Author Topic: How should NASA evolve the SLS?  (Read 178644 times)

Offline a_langwich

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Re: How should NASA evolve the SLS?
« Reply #380 on: 07/03/2013 03:08 am »
I don't know if this has been posted elsewhere but
http://www.aviationweek.com/Article.aspx?id=/article-xml/awx_07_01_2013_p0-592975.xml&p=1
The article claims that Boeing has produced a small diameter, 2.4 m test tank that is 30% lighter than Li-Al alloy tanks.

Sounds very promising.

This may be a bit skeptical, but the article didn't actually say the 2.4m tank was 30% lighter, just that the project appeared to be achieving its goals of making tanks 30% lighter and 25% cheaper.  (Which I agree is extraordinary.)

Three temperature settings is a start, but the thermal cycling plus load is where the real test is.  Or maybe that's thermal cycling plus load plus actual liquid hydrogen with all of its troubles.  I wonder why they decided to move to a 5.5m--are they not planning to cycle the 2.4m?  Maybe they already pressurized it to failure.

Finally, I'm trying to picture how you lay out ultra-thin composite plies and end up with tube structures in the walls--that sounds like combustion chamber fabrication!  Amazing if it's as complicated as it sounds and they can still produce it 25% cheaper than a Al-Li tank.

According to this paper*
upper stage mass fraction can be a major driver in BEO mission capability.

* Titled "Cryogenic Propulsive Stage Mission Sensitivity Studies:  Earth-Moon L1" under section "Exploration" in their javascript box, referenced URL
http://www.ulalaunch.com/site/docs/publications/SEI%20-%20CPS%20Mission%20Sensitivity%20Study%20-%20L1%20Departure%20revB.pdf

Offline TomH

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Re: How should NASA evolve the SLS?
« Reply #381 on: 10/08/2013 09:37 pm »
The ~200 tonne upper stage enables a truly flexible path. Advanced boosters ... don't.

You might want to read this; Scroll to part IV. Here's a rocket scientist who disagrees with you.

http://forum.nasaspaceflight.com/index.php?topic=32911.msg1106894#msg1106894


Offline sdsds

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Re: How should NASA evolve the SLS?
« Reply #382 on: 10/11/2013 01:52 am »
The ~200 tonne upper stage enables a truly flexible path. Advanced boosters ... don't.

You might want to read this; Scroll to part IV. Here's a rocket scientist who disagrees with you.

http://forum.nasaspaceflight.com/index.php?topic=32911.msg1106894#msg1106894

Thanks for pointing out that post! I have followed António's work for some time -- he does a great job putting real numbers to concepts, which I truly appreciate.

I'm curious though about how you read his post. He concludes that advanced boosters: "LRB do seem to give at very least about 20t or so of extra payload (and other performance margins) in relation to what any improved solid could do." But that 20 t to LEO is no more than 10 t through TLI. Are you sure that's enough for a flexible path approach to exploration?
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