Twenty-five years ago, I pestered my grandfather, Tom Coultas, for his recollections of his work at Rocketdyne on the lunar project. Here's an abridged version what he said then.
July 17, 1994
Dear Arwen,
Anecdotes come hard. I've got that block I used to disparage in young kids. We once wrote a proposal to the AF for some kind of acoustic cavity work on solid propellants. I assigned the proposal writing to two of the very best guys, Oberg and Kesselring. After about two weeks (we usually had a month to write), they had about 20 pages that proved conclusively that the work we were proposing could not be done. I ranted at these kids to get on with it, quit being so negative, get out of the block, etc., etc. After a good Vincent Peale pep talk and some technical hints, they went back and rewrote the thing, telling in glorious detail exactly how they would do it. We won. Great program. But I have the same kind of block they had at the outset.
But since it is claimed to be the 25th of Armstrong, I want to do a little soul baring. It was perhaps in 1959 when some guy came to Rocketdyne to do a promo. I guess he was from NASA or maybe North American. Anyway, he wanted us to show how rocket scientists (an unknown term at the time) "dreamed" of space travel. For reasons totally beyond me, (I'd guess it was the influence of Bob Levine) he got Harley Burge and me and we took a walk down to the Hot Fuel Lab, him with his complete camera entourage (VCRs also unknown at the time).
(Harley Burge came to R'dyne in about 1959, from a tour of duty in Alaska as a Lt. in the AF. [Burge: "I was in the Navy, not the Air Force. I think Tom always wanted me to have come from the Air Force, no matter how many times I corrected him."] I think I hired him, and he worked for me, directly. Among other things, we showed that alkali metal power pants were indeed possible. Art Fraaas at Oak Ridge did a little work in the 70s but I'm not sure he actually circulated a vapor as did Burge and I. Burge had a hard time at Rocketdyne, especially during that time, because of competition with his boss -- me. Bob Levine, who was our boss's boss, insisted that every good thing was done by Coultas, but really, half or more of those things were Burge's. So he transferred to work for Zettle, who was a tsar, but so inferior to Burge that it was obvious who was doing all the work for that bunch. Burge gained a great reputation in the rocket community; he left Rdyne and went to TRW, and was the guy who really got the TRW Lunar Descent Module to work. TRW is now best know for keeping track of your credit card bills. They still have a good lab in Capistrano; do lotsa laser rocket, energy stuff there. Thomas was an auto parts maker; my dad used to buy piston casings, pistons, bearings, etc. from him. Ramo and Wooleridge were perhaps the first of the techno-entrepreneurs. They built a company like WJSA that specialized in brains for the services.)
So this promo guy gave us all these straight lines, like, "It must be tough down here making weapons of destruction (Navaho and Atlas), but I suppose you dream of the day when they can be turned into plowshares and be made to explore the unknown?" Burge and I essentially said "Huh?" Like Tom Lehrer's Wernher von Braun, we didn't really care where things came down (or what they did with the stuff) as long as we had lots of fun, did novel things, and got paid well. But we soon caught on and played along with the guy. Never did see any results of it. I guess we took too long to take the bait. It was a bunch of great shots, though. An Atlas booster booming up on the hill, maybe 200 yards away, and then a tiny plasma jet in a shipping container sputtering along. I sure would like to see that film.
But then Kennedy got it rolling and the E-1 that R'dyne had been playing with on their own (?) dime was suddenly funded as a model for the F-1. The E-1 was something like half a million pounds thrust, (Atlas, per engine, was 250,000) but the F-1 would be 2.5 million. The E-1 was a wonderful thing. It always worked. The F-1 was so large that no test stand at Susy (Santa Susanna Field Lab) could handle it, and they had to build stands at Edwards.
(Susy now includes Atomics Internationals lab, which was found to have rats swimming in pools of radioactive waste! Really was dangerous, wasn't it?)
In one of the first few tests at Edwards at 1.5, the chamber melted in about 45 milliseconds. Combustion instability had reared its ugly head. Burgeons, Combs, Levine, and the rest of Levine's bunch was still puttering along on basic research—some space power plant stuff, funny little electric rockets, and miscellaneous. (I was made "supervisor of fluid mechanics." We didn't do any fluid mechanics, but as Levine said, "we couldn't call it Odds and Ends!")
But with a real problem (it would have been downright disturbing if one of these F-1s melted while some folks were on top of it) there was real money. Burge went to Thompson-Ramo-Wooleridge (TRW). I took over Combs' people, became model rocket tsar, hired some more people, and away we went with Project First's research. Immense amount of fun, some wasted money, intense "pressure" to do "something" and, so far as I know, nobody ever thought of the ultimate goal of mooning. We were, however, very dedicated to (a) science, (b) the F-1, and (c) Rocketdyne—in that order. I guess we would nowadays be considered (idiot, workaholic) egotists. We were competing not only among ourselves, but with the rest of Rocketdyne, all of NASA, and—perhaps especially—all the string of PhD consultants they paraded through Canoga Park. I think Richard Priem is the only one who ever ventured to Susy or Edwards.
