Comments by "David Himmelsbach" (@davidhimmelsbach557) on "Why Can't we Remake the Rocketdyne F1 Engine?" video.

  1.  @sparky6086  The story is simple: the construction crew left alien items inside the space craft! We're talking about sockets, wrenches, screw-drivers, etc. After Wally Schirra ripped the contractors a fresh orifice -- he was the engineer of the Mercury crew -- NASA went with one-man working and four-men certifying for every dang thing assembled if man-rated. Mr. Dan Slater had a heck of a NASA collection -- the duplicates bot and paid for by taxpayers that never left the ground -- stuff like White's hand rocket used during Gemini. Check out the old NASA photos. He had its duplicate. (!) [Bot it at auction.] What's amazing is the paperwork and seals still wired to all of his buys. The all-time-winner has to be a complete Apollo space-craft control panel. (I don't know its full story.) Every bolt and nut was torqued to spec -- every tool had to return to its tray -- exactly where it came from -- every assembly was performed in a 'clean-room.' And so forth. It proved out that such extreme measures paid off in drastically lower failure rates. So much so that America now always sticks with them. Of course, the assemblies are now performed on video, too.
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  2. BTW, the vibrations of the F-1 engines impose a heck of a stress on everything around it. Hydrogen + Oxygen burn so much smoother -- even Methane is smoother. A smoother burn lets designers trim weight -- always a huge issue in rocketry.
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  3.  @simonm1447  RP1 is so close to JP1 -- especially from an engineering point of view that I rather doubt that any other fuel was seriously considered for a booster. Let's not forget that Sp Imp is not critical for a booster. Sp Imp becomes super important the faster the rocket's velocity. This was well illustrated by the NASA team who selected H2-O2 for the 2nd & 3rd stages -- while leaving the booster with the tried and true kerosene-oxygen combo. As for a rough ride: Borman & Coy reported that Apollo 8 was so rough that they couldn't read any instruments -- and that the crew wondered if the ejection system would be automatically triggered. Borman actually pulled his arm away from the trigger -- lest he terminate the boost-phase the hard way! His body was shaking that badly. (Apollo IV ) actually did so much damage to the pad that it was out of commission for months. NASA had to re-engineer Saturn V lift-offs. (!!!) Elon has moved to methane-oxygen -- a combo that I thought fifty-years ago was what NASA should've run with. I'm guessing here, but I suspect that NASA didn't have a handle on methane compression dynamics. Here and there, I read technical literature damning methane as just wa-a-ay too much trouble. No explanation was proffered as to why. For commercial rocketry, I rather favor ethanol-oxygen as it's low Sp Imp is balanced by its tractable nature. You get a very smooth burn and the engineering challenges are very low. The von Braun A-4 was originally spec'd for kerosene-oxygen. Then reality hit. It was such a rough-burning combo that von Braun ran away from it. It was just too much trouble for a booster that was never really going to reach high velocity. I also favor a plug-design and a high-altitude launch -- say from New Mexico or the Big Island of Hawaii. I also favor a straight-up vertical booster path so that the booster's recovery is even simpler than Elon's flight profile. The booster burn does not (logically, economically) need to provide momentum towards the east. Merely getting it high out of the atmosphere -- with kinetic energy aplenty -- is sufficient. Then very squat upper stages -- with H2-O2 -- or CH4-O2 can provide horizontal momentum into orbit. With a plug-shape, you can then send up ring after ring -- large enough to craft a viable space construction station in LEO. Such a payload could be wrapped on the OUTSIDE of your upper stages. Upper stage returns could occur ablatively. The rotten aerodynamic resistance in early boost would be reduced by launching from 1,500 meters above sea-level. The boost would not reach max dynamic stress until the vehicle was, say, 30 kM up. In the event of a fiasco, the booster would be directed to fall straight back down to a designated crash zone. This is much more practical with a pogo flight profile.
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  4. Their Specific Impulse does not at all compare to the Raptor. Elon has shown that the way forward is to cluster engines and REALLY smarten them up.
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