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Thermal Protection Scaled Composites

Posted by: Klaus Schmidt - Mon Oct 31, 2005 4:22 pm
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Post    Posted on: Fri Nov 04, 2005 6:11 pm
Well, it's only called "life-support" on TV and in the movies... the people whom make their livelihood doing it call it "spacecraft environmental control"

Turbine bleed is used to provide CABIN PRESSURIZATION in high-altitude aircraft, supplemental oxygen IS actually NEEDED for breathing, i.e. it isn't a "backup"

The easiest way to cool a human habitat in a vaccuum is to use your heat exchangers to dump the heat into water, which is then vented to the vaccum. The heat boils off. The molar heat of vaporization of water is quite spectacular, it is one of the best ways of cooling anything, and this way you don't need a big radiator, you just need a tiny vent hole. BTW, this is essentially the same principle used by a swamp cooler, only slightly more complex.

I am sure I could purchase (maybe at Home Depot, not Wal-Mart) a cartridge-fillable, electric-fan circulated dehumidifier that wouldn't care if it was in 0g or 3g. Some things can be done simply.

Maybe we'll get lucky and rpspeck will weigh in on this one, he's actually done a great deal of work on this exact problem.


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Post    Posted on: Fri Nov 04, 2005 7:09 pm
My point, whonos, is that a truly amazing number of things can be done using off-the-shelf parts, as both myself and SawSS1 just said. We don't need a stupidly complex system; most machines simply don't care about gravity, as they use a powered fan for circulation anyway (fluid dynamics is the same in 0g or 50g).

So now, I'm going to quit talking, as Sigurd asked. Let's see what some people who have actually worked on this say.

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Post    Posted on: Fri Nov 04, 2005 11:05 pm
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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 11:17 pm
If its only for a short duration, 3 hours or so, why not use a canister of silica gel crystals to soak the moisture up. Blow the air through the canister with a fan.

I think they are fairly easy to get hold of, dont garden centres sell them as a means of releasing moisture to plants by mixing them into the soil?

Not sure about their absorption rate, you might have to get a special type but the principle is fairly straightforward and probably anything that absorbs moisure fast enough will work equally well. This would not be a difficult thing to make and test.

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Post    Posted on: Sat Nov 05, 2005 2:41 am
If I could put in my $.02.

Burt Rutan was a civilian flight test engineer working at Edwards, he wasn't a blue suit guy.

Rutan is on record as saying the SS1 environmental systems are fully space qualified, so I think he consideres that problem solved.

WK and SS1 both use the same sealed cabin environment, O2 tanks, CO2 scrubbers and moisture absorbers. No bleed air at all. He said that humidity and window fogging was the biggest problem.

If $$$ is not one of his problems, then my guess as which 2 of 4 problems are solved is:

1 Power to get to orbit, not solved.
2 Reentry from orbital speed, not solved
3 Environmental control, solved
4 Navigation, solved


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Post    Posted on: Sat Nov 05, 2005 11:08 am
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Last edited by whonos on Thu Jun 07, 2007 7:16 pm, edited 1 time in total.



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Post    Posted on: Sat Nov 05, 2005 1:41 pm
Hello, whonos,

off cpurse this isn't a thread about the CXV. I only mention it because Rutan and Scaled Composites are the ones who develop the CXV and have done drop tests already.

The CXV includes a water colling system for reentry - this together with Scaled being the developers of the CXV might mean that Rutan consideres reentry to be solved.



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Post    Posted on: Sat Nov 05, 2005 2:47 pm
whonos wrote:
I think power to orbit is one of the thing's he considers solved.
You may be right. I do seem to recall a statement some time ago that an engine powerful enough to put SS1 in orbit would fit in the existing vehicle with just barely enough room left for the pilot.


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Post    Posted on: Sat Nov 05, 2005 4:09 pm
campbelp2002 wrote:
whonos wrote:
I think power to orbit is one of the thing's he considers solved.
You may be right. I do seem to recall a statement some time ago that an engine powerful enough to put SS1 in orbit would fit in the existing vehicle with just barely enough room left for the pilot.


