Re: Armadillo May 2, 2004

On Mon, 2004-05-03 at 11:28, John Carmack wrote:
> The last two vehicles have been continuously variable differential 
> steering.  The difficulty with that over solenoid operation is that 
> solenoids give you instant response, where you can go from full on to full 
> of in 10 msec at the actuator, while the ball valve driven big engines take 
> 800 msec to go full open to full close.  Even though you have the same 
> amount of control authority with each engine supporting 1/4 of the vehicle, 
> the responsiveness is much lower.

OK. Makes sense.

> The decision is a no-brainer if you have more complex engines, like our 
> mixed monoprops or a biprop. 

I'm not so sure about that. It will have a lot to do with the flow
temperatures and heat flux at the vanes. Although, I suppose the
expansion cooling would be enough even in a hot bi-prop. 

>  For 90% peroxide it is less clear cut, but I 
> still think there are compelling advantages.

If the KISS engine weren't so thirsty and the POGO frame already built
(without a place to put a center engine) I'd give it a try. 

I am thinking of adding a gimble to the POGO engines - It won't help the
cross coupling issues at all, but otherwise seems to have the advantages
of vanes.

You've just about got me convinced.

Thanks,
Dave 

-- 
David Masten <[email protected]>