Real spacecraft attitude control

[Kamik423]

How do real spacecraft keep attitude control?

As of rockets during launch:

- the Saturn V first stage had gimbal

- the falcon 9, too

- how do Rockets with just one engine (Ariane 5, Delta IV Medium ...) deal with roll?

In Space:

- Voyager had RCS and used up only half of it

- how about other sattelites do they all use RCS?

thank you

[Nibb31]

Ariane V uses RCS for attitude control after the SRBs are jettisoned:

http://cs.astrium.eads.net/sp/spacecraft-propulsion/showcase/ariane5-attitude-control-system.html

Delta IV uses a secondary exhaust nozzle for roll control:

Most satellites use hydrazine RCS of some sort for propulsion and attitude control. Nowadays, some comsats are equipped with xenon ion propulsion.

The ISS uses CMGs for attitude control (control moment gyroscope), which are basically big flywheels.

Edited April 2, 2015 by Nibb31

[Kamik423]

But there isn't one common way of dealing with this problem?

[Nibb31]

That's a bit of a weird question since I just gave you several ways of dealing with the problem that are used in the industry.

Engineering is about requirements and trade-offs which are typically different for each project.

[palker]

Soyuz launchers do not have gimbaled nozzles but they use Vernier engines instead.

[Frida Space]

Vernier engines are also quite common. This is the first stage of a Soyuz FG, the rocket used to launch the latest Soyuz to the International Space Station:

You can see 5 different engines (with four combustion chambers each, for a total of 20 nozzles), but you can also see some smaller engines (4 next to the core stage engine and 2 on each booster): those are the Vernier engines, used for 3-axis attitude control.

- - - Updated - - -

I should probably add that Vernier engines can be used as main engines too. That's the case for Vega's fourth and final stage, AVUM (where the V stands for Vernier).

[hugix]

A couple of Atlas rockets had 2 vernier engines on the side to maintain attitude. Here is a cool picture of the 2 engines on the side

[Bill Phil]

Delta II has Verniers( or at least, something similar) to control roll, whereas launchers like the Saturn IB use gimballed outboard engines.

There are Verniers, actual RCS, CMGs, etc.

[Kamik423]

Yes, thanks for all the answers, I meant weather there was one way that is very common, like being used by 80% off all spacecraft, but it looks like no.

bu thank you very much!

[Frida Space]

Yes, thanks for all the answers, I meant weather there was one way that is very common, like being used by 80% off all spacecraft, but it looks like no.

Well, from my limited knowledge almost every spacecraft has an RCS/OMS system, usually running on hydrazine. I could well be wrong, but that's what I recall.

[Kryten]

That's right; even craft that mainly use reaction wheels need to use RCS from time to time for desaturation. Only very small satellites rely solely on reaction wheels or magnetic torque devices.

[Sampa]

I think the attitude control system selected per rocket depends on what you need the rocket to actually do! We don't really see too many vernier rockets anymore these days. Namely, it appears to be main engine gimbaling backed with RCS. However, I have also spotted on several rocket, that they are controlled early on by control fins mounted on the first stage of the rocket

[Kibble]

We don't really see too many vernier rockets anymore these days.

That's not true - Soyuz has vernier rocket engines on all its stages, Proton has verniers on its third stage, Long March 3 has verniers on its second stage, Long March 2 on its second stage, GSLV's third stage, Delta II for roll control, Dnepr and Rokot second stage, and GSLV cryogenic upper stage.

[Sampa]

I think the attitude control system selected per rocket depends on what you need the rocket to actually do! We don't really see too many vernier rockets anymore these days. Namely, it appears to be main engine gimbaling backed with RCS. However, I have also spotted on several rocket, that they are controlled early on by control fins mounted on the first stage of the rocket

That's not true - Soyuz has vernier rocket engines on all its stages, Proton has verniers on its third stage, Long March 3 has verniers on its second stage, Long March 2 on its second stage, GSLV's third stage, Delta II for roll control, Dnepr and Rokot second stage, and GSLV cryogenic upper stage.

Then, I will admit that I was mistaken! Thank you for correcting me, Kibble!

[Frida Space]

Some rockets (Soyuz FG and others) have aerofins installed on the base of the boosters, which contribute to attitude stability.