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Old October 20 2012, 08:44 PM   #249
Rear Admiral
Re: Envisioning the world of 2100

newtype_alpha wrote: View Post

HLVs simply don't have the work history to justify the kind of money NASA has been ordered to spend on them, even if they had a coherent plan for how to USE them, and they don't.
Again, STS is a history of HLLV scale operations and nasaspaceflight is full of coherant plans being developed for BEO exploration that VentureStar--which would have cost more than STS--would have competed with.

gturner wrote: View Post
I just did an interesting first pass calculation based on an Apollo mission using lithium aluminum hexahydride/H2O2 instead of Aerozene-50/N2O4.

With a 500 psi chamber pressure it has a vacuum ISP of 469, whereas everything above the S-IVB on Apollo had an ISP of 311 to 314.

Holding the dry mass of the lunar ascent module, descent module, command module, and service module consant would still result in a required LEO mass of 57 tonnes, instead of 130 tonnes. Using it the 3rd stage would reduce that stage's dry weight, too, meaning you'd only need one launch on a Falcon 9H to fly the same mission.
Well, it is supposed to lift only 40-53 tons or so. Now some solid augmentation might allow for that if Musk will allow it. But even he is looking at the BFR concept again it seems

Falcon MCT

"7m+ Core, Not RP-1, 150T or larger"

Now with the fuel you are talking about--this can only increase cargo to the Moon using both methods (large LVs and different fuels.) Besides, using HLLVs allows faster transit than using the pieces-parts method--and Nautilus-X was designed by Mark Holderman, who was a proponent of some form of shuttle derived heavy lifters and External tank applications: Three or so SLS launches should do the trick.

Something interesting I saw from the web:

Given the availability of high efficiency tankage and high T/W ratio engines from SpaceX, then reusable boosters make the lunar surface directly available to earth launched hydrogen upper and core stages with no interim staging, stops or refueling necessary. We've already gamed this out completely and have published our results. Given enough boosters, you could even land an SLS stage on the moon by incorporating the upper stages engines (throttleable Rl-10s) into the interstitials of the four SSMEs.

We can be there just as soon as current upper stage engines are converted to low gee landing engines. These kinds of engines were tested in the sixties (J2-S) and with the Delta Clipper (RL10A-5).


All hydrolox HLLV's with no payload other than a docking port themselves can become wetstage station modules with no chemical contamination associated with other fuels, so it isn't as if room need be an issue.

gturner wrote: View Post
Getting back to the SLS, the design has inherent limitations from the requirements to keep the same people building the same things. At what point in the SLS program will someone ask if using the same basic SRB for 50 years is the opposite of cutting edge? The core stage is already over 200 feet tall (due to using a narrow tank diameter for heavy lift).
R-7 is over fifty years old and going fine--and will be developed. The "narrow" tank was probably a result of the meddlers from DIRECT who wanted to kill off the larger Ares V for current ET tooling, which does allow things to get started off easier. BFR will be a bit slimmer if made, but Musk is already working with Dynetics on Stratolaunch--and they are the ones looking at an F-1 comeback for LFBs. They actually might play a part in MCT as well...

gturner wrote: View Post
Keeping the aluminum molten in just an insulated tank is pretty simple because it has a huge thermal mass.
Yep, I've seen molten aluminum carried by trucks over the freeway

Speaking about Gemini, you might find these links interesting
Dyna-Soar's cousin

Last edited by publiusr; October 20 2012 at 10:06 PM.
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