skywagon8a
MEMBER
SE Mass MA6
Yes, they are actually made of some type of heat formed plastic. They have only been off once in 50 years when the floats were repainted and have stood up very well. still in good shape.
Fun Wing Tip Experiment (uploaded for Skywagon)
- Thread starter Seaworthy
- Start date
teenahlake
Registered User
Had the madras tips on a pacer w/floats. One decided to part ways, flew back holding about 1/4 of aileron displacement. My thoughts are drooptips improve lift, even if it maybe due to the extra 12" of span
skywagon8a
MEMBER
SE Mass MA6
I agree they do improve lift, primarily due to the extra 12" of span. The droop portion does help with reducing the span wise flow and consequently an improvement in aileron authority. At least this is what I observed with the Ferguson tips on my 7GCB.
skywagon8a
MEMBER
SE Mass MA6
An observation. Now that it is bug season and hardly a flight is made without there being any bugs to clean off the wings after a flight, I have noticed something. I seldom find a bug on the swept back portion of the wing tips. Apparently the airflow over the swept tips is such that the bugs miss hitting the leading edge. I guess that's another plus for these tips.
skywagon8a
MEMBER
SE Mass MA6
Test #10
I noticed in the first photo that the air starts to be deflected by the compression of the molecules at approximately 8-12" ahead of the leading edge. That has made me wonder if the air also moves horizontally? The wing tip has a sharp sweep back (50* at 1/4 chord) Photo #2, in accordance with Horner's experiments and report. As a result I wondered if there was some horizontal flow which was interfering with the flow over the tip? So, as shown in photo #3 I built a leading edge fence with a collection of yarns. The idea being if there is a span wise flow which effect the flow over the tip, the fence should stop that flow. Photo #4 at a high angle of attack just above stall, the yarns on the lower edge are flowing outboard and the lower aft yarn is showing a sideward turbulent flow. Photo #5 at the cruise angle is showing less outward flow.
#1
#2 
#3 
#4
#5 
The question I had was, would the fence reduce span wise flow enough to allow the swept tip to produce more (or less) lift. By placing the fence on just one wing, if there was a difference one wing would become heavier or lighter. There was no difference noted. The swept tip lift did not change.
The fence will be coming off going, into the scrap bin.
I noticed in the first photo that the air starts to be deflected by the compression of the molecules at approximately 8-12" ahead of the leading edge. That has made me wonder if the air also moves horizontally? The wing tip has a sharp sweep back (50* at 1/4 chord) Photo #2, in accordance with Horner's experiments and report. As a result I wondered if there was some horizontal flow which was interfering with the flow over the tip? So, as shown in photo #3 I built a leading edge fence with a collection of yarns. The idea being if there is a span wise flow which effect the flow over the tip, the fence should stop that flow. Photo #4 at a high angle of attack just above stall, the yarns on the lower edge are flowing outboard and the lower aft yarn is showing a sideward turbulent flow. Photo #5 at the cruise angle is showing less outward flow.
#1
#2 #3 #4
#5 The question I had was, would the fence reduce span wise flow enough to allow the swept tip to produce more (or less) lift. By placing the fence on just one wing, if there was a difference one wing would become heavier or lighter. There was no difference noted. The swept tip lift did not change.
The fence will be coming off going, into the scrap bin.
Attachments
BC12D-4-85
SPONSOR
Fairbanks, AK.
Crosswinds STOL adds a similar LE fence to the outboard ends of their cuff. Also, Horton and Lynch add similar spill plates to both their cuff ends. Maybe it's marketing...maybe it's a way to seal the ends...and maybe it's effective.
Gary
Gary
skywagon8a
MEMBER
SE Mass MA6
Well, based upon my test ... It's marketing.
BC12D-4-85
SPONSOR
Fairbanks, AK.
And they make installing wing covers difficult plus prone to wear along the fence edges. Sportsman cuff smoothly fairs the cuff's ends into the wing root and tip.
Gary
akavidflyer
FRIEND
Soldotna AK
Most of the fences extend back the width of the wing. Not sure just a little stick out on the LE is going to do anything to hold the air on and force it to stay flowing over the wing.
skywagon8a
MEMBER
SE Mass MA6
Test #10.5
The idea was to determine if airflow around the leading edge at the tip would effect the lift or not. After sleeping on it I realized that the tuffs around the edges all flowed outboard and the plane was slower by about 3 mph. So I removed the fence and the speed went back to normal. The only thing the fence did was to create 3 mph of drag. There were no other noticeable trim conditions.
akavidflyer, This test was to determine what happened to the air at the outboard leading edge only. Just trying to fine tune the knowledge learned with the variety of tips in this thread. At this point I think it is optimized to it's greatest advantage. This was the fourth tip fence iteration.
The idea was to determine if airflow around the leading edge at the tip would effect the lift or not. After sleeping on it I realized that the tuffs around the edges all flowed outboard and the plane was slower by about 3 mph. So I removed the fence and the speed went back to normal. The only thing the fence did was to create 3 mph of drag. There were no other noticeable trim conditions.
akavidflyer, This test was to determine what happened to the air at the outboard leading edge only. Just trying to fine tune the knowledge learned with the variety of tips in this thread. At this point I think it is optimized to it's greatest advantage. This was the fourth tip fence iteration.
courierguy
MEMBER
Inkom, Idaho
https://youtu.be/woQrg4fHBt0 Right at 1:45, for his wingtip.
BC12D-4-85
SPONSOR
Fairbanks, AK.
That tip fence is a dupe of Crosswinds' wing tip w/o the lower aft drooped portion. Charly told me once the fence was installed to keep the droop from bending back up in slow flight. His dad kept drooping the tip down until it made a difference, but it needed support from above to stay there.
Gary
Gary
