Ronin's KFIII Build Thread


9 posts in this topic

Posted

Finally got the half hanger sorted out, lights installed etc, and actually did some work on (removed) the rudder pedals. Floor plywood is starting to crumble due to age and lack of finish. Going to remove all the controls, brace the fuselage sides, reshape/enlarge the tail feathers and build new rudder pedals with proper geometry and re-powdercoat everything, Going to make the tail similar to Av8r3400's and copy his fuselage and rudder pedal mods.

I want to update the controls and wing to KF4 but every time I talk to KF about it I seem to get the hard sell "buy the whole 4 wing quick-build" instead of these are the parts you need to swap out and this is the cost.  Same thing with the control system. They act like they don't want to sell the parts. I may have to flatten the wing and build a 4 control system the hard way?

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Posted (edited)

James -

It's not a simple upgrade. I documented all part #'s and descriptions for the items necessary to retrofit KF4 wings and control system to a KF3 here:

Control system: http://www.avidfoxflyers.com/index.php?/topic/4481-kitfox-model-4-control-system-retrofit-kit-19065/

Wings: http://www.avidfoxflyers.com/applications/core/interface/file/attachment.php?id=9925

Edited by dholly
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Posted

Who here has flown a Kitfox 3 and Kitfox 4 close enough together to say how much better the 4 flys then the 3?   I know the 4 has better controls in that it controls adverse yaw, but is it enough to change out all the controls?  My Avid Mk IV is much like a Kitfox 3, and it flys fine.  Now the Kitfox 4 wing maybe a different story.  Good STOL performance, plus faster then the earlier wing as well. Then all you would maybe need is the Kitfox 4 ribs, plus heavier drag tubes if those are different, leading edge plastic strip.  Maybe need to go with the 4 flaperons then as well.  Stuff you don't use from the 3 would be worth some $ to sell.  Just some random thoughts as I have a snack for lunch.  JImChuk

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Posted

The KF 4 (small rudder)seems more stable in rough air, whereas the 3 needs constant rudder correction to counter the eileron inputs.If I was to rebuild my 3 I would consider the conversion.The big tail 1200 fox is a major leap forward in stability also.

As a side note the performance of the 4 v's the 3 with a 582 is the same in all areas.:flamegun:

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Posted

Got most of the control system removed along with the floorboards. The flap lever bolt seems to hit the frame tube, not sure how it got put in but it sure doesn't want to come out. smile.gif

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Posted

The KF 4 (small rudder)seems more stable in rough air, whereas the 3 needs constant rudder correction to counter the eileron inputs.If I was to rebuild my 3 I would consider the conversion.The big tail 1200 fox is a major leap forward in stability also.

As a side note the performance of the 4 v's the 3 with a 582 is the same in all areas.:flamegun:

Forgot to mention in my other previous post.  I believe a Kitfox 4 is 9" longer between the wings and the tail then the earlier Kitfoxes.  That would change the way it flies to some extant I'm sure.   Maybe more to it then just the controls.  JImChuk

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Posted

The KF 4 (small rudder)seems more stable in rough air, whereas the 3 needs constant rudder correction to counter the eileron inputs.If I was to rebuild my 3 I would consider the conversion.The big tail 1200 fox is a major leap forward in stability also.

As a side note the performance of the 4 v's the 3 with a 582 is the same in all areas.:flamegun:

Forgot to mention in my other previous post.  I believe a Kitfox 4 is 9" longer between the wings and the tail then the earlier Kitfoxes.  That would change the way it flies to some extant I'm sure.   Maybe more to it then just the controls.  JImChuk

Measuring them side-by-side confirms this. 

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Posted

Funny thing that you mention this.   About an hour ago, I measured my Kitfox 4 classic fuselage and the new Kitfox 3 project I just picked up.  Hooking on the rear wing spar pin, and measureing to the rudder hinge, I had 10' on both of them.  So at least in mine they are the same length.  the rudder is larger on the Kitfox 4, so if you measure to the back of the rudder, then the 4 is longer..  I've proved my self wrong again  :-) JImChuk

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Posted

Funny thing that you mention this.   About an hour ago, I measured my Kitfox 4 classic fuselage and the new Kitfox 3 project I just picked up.  Hooking on the rear wing spar pin, and measureing to the rudder hinge, I had 10' on both of them.  So at least in mine they are the same length.  the rudder is larger on the Kitfox 4, so if you measure to the back of the rudder, then the 4 is longer..  I've proved my self wrong again  :-) JImChuk

I'll try that same measurement tomorrow and report. 

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