KF3 wing convert to KF4?

[NotSoAmish]

Good Lord John. You have it figured out each way I turn. All excellant point to keep in mind. You even thought about the Oshkosh flyin factor. I give up. Guess I am always trying to change things. My brother and I grew up with a father who had his own drawings of the what became the Wankel engine, before the Wankel went to patent. We have always looked to improve things like he did. I guess it is more important to have the extra HP of the Viking engine for critial climb situations as opossed to just going faster. Thanks.

[Peteohms]

John Pitkin has good points. There are a few things you can do to speed up a III. Murle Williams told me you can add a sharper leading edge to the wing and speed up some. You can add fairings to various places too. But, if you go too fast exceeding the design vne I suppose you could cause problems elsewhere. My Kitfox III cruises about 85mph. I can get 90 out of it but I prefer not to push the engine. I've flown from Austin, Tx to Oshkosh, Wi twice and survived a flight to Sun N Fun and back in March/April. I enjoy the long trips. My advice is dance with the girl who brought you.

[egp8111]

Notsoamish,

Like you I was looking as ways to make my KFIII faster during a rebuild. I installed the plastic leading edge from KF and a thicker windshield. With the 912 mine will "easily" blow through red line. I've yet to get the throttle fully open before I'm off the ground. A 912(80hp) is all the motor you want on a KFIII, anything more is overkill IMHO. The airplane will let you know what speed it wants to cruise. I cruise at 80-85 at 4200rpm. I can easily make it go faster but it just does feel happy. I don't know what the effect of the new leading edge on the earlier airfoil as I never flew without it. My impression is that it lowers the overall drag of the wing but does not have much effect on it's overall speed range. All I can say is mine does not exibit any negitive effects. Murle Williams is a good source of info about the modification.
I would advise against getting too creative with alot of unproven mods or engines. Stick with what has proven to work, you'll be flying a lot sooner and safer. Get it flying and enjoy it for what it is, you'll soon forget about wanting to go fast !

EG

[NotSoAmish]

The more pointed leading edge PVC parts are in our parts inventory. We also have the re-enforced flaperon link points and mass dampening weights for the flaperons. We have also increased our vertical fin leading edge area for about 15% increase and are buying the aileron differential mod kit. Still need to find out if our windshield stock material has been upgraded to the thicker one. I guess we are really after the best possible flying pleasure instead of speed.
If we go 4200 rpm with the Viking we should be consuming somewhat less than 3.5 GPH.

[Av8r3400]

Keep in mind the 1-3 were designed for the 75# 582 engine. A 135# 912 is pushing the weight limitations of this design.

I fear that Eggenfellner's 200# Honda auto-conversion will not add much performance and could possibly cause more problems than it solves on this model plane.

[Dave F]

582 readsy to roll is 110 lbs

912 is about 165 lbs

Honda -- not sure but 180 to 200 lbs ready t o go.
Impressive static test showing about 40 to 60 pounds more thrust from the honda so let's say 10% more
So take in account another 40 lbs or so that iwll cost you about 200 fpm climb rate loss so the 10% more Thrust might not make up what is lost in adding wieght.

SO many just continue to build tanks --adding weight that is just plain dumb.

My opinion but I do like the honda engines.

[Geowitz]

Not to spitefully answer questions you weren't asking, but I agree with the previous 2 posts. You may have a bigger concern with the weight and balance. On models 3's and earlier you need to pay extra close attention to not being nose heavy.

[NotSoAmish]

Vikingaircraft specifications are that it is 13 lbs. heavier than the 912ULS and the same weight as the Jabiru 3300. Are there no 912ULS in any KF3? The Viking is 178 lbs.