I've recently been reading "The Mars Project" by Wernher von Braun and his recently found and translated "Project Mars: A Technical Tale" which was a previously unpublished idea on how to popularize space travel. Both are very technical... I have to laugh at how the English majors who seem to have take over sci fi would react at the latter as liturature!
Anyway, it is just full of circa 1948 technology on how to do space flight. One thing is very interesting is that his boosters are reusable. His Sirius vehicle is a "space shuttle" or CEV/CLV of the day. It's a typical three stage launch vehicle with the third stage being able to operate like the shuttle on re-entry. But, he recovers stages one and two with parachutes and then reuses them for subsequent flights. My question is what has become of this possibility?
I know that the Shuttle SRBs are recoved this way. Could the be done with liquid fueled bosters like a revived Saturn V? I really can't see a reason why this wouldn't work with first stages. But, it would seem to me to be very problematic with second stages. His second stage (Sirius) was coming back starting from burn out at 20,400 ft/sec and a Saturn V second stage could even be faster. I would think that it would be damaged or destroyed by heat on reentry. By the way his proposed parachutes were wire mesh rather than cloth or synthetics.
I be interested in any thoughs people on here have about this approach to reducing Earth to orbit launch costs.
I've been over at the NASASpaceFlight.com website run by Chris Bergin and this very thing has been discussed in detail several times over there.
Basically--reviving the old Saturn 5 is impossible because so much of the booster existed outside of documentation; i.e., knowledge of the exact configuration of many small systems were tied to the people who designed them. This sounds like a cop out--but it really isn't. Many if not all of the original part suppliers have either been absorbed into other companies or have gone under--either way, many are gone and with them the documentation for the parts/assemblies/systems that they supplied.
Today's technology has advanced so much over the Apollo/Saturn days, that resurrecting the old design would end up costing more than simply 'clean sheeting' a new vehicle with more modern technology. The new system will end up better anyway...
As far as Von Braun's original idea--so much of that three stage rocket had not been 'fleshed out,' it cannot be considered a 'design.' It was a vehicle conceptualization, but it was not yet to the level of a design. For instance, nowhere have I ever read how Von Braun was going to deal with decoupling the thermal radiation from a hot skin from the much cooler interior (prop tanks, hydraulics, passenger cabin and avionics.) Insulation was not mentioned--but this is a very critical feature of the Space Shuttle TPS--to control/limit the rate of diffusion of heat into the interior structure.
Also, Dr. von Braun's original concept there was never any mention of a reaction control system for the vehicle--this adds significant on orbit mass (as much as 1/3 of the final vehicle weight!) I'm not putting his vehicle down in anyway--infact, it was really way ahead of his time. Given time, and a huge budget, we may have had something workable.
But the reason why we don't try to recycle those spent stages, is that by the time you add the necessary systems to make them reusable, you have doubled the inert mass of the vehicle, quadrupled the cost, and made it incapable of performing the mission it was designed for (no payload capacity.) This is hard medicine to take, but at the current rate of launches, it just doesn't justify a fully reusable vehicle.
Sure the von Braun's later 1940s ideas were just concepts but I'm amazed at the penalties that you are claiming. As I was saying doing that with an upper stage would be unlikely...or at least not cost effective. I would think that a first stage would be a lot more practical to reuse. It should also be a larger part of the cost. Also, one might consider just reusing the engines, fuel pumps, etc. while scaping the mangled and burned tankage?
On control systems it seems that von Braun early idea was to use gryoscopes (flywheels) for attitude control.
An idea I am currently working on (which I cannot claim credit for) is to think of the whole upperstage (or core stage in the case of an Aries 4 type vehicle) as a secondary payload. Specifically designing a vehicle so that it can easily be disassembled in orbit (a challenging goal) to resuse things like tankage, interstage structual members, engines, etc. Designing a vehicle with recycling in mind is especially challenging when one considers something like safing range safety linear shaped charges, explosive bolts, and pyrovalves. All explosive ordinance on the vehicle must either be 'safed in place' or 'safed' and removed.
How do you design that? It's challenging. Also a severe safety challenge is disposal of the removed ordinance--it must be disposed of in a safe manner--probably by stuffing it into something like a spent Progress module and allowing it to burn up in Earth's atmosphere. I don't recommend trying to recycle linear shaped charges...
Currently the External Tank is composed of three sections: the Liquid Oxygen Tank, the Intertank and the Liquid Hydrogen Tank. All of these primary assemblies are actually bolted together at flanges on the Intertank. These flanges are then covered over with polyurethane foam in what is called a "Close Out"--as in, you can't get in there! So one has to design such a joint in a manner that either the insulation is not there; it is easily and cleanly removable; or the insulation is located somewhere else. And currently mechanical scraping followed by solvent cleaning is about the only way to remove polyurethane foam off the aluminum tank--and both of these are almost impossible to do in orbit.
I can see the problem of doing that sort of work in the space environment.
On space stations what about the von Braun idea of a wheel space station consisting of inflatable sections? You fasten them together and then blow the thing up like a inner tube!
The center section would be modues like the ones in we use in the current station either launched a heavy life rocket or in modues by the Shuttle.
I've looked at the inflatable technology that Bigelow Aerospace is studying--it is interesting. It's a little immature technologically speaking--but they are making really good progress and have flown the prototype module which I think is still in orbit--although I don't know what it's current status is...
Orbital assembly has a lot of challenges which will require patient study, and a lot of training. And of course, boku bucks to implement. But think the end result will be worth it.
Rotating stations are complex structures because they must be big enough to comfortably support human activities without driving the humans nuts from Coriallis forces--in a small, fast spinning station like a big centrifuge, these forces would likely result in almost instant nausia for anyone moving about...
There are some NASA papers which apparently set some physiological standards for rotating life support systems--I have them here somewhere. I'll see if I can find them...
