[SpaceProgram] DARPA-RA-11-70 100YSS Notification

[cole santos]

Artus, there is less atmosphere at high altitude,most fuel is burned
to lift fuel so the reduction in fuel payload is exponential getting
larger as you approach the surface, hence the stratolaunch, JP
aerospace systems approach.

On Tue, Jan 3, 2012 at 6:15 PM, cole santos <cksantos85 at gmail.com> wrote:
> Check out JP aerospace luke....they are thinking huge ships. It is
> impractical, however so was atmospheric nitrogen synthesis before
> haber bosch, long distance power transmission before Tesla, etc.
>
> I think rockets (and other developed tech) is a misplaced goal with
> stratolaunch, spacex, NASA, ect. The things that need our attention
> are the things very few are doing. ie closed arcologies, asteroid
> mineral utilization, solar furnaces, biogas rockets, MHD rockets, etc.
>
> On Tue, Jan 3, 2012 at 5:59 PM, Luke Weston <reindeerflotilla at gmail.com> wrote:
>> Furthermore, if you want to launch a rocket from some sort of platform
>> carried by a balloon or something - well, it may be practical to do
>> this with a small model rocket or something, but it's going to be
>> highly impractical to carry the weight of any meaningfully large
>> rocket.
>>
>> Cheers,
>>  Luke
>>
>>
>> On Wed, Jan 4, 2012 at 1:49 PM, Atrus <atrus6 at gmail.com> wrote:
>>> Except, there really isn't that much difference in gravity from the surface
>>> of the earth, 10km or in orbit.
>>>
>>> g on the
>>> surface: http://www.wolframalpha.com/input/?i=solve+%5Bg+%3D+%286.67*10%5E-11+*+5.9442*10%5E24%29+%2F+%286378100%29%5E2%2C+g%5D
>>>
>>> g 10km
>>> up: http://www.wolframalpha.com/input/?i=solve+%5Bg+%3D+%286.67*10%5E-11+*+5.9442*10%5E24%29+%2F+%286378100%2B10000%29%5E2%2C+g%5D
>>>
>>> ISS orbit (410 km up)
>>> : http://www.wolframalpha.com/input/?i=solve+%5Bg+%3D+%286.67*10%5E-11+*+5.9442*10%5E24%29+%2F+%286378100%2B410000%29%5E2%2C+g%5D
>>>
>>> This is why launching rockets on a platform will only make the actual launch
>>> more difficult. You still have to reach escape velocity to obtain orbit, the
>>> only thing you would be doing by launching a rocket at a higher altitude
>>> would be the face that you would have to hit that velocity in a shorter
>>> distance.
>>>
>>> Tim Butram
>>>
>>>
>>>
>>> On Mon, Jan 2, 2012 at 7:48 PM, Stuart Young <cefiar at gmail.com> wrote:
>>>>
>>>> On Jan 3, 2012 11:27 AM, "Atrus" <atrus6 at gmail.com> wrote:
>>>> >
>>>> > What exactly is the benefit of having a high altitude launch platform?
>>>> > You would still need to reach essentially the same escape velocity, but only
>>>> > have ~half the distance to achieve that velocity. That seems like a worse
>>>> > trade off (assuming that your perceived benefit is less air resistance).
>>>>
>>>> Benefits (apart from air resistance):
>>>>
>>>> 1. Less gravity to escape (inverse square law).
>>>> 2. Less fuel to carry in the actual rocket (less mass to move to get a
>>>> payload to escape velocity), which should make things simpler (no need for
>>>> multiple stages, simpler avionics).
>>>> 3. Less differences in engine design (high/low atmospheric pressure
>>>> compensation in design not necessary) which simplifies engine and avionics
>>>> design.
>>>>
>>>> And that is just the ones that I can think off of the top of my head.
>>>>
>>>> Btw: Written from my phone, while on site at a client, so pls excuse any
>>>> errors in the text.
>>>>
>>>> --
>>>> Cef
>>>>
>>>>
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>>>
>>>
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