Author Topic: Hypothetical 1/3 Scale Starship  (Read 12073 times)

Offline livingjw

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Re: Hypothetical 1/3 Scale Starship
« Reply #40 on: 03/01/2022 12:33 am »
So, the scaling guide posted above is quite interesting.  If I am reading it correctly, one of the big advantages of really large rockets is that the mass percentage of TPS scales as a less than linear function and TPS is one of if not the biggest dry mass addition for a reusable rocket.  Does that also then support the argument for short stubby rocket stages since they will have reduced surface area to hold a given amount of fuel and propellant and that is less to shield?  At least maybe that argument is valid for something entering ballistic, maybe it no longer applies if you need to generate lift as well. ....

If you want similar heating loads you need to maintain similar Ballistic Coefient (BC) and CL capabilities for the scaled vehicle. You should be able to maintain these as you scale down, it might even be a little easier at a smaller scale since BC is proportional to W/(CD*A). CD will stay about the same, weight will scale with SFv and A will scale with SFa.

John

Offline FunBobby

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Re: Hypothetical 1/3 Scale Starship
« Reply #41 on: 03/06/2022 09:22 am »
Is it possible to circumvent some of the scaling issues if you employ non-structural re-entry devices?  Specifically what I was thinking about is reducing structural heating by changing the BC through the use of something like a Ballute?  I know that SpaceX briefly considered this as a strategy to recover a Falcon 9 upper-stage with minimal TPS.  I understand that you are basically inflating a structure with gas that increases surface area and drag for ballistic re-entry.  I think this has also been considered as a strategy for Mars atmospheric entry.  This is probably not the best technology for rapid-reuse with minimal refurbishment since I can't imagine the ballute itself being reusable, so it doesn't really have an application for a Starship-like vehicle.  Instead it might be something that Rocket Lab considers if/when they try and develop a reusable 2nd stage.
Cheers,
Bobby

 

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