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A fleeting thought on my sentiments about the disposability of RS-25s (rare! Only 47 made before the RS-25E/F contracts? Few remain! Complain about them being expended for SLS!) versus Raptors (one made every day or more? 39 blown up on Starship OFT and that's fine, there's plenty) got me wondering: was the 47-ish (presumably there were some test articles as well) RS-25s built for Space Shuttle a typical number? To put it another way, how many rocket engines of a type typically get manufactured?

My initial impression is that the order of "dozens, but not hundreds" of engines for a "successful" launcher held relatively constant until either Merlin or Raptor, but it would be great to have some data to back that up.

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  • $\begingroup$ You'd either need a ton of launches or a ton of engines or even both. Which leaves you with Soyuz, Falcon 9, N-1, and Starship as candidates, unless I forget something (which is highly likely). $\endgroup$ Apr 27, 2023 at 21:27
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    $\begingroup$ @JörgWMittag I expected Atlas and Delta to end up on the list too, but without literally any reason to expect that. $\endgroup$
    – Erin Anne
    Apr 27, 2023 at 21:35
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    $\begingroup$ Soyuz is well over 1000 launches, all of them expendable, which means 1000s of RD-107s and -108s. But Soyuz is really an outlier, just like SpaceX is. $\endgroup$ Apr 27, 2023 at 21:36
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    $\begingroup$ twitter.com/SpaceX/status/… $\endgroup$
    – Slarty
    Apr 28, 2023 at 11:55

1 Answer 1

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Looking at the numbers from Wikipedia's comparison of orbital launcher families:

  • RD-107 family (R-7 rockets, including the Soyuz): approximately 9800
  • RD-253 family (Proton): approximately 2600
  • YF-20 family (Long March 2/3/4): approximately 2300
  • RD-0210 family (Proton upper stage): approximately 2200
  • RD-0110 family (R-7 upper stage): approximately 1900
  • LR-89 (Atlas family): approximately 1000
  • Merlin family (Falcon rockets): approximately 950
  • Viking family (Ariane 1-4): approximately 750
  • RD-215 (Kosmos rockets): approximately 600
  • LR-105 (Atlas family): approximately 500
  • RD-250 family (Tsyklon rockets): approximately 500
  • 11D49 (Kosmos upper stage): more than 450
  • LR-87 family (Titan rockets): approximately 370
  • LR-79 family (Thor rockets): at least 350
  • H-1/RS-27 family (Saturn I, Delta II): approximately 350
  • Rutherford (Electron): approximately 350
  • NK-15 (N-1): more than 230
  • RD-170 family (Energia, Zenit, Atlas V): approximately 200
  • RS-56 (Atlas II): approximately 200
  • Vulcain family (Ariane 5/6): approximately 120

The number of engines drops off fast after this, with around a hundred engine families with fewer than a hundred examples built.

Two major omissions from this list are the RL10 family (used in the ubiquitous Centaur upper stage) and the AJ10 family (used in many upper stages, including Delta II, Titan III, the Apollo service module, and the Space Shuttle OMS engines). Since both of these engines are used across a wide range of launch vehicles, it's unclear how many of each has been built. It's likely that the RL10 sits somewhere between the RD-170 and the Rutherford, while the AJ10 sits somewhere between the RD-250 and the Merlin.

Also omitted from this list are vernier and RCS engines, solid-fuel engines, and upper-stage engines from rockets that can mix-and-match upper stages.

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    $\begingroup$ RD-253 on N-1? N-1 had NK-15, these are different families with different fuel (hydrazine and kerosene respectively) $\endgroup$
    – Heopps
    Apr 28, 2023 at 6:52
  • $\begingroup$ If anybody is wondering (like me) why there are no Indian engines in here: ISRO uses all-solid first stages. Though I daresay at least second-stage engines would deserve to be mentioned too (but probably not attitude thrusters etc.). $\endgroup$ Apr 28, 2023 at 8:58
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    $\begingroup$ On things like Titan and Atlas, do the numbers include the engines built for the ICBM / weapon versions of the booster? $\endgroup$ Apr 28, 2023 at 12:11
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    $\begingroup$ @OrganicMarble, engine counts are based off the number of launch attempts. Any engines built for missiles that weren't re-purposed as orbital launch vehicles won't be counted. $\endgroup$
    – Mark
    Apr 28, 2023 at 18:54
  • $\begingroup$ @leftaroundabout, I've included upper-stage engines when I could. It's rare for a rocket to change first-stage engines without being considered a new rocket, but upper stages are more variable, and it's not always clear how often any given engine was used. $\endgroup$
    – Mark
    Apr 29, 2023 at 0:05

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