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Thread: Leading Edge Cuff

  1. #1

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    Leading Edge Cuff

    What does everyone think of the Crosswinds leading edge cuff? I have very little experience with it and was wondering if anyone had some comments pros or cons. As I see it, it adds more wing area and chamber. Theoretically it should reduce the stall speed without increasing the aircraft deck angle. Can anyone verify this with actual flight testing or experience? How does it affect the cruise speed? I was told by someone that it weighs 14 lbs, is this true? How easy is it to install? Do you cover the wing without the cuff first and then rivet the cuff on and tape over the seams?

  2. #2
    D C's Avatar
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    I think the leading edge cuff is a great mod for the weight and the money if done at recover. I replaced the spars in one wing of my PA-12 last winter which has the cuff. Had it all apart and would be surprised if the extra leading edge material amounts to more than a few pounds per side. I did not weigh it so can't say for sure. The cuff is rivited or screwed to the leading edge before cover. The only thing I have compaired it to in flight is a PA-18. The cuff on the 12 seems to enable it to fly at a much higher angle of attack before the stall witch also makes the climb out very impressive. This may just be the difference in deck angle between the two but don't think so. Cruise speed is not affected as long as the cuff does not drop below the old leading edge. If I'm wrong you can bet these guys will set me straight. The few people I know with the cuff on their PA-18's say they wouldn't be without it. My experince is very limited compaired to the majority of poster's here so I am looking forward to hearing what everyone has to say on the subject.

  3. #3

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    The leading edge cuff will both allow you to achieve a greater aoa prior to stall and cause the zero lift aoa to be more negative. The two combine to give you a greater CLmax and a slower stall speed. If the leading edge cuff isn't dropped a bit below the old leading edge you won't see much improvement in stall. Expect a knot or two reduction in cruise speed. In rough air, you probably won't notice the difference in cruise speed.
    JimC

  4. #4

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    Leading edge cuff

    We traced the profile for a leading edge cuff from a bushmaster and then used it when we built our ribs. Photos are on yahoo wagbuilders site.Our wings are not together yet so don't know how well they will work.
    GH

  5. #5
    Marc Olson's Avatar
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    The Crosswinds STOL kit came on my PA-12. Since it's the only -12 (-18, for that matter) that I've piloted, I don't have the before and after experience.

    I do know that my plane is very stable all the way down to and into the stall. No wing dip, relax back pressure and starts flying again. One of my goals is to get some experience in other planes to see how different mine is with the cuff.

    I also have the Hendricks HotTip extended/squared wing tips and VGs, so it may be an all-together different beast.

  6. #6
    Crash's Avatar
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    Cuff

    A long time guide friend of mine had several Super Cubs in his outfit. One had the leading edge cuff. The one comment he made about the cuff was "on a cold frosty September morning, the plane with the cuff had to have ALL the frost off the wings before it would fly". "The stock wing Cubs you could just knock the frost down and go". Crash

  7. #7
    D C's Avatar
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    After asking an old pilot, how much ice will a cub fly with? He told me. "Most of the ice will fall off on impact, the rest will melt in the fire!"
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  8. #8
    Big AK's Avatar
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    Early in my Cub-flying career (little Cub experience, but plenty of SpamCan) I would never fly the Cub with ANY frost on the wings.

    A friend with much experience showed me that a Cub wing will fly just fine with smooth frost on it. NEVER the big HOARY crystals, though.

    I've done fine with smooth frost since the lesson was learned.

    Also, this friend happens to have a cub wing with the X-wind cuff on it. He told me not to bother with it while rebuilding my -11. Maybe it makes the difference on a grossed-out -18 or -12, though.

    By-the-way, this same guy believes fully, as do I, in the ability's of an extended wing with ailerons to the tips and outboard-lengthened flaps. Maybe this is another place for the X-wind cuff. The theory is certainly in place for proving the cuff.

    I wonder if the naysayers to the effectiveness of VG's pooh-pooh the cuff, as well. Seems like most VG pooh-pooher's have a preference for a stock wing. Maybe we will get some comments from those who prefer it stock.

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  10. #10

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    Leading edge cuff

    I have had 6 super cubs , one with a leading edge cuff.I have 5600 hours in those cubs. I wouldn't have another if you paid for it and paid to put it on! Thats my thoughts on the subject for what its worth......CAPTAIN CRASH

  11. #11
    Jerry Burr's Avatar
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    Cuff

    Hi Captin Crash. It's too bad with all that time that you were never able to make friends with the cuff. That probably means that you will not be able to adapt to one of the new slotted or slatted wings either. Too bad. They are a gas to fly. Jerry.
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  12. #12

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    leading edge cuff

    Keep her light ........ for slow flight!!! I'd like to try the slotted and slatted wing. I put roughly 1000 hours on the cuff 9707P it was my 2nd cub.I much prefer the stock wing to the cuff. Maybe you just can't teach an old dog new tricks. On the other hand at the Gulkana air show in Alaska I think the year was 1990 ,I saw a guy (Paul Zurkowski)in a stock cub with a 160 engine get off the ground in 22 feet . His second try 24 feet. There was this other cub there, they called it the SUPER BEAR it was suposed to put all the other cubs to shame. I beleive the SUPER BEAR had a 180 with nitrous. I know it had extended wings ,THE CUFF and who knows what else. Anyway the SUPER BEAR's first take off was like 64 feet the second was like 55 feet. I'll keep mine light you can have the cuff and the 14 pounds.

