Donald Qualls wrote:
ISTM (from the standpoint of someone who's never actually worked on a liquid fuel test or launch, just to be clear) that if you need three people to work the actual launch, you need at least one more to drive the fuel truck and connect and disconnect the hoses. And safety would suggest you really ought to have separate trucks for fuel and oxidizer, if you're running a bipropellant system, which makes it much more efficient to have separate crews for the two trucks (even if the crew is one person each). If small crew is more important than fast turn around, then one of the basic launch crew could be detached to sequentially drive the two trucks and perform all the fueling operations, but in a commercial environment turn around is typically higher priority than saving a the wages of a couple line crew people (who typically earn about 1/10 what an engineer or pilot would).Bipropellant loading is inherently a sequential operation- you do NOT load fuels and oxidizers at the same time. If the access points are arranged properly, you should be able to load inert gases (the slowest step) on one side of the vehicle, while taking turns loading fuel and oxidizer at other points. You set up the helium load, then let it run while you futz with the other things; we have, as an experiment, done all servicing of the Ez-Rocket with a two man crew, mostly to get an accurate measure of the labor requirement (about 12 man-hours total).
Our next vehicle will incorporate lesons learned, and the workload should in many ways be lower. We're aiming at one hour turn with a 3 man crew (two with the vehicle, the third fetching tools, moving trucks, etc.)
Doug Jones
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