Kitfox Series 7 Super Sport - Show Me Fox

[Jason Murphy]

Continued to refine the flaperon tips

Used a wood rasp and sandpaper to further shape the balsa blocks.

I am concerned about the lack of material on the trailing edge. I consulted with another builder TJ and he suggested to reinforce the balsa with a layer of fiberglass.

[bbs428]

Jason, fwiw, my tips curve into the flaperon avoiding the sharp tip as you have found out is very weak. One "bump" could ruin your day. Fiberglass reinforcing would help but imo, they would still be vulnerable.
I'll post some pics on my build thread for you.

Your flaperon tips are awesome btw - mui bueno!

[Jason Murphy]

Combining multiple entries, I have been task saturated and a poor historian lately.

On a side note I passed the FAA Fundamentals of Instruction exam and I am now studying for the Flight Instructor Airplane exam. Accomplishing professional goals and balancing work on this project has been a challenge.

Back to the business at hand.

Wing Tanks - Ordered Banjo fitting kits from Kitfox for future serviceability, Fitted tanks with banjo fittings. Leak tested each tank for 3 days full of water. No leaks observed. Dried the inside of the tank with low pressure from my air compressor and the Tyson tubing. I cracked the regulator open just enough to get a gentle breeze which could be felt on the cheek. Tanks are now ready to install. I have some minor prep work which needs accomplished prior to installation. I will recheck washout and dihedral prior to installation.

Sand relief in no 1 rib to provide room to service banjo fitting. Reviewing the manual I found that I did not provide enough relief for the fuel lines in the rear of the No 1 rib. Additional sanding performed.

Flaperons - Lots of work completed today. The last two to three weeks has been prep work and dry assembly. Bonded and riveted end ribs. Per manual control horns remain temporary fastened with clecos. Locate flaperons on wings and match drill to wing ribs. Cleco in place per manual.
Bond and rivet balance weights to flaperon.

Drive to Wicks Aircraft picked up plywood for pitot mount and mounting location for magnetometer. Also picked up mahogany ply with the intention of replacing the light wood floor boards with mahogany.

While at Wicks I discussed break lines. I was advised that on the brake lines which are exposed on the gear legs I should use braided line as it will be much more robust than the plastic line. I was also advised the plastic lines will be satisfactory inside where chafing is not a concern.

I didn't like how the control cables were unraveling when they were crimped. Attempted to re swage the control cables without success until I changed technique. I swaged the distal section first and worked back. This prevented the cable from unraveling. Discussing this problem at Wicks I was advised that is the best way to swage cable to prevent that problem. I will need to replace the cable because I ended up trying too many times to get a good swage and came up short. I suppose this is part of the learning curve.

After completing the flaperon clamping fixture the flaperon control horns were match drilled IAW the builders manual.

To prevent the horns from settling while being drilled they were supported with a small block of wood with tape wrapped around it.

All parts cleco and dry fit together.

Need to apply touch up primer to the end ribs prior to bonding and riveting in place. Per the instruction manual final riveting is delayed until paint has been applied

After several failures attempting to make the flaperon clamping fixture I finally came up with a good way to make one

First I tried using 2x4 lumber that was trued with a jointer and ripped with a table saw to size.

After 24 hours these materials began to twist and bow.

I made extra and took the straightest and attempted to make a fixture however I did a poor job of cutting the wing profile. So these were scrapped.

Next I obtained a few pieces of 1.5 x 1.5 square dowel.

I cut them to length per the manual. Taped them together to form a block per the manual. I used a 1/8” bit to drill the pilot hole and mate the 2 blocks together. I needed a pilot hole that was not too big for my Forstner bit to counterbore the bolt holes. I used my 12” No. 40 bit to complete drilling through the blocks.

Using a 7/8 Forstner bit I provided a recess for the bolt head and nut.

To make the profile of the wing I used the flaperon end rib for the basic shape. I centered the end rib between the two blocks and traced an outline of the flaperon spar.

I used a 1 inch paddle bit to make a hole for the spar hole.

I then flipped the end rib over and verified it was still centered. I traced the basic profile of the flaperon and cut it out using a scroll saw. Borrowing a spindle sander I sanded up to the lines and began the process of trial and error fitting of the flaperon to the clamping fixture.

It took several attempts but I don't believe I could get much better fit. Perhaps I could use Superfil to fill all the small gaps and provide a molded fit.

[Jason Murphy]

Addendum to previous post, limit of 20 attachments per post.

I am entertaining the idea of replacing the pulled monel rivets with some -3AD universal head rivets to continue the theme of solid rivets in the trailing edge. Before I do that I need to determine if I will be sacrifice strength for aesthetics which is never an acceptable compromise by my standards.

I have the problem that I am running out of clecos. I started with 100 and between the wingtip attachment strips and the flaperons they are nearly all being used.

[Jason Murphy]

Jason, fwiw, my tips curve into the flaperon avoiding the sharp tip as you have found out is very weak. One "bump" could ruin your day. Fiberglass reinforcing would help but imo, they would still be vulnerable.
I'll post some pics on my build thread for you.

Your flaperon tips are awesome btw - mui bueno!

Thank you for the compliment!

Yes, I believe that I am going to have the trailing edge taper inboard to mitigate the possibility of damage in the future. I need to come up with a way to blend the tip with the flaperon itself and create a seamless transition between the two parts.

[jiott]

It seems to be very common on these forums to see people spend much time and effort, even struggle, to make the flaperon clamp blocks to accuracies and profile fit that are show quality. That's fine if that is what you enjoy doing, but it is simply not necessary. The ONLY purpose of those clamp blocks are to hold the flaperon chord line (a line drawn from the center of the leading edge to the trailing edge point) parallel to the bottom surface of the block, for use in rigging the flaperon to the wing. That clamp block could be as simple as a curve to fit the leading edge and a narrow vee to fit the trailing edge, with just a crude profile to clear the rest of the flaperon surface. When you tighten up the bolts you just want it to hold firm without crushing the aluminum. I do admire the workmanship that some folks put into these single use blocks, but my purpose here is to maybe save some of you a lot of time and effort so you can move on to the really important things. My 2 cents.

[efwd]

A few years late for me Jim but I could have certainly used that information for sure. Rigging the plane was one of the primary concerns that I had and feared the most if it was not correct. I recall my post on the subject to this day. You may have been part of that as well. Thanks for the posts.

[jrevens]

I agree with you Jim. I also used them for locating/installing the control horns (arms) at the proper angles in relation to the flaperons.

[Jason Murphy]

I thought that was their purpose in life was to get the control horns right then to aid in the final rigging later. I really didn’t spend an incredible amount of time on mine once I got it figured out I could flip the end rib over and use that. Then it came down to borrowing the necessary tools.

I connected my flaperons tonight and have a whole lot more movement with the left one than the right but I’m sure that’s simply a rigging issue.

[Jason Murphy]

Connected the flaperon controls. Had the kids come down and make them wiggle.

Additional trimming on seat pan.

Had my kids sit in the seat pan and marked the underside of the leading edge. Took a straight edge and made a line on the left and right sides. I was required to do them separately because there is a bow in the seat pla that is removed by weight.

Also marked the edges. I have been told that I need to trim the seat pan below the edge of the door to prevent you from catching on it as you get in and out of the airplane. I aimed for approximately 1/4”.

I have also noticed a slight inward bow on the sides that I would like to resolve. I will seek advice from the community and factory.