  13. #13
    Crash's Avatar
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    Cuff

    Most of you guys have never even seen frost on an aircraft's wings so I won't go into a big explanation about frost and the cuff. This guy has over 30,000 hours flying Super Cubs in the Arctic and all over Alaska. He was a paratrooper in WW-II, jumped into Normandy, and was machine gunned in the guts by the Krauts. If he says the cuffed PA-18 wouldn't take frost, then it wouldn't take frost. I don't have enough time or experience to question him. Crash

  14. #14
    nanook's Avatar
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    cuff

    Lets see, I need more lift, I'll extend the wings, wow poor roll rate, I better extend the ailerons. Flaps don't seem to have the same effect and they look small on that big wing. I'll extend those too. Man it sure seems like a lot of drag on this thing, I better try the 180hp. Wow is this thing nose heavy, I better try the big tail feathers, maybe I'll be able to flair this thing better. Holy smokes this thing is heavy, I need more lift, I wonder if that leading edge cuff will help? How about stall fences, yea that's it, with VGs all the way to the wing tips. I wonder why this thing is so tippy on these 6"gear. If I mount a gyrocopter blade up top.............
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  15. #15
    Jerry Gaston's Avatar
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  17. #17

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    I got crosswinds cuff on my plane and didnt notice any difference with frost compared to the stock wing I had before.

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    I better try the 180hp. Wow is this thing nose heavy
    How much heavier is a 0360C4P with a lite weight starter, oil cooler, alt than a stock 0320A2B with the orginal starter, oil cooler, gen?

  19. #19
    Big AK's Avatar
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    Nanook's progression cracks me up.

    No doubt that light weight makes much difference.

    No doubt also, that increased wing area lightens the wing loading.

    Choose your weapon.

  20. #20
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  21. #21
    nanook's Avatar
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    cuff

    Don't forget to add the moment created by the 10+lbs, way out there in front of you on that bigger 180hp. prop.
    > Cobblemaster: What's up with this figuring out the best case scenario on the O-360 against the worst case scenario on the O-320? I went to the lightweight starter, oil cooler and alternator years ago on the 160hp.
    > You work for cub crafters? Sounds like one of their fuzzy math sales pitches.

  22. #22

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    Dont work for CC. I was just wondering if you can back up your statements. If you are going to compare you should compare to stock.

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  24. #24
    StewartB
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    I want to hear, too. I think the topic of frosted wings is interesting. I've flown my Cessnas with frost. I've flown Cessnas with ice footprints from mesh covers. Are Cub wings that much different? And why would a cuff be worse? My 12 won't have a cuff, but I still want to know. I like that word "Alaskanism."
    SB

  25. #25
    D C's Avatar
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    Last month I flew my cuff equiped 12 with 1/4" of frost on the entire plane less what I wipe off the leading edge and above as far as I could reach. Cruise speed was a bit slower than normal for a few miles but other than that it came off the ground like it always has.

  26. #26
    nanook's Avatar
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    cuffs

    Diggler has developed a bad case of Alaskanismitis....

    > Cobblemaster: I'm not sure of what statement I'm supposed to be able to back up? The evolving heavy cub post above is a little sattire on our nature to always be tweaking things, never satisfied, usually with mixed results.
    >I have flown 150, 160 and 180hp cubs on wheels, floats and skiis commercially for hire, and for fun.
    > My opinion on the 180hp. is if you were working it on floats, it is probably a good mod. You can keep it for the rest of the flying. I'll stick with the light cub and a 160hp.
    > DC was that at gross wt.? Empty?
    > Quite a few years back, I had a conversation with Charlie Warbelow about a bad experience he had with a frosty winged cub. I remember him saying that he wouldn't try that again.

  27. #27
    D C's Avatar
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    Nanook, about 100# under gross.

  28. #28
    wilbur's Avatar
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    I'm curious, with all the stol kits for spam cans out there, (with the cuff), why is it that they have become seemingly unpopular with the Super Cubs? Haven't really talked to anyone about the performance differences on a 180, 185, or 206, but assumed that since they've been around so long that they where a good add on. Does the wing design make the difference?
    Wilbur

  29. #29

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    flight characteristics vary so much depending on the frosts thickness ,size , shape, weight and location that anyone flying with more than a little bit can get some upfront money from me if they will put me on their life insurance policy.
    with a cuff you may tend to fly slower and thats a no-no with ice on the wings unless you want to get down real friggin fast.

