Here are some clips of the Rocket Boiler driving the three cylinder Tiger Engine. Before making the boiler needed to find out what size combustion chamber and arrangement of tubing. This is about 100 feet copper tubing spiral wound inside a 7" stovepipe and surrounded by another 8" stovepipe. The hot gases radiate to the evaporation zone and then convect up through the final 3/8" tubing. Not perfect counterflow but works better than I expected.
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