Lift strut question

[birddog486]

Does anyone know when the Kitfox changed the lift strut design so they weren't interchangeable with the Avid?

Specifically: will the lift struts from a model IV kitfox fit on an Avid?

[Av8r3400]

The short answer is no, they won't fit. I don't know if they were ever interchangeable.

[jrevens]

Here's another question: I'm in the process of fitting my jury struts. Is 1/8" offset at the center (bowing up) of a lift strut acceptable or not. The book says they must be perfectly straight. I can get the rear strut perfectly straight and have that slight amount of bend in the front one with the jury strut perfectly aligned in respect to the ribs & spars. I'm mostly asking the question from a structural standpoint, as it is really not noticeable to the eye. Is it OK like that or do I need to make another strut attach bracket to correct it? Am I being too critical? Thanks, you guys.

[Dave S]

John,

You are not being too critical. The lift strut must be precisely straight and it is a structural issue, particularily regarding negative Gs and stressing the tabs the jury strut is fastened to. Believe the book.

I had the same situation and decided to resolve it by cutting the ends off the jury strut, welding on equivalent 4130 tubing and flattening the ends/drilling/reaming and trimming to the correct length to make the geometry work out so the lift strut tubes are absolutely straight and the jury struts are exactly perpendicular to the spar tubes.

Now...having said that, I have seen more than one old certified high wing airplane with the lift struts assuming the position of a noticable bow.........but I guess I don't ascribe to that standard being an experimental type

Sincerely,

Dave S
KF7 Trigear
912ULS Warp Drive

[avidflyer]

All four of my Avid Flyers had/have a slight bow in the lift struts. The center bows up about 1/8" As far as the liftstruts being interchangeable, on the Kitfox 1 and 4 kits I have, the lift struts attach at the fuseloge to a 1/8" or 1/4" thick tab. The Avid tab is about 3/4" or 1" thick. Picture is of my Avid B model, the Avid MK IV is the same. Also, I know the Kitfox 1 and 2 used a shorter liftstrut than the later models. Never measured and compared them to the Avid for length. Take care, Jim Chuk