Hi Curt,
As far as I know, some of the early rocket models either had secondary attitude
thrusters or deflector plates placed inside the main rocket exhaust. Modern
types (i.e. anything from the 1950s onward) have used gimbaling main engines.
If you watch prelaunch space shuttle footage, you can usually see the 3 SSMEs
do a full motion cycle just before ignition. Additionally, some rockets,
including the Saturn 5 first stage, used airfoils for improved stability.
Also, the more sophisticated engines can throttle. IIRC, the Space Shuttle can
throttle between approx 65% and 104% of its rated thrust. Typically it
throttles back to 65 during a period of max dynamic pressure, just around the
time of solid booster separation. At this time, it's already picked up quite a
bit of velocity, but is still going through a relatively thick atmosphere.
Interestingly, another challenge is to restart a rocket engine in orbit,
because the liquid fuels are just floating around. The Saturn 5 third stage,
needing to reignite for lunar trajectory insertion, had a separate set of solid
fuel engines, which only served the purpose of pushing the fuels down in order
to enable a restart. Rather fascinating if you think about what kind of
extraordinary challenges space poses for things we take for granted....
Cheers,
Durk
On 18 Apr 2011, at 16:41, Curtis Olson wrote:
> I've never looked into it, but I've always wondered how (or how much) control
> they have over those giant rockets. I know the space shuttle flies a very
> precise profile and rolls over at a particular point, so they must have some
> good control. But I have never thought about how that control is
> implemented. Do they have secondary thrusters? Can they vector or deflect
> their thrust? Can they throttle? I know that some smaller rockets will spin
> along their longitudinal axis to help average out any built in imbalances and
> keep a stable course (probably the same idea as a rifle bullet.)
>
> Curt.
>
>
> On Mon, Apr 18, 2011 at 9:29 AM, Arnt Karlsen <a...@c2i.net> wrote:
> On Mon, 18 Apr 2011 06:31:09 -0700 (PDT), Gene wrote in message
> <alpine.lfd.2.00.1104180630330.13...@grumble.deltasoft.com>:
>
> > On Mon, 18 Apr 2011, AJ MacLeod wrote:
> >
> > > On Sun, 17 Apr 2011 00:39:52 +0200
> > > Torsten Dreyer wrote:
> > >
> > >> 156MB!? Isn't that a bit - huge?
> > >
> > > Maybe... but it looks like a fantastic model. If only I had the
> > > time to actually work out how to fly it :-) Really impressive work
> > > though.
> >
> > Fly it? I thought you just lit a match and then did your best to
> > hang on until the big noisy thing at the other end runs out of gas. :)
> >
> > g.
> >
>
> .."fly it", means control it well enough to do
> e.g. touch-n-go's at will, not by accident. ;o)
>
> --
> ..med vennlig hilsen = with Kind Regards from Arnt Karlsen
> ...with a number of polar bear hunters in his ancestry...
> Scenarios always come in sets of three:
> best case, worst case, and just in case.
>
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> --
> Curtis Olson:
> http://www.atiak.com - http://aem.umn.edu/~uav/
> http://www.flightgear.org - http://gallinazo.flightgear.org
>
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