Value chain · CLM-1373
In plain terms
Two years after SP-413, a later NASA study's optimised Moon launcher was far shorter, about half a kilometre, because it accelerated at 1000 g instead of 30 g. It would throw about 42 kg a second at lunar escape speed.
The claim as recorded
A mass-optimised lunar launcher in NASA SP-428 (1979), designed for 650,000 t/yr at 49 per cent operating time, with 10.5 kg payloads at 4 Hz to 2,400 m/s at 1000 g, comes out at 488 m total length, 3.13E6 kg total mass and 1.25E8 W total power, at 96.4 per cent efficiency. The authors note that cutting acceleration to 100 g saves 4 per cent of mass but lengthens the launcher by a factor of 10, to nearly 5 km.
Scope and limits
An optimisation-program example, chosen "arbitrarily" by the authors for payload and rate. It is not a mission baseline. The 49 per cent operating time allows for shutdown through the lunar night and 1 per cent repair downtime (PDF p.136).
What it assumes
A payload density of 2 x 10^3 kg/m3, the paper's stated assumption (PDF p.136).
Where it comes from
PDF p.137 (printed p.125): payload mass and launch frequency chosen "10.5 kg and 4 Hz, respectively"; "The launch velocity is 2,400 m/sec, the lunar escape velocity"; "Acceleration is chosen as 1000 Earth gravities or 10,000 m/sec2"; listed outputs "Total mass 3.13X 106 kg", "Total length 4.88X 102 m", "Total power 1.25X 108 W", "Efficiency 96.4 percent" (exponents as superscripts lost in the text layer); "the total length of the launcher increases by a factor of 10 to nearly 5 km". Arithmetic (drafter): throughput 10.5 x 4 = 42 kg/s; PDF p.136 (printed p.124): "Requirements were specified as an annual throughput of 650,000 metric tons, assuming 49 percent operating time"; "This requires a 42-kg/sec throughput."; 42 x 0.49 x 31,557,600 s = 6.49E8 kg = 650,000 t, matching; acceleration length 2400^2 / (2 x 10,000) = 288 m, inside the 488 m total; kinetic power 0.5 x 42 x 2400^2 = 1.21E8 W, consistent with 1.25E8 W total.
Basis: optimisation-program output; launch speed in m/s, payload in kg, repetition rate in Hz, length in m, mass in kg, power in W
Related records
- Answers question
- QST-015 not published in this release
Cite this
energyaperture.com/c/clm-1373
CLM-1373, Energy Aperture, as of 1979.
Connected records
Other published records linked to this one. A list, not a judgement.