Making the bottom fuse stringers

August 21, 2011

Today played around with the bottom stringers on the plane. I wanted to take away the “banana/football” shape of the bottom of the fuselage. The problem is that the torque tube can get in the way if you get to carried away and just go for the straight line. So I decided on terminating the stringer line early and splice the stringer together with 1/16” mahogany ply and T-88. This is similar to how Stuart did it on his Pitts down in New Zealand except I spliced my 5/16” by 1.5” spruce string where Stuart cut his shape of a bigger piece which is a good way to do that but I didn’t want to order the bigger stock so I thought splicing it would be just fine. I also had to modify my stringer support plywood so much that I need to make new ones. The second wood stringer support plywood was also welded in the wrong place and that coupled with the lack of metal stringer support brackets under the elevator ider have way down the fuse allowed my old stringers to buckle when the fuselage fabric was taughtened. I weld the aft bottom stringer support in the correct place (further aft) and then make some metal stringer support brackets to weld on to the cross tube under the elevator idler attach.

Time spent today 3 hours
Total time spent 742 hours


Fuselage side panel standoffs and diagonal repair

August 16, 2011

Today I cut off the old side panel support standoffs (near where your shoulders would be if sitting the cockpit), which weren’t installed in accordance with the drawings. My old standoffs were installed vertically with no center support and I wanted them to go back to the plans, which has them travel down the diagonal tube from the seat back to the rear spar mount. I bought some 0.025 4130 steel sheet and using my buddies shear and break cut and folded some angles that I could weld in place. I also had to extend the stringer attach brackets out to 1.5” (they were only about 1). After and I cut and welded in the attach brackets I checked to make sure the stringer would fit and nice and tight, perfect.

After that I wanted to repair the lower 5/8” diagonal tube that travels from the lower spar attached cluster back to the station that the elevator idler attaches. This is the longest tube in the whole frame and it is 5/8” 0.035. It notoriously has cracked at the weld near the rear spar bracket cluster in many Pitts S-1’s and mine is no different. I cut the tube back about 1 inch from the weld cluster I then ground most of the rest of the tube out of the cluster I slid a ¾” tube that fit nice and tight over the 5/8” tube and set it back. I then profiled the 3/4” tube to fit to that cluster. Finally I cut a 60 deg splice angle and welded that into place. Interestingly I went over to a friend’s S-1 and he had the same exact repair done before. It seems that if you haven’t done this yet you will.

Finally I finish welded the lower right and left lower rear spar attach bracket doublers that were installed years ago but they only did the weld on the periphery but didn’t complete it to the cluster side. I simply welded the backside of the bracket.

Time spent today 6 hours
Total time spent 739 hours

Clear coating upper wings, I-strut final welding

August 14, 2011

Today I got to work by finally epoxy coating my upper wing. This is a tedious task when doing the ribs. I used the System Three clear coat product and a paintbrush. I plan on using two coats with sanding in between coats on the to and bottom surfaces and spar faces because the epoxy inevitably has some ruff texture when dry. This took about 1.5 hours between to separate mixes to do one side plus the ribs and took about 5 mixed ounces of epoxy total.

I then moved onto finish welding my I-struts. I had partially welded the tubes in most places and this was to merely finish the welds on the streamline tubes and the brace tubes to the ¾” square tube. I am always surprised how much time it takes to weld simple projects especially when they are easy to maneuver and get into an easy welding position.

Time spent today 6 hours
Total time spent 733 hours

Re top coating the lower left aileron

August 11, 2011

So I sanded down the aileron to get it smooth again. The Top coat sands easily with the 320 grit open coat. I then got it back in the paint booth this time I mixed a bit more paint and started shooting. This time I slowed my travel speed down on all coats which used a bit more paint. By the third coat I had a great smooth shine going and by the end of the 4 coat I had a fantastic looking finish.

The next day It has flowed out even more and was a mirror finish. I am really excited because it was really not hard to paint and get a great finish with a very small amount of practice.

