I finally found my Kitfox IV on Barnstormers yesterday (hooray!). It's just about ready to cover and start on FWF.
I've been wondering about using an Aerovee instead of a Rotax. $6500 for a new engine. 80 hp, single carb, direct drive, air-cooled -- but most important -- an engine I already know how to work on. Seems like a pretty obvious choice, and yet I don't think I've ever heard of a VW powered Kitfox.
Anybody know why?
Yes, I already know how wonderful Rotax is. But with all the subie-powered Kitfoxes, you'd think someone would have tried a VW at some point. Won't any 80 HP engine work? As near as I can tell, it only weighs 29 pounds more. After all, Subaru E81 weighs 68 pounds more.
There are some IV's and 3's with VW power. I have only talked with one that is Great Plains VW powered and he is happy with it. Never had the pleasure of flying it so cannot speak from personal experience.
Hey, I built a model IV and put a Great Plains 2180 VW engine on it. I bought the engine in kit form from GP and it went together without problems. The total empty weight is around 620 lbs and the CG was no problem. I'll attempt to attach a picture.
Bob
I was at the Sonex factory a week ago, and had a very good conversation with them about the AeroVee Conversion, and looked at the engine. The workmanship appears to be quite good, all parts are brand new, and with the throttle body installed, the engine reportedly runs very well, has a mixture adjustment capability from the cockpit, and does not require any kind of carb heat. I asked about TBO, and was told they do not quote any such number, but that there were some engines out there that were approaching 1000 hrs, whatever that means.
I am considering it as a candidate for my KF II rebuild, even though my maximum gross is 950 lbs, and the engine is going to be 30-40 lbs heavier that the original Rotax 532, assuming about 121+ lbs for that and 165+ lbs for the AeroVee. I wondered, along with Jon whether anyone has had any experience with the AeroVee in a Kitfox, particularly a KitFox II. Except for the weight issue, it out to be a good candidate.
Since I started this thread, I thought I'd update it with my research and decision.
I'd still be interested to see the performance specs of a VW-based Kitfox, but I finally gave up on the idea when a used Jabiru 2200A turned up close to my home (for not much more than the price of the Aerovee). In the process of researching VW engines I learned some very interesting things that led me to think that a VW might not be the best choice for a Kitfox. Here's what I learned.
The main problem is the RPM range. In order to get 80 HP out of it, you have to spin it at 3600 rpm or put a redrive on it. 3600 rpm means you have to use a small prop. That doesn't hurt it much on a fast plane like a Sonex, but it's not desirable on a slower plane like the Kitfox.
Of course, you could always use a redrive, but I hate redrives. It's one of the reasons I was interested in the Aerovee in the first place. Great Plains has a redrive version, but I don't know if it would fit in a Kitfox cowl.
Sonex doesn't offer a motor mount for the Kitfox. Great Plains does, but I felt a little weird about buying the engine from one vendor and the motor mount from another one.
There are two ways to get power from a VW -- the rear, which was designed to be the business end, or the front, which was originally intended to drive the fanbelt. Sonex and most of the other conversions use the front end. Although it's beefed up, it's still not as strong as the other end that was designed for the power load. Plus, it means the prop turns the wrong way. Great Plains offers a flywheel-end version, but it's much more expensive and I never did find out if a Kitfox motor mount was available or if it would even fit.
The other thing that bothered me was that I kept running across articles that said it was impossible to get more than 65 hp from a VW for any length of time because the heads aren't capable of dissapating the heat fast enough. I suppose that just means you can't climb at full power for very long and you wouldn't do that anyway, but it still bugged me. Airplane engines ought to be conservative designs, not hot-rods.
Maybe all this explains why there aren't very many VW Kitfoxes. If so, it's a shame.
Maybe the LIMBACH 2000or 2400 engines are usable,that are VW based aircraft engines who are used very much in Europe for motorgliders.
They are about 80-90 hp
Aerovee for a IV?
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