I have doubts that NASA can get heavy payloads into a vacuum. It appears to me, from watching Apollo rocket launches, that a rocket engine works just like a propeller on an airplane; by moving lots of air. When they get into a vacuum, they fizzle. So they might move a light payload. But no landing four ton crafts on the moon, and no rover on Mars.
I think you're making heavy weather of this. Let's just consider the problem of a rocket with a payload launching and going through space. I'll use a book edited by Andrews & McClone (1977 - not long after the supposed lunar landings, which were themselves preceded by Intelsat, from 1965. The Space Shuttles started after the lunar stuff had been closed - and must therefore be suspected as another scam). Here's the cover-design to add visual interest.
According to my '1985 World Satellite Almanac
', a typical satellite weighed about a ton, had a planned life of about ten years, and is kept in orbit by occasional squirts of compressed air - think 'Robot Wars' where robots use remotely-controlled compressed air cylinders.
B. Noble, of Wisconsin and Oxford, contributed the chapter 'Why Build Three-Stage Rockets?
' which is easy enough to understand, though the maths uses calculus - as the fuel gets used up, the total weight drops, so there's a slow exponential change. It's quite easy to understand the general outline, if not the algebra - it isn't rocket science! [Hilarious pun intended]. Conservation of momentum.
The point here is that in free space any action has an equal and opposite reaction. (How difficult it is to word these things...) Imagine you're in an office chair on wheels, preferably on an icerink, and not allowed to put your foot on the ice. If you contact another such office chair, maybe pushing against it, if the weights are the same they will move apart in a fairly obvious way - there's no reason one gets priority. If someone shoots a gun or throws a ball, his chair moves in the opposite direction. The actual effect depends on the weights (or masses) of the various parts of the system. E.g. if one chair and person is very heavy, it'll move more slowly. Or imagine billard balls colliding; or hot air balloons. This would work in a vacuum. In space you don't need the rink - you can be in free fall, and as long as you're not going towards the earth you'll orbit it.
Momentum is measured by mass x speed. A rocket works by in effect projecting part of itself away. However exhaust gases don't weigh much. Hence the trick is to get them moving as fast as possible. This needs expansion and hence the use of special fuels, which typically get very hot. (The argument also applies to jet engines - BUT in the upper atmosphere these would need oxygen, which adds to the weight and engineering problems). Empirical Facts.
B. Noble gives these facts (altered from metric system; I don't think they can be very outdated)---
(1) A satellite (or anything else) in orbit round the earth a few hundred miles up, moves at about 5 miles/second.
(2) The approx typical speed of expelled rocket gases is about 2 miles/sec.
(3) '... it is difficult to build engines and fuel containers with a total mass less than about an eighth to a tenth of the weight of the fuel.'
(4) With a one-stage rocket, ''When the fuel is almost exhausted, the engine is expending most of its effort on accelerating and almost empty fuel tank.'
Note that (2) and (3) are empirical - for engineering reasons, they apply. (1) is a consequence of the earth's gravity; (4) assumes the payroll weighs much less than the rocket's structures. Deductions applied to stages of rockets.
Noble considers a one-stage rocket which however burns away continuously
, so there's no deadweight of fuel container. With the assumption that empty weight: original full weight is about one in ten, he derives payload approx = 1/50th of full weight. A 50-ton rocket of this type
could launch a 1 ton payload - assuming the assumptions apply. Approximating the idealised rocket.
Dropping the assumption of a fuel container which burns away, Noble calculates the ratio of payload weight to rocket weight, and derives this table--
Number of stages .. 1 | ...2 | ..3 | .4 |....
Ratio ............... ---- | 149 | 77 | 65 | ...
A single-stage rocket can't get up to speed. A three-stage rocket can - and lifting a 1-ton payload uses fuel at about 20 tons/minute. Possible Problems.
Noble selects a payload of 1 ton, which is OK for satellites. However there must be scaling problems with heavier items. If a rocket is doubled in every dimension, the areas quadruple, and the weights multiply by 8. There are engineering difficulties analogous to those in nature, which cause elephants to have hefty bones and big feet. If the payload is (say) 5 tons - I think this was something like Apollo 11- there would be problems. Skylab is, or was supposed, to weigh about 1 million pounds - about 500 tons. A B52 can take about 40 tons. This is why personally I believe in satellites, but am open to arguments that space stations are impractical and may have been faked. In fact, possibly Noble avoided the issue of heavier payloads for that very reason.
FirstClassSkeptic considers the question of 'push' against air. This seems correct - in the same way that falling into water from a height is dangerous - the water hasn't got time to move - air isn't completely compressible - a bird's wing pushes against air. I don't know if this is considered in detail in calculations, or whether air resistance is.
The definitive pre-lunar 'landings' rocket calculations book is Ball and Osborne (1967) - 'recommended for the serious student rather than the casual reader.' This book predates the 'space shuttle' practice, with its (alleged) rather low orbit, though the idea must have been considered.