to be that big of a problem, SS1 didn't have any trouble, except for a few minor wiring SNAFUs.


I think it could be a bit more difficult. If you go orbital (and let's assume he doesn't just make a 90 minutes orbital hop but targets some kind of space station) he needs two kinds of control. First a rendez-vous technique to get his craft to the station and dock with the station. Second (even if he's not targetting a space station) he needs a reentry control system.."correct" alignment, timed reentry-burn..

Quote:
Life support shouldn't be a problem; nobody's going to be cooped up in the thing that long. For air, you shouldn't need anything spiffier than a compressed air can duct-taped to the back of the seat.


Well, as said, I don't think he's targetting a 90 minutes single-orbit flight. So even if you rendezvous with a space station he'll need a system, that keeps his passengers I think at least 2-3 days alive. If the docking fails, he must have enough a safety margin high enough in order to land the craft.

And I think he is targetting a space station because of the costs. Why should he make only short flights once he is in orbit? It's much cheaper to stay there and as he is targetting the tourism he needs arguments to get the girls and boys buy his tickets. If you only go there for a few orbits for let's say 2 million dollars, it's "worse" than the russian 20-million-for-a-week flight.


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Post    Posted on: Fri Nov 04, 2005 4:42 am
Right; for some reason I was thinking SS2 was suborbital.

As for the guidance, all he needs is a GPS receiver that can process signals from altitude -- remember, GPS sats are in GEO, and will quite happily cover anything in LEO.

And yes, life-support would be a slight issue, but still, not much bigger than in the fighter jets that were around back in his blue-suit days (yes, folks, much to publi's chagrin, our hero used to be in the U.S. Air Force).

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Post    Posted on: Fri Nov 04, 2005 11:01 am
...


Last edited by whonos on Thu Jun 07, 2007 7:17 pm, edited 1 time in total.



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Post    Posted on: Fri Nov 04, 2005 4:29 pm
whonos wrote:
SS2 is suborbital

Then why are we worrying about hooking up with a space station?

whonos wrote:
A guidance system can't use just GPS, it's not accurate enough (10 meters), so most systems use a combination of GPS (for long term accuracy) and inertial guidance (for short term accuracy) and filter the outputs.

Is that civilian or military spec (I'm honestly not up to date on GPS systems)? Oh, by the way, GPS sats orbit at about 12,000 miles.


whonos wrote:
How can you (being an AE major) even think about comparing life support in an atmospheric vehicle to life support in a space vehicle?

Easy: the pressure differential between 30,000 feet and hard vacuum is so low as to make no odds. Jump out at angels 30 and you'll die just as fast, it's just that in space, you'll take longer to hit the ground.


whonos wrote:
As you can see they are not even remotely comparable.

Actually.......Here let's compare the complexities of both:


Okay, sounds like a plan.

whonos wrote:
Life Support in a Fighter Jet:
*Compress incoming air
*Exhaust used air

Wrong. All aircraft capable of operating above 25,000 are required to carry oxygen at all times. (FAR 135.89 -- that's when they're required to use it; I don't know about when the requirement is to have it installed), and above 35,000, one pilot must have a mask on and running at all times. That's no compressed air, friend, that's an O2 tank strapped to the back of the seat. This is for civilian aircraft, and undoubtedly less strict than military standards.

whonos wrote:
Life Support in a Space Vehicle:
*Carry all oxygen and inert gases to be used (consumed, leaked, etc)

Yup. Jet's got that.

whonos wrote:
*Use oxygen sensors to maintain constant oxygen partial pressure levels

Anything certified to fly above something like angels 20 or 25 is required to have that.

whonos wrote:
*Scrub air of carbon dioxide using a CO2 aborbant material (sodalime/lithium hydroxide), a molecular sieve adsorber, or a chemical reaction (Bosch/Sabatier reactor)

Don't really need that unless you're dealing with very extended periods in space -- a bleed valve is easier. But that's okay, they're not that hard to do.

whonos wrote:
*Remove water vapor from the air using a dehumidifer

I can get one at Wal-Mart for about twenty bucks -- and all airliners have 'em.

