3 Upgrade to 4?

[Ronin]

Hi Guys,
If I were to acquire an untouched 3 airframe kit what items would be worth upgrading to more like a 4? I'm planning a 912 and the Grove gear. Can a 3 wing be updated to 4 standards? What about the bigger tail surfaces? Anything else?

James T
Valrico, FL

[av8rps]

I love my Model 4. But if I had a virgin model 3 kit I would probably just build it as a stock Model 3. Converting it to a real Model 4 would be a big project.

And frankly, a Model 3 is still a very nice Kitfox. It will fly slower and have a slightly lower gross weight, but if built reasonably light it will make for a very practical and fun Kitfox.

Oh, and if STOL/ Back Country flying is by chance your preference, it will outperform the Model 4 as the high lift undercambered wing is superior in that environment. In fact a Model 3 with something like a 100 hp Rotax 912 would be a kick ass STOL plane that would most definitely garner some serious attention from the back country crowd.

[cap01]

even if you were to keep the under camber wings i would replaced the wing struts with the larger diameter material. also i would install a solid rod inside the tubing that connects the lower strut attach fittings . i did installed the larger classic rudder and make the vertical stab taller to match the rudder on my early model 4. also the larger elevator would be nice. wish id done it on mine. be sure to install elevator trim, its well worth the trouble.

[PapuaPilot]

It's best to call the factory and get their input.

[Ronin]

I've spoken to the factory and am sure I will again, thank you.

Would it be worthwhile to "airfoil" the tail like a speedster?

I'm also going to put a pitch and roll trim servos on it, so buy the tail kit or modify the one I have?

I plan on doing the widebody mod.

I read that more tail surface all around would benefit the 3. I have tube & rag experience, I built a Spacewalker II from plans in the early 90's so welding is not an issue.

Also planning the 4-style control system upgrade.

What would be the holdup about a small GW increase maybe to 1200, wing struts, spar carry-through?

I have a 13.5 gl fiberglass tank and a 6 gl aluminum one. I'd like to put two 13's in the wings, do I just get the factory ones?

Also thinking I'm just going to sell the complete original gear setup, legs, wheels, brakes, tail-wheel all of it.

James T
Valrico, FL