Re: balloon tanks

On Wed, 2004-05-05 at 18:50, [email protected] wrote:

> "Excellent structure"? I doubt it. If nasa did it, it's wrong. That is a good 
> starting point for CATS rocket analysis. Don't copy nasa. Do the opposite. 

	NIH syndrome won't serve the alt.space community any better than it's
served NASA. If you don't like NASA as a precedent for this sort of
structure, then go examine a soda can, because they work the same way.
NASA has done a lot of good work, and ignoring it due to some misguided
ideological bias is foolish.

>      When you attach a piece of rocket structure to a stressed metal balloon 
> fuselage, you create stress failure points. 

	When you attach a piece of structure to any other piece of structure,
you create potential stress failure points. The key is good analysis,
and with readily available software (like Pro/E's thermal and structural
modules) that is not particularly hard for a group with the financial
and technical chops to contemplate a vehicle for which a balloon
structure might have an advantage. 

> The lightest-weight design isn't 
> the safest and easiest design for our alternate access to space.
>     Simply put, a tank needs internal reinforcement to be a strong fuselage. 
> You don't want the ship breaking apart when strong aero dynamic turning 
> moments are applied. Balloon tanks? C'mon. Highly inappropriate. 

	Actually, the problems with balloon tanks are not in flight, but in
ground handling. The Atlas had to be pressurized during handling in
order to have sufficient strength to resist handling loads. In flight,
the internal pressure gave them all the strength and rigidity they
needed. Inflatable structures can be amazingly strong and resilient when
fully inflated and pressurized -- for fun, try calculating the slamming
loads on a Zodiac inflatable skiff at high speed. 

	-p