Adrian Tymes wrote:
> 6 engines, arranged the same but at corners of a
> triangle, would also work. That's the magic number
> for this pair trick: you have to have an even number,
> and 2*2 or 1*2 doesn't give you both yaw and pitch (or
> gives you at most three of +yaw, -yaw, +pitch, and
> -pitch).
>
> For identical engines which can only be set to +roll
> or -roll, and not, say, +0.5 roll, the magic number is
> probably either 6 or 4. 6 works as described above; 4
> works as Dave M. described. 5 or 3 would not seem to
> allow for symmetrical solutions - if +p, +y can get no
> roll, then -p, -y can't, or maybe +p, -y or -p, +y -
> without placing two engines so close together they
> might as well be one. And of course one can't
> robustly balance a rocket on 1 or 2 immobile (relative
> to the rocket) engines (place one engine a millimeter
> off, and...).
Well ... the way to make 5 engines work is the original POGO
configuration with one central engine (that just has an on/off relay)
and 4 outer engines that have throttle control. This allows you to
maintain a reasonable thrust level even when using differential
throttling to control your flight. And the failure modes are much
nicer too:
- center fails
- land on 4 outers
- an outer fails
- turn off the opposite outer and land on 3 engines
That ability to keep a reasonable thrust level even in an engine out
situation has a lot of merit.
Michael
----------------------------------------------------------------------
Michael Wallis KF6SPF (408) 396-9037 [EMAIL PROTECTED]
Mark Twain:
"Always do right. This will surprise some people and astonish the
rest."
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