peterz(at)zutrasoft.com
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 Posted: Sat Aug 05, 2017 9:39 am Post subject: Engines....con't |
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The following is some engine trivia for the Europa builders out there not yet having sourced an engine: Having spent yet another year at Osh attempting to educate myself, on the subject of engine choices I have come to the following personal conclusions fwiw (my opinion only, "you mileage may vary" etc. 
1- The only feasible/reliable geared engine I saw at the show is the Rotax 9-series with its thorough engineering to deal with the resonant issues with it's newer (since the 100hp) 30deg dog clutch and additional integrated pack-clutch, set to ~500lbs. I have attached a few cut-away pics of the gearbox of it's clever dense packaging). The auto conversions, with their solid engine cores have a weak link in the gearboxes - the simplistic rubber bushings... a design that I do not believe is adequate. The European BMW two-cyl with gearbox appears to now have some good in-service experience, but was not at the show to check out, and it's gearbox design is still unknown to me.
2- For direct drive engines, there are two feasible designs:
- the ULPower engines: a turbo'd small short-stroke low compression four cyl, or a naturally aspirated larger long-stroke higher compression four cyl - either would be lighter than the 914 installation.
- The still unproven but incredibly light and low parts-count flat-head water cooled designed D-motor: either a turbo'd four cyl, or the 6 cylinder, with the 4 being lighter than the 914, and the 6 cyl being about the same weight as the 914, albiet not as good at altitude. A turbo'd 4 cyl would get around the flat-head's inherent lower compression ratio, and should be good performer.
The 915 is too heavy for the Europa (215lbs as per the factory rep), and with an even longer gearbox putting that CG even further forward it is not a good option for the Europa, if one wants FI and Turbo. The smaller ULPower engine would be terrific turbo'd, but the factory is not wanting to deal with customer turbo customer support head-aches and reluctant to provide custom FI maps. That leaves the D-motor..... which I will be watching carefully over the next year or so before I'll need to make a decision.
Chatting with Airmaster at the show, a geared prop for the Rotax would be 1-2k$ (~10%) less expensive (and lighter) than the equivalent prop for the direct drive engines which have to deal with the increased engine pulses and harmonics.
FWIW,
Cheers, and blue skies,
Pete
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