Ye Olde Rocket Forum - View Single Post - NASA Study Summary: "SATURN V DERIVATIVES"(1968)

The S-1D report inspired a couple of thoughts. Because an S-1D (or its equivalent if built today, by someone like SpaceX) stage would quite possibly use rare metals such as niobium (the Falcon vehicles' Kestrel and Vacuum Merlin engines' nozzles are made of niobium), it might be worthwhile to design such stages to be "salvageable" rather than reusable. As long as they would float after impact (which has been not uncommonly observed with expendable first stages after impact), any kind of vessel that is capable of towing a barge or another disabled vessel could tow the spent stages back to a collection site. The launch vehicle operator wouldn't even have to maintain two specialized ships like the SRB retrieval ships, but could simply contract with existing barge towing firms to retrieve the first stages.

A heavy, MCD (Minimum Cost Design) pressure-fed first stage of this type would be robust enough to be reusable, and it could also be recovered in this way. (McDonnell-Douglas' Phase B Double Prime Space Shuttle design had a beefy, seven-engine [975,000 lb thrust each] LOX/propane pressure-fed reusable first stage, on top of which the delta-winged orbiter with its [smaller] external tank would have been mounted [the orbiter's main engines would have ignited after staging]. That LOX/propane reusable booster would also have made possible a whole host of heavy-lift launch vehicles by substituting various upper stages for the orbiter/ET combination.)

I know that such operations (fishing "salvageable" or reusable boosters out of the sea) are not elegant or airline-like, but as the Shuttle has hopefully made clear to NASA, rockets and spacecraft are not airplanes and they should not be expected to operate as such.

Regarding down-mass, the biconic heat shield (that doubles as an ascent payload fairing) sounds like a very good idea. To placate the "Shuttle-huggers" (I like that term!) who pine for the down-mass capability of the orbiter's large payload bay, this capability could be retained (and even increased) if desired by developing a large re-entry cargo carrier that would look like an enlarged Atlas D or Titan I ICBM re-entry vehicle (a cylindrical body with a blunt conical nose and a flared conical aft stabilizing skirt). It could parachute into the ocean or, perhaps, touch down horizontally on land by means of a large parafoil. To simplify and lighten its structure (and to make it easier to waterproof the vehicle for ocean landings), it could have a rear loading/unloading hatch instead of longitudinal payload bay doors.