Return to Apollo?

If you are serious about visiting (not just joking about the drawings under the bed) please email me to discuss details. My condo is too small for a club trip, but I can deal with a couple people comfortably. You can set up your laptop and scanner on the kitchen table.

I consider any copying of my data collection to be fire insurance.

Peter Alway

Saturn Press PO Box 3709 Ann Arbor, MI 48106-3709

scale data at:

Rutan did it!

Everytime I hear the words "bong launch", I picture stoners stuffing D12's into drug paraphenalia while giggling hysterically. Lends new meaning to the phrase "up in smoke".

These mass fractions are for stage weights alone, i.e. engines, tankage, and controls. No payload. The Saturn V first stage used LOX/RP-1 with the higher overall propellant density to reduce atmospheric drag losses (same reason we use solid parallel stages on Delta & Titan), but you have sacrificed Isp - which is about 300 seconds with that combination (APCP is even lower). So the Saturn first stage couldn't get itself up to LEO with any maneuver capability left - and no payload. The Titan II stage I used nitrogen tetroxide and Aerozine 50 storable hypergols - even lower Isp than RP-1/LOX. The Saturn V stage III used LOX/LH2, so you get the high Isp but the tankage for LH2 just kills you - the stuff has the density of whipped cream and needs insulation for ground handling. None of these stages could make it to orbit by itself while carrying anything useful.

The Space Shuttle External Tank is a marvel of lightweight design, by the way.

Yes, that is true to the extent you can do it. The shuttle was certainly banking on much higher flight rates to improve the economics. But with present propellants we have to build so light that the safety margins are really thin, so it takes alot of design effort and inspection time to make sure it's safe, and things break easily. If we could use the low allowable material stresses from the ASME Boiler and Pressure Vessel Code we could build launch vehicles that would be as robust as a truck - but they wouldn't make it to orbit with the propellants we have in hand. We need lots more energy in the propellants to build a real space truck that can get to orbit with even aircraft-type fuel mass fractions of 50-60%. Ideally, I'd like the fuel mass fraction of a semi.

Please do the calculation backwards - what Isp is required to power both up and down with a 50% initial fuel mass fraction?

Driven by super lightweight design and no capability to "power down" the same way I went up. That's why we have to bleed off all of the orbital energy through friction with the atmosphere.

More Power, Scotty!!! Give Me More Power!!!!

Brad Hitch

I am very much aware of the propellants used in each of these stages and that they had no payload. Several other items:

1) A SSTO design based on the Saturn V third stage (S-IV-B) was proposed in 1969. (SASSTO). If someone thought it could be done in 1969, surely we could do it now with the vast improvements in structures and electronics since then. 2) Sure the S-IV-B only has a mass fraction of .905 by itself with no useful paylod. But as you increase the size, structure weight is going to drop because it is largely driven by the tankage weight. Tank weight does not scale linearly with volume. The bigger the vehicle, the better your mass fraction. 3) No one will ever (oops, I probably shouldn't say this :-) propose a spacecraft design that has a fully powered descent to landing on earth. It requires just way too much energy. Does your car perform powered braking? No, friction is easy.

I found an interesting paper that does a rough analysis of many fuels and oxidizers for SSTO application at:

To get the mass fraction of a semi, you will wait a long time. Perhaps forever. Let me know when you find that supply of unobtainium.

Isp = delta V/ g * ln (mass ratio)

V = delta V required g = acceleration due to gravity at sea level Isp = specific impulse

The numbers I saw for delta V required to get to orbit were about 9100 m/s including gravity and drag losses. Those hurt on the way up but hurt and help on the way down. So figure 18,000 m/s delta V required.

Isp for your hypocritical case would be 2650 seconds.

Do you have a link to a site with the math or code for the math to calculate boost to orbital insertion? That would be an interesting feature to add to my consumer rocket programs :)

Jerry

The airplane is the first stage.

The upper stage may only go 62 miles.

Jerry

nope, he got a vehicle to go full orbital ;)

Oh, you're talking about the time he cheated and used lift - the "Voyager" airplane circumnavigation!

What do we call that - VLEO?

-dave w

thats it (chuckle)

On one tank of GAS. :) The OTHER Rutan, BTW.

Check out the sigh that's along I94 as you drive north from Chicago to Milwaukee:

It's just below halfway down on the page...

Then to see who it's named fro, check out

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

:) hey, i thought one designed it, and the other flew it? maybe i misread the website

Heheh. I've seen that one in a book somewhere. I also like another one on that site, the big sign with directions to the "Secret Nuclear Bunker". Reminds me of those old WB cartoons where the bad guy's hideout is lit up with neon signs.

1) A SSTO design based on the Saturn V third stage (S-IV-B) was proposed in 1969. (SASSTO). 2) Sure the S-IV-B only has a mass fraction of .905 by itself with no useful paylod. But as you increase the size, structure weight is going to drop because it is largely driven by the tankage weight. Tank weight does not scale linearly with volume. The bigger the vehicle, the better your mass fraction.

The real reason is the most expedient method of energy management for an earth to orbit mission is to drop off mass as you go along. A single stage to orbit vehicle cannot even make it in theory and none have in practice.

George,

I think part of the earlier discussion of Rutan was inferring that the "Voyager" flight was 'orbital'. Granted, it was only one orbit, and very, very low, but I don't know that the definition of 'orbit' has an altitude...

David Erbas-White

Listed on page 42 of "Halfway To Anywhere".

Ditto.

SASSTO was supposed to be reusable with a payload of 2,800 kg.

I wonder why the numbers worked for SASSTO in 1969 and they don't today?

Notice that NASA selected the design for the X-33 that required the development of the most new stuff. Linear aerospike engine and cryogenic conformal composite tanks leap to mind. I am still absolutely astounded that the Lockheed Martin stinker was chosen. And totally unsurprised when it died.

It was the 2nd stage, the S-II.

I wonder why the numbers worked for SASSTO in 1969 and they don't today?

Notice that NASA selected the design for the X-33 that required the development of the most new stuff. Linear aerospike engine and cryogenic conformal composite tanks leap to mind. I am still absolutely astounded that the Lockheed Martin stinker was chosen. And totally unsurprised when it died.