Research had no direct effect on the solution to the F-1 problem because the engine was so large that even decent models utterly failed to reproduce some aspects of the engine. The fundamental combustion part was perfectly replicated (I think), and agreement between our 2-D models and the F-1 were excellent. But I doubt that many people, even Priem, recognized that.
In the process of diddling with all that money on the F-1, we did a lot of acoustic modeling stuff using a microphone and speaker. In the process, somebody (Evers, Huebner or me) found an anomaly. If the parts didn't fit well, it was very difficult to get amplitudes high enough to really measure. About that time, Bob Levine went to Purdue to recruit. There was some poor guy there trying to get a PhD on combustion instability under John Osborne (a real good ol' boy), and he too couldn't get his lousy experiment to go unstable. It was "just like" the ones that students had been using for years, but it was also new. Bob looked and looked and finally found that some of the fits between parts were on the loose side of the tolerances. When he brought that back home, we went to modeling with a vengeance. By introducing a tiny cavity into the acoustic space, it really damped the oscillation. It was really impressive when the length of the crack was equal to a quarter-wavelength of the sound. Tried it on F-1, 2-D, no effect. Ah, well, so it goes.
About this time, Rocketdyne was making a pulsing engine for JPL's planetary missions. (I guess they are still working?) This RS-14, as it was called, might start 1 to 5,000 times a second. Turned out that about 20 or more percent of the starts, the combustion would be "unstable" and that would really louse up the very close tolerances desired on total thrust (integrated over time). Rocketdyne tried all kinds of F-1 fixes; although the instability might be reduced to 10% of the time or so, it still persisted. JPL was on the verge of canceling the contract and going to Marquart. Jack Han was the boss on this project, and at this very critical time he went to Hawaii. He had planned it for couple of years, it was his 25th wedding anniversary, and he went. But before he left, he instructed one of his henchman to let me try a "Coultas Cavity" and the designers and the machinists would make whatever I wanted and test it. We did. Over 2 million times the RS-14 has started, and no instability. Wow!
So our peddler in Houston suggested we try the cavities on an unstable engine, like Bell was making fo the Lunar Escape Module. Without the cavity, the engine was unstable every time it was "pulsed"; with the cavity, never. NASA was so impressed they took the injector part of the LEM from Bell and let Rocketdyne do it. Needless to say, that was quite an ego trip, having the president Sam Hoffman say that "Coultas Cavities" had saved the RS-14 and won the LEM. To exaggerate a bit, Armstrong et al. would still be on the moon if it weren't for Coultas Cavities. Nowadays, no rocket engine is even designed without cavities. Oberg, subsequently, got several contracts from Houston NASA to try to figure out how they worked. Apparently it is totally viscous dissipation.
And that, little children, is how the west side of the Moon was won. In reading about the trails, (Oregon, Santa Fe, etc.) I find a lot in common with us Rocketdyners. The trekkers did not care about making Oregon a yuppie state, California a home for hippies or New Mexico a Mecca for artsy-fartsy folks. They wanted to do something for their families and even if they died, it appeared they worked like heck, and if successful, it really helped their ego. Of course, things were very different in the 1860s from the 1960s, but the adventure, possibility for success, adulation, and especially self-satisfaction were similar. And neither time was all "me-ism." Sure, we liked to be singled out as individuals, but generally among the research folks they truly liked, respected, and worked for and with one another. Paul Combs hd a team of old-line Rocketdyne mechanics who assembled and plumbed the 2-D engine years before Project First. Generally, it was two months between firings. If really pressed, we could do three or four a week. I remember one we started to design on Friday night at 4, and had to have results in and reported by midnight Sunday. Made it at 2 a.m. Humphries, Hoehn, Hines, Safechuck, Juleff, Wallace and I all got in over 50 of those 60 hours. Some clock punchers even punched out and came back because they couldn't work over 60 hours in a week. None of the rest of us got extra dollars. Dedication like that is pretty well gone—at least from industry. Maybe brokers, bankers or lawyers do it, but craftsman? Nah. Too bad.
August, 1994:
You asked me to explain instability, and I'm not sure you realize how complicated a question this is. Rocket engines that burn liquid fuel get very hot inside, like 7,000 degrees F. Further, the gases are going very fast, like Mach 3 or 4, and velocities over 10,000 ft/sec. This make the heat transfer to the container of these gases very good, and it must be vigorously cooled, usually with the fuel that is burned, leading to the term "regeneratively cooled." The can that holds those gases during the combustion is called the chamber. When it necks down to speed the gases to Mach 1, it is called the throat, as they expand on to higher Mach numbers, the can is called the nozzle. Normally these cans are sufficiently well cooled that they don't get over about 1,000 F., where steel or whatever has good strength.
