Something I noticed in there that struck me as odd was the assumption of F-1 engines instead of the F-1B. The F-1B increased thrust by about 250K pounds and it was tested. I don't know when it was tested (I'd have to go look), so maybe it was not around at the time that this study was conducted. But assuming F-1Bs for the first stage adds over a million pounds of thrust. You'd think they would want to baseline that performance.I wonder what kind of performance you could have gotten out of a Saturn V with only modest upgrades--assume F-1Bs, J-2S's, and perhaps some weight reductions in certain areas. Of course, everybody has a different definition of "modest," and it is also possible that adding these new engines would have required stretching the tanks and so forth, so there might not have been a simple upgrade path.
This got me thinking--we know the performance for the F-1A and also the J-2S (the latter was planned performance, since the J-2S was never built). Is there a program where both could be plugged into a Saturn V performance model and indicate how much the performance would be improved, at least to a rough order?
I'm sure that adding the engines would force a bunch of other changes to the vehicle. You'd probably want more fuel for those engines, and of course somebody would have to go through the vehicle structural limits to see what needed to be upgraded or changed to deal with that extra thrust and vibration. And the trajectory would have to be re-shaped. But I'm wondering if there is a rough order estimate of just how much improvement they would have gotten from the engines alone.
I did not realize that no J-2S had ever been built. From the confidence with which it was discussed, I had assumed that, like the F-1A, it had made it to the test stand.
Quote from: Proponent on 11/16/2015 09:44 pmI did not realize that no J-2S had ever been built. From the confidence with which it was discussed, I had assumed that, like the F-1A, it had made it to the test stand.I don't know if anybody has ever done a history paper on the J-2, but if they have, they probably never covered the proposed upgrades. There was a J-2S, of course, but I think I have also seen evidence of a J-2T and a J-2X.
I don't know if anybody has ever done a history paper on the J-2, but if they have, they probably never covered the proposed upgrades. There was a J-2S, of course, but I think I have also seen evidence of a J-2T and a J-2X.Okay, I just looked at Wikipedia which mentions both the J-2S and J-2T, as well as the J-2X. However, I believe that there was a J-2X design considered back in the late 1960s or early 1970s, prior to the J-2X of the Constellation program.https://en.wikipedia.org/wiki/Rocketdyne_J-2#cite_note-EAJ-2T250k-8In addition, the Wikipedia article does not mention the J-2 aerospike considered for the X-33 program, although the X-33 entry does mention the J-2S linear aerospike engine. Confused yet? If you aren't, then you're not paying attention.In other words, I think that there were two J-2S proposals (the Apollo era and the X-33 era), and two J-2X proposals (the post-Apollo era and the Constellation era).And just to confuse things even more, when I was doing some digging about the F-1, I found some slim indication that there was an F-1B proposal in the 1990s as well as the one a couple of years ago, but also a more recent F-1C (possibly "C for Commercial") in the past decade. So the designations have been reused a bit.
The J-2S was tested, I believe sometime in '68.All the technical details that you could ever want, a mere 1400 pages' worth:https://archive.org/details/nasa_techdoc_19690072871
Quote from: STS-200 on 11/17/2015 10:42 amThe J-2S was tested, I believe sometime in '68.All the technical details that you could ever want, a mere 1400 pages' worth:https://archive.org/details/nasa_techdoc_19690072871Thanks very much for that source. Looking through it, though, I still don't see any concrete discussion of J-2S testing. Have I missed something?
I did a quick rocket equation check. SA-512 (Apollo 17) put 46.807 metric tons (tonnes) to TLI not including the SLA. Using F-1A engines on the first stage and J-2S engines on the upper stages, and shedding five or six tonnes of dry mass from the rocket as was planned for SA-520 results in a mass of nearly 51 tonnes going to TLI. This doesn't assume any tank stretching to gain performance from more propellant, which would be possible.If the first and second stages were stretched with the upgraded engines to keep T/W1 at 1.2 or so and T/W2 at 0.778, it would be possible to boost about 58 tonnes to TLI.
In other words, I think that there were two J-2S proposals (the Apollo era and the X-33 era)
I did a quick rocket equation check. SA-512 (Apollo 17) put 46.807 metric tons (tonnes) to TLI not including the SLA. Using F-1A engines on the first stage and J-2S engines on the upper stages, and shedding five or six tonnes of dry mass from the rocket as was planned for SA-520 results in a mass of nearly 51 tonnes going to TLI. This doesn't assume any tank stretching to gain performance from more propellant, which would be possible.
Look at SA-520, a few posts back.
Tri-core Saturn 5, anyone?
Quote from: Proponent on 08/27/2018 02:57 pmTri-core Saturn 5, anyone?"Three-stage core" means that the core would have 3 stages, this 1992 document (on page 9) shows it having four side boosters with three F-1A engines each.
