easy front spar stiffener

[TJay 1041]

cut off old bushings and drilled out, slid in .035 chrome-alley tube glued while sliding it in to stop any chance of small vibration, will drill and weld in new bushings tomorrow. less than 2 hrs of work and double the strength.

[EDMO 1078]

Have you measured the little mount tubes? Just make sure that the upper part extends the same on all 4 of them - You may find that the originals are a little long on the bottom end since they were made for .065 spars - after you get the steel inserts into your spars, you can measure the ID and know how long to make the little tubes and grind the bottom ends if need be. Hope this is clear - sometimes I wonder what I am saying!

EDMO

[TJay 1041]

crystal clear I know what your saying

[1avidflyer 1983]

Real important that the rear bushings/tubes are in line with the bottom lift strut attachment.  Otherwise it will bind when you try to fold the wings.  Basicly they act as two hinges to fold the wing. I have to give you another atta boy TJay, you really are moving right along on that plane.  It's good to see.  Take care,  Jim Chuk

PS I was thinking you doubled up both front and back carry thru tubes when I mentioned getting the rear bushings in line with the bottom lift strut attachment... never mind!

Edited 8 Jan 2015 by Jim Chuk

[EZFlap 12]

My question is whether there is any lack or shortage of strength in the original bushine/tube design that justifies the added strength? It looks like a great idea, and will definitely be stronger, but is this fixing some known problem?

[TJay 1041]

Probably not and it would probably never break, I looked over a kitfox 4 1050 a while back and noticed our rear spar carry throu is exactly the same but his front one is way thicker, thought must be a reason for it, now mine is a little smaller tubing but a bit thicker. It figures up to .801 lbs for a 3 foot piece, aint bad, this way when I load her up to 1000 lbs its one less area I need to stair at the whole flight.

Edited 8 Jan 2015 by TJay

[EDMO 1078]

If you look at more of the later model Kitfoxes, I think you will find that they enlarged and thickened the cross tubes - I have a drawing of an enlarged rear spar cutout for the Kitfox 5 that is larger than a Kitfox 1 cutout - a necessary modification for folding the wings-

If I remember right, my little vertical mount tubes were about .380" high from the cross tube, and about 2.125" long. But yours may be higher, since I went to a larger diameter and heavier wall cross tubes. Aiming for 1320 GW, I also am making 1" diameter x .058 wall struts, although Kitfox uses .049 wall.

EDMO

Edited 8 Jan 2015 by Ed In Missouri

[EDMO 1078]

I believe the rear cross tube has the most strain on it - see my post above.

EdMO

[TJay 1041]

and finished