KFm-2 vs KFm-4

by FPVTrond | December 9, 2012 | (18) Posted in Tips

In the video attached I did a comparison of two flying wings that are similar in almost every way except weight and airfoil type. The white one uses KFm-2 and the red one uses KFm-4. 

The videos shown side by side was shot within a few minutes on the same day so weather conditions was similar for both flights.

My conclusion is that the KFm-4 seems to be a lot more stable under the same conditions. This is just my opinion and may or may not be true for other types of planes, builds, setups or pilots.

So based on my own experience, my tip for any potential FPV49 builders would be to go for the KFm-4 instead of the KFm-2 if you want to have smooth and stable FPV video :)



COMMENTS

Benn Gunn on December 10, 2012
Thats interesting i always build KFM2 wings ...but your footage and comments speak for themselfs ... your quite right....will have to have a go with my next build
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RedBaron1 on December 12, 2012
You mention that the planes are "similer in almost every way except weight", but what IS the weight difference?

AsI'm sure you realize, the weight differnece alone can make a big difference, and there's benefits to both a lighter and heavier weight. A heavier plane will penetrate and handle more wind or turbulance, but a lighter plane will glide better in smooth air.

Looks like you've found a real difference, as long as the weight difference isn't too great.
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FPVTrond on December 12, 2012
Hi Baron,

You may be right.

The weight of the KFm-2 plane was 1450grams
The weight of the KFm-4 plane was 1850grams

The main reason for the weight difference is that the KFm-4 plane was flying with 2 x 2650mAh 3cell batteries while the KFm-2 only had one. Also the motor and servos are slightly heavier on the KFm-4 plane.

I have flown the KFm-2 with dual batteries as well, but it still feels like it bounces a little more in the air. The KFm-4 wing feels like it flies on rails compared.

Keep in mind that these are scratch built planes and there are many potential sources of errors in my test.

Best Regards
Trond
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casehatter on December 11, 2012
I would agree with you, the KFM-4 seemed very stable IF the pilot was trying to maitain stable flight on both flights.
Good tip thanks
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KFm-2 vs KFm-4