Interesting fact : the RD-0146 developped for LOX/LH2 upper stages such as the KVTK or KVRB is the result of a partnership between the design bureau KBkhA, Voronezh and... Pratt & Whitney, USA. Here's a paper that was published in 2006 :
So the RD-0146 "father" is the RL-10, workhorse of the very successful Centaur stage. It seems that while russian (soviet) engineers had quite an expertise with massive LOX/LH2 first stage engines (Energia/Buran RD-0120), they never fully developped a reliable cryogenic space tug engine (they were studies). So in the late 1990's Russia decided to fill the gap and learn from experts rather than struggling with a brand new design. And it seems it worked very well.
The RD-0146 features a nozzle extension that is deployed in flight, like the RL-10, which shouldn't be too hard to animate in Orbiter.
So our engine with nozzle fully deployed :
... and with the extension retracted :
So the RD-0146 "father" is the RL-10, workhorse of the very successful Centaur stage. It seems that while russian (soviet) engineers had quite an expertise with massive LOX/LH2 first stage engines (Energia/Buran RD-0120), they never fully developped a reliable cryogenic space tug engine (they were studies). So in the late 1990's Russia decided to fill the gap and learn from experts rather than struggling with a brand new design. And it seems it worked very well.
The RD-0146 features a nozzle extension that is deployed in flight, like the RL-10, which shouldn't be too hard to animate in Orbiter.
So our engine with nozzle fully deployed :

... and with the extension retracted :

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