Robert Truax is said to have advocated a "space truck". From the NYT:

He did calculations showing that complexity, not size, drove costs. Hence, his proposed “space truck,” two football fields long but relatively simple in design.

I can't easily find anything online that tells what this idea was exactly. The quote would seem to point toward fewer stages, but that's speculative. Are there any references that give an idea of what he had in mind?

  • $\begingroup$ He was the proponent of BDB's. Big dumb booster. Pressure fed, built in shipyards like a conventional ship. Float it out to an ocean launch site, and launch it. Steel, not light, just BIG, so what you loose in efficiency, you gain by the fact that 1% of dry mass instead on 3% when talking about 10,000,000 lbs, does not matter so much. $\endgroup$
    – geoffc
    Commented Jul 31, 2013 at 14:17
  • $\begingroup$ The above "LEO on the Cheap" link is dead. The PDF may be found at upload.wikimedia.org/wikipedia/commons/7/79/LEOonthecheap.pdf $\endgroup$ Commented Nov 11, 2014 at 5:54

3 Answers 3


There's a good reference to more specifics of the design in "Realizing Tomorrow: The Path to Private Spaceflight"

Basically, it's a huge 2 stage rocket constructed out of 8mm steel that wasn't expected to be as reliable as most rockets, but because of the simplicity in design and higher tolerances while being able to deliver much greater lift capacity would make it cheaper. Further cost reductions would come from lower transportation costs to the launch site and relatively mass production.

  • $\begingroup$ Thanks for the ref! I won't be thrilled to have my pet spacecraft sent aloft on something even less reliable than present-day rockets. $\endgroup$ Commented Jul 31, 2013 at 14:42
  • $\begingroup$ I would note that I think the "less reliable" part was more about the earlier launches than the long-term for the rockets. No one ever wants to loose a rocket (let alone its payload), least of all the engineer that designed it. $\endgroup$
    – css
    Commented Jul 31, 2013 at 14:49
  • $\begingroup$ A payload of a million pounds?! We could almost put up the entire ISS in one go. That was quite a vision. $\endgroup$
    – AlanSE
    Commented Jul 31, 2013 at 14:54
  • $\begingroup$ If you continue to read the book, somewhere in there it talks about the first version of it that he was looking to build out of basically junk parts from retired missiles, where it would launch a person to 50 miles. He wasn't shooting for a million right off the bat, but I'd believe you could build it economically with the way he was approaching it. $\endgroup$
    – css
    Commented Jul 31, 2013 at 15:02
  • $\begingroup$ This explanation reminds me of OTRAG, who I believe Armadillo considers an inspiration. The OTRAG approach would involve simplified mass produced components - similar idea of 'less launch-efficient, but ultimately more cost-effective'. (Although a somewhat different actual design) $\endgroup$
    – hunter2
    Commented Aug 1, 2013 at 6:20

Truax was advocating "design for minimum cost". As this paper here (starting on page 140) explains, this philosophy of design would probably include a number of changes to how spacecraft were designed.

I think this sentence is the key:

The fundamental premise that the DFMC concept rests upon is that, by using a clean-sheet design approach, a space launch vehicle can be optimized for minimum cost, instead of being designed like current launch vehicles, which are optimized for maximum performance and minimum weight.

From reading through the section titled "Cultural Changes to Get a Space Truck", I think that the main point of the term "space truck" is to emphasize that it doesn't really matter how pretty or elegant the final design is, it only matters how much it costs to get the payload into orbit.

For non-engineers this sounds completely obvious, but it goes completely against the grain for many engineers. "Elegant" design (where the exact criteria for what is elegant varies from discipline to discipline) is considered particularly beautiful and is often striven for at the expense of other concerns. (Yes, I have been guilty of this) Mostly, this is a matter of culture (simple, robust design is rarely stressed, either in training or practice) and egotism (engineers like to brag about the beauty of their designs).

  • $\begingroup$ Donald, do you have any references? I'm specifically interested in the feasibility of simplified designs for turbopumps. $\endgroup$ Commented Jul 31, 2013 at 14:31

Source: http://www.projectrho.com/public_html/rocket/surfaceorbit.php

Sea Dragon

Payload mass delivered to LEO 550 metric tons Cost per payload kilogram $59/kg to $600/kg

Details here, here, and here.

Sea Dragon was designed by Robert Truax in 1962 to be a low-cost heavy lift launch vehicle. To reduce costs for launch pads and gantries, the vehicle was to be launched from the ocean. It would be towed out to the watery launch site, and the ballast tank in the first stage exhaust nozzle would be flooded. This would drag the tail down and the nose up, orienting the rocket into launch position. The rocket would then float with the second stage cargo hatch conveniently just above the waterline, ready to be loaded.

At 150 m long and 23 m in diameter, Sea Dragon would have been the largest rocket ever built. To lower the cost of the rocket itself, it was designed to be build of inexpensive materials, specifically 8 mm steel sheeting.

The project was shut down by NASA in the mid-1960's due to budget cuts.

Sea Dragon schematics


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