Kitfox 4 rebuild

[avidflyer]

Hi all, well I'm finally getting around to rebuilding the Kitfox 4 I hauled up from Texas about 5 years ago (thanks Pete Ohms :-) ) I redid the wings last summer, in between other projects and am now back to work on the rest of the plane. Stripped most of the stuff out of the fuselage yesterday and today. Just before I quit for the evening, I went to remove the rudder. The 2 top bolts were rusted into the heim joint bearings. Still haven't gotten the top one out, will probably move the plane outside where I can spin the rudder around to unscrew the heim joint out of the tail post. I've got other heim joints so I can wreck this one if need be. Anyway, the point of this thread is to advise those that have this type of fitting, it might be a good idea to oil them once in a while so the bolt doesn't rust into the bearing in the heim joint. It will make removing the rudder much easier if you ever choose to. JImChuk

[Av8r3400]

I had to torch the bolts out of the Mangy.

This is when I decided to torch off the fittings completely and put normal hinges on the rudder instead of this silly design. :mad:

[HighWing]

To each, I guess, I like the silly design. One of the options with the early IVs was the Speedster version. Without the Rod End design on the Speedster and many models after the IV, the vertical / Rudder closeout (gap seal) would be a real challenge. Been there done that.

[Dave S]

Lowell brings up a good point on adjusting the rudder - had to do a little of that on our S7 also and the rod ends made it easy.

I am sure Larry's modification works out well too, just a slightly different & classical approach.

To keep the rod end in good condition, this is one of the points that lubrication on the ball, bolt and post is an antidote to rust and corrosion.


Reminds me a bit of an A & P acquaintance with a tripacer who ended up with the HS trim getting progressively stiffer and finally sticking. Piper had engineered a small hole on the top of the tubing intended for applying oil between the tube surfaces on which the HS spar rotates for trim which had apparently not been used for its intended purpose. The joint had not been lubricated for an eternity and a very difficult time of separating the parts and freeing them up resulted.

A little lubrication of the right type in the right places goes a long way in keeping things un-stuck.:) I second Jim's advice.

[avidflyer]

Got the rudder off today by turning it around and around and around ect, ect. Lots of turns on that fine thread heim joint bolt. Anyway, got pretty much else off the fuselage except the paint and butt rib and center rib. I'll be widening the fuselage and adding some extra metal above the landing gear area before I strip off the paint. Anyway, I'm wondering if I should make any provision for locating the battery near the tail of the plane for weight and balance issues. I'll be using a 912 Rotax in this Kitfox 4 classic. Where do most of you end up putting the battery in this model of plane. It used to be back behind the turtle deck, but the previous owner was trying to offset the weight of a Subaru engine up front. Also, what was your finished empty weight in a plane like this? Thanks, JImChuk
PS one last question, looking at Lowell's pictures, how much benefit is it to add the wood ribs to the elevator, rudder, and stabilizers? Mine doesn't have them

[DesertFox4]

Battery placement in the tail will not be neccessary with the 912 up front.
Mine is on the inside of the firewall on the passenger side.

I put the wood ribs in the tail of my 4 Classic. Like the looks. The 4 flys just fine without them.

[Dusty]

My battery is behind the seat and I still have a tail wheel full of antifreeze to get the cg near the rearward limit (912 ivo cabane gear and Nanco tyres)
It's easier to bring the cg back than move it forward:)

[HighWing]

...how much benefit is it to add the wood ribs to the elevator, rudder, and stabilizers? Mine doesn't have them
The only thing I can verify is that with the original elevator, modified with ribs and gap.seal I haven't had any problem with inadequate elevator authority as.reported by many Model IV owners. Other than that, since the mods were in place for first flight with no before and after comparison, no other verifiable difference is possible.

[jiott]

Just from a theoretical standpoint, the airfoiled horizontal stab should increase the efficiency of the stab. The airfoil shape will give more up (lift) or down force without having to set it at as much AOA, thereby reducing the drag. So it does its job with lower drag; how much this is would require an aeronautical engineer to calculate. Personally I just prefer the look.

[David47]

Thanks, JImChuk
PS one last question, looking at Lowell's pictures, how much benefit is it to add the wood ribs to the elevator, rudder, and stabilizers? Mine doesn't have them[/QUOTE]

Without doing a direct comparison between an airfoiled and non-airfoiled h/s and elevator, on the same aircraft in the same atmospheric conditions, I think you'd be hard pressed to calculate a meanful drag delta. But then the "speed kit" which I have on my build isn't just confined to the h/s stab etc. It also includes the vertical stab and Rudder so I suspect there would be a drag reduction overall. How much ?. Ask John McBean. Kitfox may have the data.

But then like Jim Ott said, I like the look. :D

Ps. A friends Super Decathlon I'm currently flying just has slab empennage surfaces. Nothing fancy there ....

[Eric]

Hello

does anyone know where I can find drawings to make te ribs for the elevator and vertical fin
.
I have a 3 and that has the flat surfaces.