  30. #30
    Jerry Burr's Avatar
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    Cuff , Ice/Frost and stuff.

    Hi again. I would like to talk about the X-winds Leading Edge Cuff. First a little story. It was Christmas time and all of the relatives were visiting and the wife was preparing the ham to be cooked for dinner. As her husband was walking through the kitchen she chopped the end off of the ham and threw it in the trash and set the rest of the ham in the pan. Her husband saw the action and asked her why she threw away that good piece of ham. She answered ?because her mother used to do it?. He said, well she is here, lets ask her why. Her answer was ?because her mother used to do it?. So they decided to ask grandmother why she cut the end of the ham off. Her answer was ?because it wouldn?t fit into the pan otherwise?. With this in mind, I?m very sure that Crash?s friend had experienced a situation in which he believed that a frost covered cuff wouldn?t perform as well as a plain frosted wing. My experience and testing of the cuff has been contrary to that belief.
    There has been a lot of input on this string that to me is long on book learning and short on logic. I will deal with ice first and then frost. First a definition of terms. Frost as dealt with here is 1/8? to ¼? thick. Sometimes as much ice as frost and spread evenly over the surface. I?m not talking about ½ ? hoar frost. Which can sometimes be roped down to the former. Ice is clear and spread evenly over all of the leading edge surfaces, including windows etc. Rime ice is another matter. I have never picked up rime in VFR conditions. But clear ice is common in VFR.

    http://www.supercub.org/upload/burr/104.jpg

    This is 1/8? of clear ice on a cuff. Notice that the ice is confined to just the small radius of the cuff and does not extend more than 1 5/8? up on the top contour of the cuff. This ice was picked up at cruise speed. A lower speed would have moved the ice to an area lower on the leading edge in accordance with the increased AOA. Even with the iced leading edge there is still more upper camber available to the relative wind than there would be with a stock leading edge. The flatter stock leading edge tends to build ice farther up the camber. The additional 1 ½? of chord provided by the cuff gives an additional ramp effect to the upper camber. In either case the V.G.?s located in this area tend to energize the relative wind going over the ramp area a great deal better than those mounted back at the spar where dis-attatchment is already taking place.

    http://www.supercub.org/upload/burr/103.jpg

    You can see the additional ramp area here, and the fact that the V.G.?s and ramp area are completely free of ice. For what it?s worth, getting on the ground before the ice melts and taking pictures of clear ice on a white airplane is a story in itself.
    Another story. I stayed over at Teslin Lake on the way to Gulkana one year and the next morning we had major frost everywhere. The runway is on the side of the lake and is situated east and west. I unloaded the heavy junk out of the airplane and mounted the tripod and 35mm in the back seat area looking at the trailing edge of the right wing. Then after a warm up took off to the east and stayed low in the cold air. When over the center of the lake I climbed into warm air and into the rising sun. The effect of the water pouring off the wing into the rainbow was dramatic. And the lake provided a clean backdrop. Now I am not suggesting that ANYONE TAKE OFF WITH ANY FROST ON THEIR WINGS. If preheat is not available I usually go up light and clear the frost and warm the engine, then come back and load up and leave. I have tried to do stall tests with frosted wings, but the frost is usually gone by 200 feet so it has never panned out. On the other hand loading a Cub over gross, with frost on the wings and a short runway, would be non-habit forming in my opinion.
    For those of you who feel obligated to preach me a sermon about my ideas, FORGET IT. I have already included a disclaimer, and in case you missed it, here it is again. I DON?T SUGGEST THAT ANYONE TAKE OFF IN A CUB WITH ANY FROST ON THE WINGS. Jerry.

  31. #31
    cubdrvr's Avatar
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    Did your Dad and Grandpa do it..... ....??
    "Sometimes a Cigar is just a Cigar"

  32. #32
    Dave Calkins's Avatar
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    Whew, a breath of fresh air......and soemthing for the stock-winged Cub boys to pick out of the trash and eat.

  33. #33
    nanook's Avatar
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    cuff

    That's quite the analogy. Let's see, intead of listening to oldtimers that somehow survived 30+years of bush flying, we should brush it off as something he probably just heard somewhere.
    > I'll tell you what, while I'm cooking up that end piece of ham with the spuds in the morning, listening to some oldtimer tell stories in the cabin. My black mesh wing covers will be melting that frost in the morning sun. That way I can skip all that idiotic test pilot BS and maybe live to a ripe old age. I can of course understand why you wouldn't want to use those covers with all that crap sticking up on your wing.

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    cccccccc

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    Does frost effect later model Cessnas with the factory leading edge cuff? I think the old guy didnt know what he was talking about either. He probably had a plugged muffler.

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    Nanook, apparently you dont know Jerry.

  37. #37
    nanook's Avatar
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    cuff

    Diggler: One of the first signs of Alzheimer's is losing the ability to spell.

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    Ive never heard such a bullshit story in my life.

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