Questions on the RCS systems

The various thrusters that are used on the
shuttle, how powerful are they?
What thrusts do they have compared to the mass of the craft?
Are they throttleable, or just on/off?
Are they all the same or are different
varieties used on different parts of the ship?
How much fuel does the shuttle carry for them?
Is it one central propellant tank(s) or does each one have
it's own tank?

Just trying to build a mental picture...

JazzMan
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Note: I'm not an engineer, just an enthusiast. If I'm wrong I'm sure I'll be
corrected by qualified parties.

The various thrusters that are used on the
shuttle, how powerful are they?

The number I've seen in some recent... Er... "discussions" about this
specific subject, is 800lb thrust. The reference below (linked) gives 870lb
per engine for the big ones and 24lb for the little ones.

What thrusts do they have compared to the mass of the craft?

You mean, how much do they move the Orbiter when they're fired in a typical
situation? If that's your question, I don't know. But I think the value
would be expressed in how much velocity they can impart on the Shuttle -
what's called "Delta V." I don't know the numbers for this.

Are they throttleable, or just on/off?

On/Off. If more thrust is required, more of them are fired... They're
configured in sets. Throttleability would unnecessarily increase the
complexity of the RCS design. It's easier & safer to just just use a bunch
of small, simple rockets, and configure them to fire as necessary via
software control.

Are they all the same or are different
varieties used on different parts of the ship?

"We have three sizes: Wee, Nae' sa wee, and FRICKIN' HUGE!"

(I typed that as a joke, but when I went to the kitchen to get a beer I
realized that it's actually not too far off the mark... Vernier, Primary,
and OMS, respectively!)

How much fuel does the shuttle carry for them?
Is it one central propellant tank(s) or does each one have
it's own tank?

Just trying to build a mental picture...

General technical overview is he

http://science.ksc.nasa.gov/shuttle/...s.html#sts-rcs

Note that it is a sub-section of this page here, with lots more info:

http://science.ksc.nasa.gov/shuttle/...tsref-toc.html

Somewhere there's a version of this with graphics, but I can't find it at
the moment.

delurk

"Terrence Daniels" wrote in
ink.net:

Note: I'm not an engineer, just an enthusiast. If I'm wrong I'm sure
I'll be corrected by qualified parties.

I'm not qualified, but I'll contribute my $0.02 anyway.

The various thrusters that are used on the
shuttle, how powerful are they?

The number I've seen in some recent... Er... "discussions" about this
specific subject, is 800lb thrust. The reference below (linked) gives
870lb per engine for the big ones and 24lb for the little ones.

What thrusts do they have compared to the mass of the craft?

You mean, how much do they move the Orbiter when they're fired in a
typical situation? If that's your question, I don't know. But I think
the value would be expressed in how much velocity they can impart on
the Shuttle - what's called "Delta V." I don't know the numbers for
this.

Typical orbiter mass ranges from 200-250k lb. Delta-V depends on how many
thrusters are fired and for how long. The Digital Auto Pilot (DAP) operates
on an 80 ms cycle time, so all firings will be a multiple of that. A single
primary RCS thruster firing for the minimum time on a heavy orbiter gives a
delta-V of around 0.01 fps.

Are they throttleable, or just on/off?

On/Off. If more thrust is required, more of them are fired...

That depends on the phase of flight. It's true for the Aerojet DAP (entry),
but not the Orbit DAP or Transition DAP (insertion/deorbit). Those DAPs
only fire the highest priority thrusters in each group (determined by a
priority table in the software), and simply fire the thrusters longer to
get more delta-V.

OK, back to your regularly scheduled flame wars.

relurk
--
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check "Organization" (I am not assimilated) and
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"Terrence Daniels" wrote:

Are they throttleable, or just on/off?

On/Off. If more thrust is required, more of them are fired... They're
configured in sets. Throttleability would unnecessarily increase the
complexity of the RCS design. It's easier & safer to just just use a bunch
of small, simple rockets, and configure them to fire as necessary via
software control.

The other method to aquire more oomph is also to fire them longer.

D.
--
The STS-107 Columbia Loss FAQ can be found
at the following URLs:

Text-Only Version:
http://www.io.com/~o_m/columbia_loss_faq.html

Enhanced HTML Version:
http://www.io.com/~o_m/columbia_loss_faq_x.html

Corrections, comments, and additions should be
e-mailed to , as well as posted to
sci.space.history and sci.space.shuttle for
discussion.

Terrence Daniels wrote:

Note: I'm not an engineer, just an enthusiast. If I'm wrong I'm sure I'll be
corrected by qualified parties.

The various thrusters that are used on the
shuttle, how powerful are they?

The number I've seen in some recent... Er... "discussions" about this
specific subject, is 800lb thrust. The reference below (linked) gives 870lb
per engine for the big ones and 24lb for the little ones.

What thrusts do they have compared to the mass of the craft?

You mean, how much do they move the Orbiter when they're fired in a typical
situation? If that's your question, I don't know. But I think the value
would be expressed in how much velocity they can impart on the Shuttle -
what's called "Delta V." I don't know the numbers for this.

Are they throttleable, or just on/off?

On/Off. If more thrust is required, more of them are fired... They're
configured in sets. Throttleability would unnecessarily increase the
complexity of the RCS design. It's easier & safer to just just use a bunch
of small, simple rockets, and configure them to fire as necessary via
software control.

Are they all the same or are different
varieties used on different parts of the ship?

"We have three sizes: Wee, Nae' sa wee, and FRICKIN' HUGE!"

(I typed that as a joke, but when I went to the kitchen to get a beer I
realized that it's actually not too far off the mark... Vernier, Primary,
and OMS, respectively!)

How much fuel does the shuttle carry for them?
Is it one central propellant tank(s) or does each one have
it's own tank?

Just trying to build a mental picture...

General technical overview is he

http://science.ksc.nasa.gov/shuttle/...s.html#sts-rcs

Note that it is a sub-section of this page here, with lots more info:

http://science.ksc.nasa.gov/shuttle/...tsref-toc.html

Somewhere there's a version of this with graphics, but I can't find it at
the moment.


Ok, I'm boggled.

Will take me a few readings to absorb those links.

JazzMan
--
************************************************** ********
Please reply to jsavage"at"airmail.net.
Curse those darned bulk e-mailers!
************************************************** ********
"Rats and roaches live by competition under the laws of
supply and demand. It is the privilege of human beings to
live under the laws of justice and mercy." - Wendell Berry
************************************************** ********