Dietzler wrote:
notes on space freighter
1) maybe this discussion should be moved??
We don't really have a forum area specifically dedicated to design of spacecraft, although perhaps we should. Peter requested this area and he is the moderator; if he wishes to move it he is free to do so. I was thinking about moving it to "Lunar Surface Logistics", but I think his vision for that forum is to focus on lunar surface transportation (lunar railroads, moon rovers, and the like). If this discussion really takes off I'll go ahead and give it its own area.
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2) an ore carrier would probably be best to consist of just metal and glass fiber mesh bags and be fully robotic and use nuclear electric propulsion. mass drivers don't reach exhaust Vs as high as VASIMR so more propellant is needed with mass drivers. VASIMR can use many different propellants-hydrogen, vaporized metals, even oxygen
I haven't heard of VASIMR before this. Do you have a link for more information?
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3) the space freighter above was originally envisioned for carrying crates of finished products thru space. magnesium boxes with finished products (glass wares, electronics, even canned goods, etc.) packed in glass or mineral wool. The cargo hold is rectangular because aerodynamics don't matter in vacuum and flat plates and straight beams are easier to make and put together. As one engineer at the Moon Soc. St. L chapter says,"flat is good, flat is your friend." Titanium alloy has higher strength to wt. than aluminum alloy and we don't have much to alloy Al with on the Moon so our plain Al won't be real strong. Al is hard to produce also. Magnesium is "Moon makeable" and lighter than Al and the cargo hold skin won't endure much stress. Titanium is "moon makeable" also. So we have a square ship packed with square boxes.
Building the first true space-to-space ship with nuclear (or equivalent) drive is going to be a HUGE milestone on the way to developing a spacegoing civilization. I agree that it should be a cargo/passenger carrying design—perhaps with modular containers which can be swapped out as needed for each mission.