A pretty good article about the work done to model and characterize the F-1 engine in preparation for designing an F-1B. The part about CAD modeling is cool:

http://arstechnica.com/science/2013...t-back-to-life/

Kurt,
Thanks for posting this. Really fascinating.

What also was interesting was the mention of the highly mechanical controls on the engine (as opposed to electronic), as well as the description of the massive number of handmade welds.

And that's an interesting tidbit of trivia too, ""[T]he power output of the Saturn first stage was 60 gigawatts. This happens to be very similar to the peak electricity demand of the United Kingdom.""

Interesting reading this with background sound of Amish carriage heading down the road out back.

The discussion of the turbofan exhaust and the accompanying article about the plans for the F1-B were what really intrigued me. Especially the info about the parts reduction from over 5000 to ~100.

The discussion in the accompanying article about relative propellant densities and the politics of rocket and motor sales was also fascinating.

Really interesting articles.

I never knew that the dark appearance to the F-1 flame was due to the turbine exhaust. I always thought it was an artifact of the photography or something else.

That second article is here in case anyone is interested:

http://arstechnica.com/science/2013...-lbs-of-thrust/

The ability to model the combustion is huge. In Murray and Cox’s Apollo: Race to the Moon they devote (IIRC) a whole chapter to the development of the F-1 and how combustion instability nearly scuttled the project. Combustion instability in rocket engines was well known before the development of the F-1 but it was worse in this engine due to its size. No one really knew what caused it and the way it was cured was to use baffles (as described in that article) to dampen the pressure waves. The F-1 was dynamically unstable such that when instabilities in the combustion occurred, the engine tended to amplify them rather than dampen. This led to a rapid and catastrophic failure of the engine. Worse yet, the instabilities were random and during testing and development, some engines operated for very long cycles with no problems. Other times the engines became unstable and self-destructed in short order.

The engineers knew they needed baffles in the engine but in order to test different arrangements, but they also realized they needed to trigger a combustion instability on command rather than waiting for one to spontaneously appear. They designed a small bomb that could be placed into an operating F-1 and detonated on command. This generated the needed pressure wave to initiate an instability in the combustion chamber and the response of the engine could then be observed. Eventually through a lot of trial and error an arrangement of baffles (as seen in that picture) was obtained that allowed the engine to be dynamically stable and dampen out the instabilities by itself. But still, no one knew why they were happening and at the time there was no way to model the engine to find out why.

That was a great article. Like it was written for us.

The welds. So many welds, and beautiful welds. I'm not a welder, but from what I know you have to REALLY good to get a good, consistent weld bead.

Greg

That was a good read! Wow!

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Cool stuff, Maynard.

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Kurt-

That is a great book......for those who may not have read it, it is basically devoted to the 'ground' details of the Apollo program such as the engineers, designers, mission control, etc. VERY little mention of the astronauts, which is a nice departure from a portion of the Apollo program that has been covered ad nauseum by other writers.

Though their book is over 20 years old now (I think it came out in '89 to coincide with the 20th anniversary of Apollo 11), it still is a great read today.

And that chapter on the F-1 was great. They say that main engineer from North American or Rocketdyne (Castinholz....or something similar) basically gave his life on the F1 engine problems. I think he died of a heart attack shortly after the problems were finally solved.

Earl

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