Soyuz space capsule oddity; can someone explain this?

Question

Last time I visited Kennedy Space Center, I noticed something peculiar about the Soyuz compared with the Appolo capsule. On Appolo, there are small boosters at 90 degree intervals to control roll, pitch, and yaw. Each little booster can fire in 4 directions. On Soyuz, there are also boosters at 90 degree intervals, but they all point straight out. I don't understand how you'd be able to control the roll of the capsule with these boosters. I asked someone at KSC, and we were going through books of drawings for about 45 minutes before we finally gave up without figuring it out. Anyone here have a clue about this?

*should be spelled, Apollo*

Answer 1

The Soyuz roll thrusters are at the extreme rear of the module, and have 1/10 the power of the pitch and yaw thrusters. The reason being that pitch and yaw thrusters are also used for spacecraft lateral motion during rendezvous and docking, while roll is used only for orientation.

You can see the location on the diagram below.

Answer 2

Perhaps you were seeing only the thrusters used to move the capsule in pitch or those used to translate the spacecraft sideways. Roll thrusters might have been out of your sight and, indeed, these need to be perpendicular to the longitudianal axis of the craft. It is also possible (not likely due to the complications added to the system) that the thrusters you saw could be made to gimbal into a configuration to cause roll of the Soyuz.

Answer 3

The Soyuz capsule had attitude boosters around the middle, as you saw, and also around the base. Perhaps this second set controlled roll; I am not certain. You can see the two sets at www.svengrahn.pp.se/histind/Soyuz1Land/Soysens.htmn

Answer 4

I can't say for certain--but as you describe it, the thrusters could not be used for roll maneuvering. However, if that's the case, the most likely alternative is that the Soyuz uses it's internal gyroscope(s) to induce/stop roll. That's entirely feasible--and would have the added advantage of simplifying the attitude control system--as appears to be the case from your description.

Answer 5

Not really, but consider this. The thrusters you mention on Apollo are only on the service module, not on the command module. And the command module separates from the service module just before reentry. Yet the Apollo command module had no problem controlling roll during reentry. So I assume the direction of thrust is not perpendicular to the axis of the vehicle even though there are no protrusions.

Answer 6

I don't know but excellent question!

Answer 7

Please visit http://www.russianspaceweb.com/soyuz.html

Enjoy!