Seriously ) (I can be, I’ve been assured of it )
This actually blends well into a ‘concept’ that’s been mulling around in my head. Jon, I’m hopeful you can devote some time to comment on an aspect of ‘design-and-engineering’ in regards to propellant tankage that I’ve been wondering about for years.

There was much discussion over the years on the merits and possibilities of using “expended” propellant tanks as temporary and permanent storage, living, and other facilities on-orbit. From the concept of the Atlas Space Station, through uses of various upper stages to the Shuttle External Tanks, (last most recent being the Space Island Group http://www.spaceislandgroup.com/home.html tank-derived stations) the idea has been to “re-purpose” already existing ‘resources’ on-orbit in the form of expended propellant tanks. Skylab was originally concived as a ‘wet’ station having orbited itself and the crew and materials to turn it into a spartan space habitat, the Space Cruiser http://www.astronautix.com/craft/spauiser.htm proposed by In-Space Operations (ISO) planned to use the 4th stage of a proposed Air-Launched Launch Vehicle as a series of “mini-stations” for the small spaceplanes to visit, similarly Interorbital Systems (IOS) orignally intended to use the expended tankage of their orbital 1.5 stage-to-orbit system for a tourist manned space station.

I’ve seen the idea proposed again and again, but it seems to me the concept is most often met with pretty hostile commentary and a lot of assumptions and rhetoric on why the concept won’t ‘work’ at all. However I’m confused the only “major” drawback I can find is the amount of on-orbit manual labor required to re-fit the tankage as liveable space, and of course the given fact that no such infrastructure is required by any space-faring nation so there is little interest in the idea.

My question I suppose then is this: Is the basic concept flawed or are there engineering, safety, or structural reasons inherent with the idea that make it unworkable?
Thanks in advance for comment and feedback but mostly I’m hoping you take this on in a seperate entry ;o)
Randy Campbell

Inherent

Now we will see if:
The first stage can reenter in a controlled fashion from 200+ km altitude with just parachutes. (No hyper-cone.)
Whether they can find the descending first stage.
How much they can learn from the post-flight analysis of the engines.
Whether any hardware is usable after reentry, impact, and the salt water soak.

I did spend some time (mostly while running) thinking about how SpaceX could deploy something from the front end of the first state that would cover the engines and create something like the hyper-cone. We could discuss this off-line.

There is a statement on
http://forum.nasaspaceflight.com/index.php?topic=13507.570
“Anteres: Another site said that 1st stage recovery was not successful. Needs better TPS.” No basis cited.

Yeah. From what I’ve heard, I think it was someone in the AFRL that got them to investigate doing an F9 sized vehicle.

SpaceX now has a much more powerful engine ( 125 vs 71.5 klbf) so that an F5 with the Merlin 1C would have nearly the thrust of the F9 with the Merlin 1A engines, and less mass by 1.6 mT. But…whatever.

I know. But part of the upgrade may have been in the works all along for the F9. Not sure though. Pure speculation on my part.

While we can dream, the most practical result might be for SpaceX to incorporate some of the LM concepts, shy of MAR, for improving the condition of the recovered F9 first stage. While dunking precision hardware in the ocean may be barbaric, it may yet be possible to make it workable, even if it is not graceful or thrilling.

Yeah. The first step is finding out if they can get the stage back at all, and what the actual loads are. I figure it’s going to take them several tries on recovery until they have enough data to know what they really need to do to make it work.

~Jon

While we can dream, the most practical result might be for SpaceX to incorporate some of the LM concepts, shy of MAR, for improving the condition of the recovered F9 first stage. While dunking precision hardware in the ocean may be barbaric, it may yet be possible to make it workable, even if it is not graceful or thrilling.

~Jon

Oh, and regarding the F9 FS dry mass, my best guess would be 30klb plus or minus. If you know anyone with an Mi-26 handy, it could work. Falcon 5 would’ve been light enough to mid air recover however….

~Jon
~Jon

You may have read my post (#175 in http://forum.nasaspaceflight.com/index.php?topic=13507.165) wondering if perhaps SpaceX wouldn’t have been better served if their primary initial goal was recovery instead of orbit. Perhaps if they had a more robust recovery method, one that somehow attenuated the shock of splashing into the ocean with something to protect the engine, they could have gotten some of the build-a-little, fly-a-little of classical X planes, as you advocate in your discussions of recoverable first stages. Perhaps one or two of the proposed LM techniques could have enhanced SpaceX’s recovery to where it could be relied upon. Imagine a series of flights with under-fueled stages, flying short trajectories and gently spashing down, then being hauled back to the launch pad. (Probably one better equipped than Omelek.) SpaceX certainly wouldn’t have any less results than they have today. Perhaps by next week their actual plan will be proved superior.

PS Do we have any idea of the mass of the F9 first stage? Wonder if it is more or less than 10 mT. The 9 engines must be <4mT. Most of the rest is ~25×3.6m of AlLi isogrid tanks. You can probably estimate that better than I can.