KitfoxIV and Jabiru 2200A Prop Recomendations

[djmc4344]

I have a Kitfox IV with a Jab 2200A, SN1311. The propeller is a Sensenich 62x46. My max rpm is about 2900 @ 2000 Ft, and airspeed is only 80-85 Mph. I think my cruise should be higher so I'm thinking I have mismatch engine and propeller. Any opinions or recomendations out there??
Thanks

[jtpitkin06]

Dan,


I’m not sure what speed you are expecting from an 85 HP engine. However, the Jabiru is rated for max power of 85 hp at 3300 rpm. I’m not aware if your engine is restricted to a lower rpm.


If your red line is indeed 3300, then you can use a flatter pitch to get the rpm ( and horsepower) up a littler higher.While the 46 pitch prop may be recommended for the Jabiru on less draggy aircraft, the high drag Kitfox is preventing you from reaching max rpm.


At 2900 rpm I’m estimating you are only getting 70% power or about 60 hp.


Try borrowing a prop before blowing a wad of cash on a new fan. If you can find a ground adjustable prop for some test flights it will really help you find a good match.


Good luck.

John Pitkin
Greenville, TX

[DesertFox4]

Dan, regardless of engine/prop choice you can pick up some free speed by fairing your wing struts. Best of luck with the prop. hunt. Nice looking Kitfox by the way.

[Av8r3400]

Dan - The speeds that I have heard are in the range of 8-10 mpg for faring just the lift struts.

Faring the tubes on you landing gear, the ones going up to the bungees, will also gain you several mph.


(I agree with the other Dan, that is a really nice looking plane. )

[djmc4344]

Thanks for the info guys. I think farings might be the way to go. Cheaper than a new prop.

[jtpitkin06]

Dan,
I'm still concerned that you are not getting full rpm. If you don't get full rpm in cruise, then you certainly are not getting full rpm in climb. This tells me you never get full power from your engine and your performance is well below its potential. If you were just 50 rpm off the maximum I would blow it off. but 400 rpm is a significant hit.

I'm sure you could sell your present prop once you find one that gets full rpm.

John Pitkin
Greenville, TX

[djmc4344]

Going to fly tommorrow weather permitting, I'll make some more speed and rpm checks.

[djmc4344]

Flew today, and found that I get 3100 rpm max & 90 mph. Not as bad as I thought. I'll check the throtle travel and make sure I'm getting it all. Farings should bring the speed up to near 100 mph I hope.