Sullivan vs Madras (Demmer) wing tips

[Stephen]

My plane a PA 22/20 has had Madras wing tips since I purchased it in 1983 as a PA 22. I've extended the wings with the old Ferguson STC and it now has the Bushmaster STC. But, I kept the Madras (Demmer) tips. Each mod through the years has improved the planes STOL abilities. Now, I've switched to the Sullivan wing tip STC. I just installed new carbon fiber Sullivan wing tips. All I expected was that the Sullivan tips would be over 3 pounds lighter per wing, my visibility would improve and I would not bang my head on the dropped tips anymore. Today, after waiting out illness and weather I made my first test flight.

1. My first turn I noticed that the ailerons were lighter.
2. There was a big improvement in turns. The plane was more steady and coordinated in a turn. The Madras tips with their long droop made turns difficult to stay coordinated, I was always chasing the ball. With my new Sullivan tips the ball was much centered and my turns more easily coordinated.
3. Cruise was unchanged, I was hoping to see some improvement without the long droop on the wing tips, no luck.
4. The big-time improvement was a major decrease in the low speeds. When my plane was a Pacer with squared off (Ferguson STC) my plane stalled "power on" and full flaps at just under 40 mph indicated. When I did the Bushmaster STC the stall speed dropped to about 34 mph, using a gps average. Today, my first flight using my new Sullivan tips, it was stalling under 30 mph. It was so slow my AS indicator was worthless, it indicated under 20 mph. I did power on stalls in four different directions 90 degrees apart and averaged the gps stall speed to 29 mph. Apparently, the tips increased the wing surface area and added lift and significantly decreased stall speed. I am impressed, so far.

Now, I wonder if I will be able to get anyone to purchase my Madras tips.

[Steve Pierce]

Now, I wonder if I will be able to get anyone to purchase my Madras tips.

I bet you can when someone tears one up.

Interesting results. Thanks for sharing this information.

[Stephen]

I bet you can when someone tears one up.

Interesting results. Thanks for sharing this information.

Yes, I'm a bit surprised. I'll do lots more verification testing and report results. I'm also considering moving my pilot tube to the jury strut similar to the PA18. Since the Bushmaster now has jury struts. I would like to get a more accurate airspeed if possible.

Stalls are quit benign although, it is a steep deck angle.

[SMO22]

sitting in the sfo terminal and looking out at the new Boeing 737 wingtips, droop tip combined with upward wingtip, must be the way to go at high speed to reduce those vortices that tilt the lift vector aft pulling the ship backwards slowing it down. All new high speed jets have at least an upward wingtip and theyre not small, they are higher than the wing chord at tip, 30 -40% increase in cruise performance according to article linked below. I bet you'd get that increase in cruise if you experimented more with droop and upward winglets.
https://gizmodo.com/how-these-simple...hole-837341873

[Stephen]

Wing tip mods generally increase performance by reducing induced drag. But, there are down sides. Significantly dropped tips also increase adverse yaw. Which makes sense. The dropped fins tend to make a plane track straight ahead when the plane is banked. More rudder is necessary going into a turn as well as coming out. In my plane I always found myself slightly behind trying to keep the ball centered. I did not realize how bad it was until I removed the Madras tips and found turns much easier to keep coordinated.

[Brian]

Thats amazing low speed preformance Stephan. Better than a Carbon Cub.
Whats next? O-360?

[Stephen]

Thats amazing low speed preformance Stephan. Better than a Carbon Cub.
Whats next? O-360?

I'll get more data.

My narrow deck 0-320, it putting out near 180 hp with an 82 inch prop.

Like everyone else, I've got to decide on the ADSB next plus I have a number of small projects (need to paint tips and engine cowl). Maybe Trimmers PA 18 gear next year. As you can tell, I'm enjoying retirement.

[Steve Pierce]

Have you talked to Jerry about you tip test results?

[Pacerfgoe]

In my plane I always found myself slightly behind trying to keep the ball centered. I did not realize how bad it was until I removed the Madras tips and found turns much easier to keep coordinated.

I find this a very interesting observation, as I too have a hard time trying to keep the ball centered. I just assumed it's a stubby fuselage trait, I've never flown any other shortwing to compare.

[Stephen]

Have you talked to Jerry about you tip test results?

No, but I will. He has studied both tips and rates them high. Although, his plane is a bit different, lighter, greater angle of incidence, leading edge cuff, flaperons. Which might test differently. I've been in his Cub slow flying under 30 mph.