Re: Current airship project



> Hi Pat,
> 
> > There's also something to be said for rapid-prototyping, as it quickly lets
> > ideas bounce around and cross-pollenate different people.
> 
> I agree, is there a brainstorming mailing list, message board or IRC channel?
> 
	Not yet (that I run), but it's a very good idea! Perhaps I'll start up 
a few of the other lists that I've been thinking about for a while...

> >  How is it inflated? I thought it was helium inside, not just regular air,
> >or do you have a helium bladder inside of the main body? Seems like the
> >helium would be pressurized, and wouldn't need a fan to inflate...
> 
> The purpose of this model was to test how it flew without a lifting gas. I ca
> n't
> use lifting gases for airships that I can't recompress or liquefy because a
> design requirement is that I have to be able to fit everything back in my
> apartment afterwards. This afternoon I tested it outside and it's unstable in
> pitch. I believe the reason is that the center of lift is ahead of the center
>  of
> buoyancy. The center of lift is about 30% of the way along the chord of the
> airfoil; since the balloon is symmetric, the buoyancy is 50% of the way along
> the chord, so when the airship speeds up, it either pitches up or down. I
> believe a large wing at the rear would balance this by bringing the center of
> lift to the center of the airship; but, this would add weight and complexity,
> which is what I tried to avoid by modeling blimps instead of aircraft. Becaus
> e
> of this problem, I'm going to try out a pure lifting black airship, the lifti
> ng
> gas being solar heated air. For propulsion, I'll try to tap the convection
> currents around the balloon using a wing at the top.
> 
	Sounds cool. I like the design, but I do see how it could get tossed 
around, since it provides a very asymmetric design (in 3D) which allows for 
currents to catch it and throw it about.




Pat





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