The problem is we're still talking vertical takeoff with 100% of the required fuel and oxidizer from ground level. I know you're promoting nuclear, but that's never going to happen politically.
By using air for oxidizer for roughly half the acceleration, you drastically reduce the required weight for oxidizer, and thus reduce the fuel required and the size of the vehicle that must carry it, thus saving even more fuel. The savings snowball.
Aerodynamic lift up to 100k feet is far more efficient than vertical takeoff, saving even more fuel, and allowing smaller engines.
Taking off with only partial fuel, and tanking via garden variety Air Force tanker allows takeoff with even smaller engines than lifting the whole thing from a runway. An SR-71 can't even get off the runway with full fuel, and I'm sure a runway to orbit vehicle would not either.
The months required, if not years, for building/refurbishing very large rockets will run the cost up just as it did the Shuttle, which originally was supposed to have turn around times measured in weeks.
Yes, we need high lift unmanned rockets to get large components into space, at least until we can fabricate them on the moon, mars, or asteroids (which will be a long time from now). But human transport and resupply should be via some kind of Turbo/Ram/Scram/Rocket aircraft. Yes the development cost would be extraordinarily high. But until we build such a thing that can be re-flown within a day of landing, or less, then space flight will be only dreams and fodder for government pork.
No thanks.
Narby, man I agree, I know what the smart play is, I just don't think you can convince the general populace that were right.
The new project NASA is talking about is 109 Billion dollars over 5 to 18 years and you already hear squawking over that, and that’s less than .5% of today's national budget. Heck if we wanted to do what NASA is proposing we could spend the money and have it all operational within 2 to 3 years and the public wouldn't even notice the expense.
All this, All this crap about the expense of what NASA is currently planning is just that, crap.
My only idea on how to correct the public perception is to have a huge advertising campaign and a income tax check-off for direct spending on NASA like we do with state projects on beef/pork promotion or if you don't like NASA then do the same thing except it goes directly toward private investment.
Firstly, horizontal take-off is not more efficient than vertical take-off. Wings only translate the energy you use in thrust into lift, and they translate it badly. Getting low altitude lateral velocity is a waste because all of that is lost in aerodynamic losses at low altitude.
Secondly the 'Cold Equations of Space Flight' article is absolute BS by a fool who doesn't know anything but NASA propaganda. For example, an LH2/LOX SSTO required mass fraction is actually .87, but only if your engines are altitude compensating (like SSMEs and aerospike engines are).
Thirdly, the biggest error in chemical SSTO designs is using LH2 as the sole fuel. LH2 has a terribly low density, which mandates very large fuel tanks and very large aerodynamic cross sections (thus adding lots of aerodynamic losses). Dunn has done a lot of good writing showing that denser fuels like UDMH, methylacetylene, and chilled propane are significantly superior fuels for an SSTO than LH2, to the point of putting as much as two and a half times more payload in orbit.
While the writer is right that air breathing to reduce oxygen load is a right direction to go in, doing so mandates spending lots of time in the 100k-200k altitude range, collecting air, incurring lots of aerodynamic losses. If you are using a low density fuel like LH2, you are wasting your time because the fuel has given your vehicle terrible aerodynamics.
There is an alternative. The RBCC (rocket-based combined cycle) engine that NASA has developed and all but cancelled (what is new, eh?) is the solution. This uses a rocket wrapped in a ram/scramjet and gives an average Isp of over 1500 secs. It needs to be dual-fuel: UDMH or Methylacetylene (welders MAPP gas is a suitable substitute) for the air breathing modes, LH2/LOX for the high altitude pure rocket mode. I'd also replace the LOX with liquid nitrogen. Yes, its not an oxidizer, but it is half the weight of LOX. As your vehicle is in air breathing mode, you bubble air up through the LN2. This liquifies oxygen in the air and evaporates the liquid nitrogen, so by the time you reach full rocket burning altitude, you have no more LN2, it is now a tank full of LOX.
LOX is normally 80% of a launchers gross lift off weight. Between this technique and the air breathing you can reduce this mass by 5/6ths. By using a denser fuel instead of LH2, you cut your vehicle mass empty by another 30-50% by reducing the tankage.
What does this mean? Lets assume you have a 1 million lb GLOW launcher burning LH2/LOX capable of putting 20,000 lb of useful payload in orbit. Using the above suggestions, you can reduce the vehicle GLOW to under 500,000 lb and automatically dropping the cost per lb to orbit by half.
Nor is, as is claimed by Chris Bell, an SSTO impossible. Putting six space shuttle main engines underneath a shuttle external tank is automatically an SSTO capable of putting 50,000+ lbs into orbit. Did you know a shuttle external tank only costs about a half a million dollars? If you put the six shuttle main engines in a recoverable pod, and left all the external tanks in orbit (to be collected for use in building a space station of proper size for the 21st century), since the engines are the only thing worth saving, you have a cheap to operate reusable SSTO. Carrying 1.6 million lbs of fuel at about $1/lb, you have a total launch cost of $2.15 million (versus the STS' $200-300 million), and a per lb consumables cost of $41/lb. Add in the cost of building and maintaining the engines and engine pods, facilities and launch fees, taxes and other overhead BS, and we are still talking only a few hundred bucks per lb.
Most of the insane $20k/lb cost of the shuttle system is in the 10,000 personnel that NASA employs to rebuild and reinspect every component of the STS for every flight (most of whom are union workers). Learning from the DC-X experience, as well as that of private companies like XCOR, whose EZ-Rocket is capable of multiple flights per day, we can trim assembly and launch staff to a few hundred at most.