Question on the R-7 rocket

[Mark Dave]

I noticed in some videos the smaller thruster engines  on the bottom of the core and four boosters move, and yet in watching Expedition 17 launch I heard that the Soyuz rocket doesn't have gimbal engines. What are these smaller engines used for?

[Downix]

I noticed in some videos the smaller thruster engines  on the bottom of the core and four boosters move, and yet in watching Expedition 17 launch I heard that the Soyuz rocket doesn't have gimbal engines. What are these smaller engines used for?

The Soyuz does not gimbal the engines.  It uses vernier thrusters instead as jet vanes.

[hop]

I noticed in some videos the smaller thruster engines  on the bottom of the core and four boosters move, and yet in watching Expedition 17 launch I heard that the Soyuz rocket doesn't have gimbal engines. What are these smaller engines used for?

The Soyuz does not gimbal the engines.  It uses vernier thrusters instead as jet vanes.

The verniers gimbal. The main engines do not. There are no jet vanes.

[Stan Black]

 Soyuz takes off under the power of five engines. Blok B, V, G and D each feature a single engine with four fixed combustion chambers and two gimballed verniers. Steering is provided by those verniers and assisted with four aerofins. In addition there is a fifth, central stage the Blok A. The central core which is in operation during both stages 1 and 2, features a similar engine with four fixed chambers, but four gimballed verniers.
 At the very start there is 32 combustion chambers in operation. 12 verniers fitted to gimbals in control of the attitude assisted by the aerofins.

[Mark Dave]

I see. Are there any photos or test footage of an R-7?

[kch]

I see. Are there any photos or test footage of an R-7?

(you might want to back the sound down a bit -- save your ears) 

[Stan Black]

I see. Are there any photos or test footage of an R-7?

(you might want to back the sound down a bit -- save your ears) 

 I was trying to find that one! I corrected my post above because the test of the verniers shows them in operation at the same time with the central Blok A.

[Mark Dave]

Thanks. This will also help with the new R-7 model I'm building, I'm adding all the details to this.

[hop]

Some technical details may be found at http://www.lpre.de/energomash/RD-107/index.htm

(google translate: http://translate.google.com/translate?js=y&prev=_t&hl=en&ie=UTF-8&layout=1&eotf=1&u=http%3A%2F%2Fwww.lpre.de%2Fenergomash%2FRD-107%2Findex.htm&sl=ru&tl=en )

In addition, the engine RD-107 has two steering unit, and the engine RD-108 four-steering unit, which serve to create moments of Governors during the flight. Steering units include steering the camera and sites with hydraulic drives, providing the swing steering chambers in a single plane to an angle of 45 degrees and the supply of components. Steering units are fed from the main turbopump.

[Stan Black]

http://bob-pot.narod.ru/tbra/RAC-140.gif
http://spacemodels.nuxit.net/Soyuz/soyuz-blueprint.jpg

[Mark Dave]

Those blueprints help. Thanks for posting them.

Here is a vid of the Soyuz U someone posted

What are those red barrels for that are near the engines?

[zaitcev]

What are those red barrels for that are near the engines?

I think they are filled with silicagel and are removed before flight. In fact the rule is that everything red is removed (e.g. the protective cones in the engine nozzles are the same color).
-- Pete