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Re: starship-design: HOTOL SeaDragon idea.



In a message dated 12/3/02 1:36:38 PM, bfranchuk@jetnet.ab.ca writes:

>KellySt@aol.com wrote:
>
>> 
>> Subj:  Re:SSTO + Tug launcher?       
>> By: ==
>> 
>> On your SSTsub-O w/Tug idea, I ran some numbers:
>> At lift-off, 90K of fuel, 9K of structure, and 10K of payload.  With
>LOX/LH2, 
>> that ought to leave you just 6,000 fps shy of LEO.  A tug with 5.5K of
>fuel 
>> and 0.55K of structure could boost your 10K payload up to LEO.  For 
>> simplicity, let's say that the previous payload supplies the fuel.  10K
>
>> payload minus 5.5K for fuel minus 0.3K of fuel to take the Tug from LEO
>to a 
>> rendezvous trajectory minus 0.2K for a fuel container, leaving 4K of
>usable 
>> payload.  That's a four-fold increase, IT WORKS!
>>   
>I like the idea of useing methane or propane as the main fuel because
>fossil fuel will run out in the near future, and synthetic fuels will
>hve to be used. Could somebody check the numbers on this.

Sorry thats a myth.  We have a estimated 4 centuries of oil if consumption 
grows at current rates.



>Note the space tug could also supply some re-entry thrust so I expect
>you would only get a 3x increase but a bit of a safety margin in your 
>design.


But that would require the tug to then reboost itself even more, before 
rentering.  It might be dangerous, or completly cancel out the advantage of 
using the tug.

Kelly