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Thoughts/Experience with BMW K1200?

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Peterson

Well-Known Member
Joined
May 25, 2014
Messages
160
Location
St.Rober, MO
Initially i wanted to use a rotary 13B, but as i'm leaning towards a Falconar F12A i worry that even a stock Mazda would overstress the aircraft, not to mention the headache of trying to fit an adequate cooling system for one under the cowl.

BMW makes some inline 4 (and 6, but that would also have me worried about airframe overstress) motorcycle engines of around 1200cc that put out between 140-165 HP. The F12A is designed for engines between 125-200HP, but with gap sealing (first hand info from HBA member Pops) can exceed Vne with 165 if you aren't careful. The engines are reliable, parts are readily available, and they aren't hard to find at a good price. I am thinking of going with a redundant cogged belt redrive of around 2.75-3.25:1 or so after looking more into the power curves of the engine and recommended prop diameter of the Falconar i plan to build.

Anyone have any ideas as to whether or not this would be a valid option. I am also looking at BMW R1200 or Yamaha Vmax or Raptor 660/700 as possible alternatives. The R1200 and Raptor engine are slightly underpowered and the Vmax prefers a bit higher revs, but i could probably fly any of those with a properly designed PSRU.
 
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