Does thrust vectoring by a gimballed nozzle in rockets affect thrust/efficiency?

Question

I was wondering if thrust vectoring via a maneuvering gimballed nozzle affected the thrust of a rocket. I've read a couple times that a gimballed rocket engine's thrust doesn't change while exhaust vanes do, (I imagine they're similar to how an aerodynamic control surface works).

It seems logical to me that a gimballed nozzle shouldn't affect thrust of rocket when deflecting the exhaust, however I am unable to find anything that states this.

It also seems that gimballed nozzles are used on solid fueled rockets, and not on liquid fueled ones. I'm assuming gimballing a solid fueled rocket engine would not be possible due to the propellant basically being the combustion chamber?

In short: do gimballed nozzles have any effect on raw thrust output? If not, why aren't they used on liquid fueled rockets?

Answer 1

Gimbaling a nozzle is not that easy - you have to handle high loads, temperatures and pressures. So on liquid engines the hole engine is gimballed, not only the nozzle. Solid engines are "a bit too large" for that - so you need to gimbal the nozzle. (or use other methods for thrust vectoring)

Vanes do create quite a significant drag in the rocket exhaust, so they suffer a higher impact on the thrust than other methods - so they were discontinued quite early (except on some amateur rockets - where the mechanical simplicity still is an advantage)

But all thrust vectoring does have an impact on the performance of the vehicle. But it is quite low for gimballed engines so one can nearly disregard it. The change in the axial thrust is cos(alpha) which won't change much in the few degrees of rotation. But it still takes power to move the engine around - and it also adds some weight.