Time spent today 3 hours
Total time spent 730 hours

Top coat the lower left aileron

August 10, 2011

So tonight after much pacing around the basement I decided tonight was the night I would try the topcoat paint. I rubbed the aileron down with scotch-brite first. After that I mixed up a batch guessing the amount. I mixed by weight and just to see how my scale was working I tested a batch in the M50 viscosity cup. It came out too thin at 17 sec. That sucks because I can’t do anything about fixing it besides just throwing it away. Next time I rounded down on the water measurement and didn’t add it all this time before checking the viscosity. It came out at about 27 sec so I added the rest of the water and it dropped to 20 sec. I went ahead and sprayed that fogging (fluid at 3/4 turn) with the the first coat which is really hard not to want to spray more but I resisted. The next coat went on with the fluid knob up 1/8 turn and at exactly 10 minutes later. The third coat went on with fluid knob up another 1/8 (so 1 full turn from closed) again 10 minutes later. I ran out of paint so i mixed some more in the 15 min I had. I sprayed the rest with the knob up 1/4 turn further. I was a little disappointed as I could tell orange peel was forming, but I hoped as it flowed out it would clear up. The paint glossed up nice but I had some orange peel to deal with.

The next day I took a look and there was definitely orange peel but it did flow out some. So I call Dan Stewart at Stewart Systems to ask what I can do to correct this. He said I didn’t put enough fluid on the part. He said I could crank up the fluid a bit more or slow my travel down. I thought that I was traveling a little fast not wanting to have any runs. So i thought I slow it down next time.

Time spent 3 hours
Total Time spent 727 hours.

Finish filling the upper right aileron

August 4, 2011

Roll up post again on the coats of filler for the upper right aileron. So using the scotch-brite technique works really well especially if you attach it to a jitter bug sander. The only problem is that if you have a few bumps or places that need to be leveled you still need to have the sand paper around. What I found is that if you lightly sand all the bays just to level things out and then follow with the scotch brite you will get a great finish.

Time spent 4.5 hours
Total time spent 724 hours

Upper right and upper left coats and call to stewart systems for some help

August 2, 2011

After I got done with the upper right ailerons 3rd sprayed cross coat and it still required sanding I thought how much work this was going to to be to do the wings and everything else. I knew my fingers just wouldn’t take the rest if it was going to take this kind of time. So I called Stewarts to see if I was doing something wrong. Dan Stewart answered and I told him my issues he said first off the ailerons are the worst part of the whole plane to cover and finish. So that part was good news. Also he said since the videos have be out and the manual too that they have some new variations to the technique that may help. He asked what gun I was using and I told him the Devilbiss Finish line 3. The next question was how much pressure I can get to the gun I and I said 25 psi no prob he then asked which tip. I said 1.5 mm using 20 psi. He told me to try 1.3 mm at 23-24 psi will help some. To solve my 1 hour to sand each aileron he told me to try sanding down with red scotch-brite pads and even using an air sander when I get to the wings in the bays away from structure. He told me it should only take about 15 min to sand an entire wing and only a few minutes to sand the aileron. He also told me to try this about 30-45 min after each cross coat.

So I had some red scotch-brite went straight down stairs to try it and holy shit this technique worked awesome. The scotch brite really smoothed out the filler quick and it makes sanding around the rib stitches way easier on the upper right aileron which was through its 3rd cross spray coat. I decided to see how this works on the upper left aileron since it was still at a brush coat and I could try it on each spray coat. So far I am pretty excited on how much easier it is. After that was scotch-brited down I sprayed the upper right for 1 cross coat and the first cross coat of the upper left. About 30 min later I was able to use the scotch-brite and it smoothed right out. So that along with the tip change really really helped. Dan did say that they are in the process of putting out a new website with a forum and also a new video on this technique to the Eko Fill so the rest of the world can have this process.

Time spent 3 hours
Total time spent 719.5 hours