Good description by Durk.
If you want to know more about ascent guidance and control, this is an
interesting and more basic look at that:
http://www.aero.org/publications/crosslink/winter2004/06.html
And this,
http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2
<http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=AD0643
209> &doc=GetTRDoc.pdf&AD=AD0643209
"Derivation of Linear Tangent Steering Laws."
Jon
From: Durk Talsma [mailto:[email protected]]
Sent: Monday, April 18, 2011 10:17 AM
To: FlightGear developers discussions
Subject: Re: [Flightgear-devel] Vostok-1
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 <[email protected]> wrote:
On Mon, 18 Apr 2011 06:31:09 -0700 (PDT), Gene wrote in message
<[email protected]>:
> 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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