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From Wikipedia:

Under RD AMROSS, Pratt & Whitney is licensed to produce the RD-180 in the United States. Originally, production of the RD-180 in the US was scheduled to begin in 2008, but this did not happen. According to a 2005 GAO Assessment of Selected Major Weapon Programs, Pratt & Whitney planned to start building the engine in the United States with a first military launch by 2012.[3] This, too, did not happen. In 2014, the Defense Department estimated that it would require approximately $1 billion and five years to begin US domestic manufacture of the RD-180 engine.[4]

From my understanding, Prat & Whitney have technical plans and documentation, why they still can't manage to produce engines independently?

mark.g
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1 Answers1

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In something as complex as a rocket engine, there are specs and docs, and then there are things that only the people on the production line seem to know.

I recall an anecdote for the center body of some fighter jet, where they were having a problem separating the product from the mold. They called in an old timer who used to work on the line, and he explained that they had applied a thin coat of ranch dressing before starting as a lubricant. But it had never been documented, it was just how it was done.

Rocket engines are tricky beasts. The Russians have coatings and materials that are not available in the United States, which is one of the main complaints I have heard. Is it really a US based rocket engine if you buy all the components from Russia? So how many do you have to make inhouse? How far down the chain do you need to go? 100% US based? If so, then you have to start with making tools to make tools to make tools sort of things.

geoffc
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  • Surely it isn't just the exact copy. Today new alloys, electronics, etc are available than before 30 years. – mark.g May 31 '16 at 17:43
  • @mark.g Every change you make opens you up to more testing and development. There are no drop in equivalents. Also this is a very extreme environment, where the very very specific material requirements are quite extreme and unique. – geoffc May 31 '16 at 17:45
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    Got a reference on that ranch dressing anecdote? That sounds hilarious and I'd like to read more! – Ezra Bailey May 31 '16 at 17:50
  • NO! It might have been the SR-71 since I remember Titatnium being involved, but it was just that, an anecdote. – geoffc May 31 '16 at 17:53
  • @geoffc the anecdote sounds plausible. Cottonseed oil is a lubricant used in salad dressings that is also used for molded part separation. – called2voyage May 31 '16 at 18:20
  • @geoffc Then why US don't develop their own engine from scratch if licensed one is taking to much time and money to develop? – mark.g May 31 '16 at 20:37
  • @mark.g BE-4, AR-1 would be the technological counter arguements. The reality is one of priorities and money. When the deal was signed, they said "We could always just do it onshore, anytime" but oddly never did. – geoffc May 31 '16 at 21:53
  • @mark.g I suspect the answer to that is something like "five billion dollars and ten years"! Starting from scratch still means you have a hard problem... – Andrew is gone Jun 01 '16 at 17:43
  • @Andrew Seems that license expires in 2022. Unless it gets renewed, there are no much more options left. – mark.g Jun 02 '16 at 11:24
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    RD-180 uses an oxygen rich preburner, P&W might still not have the metallurgy to pull this off (RS-25 uses a fuel rich preburner because the US had no alloys suitable for an extermly hot, high pressure, oxygen rich environment back when it was developed). SpaceX developed a new alloy SX-500 for the oxygen rich preburner of Raptor engines, which might be usable. – Georg Patscheider May 28 '19 at 10:04