gap seal and aileron fence testing

Pete, do your overall aileron gaps and aileron form duplicate Piper's dimensions? The next evolution might be increasing the LR radius of the aileron (fatter than the trailing edge of the nearby wing) similar to CC and Husky? Tape on material and test?

Earlier: https://www.supercub.org/forum/showthread.php?60266-Aileron-Design

Gary

I believe the airfoil shape and size is identical to Piper's. I don't have access to a Piper -18 to make a direct comparison of the gap and wing trailing edge cove shape. The performance and handling as is is very acceptable.

If you are going to test an item on one wing only, your feet have to be flat on the floor or the test is not valid. Your rudder input, even though unintentional changes the results. Do the same to both wings and you will have good data. Also do your tests as close to gross weight as possible. A lightly loaded Cub wing really doesn't really care what you do it. Especially if the item is small. Jerry

The feet were both flat on the floor and on the rudders. It was done on one wing in order to determine whether there was any more or less lift created. It was loaded lightly. I'll fly it again fully loaded.

Could you do a fully loaded climb test? Maybe 60 or 65 mph

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Looking for what? It climbs like a homesick angel depending upon the prop pitch setting.

Looking for better lift when climbing high and heavy. An improvement of 50 fpm would have me trying the fairing. Same for those cool wingtips

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DJ,
In my view the aileron gap fairings do nothing. At least on my plane. Your best improvement for altitude performance would be more wing span. My current span is 41' 8". You could copy my wing extensions now during your build by building in the components and covering with fabric. This would save some weight. Mine was made in two separately removeable sections as an afterthought. If I were to do this again I would use the method which was done on Dave Caukins' wings.



Jerry,
The feet on the floor test produced so much adverse yaw in both directions, there was nothing to be learned. I think a better improvement for a Cub would be changing the aileron throw to produce more up travel than down, differential travel. That I believe would require changing the aileron control horns. Perhaps even creating an opening in the trailing edge to enable more up travel? I thought of that during the build. Getting the build finished was more important than a major modification in this area at the time. As it is now, there are no aileron travel limiting stops so the travel is set as far as the controls can push them. The lack of differential is noticed.

8a. Yes, the yaw is my point. When you correct for it the results are not accurate. Examples. Slow on final, starts to drop a wing, do you use aileron or rudder? The rudder corrects the problem, the problem you are trying to measure. When testing in experimental, I fastened a 1x4 between the outboard end of the lift struts on the right wing. I then attached a 30 lb block of lead to the 1x4. I had 4 different sets of wingtips to test. The plan was to put a wingtip on and fly slower and slower to see what airspeed the tip let go. Then repeat with all the tips plus no tip. ( flat end ). I had to keep my feet flat on the floor for the above reason. As I slowed down the left wing gave way and it rolled left. The 30 lb weight was the light wing. After six or seven tries it was obvious that p-factor at that speed and attitude was the controlling force. I went back and put each set of tips on both wings and got the results I was looking for. When you make small changes on one wing the results are just not massive. As I found some tests are just not valid. Jerry

Flew it loaded today in smooth air. 1924 lbs @ 17.6". This is a widebody injected 180 hp, Whirlwind 200G prop, -18 clone on floats with two different sets of wing extensions and 110" flaps. The inboard aileron hinge is in the same location as the center hinge on a stock Cub. Aileron span is less than a stock -18.

At cruise speed, 21"mp/2400 rpm 108 mph IAS, the wing with the aileron gap seal was maybe a touch heavy.
Power idle, full nose up trim at 59-60 mph IAS, reduce speed at the standard 1 mph/second rate. Stall, the right wing started to settle first each time. This was not an abrupt stall.
At the same power/trim condition full aileron was applied in each direction. Counting 1,2,3,4,5,6,7 to a 30* bank angle. Same imprecise rate in both directions.
Even with the large ventral fin, rapid full aileron movement in both directions provided excess adverse yawing without rudder input. Definitely, the lack of differential aileron travel is the culprit.

This airplane is rigged correctly, so any change in lift should show in a requirement to adjust the rigging. Minimal to none was noted.

Conclusion: The aileron gap fairings only provide a cosmetic change. I may as well remove this one and call it a day. It does close the gap and provide a neater appearance.
If I was covering a wing, I would make a fairing using Balsa wood sheet then covering it with fabric. Just for appearances sake.

I've mentioned this before, but pre-war to post-war Taylorcraft went from J-3/PA-18 aileron cove design (abrupt trailing edge close to aileron) to PA-12's design (a contoured trailing edge like used for PA-18 flaps). Not sure why or what it affected in control performance. It's a mystery.

Gary

BC12D-4-85 said:

I've mentioned this before, but pre-war to post-war Taylorcraft went from J-3/PA-18 aileron cove design (abrupt trailing edge close to aileron) to PA-12's design (a contoured trailing edge like used for PA-18 flaps). Not sure why or what it affected in control performance. It's a mystery.

Gary

Click to expand...

Remember, just because a manufacturer makes a change, it may not change the performance or handling at all. The change may be done for marketing purposes or just to be able to call it a different model year. It may be a cost adjustment or a labor hours change.

8a. I definitely like good tests as opposed to opinions. Good job. will you send me your email in a pm and I'll send some stuff for you to scrutinize. Jerry