I think that an engine might fit in theory but practice might be a totally different thing. If such a hybrid engine were that easy to make then why haven't we heard much recently about SpaceDev's Dreamchaser or the craft they are building in partnership with NASA (based on the X-34 I think)?

I also found it interesting that Scaled used their 2 smallest test pilots in SS1 (while not exactly huge I think that Matt Stinemetze was heavier than Mike Melvill or Brian Binnie) and stripped out everything they could for the second flight, I dont think there is room to double the engine size in the existing vehicle and I would expect an orbital SS1 to need an even bigger engine given the additional weight that would mean.

All of which means that I think that propulsion is one of the issues for Burt Rutan.

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Post    Posted on: Sat Nov 05, 2005 4:21 pm
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Last edited by whonos on Thu Jun 07, 2007 7:16 pm, edited 1 time in total.



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Post    Posted on: Sun Nov 06, 2005 3:53 pm
Since I too remember Rutan's issue - might there have been a progress? It has been announced recently that Rutan and Virgin Galactic will develop an orbital SS3 if SS2 is a success.

Could that mean, that the two remaining problems are solved?



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Post    Posted on: Sun Nov 06, 2005 5:56 pm
I would imagine that all it means is that Virgin and Scaled plan on driving forward with their space capitalization plans (they plan on developing it), not that the problems have been solved (which would be more like "we will shortly be building it").

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Post    Posted on: Mon Nov 07, 2005 12:53 am
whonos wrote:
Not even remotely close. The orbital version has a booster that's many times larger than the vehicle, Burt even showed a rendering of it on the "Black Sky" special
Yes, I saw that too. Presumably that is a concept vehicle capable of carrying several passengers to orbit, but I recall another occasion where someone, Burt I think, said that by expanding the NO2 tank into the passenger area and putting a bigger CTN on the back that the existing SS1 could make it to orbit with just enough room left for the pilot, although not as much room as he has now. It sounded wrong to me at the time and I never heard it again. It wasn't an actual proposal to build a vehicle and no mention was made of reentry, I think he was just trying to say that the energy required was more easily obtained than we think. Now if I could just find the reference.


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Post    Posted on: Mon Nov 07, 2005 3:18 pm
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Last edited by whonos on Thu Jun 07, 2007 7:16 pm, edited 1 time in total.



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Post    Posted on: Mon Nov 07, 2005 4:52 pm
whonos wrote:
they stated something to the effect of "to build spaceshipone we had to scale up our biggest hybrid by 100 times, but to scale that engine up to orbital we only have to do it by 4 times".


Orbital velocity being something like five times that of SS1's previous trips, and kinetic energy being Mass times Velocity squared, the statement above seems like it cannot possibly be true. Whonos' research at astronautix proves it out below:

Quote:
At 250 sec you would need a vehicle with a mass ratio of 40:1, or 98.5% fuel. Just the propellant tanks and the rocket engine weigh a lot more than that. Even if the much larger tanks and engine weigh absolutely nothing, the 1200kg spaceshipone would still need 48000kg of fuel to get into orbit. Even at 1 g/cc (both propellants are less dense) thats 48 m^3, or a cylinder 26.45 meters long with the same diameter as SS1


...the remark about 100 times bigger is inaccurate as well, the SaceDev folks bought up all of the AMROC technology, much of which was very mature; check out this hybrid at 95000 kgf thrust: http://www.astronautix.com/stages/amroc.htm (motor built 18 years ago)
...and on Space Dev's site http://www.spacedev.com/newsite/templat ... hp?pid=185 we can read the following:

Quote:
AMROC completed approximately 300 hybrid motor tests from 100 to 250,000 pounds of thrust.


However, there is presently no air-launchable booster that will place a payload of the appropriate size into orbit. This is clearly a problem that needs to be solved for Burt to proceed to Tier Two.


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