The rationale is saved weight - since each stage would be using the same engine.
That makes no sense, the heavy stuff is at the bottom. Engines and the tanks which carry all the load.By the way, there's something I wanted to know for some time: Why do hydrolox launchers like D4 have the LOX tank at the top of the stage? Should it not be at the bottom to minimize structural mass?
By the way, there's something I wanted to know for some time: Why do hydrolox launchers like D4 have the LOX tank at the top of the stage? Should it not be at the bottom to minimize structural mass?
Atlas did the opposite it staged off engines and kept the tank.
You don't save weight when you take unnecessarily powerful engine all the way to orbit. Consider Falcon 9, it takes off with nine engines but does most of the ascent with just one. If it would fire all nine all the way to orbit it would either have to be beefed up to handle double digit g-forces or do very deep throttle down.
If you figured it out in a matter of a few sentences why would there have to be a formal study?
1. In the case where you can shed only tanks, you could achieve orbit with a less powerful engine/cluster.
Higher Isp.
2. We really ought to have an NSF-corollary of Godwin's Law, for SpaceX mentions.
If anything, you'd have lower Isp with this concept since the engine would have to work at sea level so couldn't expand as much.
Quote from: Robotbeat on 09/16/2013 09:00 amIf anything, you'd have lower Isp with this concept since the engine would have to work at sea level so couldn't expand as much.There have been concepts that get around that problem. Aerospikes, deploy-able nozzles, chamber throat plugs that jettison, ect... The issue has been studied by many, just never flown by any.