But when the combustion starts to oscillate—i.e., increase/decrease in rate—the heat transfer is increased by orders of magnitude because the oscillation causes waves, alternately stopping and starting (in opposite directions) in the gas flow. This erases the protective boundary layer and exposes the base metal to the very high core gas temperatures. Because steel and other metals melt at about 2400 degrees F, the 7,000-degree stuff is deleterious to their strength and continuity. Always, these waves become of an acoustic nature. That is, to satisfy the boundary conditions, both real and mathematical, the only way the wave can exist is to oscillate at an acoustic frequency of the chamber. Rooms have acoustic frequencies. For instance, a 10-foot dimension in a room would promote about a 50-cycle oscillation. (The formula is F = a/2/l; "F" is the frequency, "a" is the speed of sound (about 1000 fps at room temp), and "l" is the length of the room. This math is more complex for cylinders.
So, this oscillatory flow heats the bejabbers out of the can, and the thing melts. That is why one does not want instability. The F-1 was nasty in its instability because it was, at the time, the biggest and highest-pressure ever done. Both of these made the oscillations larger (higher amplitudes)—sometimes, instead of being 1100-psi constant, the pressure would vary from 0 to 6000 psi -- nasty. No matter how well-cooled the can (chamber/throat/nozzle) was, the thing would melt very quickly, in milliseconds.
Nobody, even today, has a clue as to why combustion "goes unstable." I did some work for WJSA a few months ago, and I needed to see what was done on that score years ago. I looked it up and there were only a few pages in the reference book. After reading them, I thought, "well, that's about what I remember," and then discovered the author of the piece was T.A. Coultas. Many theories of causes have been projected, and all proved to be drivel. So we thought in the 60s that since we didn't know what to do to prevent it, we would cure it instead. To assure it was cured, we artificially started the instability with a bomb in the chamber. It work wonderfully-- too well.
The Saturn moon rocket stack had 5 R'dyne F-1s, then four (I think) Rdyne J-2s, then another J-2. This put it in orbit around the moon. Then there was an Aero Jet "service module" that stayed in orbit. The descent engine (TRW) landed on the moon, and the Ascent (Bell) took off from the moon. In the beginning, R'dyne competed for all of these except the service module. We lost the Descent engine (to Burge), and Bell was starving, so they got a crumb. Burge almost lost the Descent because it was so heavy and inefficient, but R'dyne saved it by making the J-2 and F-1 better, bigger, and more efficient. Bell had another problem. Their ascent engine was efficient and light enough but didn't work reliably. Because R'dyne had shown how damn smart Tom Coultas was with the RS-14, we got a shot at the Ascent too. Bell retained all the stage, but R'dyne provided the injector, including the baffles and the Coultas Cavities. This minor triumph still chills me—when I waltzed my EPA guy (Pershing) through the Combustion Symposium halls and had all the combustion guys running out to shake my hand for not only proving the cavities in the LEM but beaten Pratt and Whitney on a turbo-jet contract. (That was also the day your uncle decided to go to Utah.)
In 2002, my grandfather sent me an email after a visit with some former R'dyne colleagues:
I had an ego boost in Utah. Seader was going on and on about how great it was to work for me at R'dyne from 60-65. I said we were lucky have Lawhead and Levine who gave us (me) so much freedom to do as we pleased, and that we had all those facilities, great hands, smart guys .. and then I slipped and said "and I was the brains." I didn't really mean exactly that, but before I could back things up, Seader jumped in with "yes, you were!" Over my shoulder, Joyce [my grandmother] said, "Brains?! Hammer!" Now that is really something, for I had never heard Joyce use that word in that way—I guess I intimidated her, huh? But upon reflection, our old friend Larry Carlson has often said "you were an old curmudgeon, everyone was afraid of you!" So I guess I was the hammer, though I prefer to think of it in a different context -- as in the way that Chick Webb, Gene Krupa "hammer" the drums and set the tempo. That I would agree with. Damn, ain't I a wonderful grandpa to have around to tell you how it was?
He really was. I miss him. Shortly after he died, I got in touch with Harley Burge. He sent me a longer reminiscence, some very kind words:
First of all, you are the granddaughter of a man who poured his heart and soul into research and development of propulsion for this great country. His guided research in combustion and heat transfer was highly instrumental in the later success of the rocket engines being developed at Rocketdyne, including Atlas, the Saturn booster F-1 engines (burning liquid oxygen and JP fuel and the largest propulsion engines in the world), the second stage J-2 engine (burning liquid oxygen and liquid hydrogen), the lunar ascent engine (burning N204 and UDMH). When combustion instability problems arose with the F-1 and the lunar ascent engine, he supervised Paul Combs in very sophisticated research to understand the instabilities and how to control the instabilities. The combustion and heat transfer research under his supervision was first rate and provided the basis for the thermal protection of these engines.
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