I'm looking at buying a used Kitfox as my first KF, then building one as a second airplane. But I'll admit, the more I look, the more confused I get.

Put the flamethrowers away for a second, but I had looked at a meticulous Kitfox 5 with a Subaru on it. With 370 hours on the airframe and a VERY clean install, I think he got one of the "good" NSI engines and gearbox, but of course the airplane is heavy. I've also looked at a Lycoming KitFox 6.

I've been flying since '86, commercial, CFI, ASEL/AMEL/Glider and have my A&P. I have a BS in Aeronautical Engineering, but I'll admit I've used the education more in engineering project management than design and the education is 20 years old. My theory knowledge seems to be causing me more stress than maybe is necessary, so I thought I'd come here to the Forums and get experience and practical knowledge.

So... the 1º forward sweep on airframes that had the heavier engines on them? In theory a forward sweep can increase performance, but can also have poor side effects in out of coordination yaw (retreating wing drag increases, making it a balancing act to stay coordinated), it can also negatively affect stall/spin characteristics. More so if the rigging isn't perfect. There are plenty of gliders out there with negative sweep, but I have no experience with them.

Being an A&P a Lycoming is attractive, and being experimental I can put on electronic ignition, fuel injection, port and polish, etc... bringing the engine ahead 50 years or so in technology. And designed to run 100LL I have 50 hour oil changes without lead issues in a Rotax, Subaru, or other. If I got the Subaru airplane I could always put on a Lycoming with FWF, Engine, prop, cowl if I ran into NSI issues.

So, pick the flame throwers back up and let me have it....

Wing sweep? Issue? Things to look out for? Performance gain? Unforgiving, or don't notice?

Without the conversation of the NSI, that's been discussed on other threads, heavier engine choices like the NSI or Lycoming, who likes the heavier weight w/ forward CG (more stable?) and who doesn't (light is almost always better in aviation, but not always) and why?

One more thing, this first kitfox is either a 3-6 year ownership experience, selling it after building a 7, or I may keep both. Selling it means how does the above affect value and ease of sale?

I've reorganized my hangar so I can get a KF and my 182 in there, and I have funds, I just need to feel comfortable in a purchase decision :-)

Thanks for your experience and wisdom!
-Andrew