Hi!

I've been flying a Kitfox IV Speedster that I built and completed in 2013. Although I have flown off airport quite a bit over the years I have never really optimized the aircraft for this type of flying. I never wanted to slow down an airplane that has never been very fast to begin with. I cruise at around 105 mph with my 912ULS running at 5200 rpm with a cargo pod attached. This gives me decent fuel economy. But, late last year I completed a Van's RV-12iS which is much faster and is fully IFR and I will be using it for flights where I'm in a hurry (relatively speaking). Now I want to make some changes to the Kitfox.

It is a Model IV 1200 Speedster (clipped wings, streamlined tail feathers) with a Rotax 912ULS. Warp Drive 3 blade propeller. 6 600 tires on Matco W62 wheels. It weighs in at about 700 lbs and has a two axis autopilot (dynon) and is basic IFR. I built the wings such that the portion that was removed can be reattached very easily and flown as a long wing. I have not done this in years as it floats enough with the short wings (IMHO). It seems to get off the ground just fine with the short wings. I weigh 150 so I can carry all the gear I need to camp, full fuel and still be 100 lbs under gross. I store it folded in my hangar with the RV-12 and shorter wings make this a bit easier.

I'm not looking to do STOL/DRAG or anything like that. I just want to be able to land on softer and rougher sites than I feel comfortable with now. I am thinking of changing to 6 850 4 ply tires and an E-prop. A lighter and softer tailwheel would be nice also. I have the solid rubber Maule tailwheel now, Any suggestions or comments will be appreciated. Any comments from Kitfox I-IV flyers especially appreciated. I'm really interested on any comments regarding the change from 600-850 tires. The Aero Classic Smooth TSO'd tires.

Thanks!
Henry

Hi Henry, welcome!

I learned to fly in a model II kitfox with a 532 and now occasionally fly my dads model IV with a 912. The model 4 is on spring gear and 29'' airstreaks.

The bigger the tire you run, the lower psi you can run. If you are wanting to fly off airport more, I wouldn't consider anything else other than airstreaks. Big tires at low pressure are the best insurance you can buy, for off airport flying.

The drawback of the big tires is the weight and CG. Early kitfox's have a fairly light tail so I wouldn't get to carried away out back, but most likely you will need the weight back there so it doesn't hurt to go with a tailwheel with a shock and big tire.

If you are comfortable with the landing speeds and takeoff distances as is, then the wing may be fine in the short config. Will be interesting to do some testing on landing/takeoff distances with the different wings, especially with the higher angle of attack from the big tires.

Brent