At 04:26 AM 10/30/2002 +0000, Ian Woollard wrote:
Doesn't iron (oxide) work at high temperature?
Preheating might give you a long lived and cheap catalyst. You don't want it self warming though- I think it tends to hard start.
Probably depends on the initial oxidization state of the iron. The only serious problem I see is that since the iron oxides are not tenacious, you will get particles in the exhaust, which will abrade the nozzle and lower your Isp.
-p
Donald Qualls wrote:Randall Clague wrote:On 29 Oct 2002 13:55:07 -0800, "Sean R. Lynch" <[EMAIL PROTECTED]> wrote:>Unless I'm mistaken, Gizmocopter's battery packs would heat 1kg of tungsten by >3600K.For how long?
I don't know that it really matters, as long as it can stay hot until you're up to full flow. Once the peroxide is flowing, decomposition will keep the catalyst hot, as your glowing engines have demonstrated in several videos. I'd expect that you only need to heat the catalyst for a few seconds on each engine start. Using a nichrome wire catalyst, a properly sized battery could bring it up to orange (that's, what, 1200 F?) in about ten seconds, and hold enough energy to do that half a dozen times (though the last start might be noticeably slower than the first).
A battery like those used in cordless tools (weighing, what, about a pound?) could heat an element about the size of that in a hair dryer, assuming the wire were sized to match the available voltage. That would probably be enough to get the reaction started and self sustaining with a slower catalyst.
Say, has anyone tested copper or bronze as a high temperature catalyst? Melting point significantly higher than silver, 1083 C for pure copper; bronzes can be had with either higher or lower melting points. The high corrosion resistance of these metals suggests a tenacious oxide coating, and copper's reactivity is similar to that of silver in many ways -- but it costs about 1/10 as much.
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