A configuration I’ve considered for the same objective has a throat something like a needle valve. For full throttle / sea level the throat is unobstructed. As the rocket climbs and throttles down, a conical rod lowers into the throat reducing throat area and keeping chamber pressure up. Biggest difficulty I see is cooling the conical rod.

With LO2/Kero with singleprop tanks, empty two LO2 and one Kero with just a little off center mass later in the flight. The center tank could still use your monoprop of choice.

I think the concept is flexible enough that dropping tanks or shutting down engines could be done in threes just as well as twos.

I have seen a description of the nested annuler chambers. I think it was in Hutzel and Huang, but can’t remember the proper name offhand. I’ve really got to get my references out of storage.

Would it be possible to configure the tanks so you could drop them three at a time instead of two at a time? I’m thinking this could possibly add some mission flexibility. Additionally shutting down the engines in threes leaves you with pitch/yaw control from the engine until you shut down to the sustainer, while shutting down in twos means that you lose one of these axes before the last shut down.

Looking at the “Peroxide and Aerospike” post made me wonder about using concentric annular combustion chambers instead of conventional ones, but that sounds exceedingly complicated.

If crazy stuff embarassed me, I’d be in serious trouble. As I’ve said before thoigh, I consider this to be serious fun. Just for fun unless we get something worthwhile, then it’s business.

For certain strange and unorthodox solid rocket configurations (I’ll save myself the embarrassment, it’s crazy stuff ^_^) a possible benefit could/should be that one can launch and circularize with the same engine/nozzle with a minimal amount of additional equipment and perhaps also achieve smoother flow.

Or if you mean that the 19 V2/A4 burner cups were lifted straight off the 1 cup A3, then exactly. Clustering something that you know works is frequently a good thing.

If you put all the chambers in a single plane it would make development and testing much simpler also. A company could mount several low ratio nozzle engines on a flat plate with large expansion nozzle attached. A few charictoristics burns would answer a whole lot of questions without the complex nozzle construction I was thinking of.

As an added bonus, the number of thrust chambers becomes arbitrary. Two or nineteen could work if the flat plate works. That would simplify building larger total thrust vehicles with common sizes of well known thrust chambers.

In your diagram, you place multiple combustion chambers in a heavy/complicated looking staggered cone. Could you put all chambers in a single plane for design and cost simplicity and get the same result?