A40 is awfully heavy for its HP/displacement.
2A-042 two cyl opposed? Lots exist on gov surplus sites. Some are even flying. The bigger brother is the 4A-084 4 cyl. Also flying.The A-40 likely had plenty of torque for its size with 3 3/4" stroke about 81 foot lbs ( 40 x 5252 = 210080 / 2575 = 81.58). But to heavy by todays standards. If it could be refined to lose some weight though it is only 26" wide. It looks like a lot of weight just to hold oil and the intake runners. A pair of modernized A-40 side valve type cylinders mounted on the O-100 would be sweet.
View attachment 114703
Don’t know what to tell you on that one. I seem to recall all four cylinders and a sort of frame making up the perimeter of the crank case being one big casting. There was a top cover that bolted on and an oil sump that bolted on the bottom. No idea how you’d wrangle in a crank shaft or hold it there. Maybe Toobuilder knows, IIRC he has an O-145 in his Taylorcraft.your claim proves false.
That can now can be measured in millennia.Interesting thread, though it seems like the problem of powering light personal single seat planes goes back decades.
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After it is all hung out to dry, cost is a major factor as well too low of a power to weight with the current crop of available engines.
Watch out for "Free Flying Cylinders"View attachment 115722
Szekely 1928 Triye.
Hope one of those projects, that you can't say too much, about bears fruit.it is hard NOT to consider 2 cycles as the best solution
Thanks. Hoping S&F but realistically OSH 22. In this thread I was kind of thinking almost DIY simple. 2 stroke radials can do that. For TV reasons, 3 cylinders are the absolute minumum, but if we miniturize, 5 could make sense. I was thinking something like a 3:1 PRSU from a small automatic trans, 3 AL/Nik chainsaw cylinders, some magic small 4 or 5:1 planetary driving a centrifugal blower rotor (OTC from somewhere) that would be direct driven from a PM DC starter motor. For the kind of simplicity I am imagining, a single carb is a must. Can see the major elements in my mind, but have no idea where to get existing components.Hope one of those projects, that you can't say too much, about bears fruit.![]()
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