Wait, isn't the Blok-D on the Signal version of M-1 the same as the Blok-V on the R-6-Varya? Dry masses, fuel masses, engine thrust and ISP are all listed as identical, so I figured Mishin simply took the kerlox third stage he added to R-6 to enable it launch the small original Varya, one-cosmonaut version, and put it in place on top of M-1 to get the Signal 3-stage version. (If anyone is confused by the letter-stage terminology--the Cyrillic alphabet goes, transliterating into Latin letters, A,B,V,G,D. So if the Russians also count three identical stage units burning as one as three separate stages, they account for the first three letters, then the stage we'd call the "second" stage, lumping the first three into one, which is about 2/3 the mass and perhaps length of any of the three lower units and has a single engine giving half the (vacuum) thrust, would be Blok-G, making the addition for Signal Blok-D. On R-6 we had two hypergolic stages, -A and -B, making Mishin's addendum stage Blok-V). If this is in fact the case, then nixonshead and his advisors have the dimensions of this small kerlox stage handy--it originally had to fit on top of R-6's Blok-B and so presumably has the right bottom diameter to do that, and the top diameter was designed for a Zarya-A to sit on top of. If so, then the extended PA's of the later Zarya versions appear in the illustrations to maintain the same diameter, so presumably there would be no problem mating a Zarya of whatever version to the top of an M-1 bis aka "Signal" rocket. This also constrains the taper, if any, of a monolithic M-1 concept; the top of the second stage must match the bottom of Mishin's R-6 kludge stage. Or come close anyway; otherwise the M-1 "Blok-D" would have to be redesigned for a greater (or more likely, lesser) diameter. There is some wiggle room for connecting stages that don't quite match I suppose, even the hammerhead effect of a wider upper stage overhanging the rim of a narrower lower one. Still one would think it had to be redesigned somewhat--and indeed, why keep using exactly the same stage as he came up with in 1963, in the later '60s when presumably the engine has had time to be refined and improved, and the state of the art of tankage etc has also evolved? Supposing the M-1 uses monolithic tapered stages also demands retconning the stage terminology given as the labeling of the first stage with three separate blocks would then make no sense; we'd have then an A block, a B block, and the Signal addition would be -V just as it was on R-6. I still think the tapered monolithic design is cool, and would lend itself to experiments with recoverable first stages, and the OTL Soviets did indeed build a helicopter that could lift such a spent stage from a landing downrage in the steppes. But really I have to admit the evidence is stacking up against it, and as I've said all my thrilling at the potentials of TTL's Soviet hardware is darkly clouded by my skepticism this timeline's Kremlin regime has the right stuff to follow through very impressively. If TTL Mishin is thinking of developing a reusable Blok-A, he's going to have the rug pulled out from under him I'm afraid, with the Soviet space factions split up two or three ways and Shelepin neither going away nor mustering up enough personal enthusiasm to pick one faction and back it. The regime's demise and a time of troubles at least as lean as OTL's (if not made worse by possible civil war, possibly one that goes at least a bit nuclear) seem inevitable, and the expiration date is probably coming sooner than OTL too. So although I remain truly excited by the alternative idea of M-1 being made of modular units that can be hauled by rail and can be mixed and matched a la Minerva to get a whole system of launchers made from common units, and would assume that if that is what an M-1 is then Mishin does indeed plan to promote adopting the potential system as a standard one for all Soviet launch purposes, again he'd have the rug pulled out by the factionalism and scarce resources of a Soviet system going into terminal arrest. I started a post a long time ago, on Sunday or Monday in fact, trying to fish for a comparable cultural "weather report and forecast" for the USA, which is going to have troubles of its own in the 1970s I fear. Perhaps these will be no worse than OTL, but they will still seem somewhat traumatic to people who didn't have to live in our timeline! We are mainly concerned here with how world history unfolding affects the space race of course, and so the author can use very broad and diffuse brushstrokes to indicate this "climate." I'm certainly being kept guessing, which is good for dramatic suspense!