whonos wrote:
*Remove odors using activated carbon

My fishtank's got one of those.

whonos wrote:
*Maintain proper temperature using heat exchangers and radiators

Uh, you mean an A/C unit, right? Anybody got a Yugo they can rip one out of?

whonos wrote:
*Do all of this in zero gravity

Whoop-de-doo.

whonos wrote:
(makes things much harder)

Nope, actually, it doesn't. All it means is that you have to use a fan to move the air around, which you already were using if you had the A/C and the dehumidifier. So just install the activated carbon and the scrubber on the A/C unit and put the dehumidifier right after that in the cycle. For something of SS2's size, you can cram all that in about a 2-3 cu. ft. volume.

Oh, and I still want the O2 tanks on the seatbacks, just in case.

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Post    Posted on: Fri Nov 04, 2005 5:04 pm
Howdy spacecowboy ;)

Quote:
Quote:
SS2 is suborbital


Then why are we worrying about hooking up with a space station?


Because I started the thread mainly for a discussion about orbital flight (and reentry/heat shield technology) ? :)


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Post    Posted on: Fri Nov 04, 2005 5:23 pm
OK, Kids... first of all TIER TWO is the orbital program of Scaled Composites/MAV; SpaceShipTwo is the expanded-capacity Tier One craft being built by The Spaceship Company for Virgin Galactic.

The Tier One vehicles are in fact equipped with simple gas bottles to maintain cabin pressure and chemical CO2 scrubbers/dehumidifiers. This is sufficient to sustain life support in "hard vacuum" at >100 KM for ~15 minutes, if we are to believe Burt's design specs. (He's a decent engineer by all accounts, I think I'll take his word)

Now as far as orbital activity, if we are looking at life support criteria, we have the following things to consider: Burt has said on a number of occasions that the Tier Two ship will be a taxi/van kind of vehicle, that an orbital destination must be present for the tourism model to make sense. In another thread in this forum, the problem of rendezvous timetables was addressed and it was widely concluded that it would be possible to rendezvous with an orbital target within 45 minutes to an hour, and more than one example of that kind of performance was cited in that context. This seems to suggest that it would be possible to simply scale the Tier One life support model to provide the necessary 3 hours (one hour each way plus 50% margin) of life support required. Given that Mr. Rutan is known as something of a minimalist, I'll bet money that he considers the life-support issue solved.

I expect that GPS for space operations is more than adequate for LEO navigation. I know some folks whom were working on GPS back when there were only 3 birds in the constellation so I am confident in making that statement.

If Burt feels that he hs two problems, I expect they are booster and OMS, seeing as how he seems to shop his actual rocket work out, and since the QuickReach is still way too small and has not flown, that one seems obvious.

The whole CORONA capsule and heat shielding seems to be pat if you listen to the things he says and examine what is on the t/Space pdfs. But the old CORONA spybirds may not have been built for on-orbit manuvering, certainly not rendezvous, and there may not be precedent for hull penetrations to accommodate RCS thruster ports. Not to mention that the hatch is on the aft end of that capsule, meaning that there has to be a thruster to push it backward for docking, and the NOSE of this beast is where the bulk of the re-entry shock is centered. Maybe you could rig some kind of rear-deployable "elbow" nozzle, but it would have to fold up or something during launch and recovery, meaning it would be a possible critical failure point.

Anyway, that's my gander, but only Burt knows for sure... and he ain't tellin'


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Post    Posted on: Fri Nov 04, 2005 5:40 pm
...


Last edited by whonos on Thu Jun 07, 2007 7:17 pm, edited 1 time in total.



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Post    Posted on: Fri Nov 04, 2005 6:00 pm
Spacecowboy and Whonos behave yourself!

Stephen (Spacecowboy) I know you where amusing yourself, with challanging whonos, quit it.

whonos, just relax, we don't need such styke of conversations on this forum.

Stephen, you shared with me in aim messenger that he would react this way, and you made it come true.. congrats.. now fix your mess! :wink:

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