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Armadillo Aerospace News: Good warmup test
We tried building another 7” engine with only 600 grams of ring catalyst in the hot pack, since the 700 gram engine from last week seemed to still be running at full temperature after the screen burned away and let the rings jump around. The engine came up to temperature fine, but on throttle up it lost a lot of temperature and never gained it back. We decided to stick with 700 grams of rings in the hot packs.
We built up a complete ship set of engines like this, and tested them individually. They all make a bit over 800 lbf at 250 psi feed pressure, generally losing about 18 psi through the hot pack and 36 psi through the plumbing / spreading plate / cold pack. The temperatures still aren’t quite as high as the engine that burned the retaining screen (the stainless burning may well have added the extra heat), but they are plenty good enough. Two of the engines are running a bit rough, probably because the rings weren’t able to be packed as solidly in the recycled engine chambers with stubs of old plates still on the sides. The next time we build fresh engines, we are probably going to try vibration settling, then weld the retaining plate on top under a fair amount of hydraulic pressure. Read More

posted by Sigurd @ 3/29/2004 02:40:00 PM