I still need float-rigging info

[Lynn Matteson]

I put at the end of this post a random bunch of old photos I had saved of Kitfoxes with Zenair or Czech floats installed....Paul

Thanks for the updates, Paul. I haven't re-read the original posting (with edits) nor all of the latest, but just skimmed it enough to make a reply. The one thing about rigging that Zenair DOES make available are machined fittings that fit the Kitfox IV factory-welded brackets. I already have these fittings and all the strut and diagonal brace material, and of course the plane has the 4-on-each-side float/ski brackets. Yesterday morning, after thinking of how to make the rigging somewhat adjustable, I laid an aluminum bar across the pickup tubes on one of my floats...fore and aft...to check on the feasibility of making the throat adjustable. I leveled the float so this bar was reading "zero" on a digital level. Then I placed a 1/2" shim under one end of the bar....the dig. scale read 0.5 deg. Then I removed the 1/2" shim and used a 1.5" shim (2x4) and the reading was 1.5 degrees. Swapping the shims to the other end, one at a time, and the reading were the same. In short, as luck would have it, whatever the thickness of the shim is in inches, adjusts the reading a similar number of degrees. So if I were to use, say, a 1" shim under each of the four rigging blocks that bolt to the spreader bars, then set the plane-to-float (throat angle) angle at say, 4 degrees, fly it, and if an adjustment were necessary, I could remove the front 1" shims, and the throat would close up 1 degree to 3 degrees, or remove just the rear shims, and the throat angle would open to become 5 degrees. Or, if the plane flew well at the original setting, I could remove all four shims, and still be at the 4 degrees of the original setup. Now, is this what others have done to have some adjustability, or am I all wet (no pun intended) on this theory? Using shims judiciously under what Zenair calls the "pickup fitting" which is shaped like a pillow block and to which all the fittings are attached, raises or lowers the entire rigging package...struts, diagonals, x-wires, and airplane....at once, and no changing of the struts or diagonals is needed. So, in my thinking, I can easily change the throat angle, but it's the placemant of the step in regards to the C of G that would involve drastic changes of strut/diagonal tubing length if that original step/CG placement were not made right to begin with.
Your thoughts?

Lynn

[av8rps]

Lynn,

Typically people use extended float fittings at both ends (float and fuselage) so that you can move it up and down in the other bolt holes to adjust it wherever needed. But the way you are describing yours with using shims, I can't see why that wouldn't work just as well.

And yes, I agree it is much more difficult to be able to adjust the step location. I've seen people use a c-channel mounted upside down to the top of the float (usually attached to the area where the spreader bars are) so the struts could be moved to different bolt holes in the c-channel, allowing the float to be moved fore and aft by just moving the strut fittings in the bolt holes. If you can figure out a way to do that even temporarily until you are ok with how your airplane performs, that could save you a lot of time and frustration (and probably money because you won't need to cut up so much strut material). Once you know you are happy with how the floats perform, you can always make a permanent fitting for attachment.

Half the battle with installing floats is understanding what you are trying to actually accomplish. And from what I'm hearing from you, you are most definitely on the right track

Paul

[Lynn Matteson]

Lynn,

Typically people use extended float fittings at both ends (float and fuselage) so that you can move it up and down in the other bolt holes to adjust it wherever needed...

Thank, Paul....I hadn't thought of the C-channel idea for fore-to-aft placement, but that's a good idea. I might even be able to incorporate the shimming-for-throat-angle method into the C-channel idea, and have a more or less universal temporary flyable mount. This is getting exciting!

Lynn