Re: Steering

Alex Fraser wrote:

> The choices are?
> 
> - Change the thrust direction, gimble mount for engine or bell.
> - Alter the stream of gases, vanes or diverters.
> - Fins, aerodynamic forces
> - Multiple engine thrust control
> - Separate attitude thrusters
> - and dimly in my memory from this list, a discussion of altering the 
> plume by injecting  fuel off center
> 
> Are these the only ways? Have I missed any? Gyros?

Reaction wheels, as used to point the Hubble Space Telescope, sometimes 
incorrectly referred to as gyros.

Fluid injection amounts to non-solid jet paddles; same class as the 
Jetavator (a ring around the nozzle that can be impinged on the exhaust 
stream to divert it) and paddles that do the same thing with a 
non-continuous actuator -- no roll control.

Theoretically, CG shift could be used to provide pitch/yaw control, but 
not roll (well, in a vehicle that looks like a collection of strap-on 
boosters, with some flexibility in the couplers, perhaps, but I wouldn't 
want to fly in it).

While in atmosphere, fluid (gas) injection at the nose can be used to 
steer in much smaller flows and velocities than attitude jets by 
altering the stagnation point, though it has little effect at low (i.e. 
subsonic and low supersonic) speeds on vehicle shapes suitable for high 
supersonic flight.

Similarly, boundary layer control by surface suction could be used to 
create body lift differentially for pitch/yaw steering, and depending on 
shape possibly also roll; mostly good at subsonic speed.

A steerable shock wave probe in the nose (like the probes used on some 
sub-launched missiles to give a better aerodynamic profile to a missile 
that had to fit maximum volume in a fixed diameter tube) could give 
pitch/yaw at supersonic speeds.

-- 
I may be a scwewy wabbit, but I'm not going to Alcatwaz!
                                                     -- E. J. Fudd, 1954

Donald Qualls, aka The Silent Observer
Lathe Building Pages  http://silent1.home.netcom.com/HomebuiltLathe.htm
Speedway 7x12 Lathe Pages     http://silent1.home.netcom.com/my7x12.htm

Opinions expressed are my own -- take them for what they're worth
and don't expect them to be perfect.