hershey bar wings

[lv2plyguitar 172]

Have any of you squared off the end of AVID wings with any success?  Has it increased STOL performance?  If yes do you have pictures and ideas where to get parts?

Edited 29 Sep 2016 by lv2plyguitar

[EDMO 1078]

See my post on "Droop Tips and Others" - I think that any addition of more wing area and square tips added to round ends will help STOL, like extending Speedwings and/or replacing your round tips with Kitfox Droop Tips.   You certainly would not want to take any surface away just to square tips.   I would like to see a report on any changes made and the results / differences reported.   I think Snaps was getting some Kitfox tips?   I have some used droop tips for sale, but they may be a shorter span than new ones, I haven't measured them.  EDMO

Edited 29 Sep 2016 by EDMO

[C5Engineer 1170]

I think the ugly factor would outweigh the benefits on that mod....

[lv2plyguitar 172]

LOL

[EDMO 1078]

I think the ugly factor would outweigh the benefits on that mod....

Nobody ever said that STOL, or Kitfox wings, had to be pretty - and look at the Catalina monsters!   I like whatever works best!   EDMO

Edited 30 Sep 2016 by EDMO

[Av8r3400 1179]

I still haven't completely eliminated the idea of flat tips on the mangy. 

Ugly is in the eye of the beholder. 

[EDMO 1078]

Regardless of what you consider to be ugly, eliminating square feet of wing surface (aka tips) does not enhance STOL, although it may increase cruise speeds.   Yes,  shorter wings and flat board tips look cool, but are not really helping with STOL. 

IMO,  Lighter Weight, more wing surface, and more HP, Bigger prop, plus a shock-absorbing landing gear  = STOL. 

The Storch was a good example.  Everything in Plane Design is a compromise.   Here is one in SA this month:

A cool STOL 912 powered 533 lb EW Kitfox 3 with 82" prop and big gear, if you don't have baggage or cowl! 

Is TKF starting to Strip-Tease?   I like them better with all the clothes on!  EDMO

Edited 30 Sep 2016 by EDMO

[akflyer 1427]

looks like this guy is trying to give frank a run for his money... looks an awful lot like lil cub...

 

 

[EDMO 1078]

looks like this guy is trying to give frank a run for his money... looks an awful lot like lil cub...

 

 

I think he said that LiL Cub was the pattern for the Fox - Wonder if he can match Frank's flying skills too?   EDMO

Edited 30 Sep 2016 by EDMO

[dholly 718]

Ed - link not working.

Kitfox would be very pleased to sell you a new set of wings with flat fence tips...

 

Edited 2 Oct 2016 by dholly

[EDMO 1078]

Doug,  The chord of those squared Kitfo$ wingtips is too short for my Cessna 210 sized wing tips.

If I was into the $TOL (Short Take Off / Controlled Crashes) crowd, I might be ready to spend $$$$ if Kitfox could show me the wind tunnel test results on all of the tips they sell so I could compare the results, but I don't think they can prove that the flat ones are better, or maybe they are not even as good as the drooped tips, but they have to be better than the round tips. 

I just want my plane to fly - it don't have to be pretty, naked, or act like a Kangaroo!  EDMO

Edited 30 Sep 2016 by EDMO

[akflyer 1427]

I can give you some unscientific results... I have played with many wing tips on my RC planes.  By far, the flat plate tips reduced tip stalls more than any other.

 

 

[lostman 198]

Leni, did you include STOL type down turned tips in your unscientific research? Just curious because from everything I've ready they will typically beat out the fences.

[akflyer 1427]

Leni, did you include STOL type down turned tips in your unscientific research? Just curious because from everything I've ready they will typically beat out the fences.

Yes I did, however, take it with a grain of salt.  The tips were hand carved and sanded and were probably not at some optimum angle etc.  I don't know the science behind the droop tips I just carved and sanded until they looked like the ones on the cubs at the airport.

 

[lostman 198]

Good to know. Now if you'd try all the different tips on your Avid and report how they do we'll see what your type of flying works better with. All I know is after a lot of research and actually reading NASA documents on STOL type up or down ward turned tips, they suggest they do better in the wind tunnel. That was good enough for me and I built them for my Teenie Two. The decreased my ground roll from 600' to 450', plus added 6 knots on the upper end. I would never have believed the 6 knots but I carefully replicated the exact conditions every flight to do the testing for them. I've never tried gates though so have no experience with them. I suppose it would be extremely simple to make up some out of thin plywood just to test. 

[EDMO 1078]

Good to know. Now if you'd try all the different tips on your Avid and report how they do we'll see what your type of flying works better with. All I know is after a lot of research and actually reading NASA documents on STOL type up or down ward turned tips, they suggest they do better in the wind tunnel. That was good enough for me and I built them for my Teenie Two. The decreased my ground roll from 600' to 450', plus added 6 knots on the upper end. I would never have believed the 6 knots but I carefully replicated the exact conditions every flight to do the testing for them. I've never tried gates though so have no experience with them. I suppose it would be extremely simple to make up some out of thin plywood just to test. 

Unfortunately, most Avids do not have the option of removable wing tips like Kitfox.  One other difference between flat plates and droop tips is that the droop tips add about 12 square feet to the Kitfox wing area which is already larger than the Avids - Lift is dependent on surface area of wings.   I see that Kitfox may have added some area on the plate tips for the later wings rather than just ending them at a rib - sort of like adding extensions to Avid Speedwings. 

I also believe that the droop tips act like winglets, in that they make the wing fly like it is longer, because they keep the pressure from flowing outward at the tips and keep it underneath for the full chord of the wing.  But again, that is a non-scientific analysis.  EDMO

Edited 2 Oct 2016 by EDMO

[Bandit 286]

Does it really make any difference to most pilots if we use 150' ft more of runway?

[EDMO 1078]

Does it really make any difference to most pilots if we use 150' ft more of runway?

For Alaska flyers like Leni it could mean the difference of flying out or a helicopter ride! 

For others, it is $$$$ spent on bragging rights or repairs in the STOL competitions!  

For most of us it probably don't matter, but something to talk about and think about if the fan stops turning! 

  EDMO

Edited 2 Oct 2016 by EDMO

[Bandit 286]

True.

[TJay 1041]

So what exactly do the green strips in the middle of the wing Do, other than look really neat,

[EDMO 1078]

So what exactly do the green strips in the middle of the wing Do, other than look really neat,

add Drag?    If they were under the wing, they would produce an extra vortex.   EDMO

Edited 2 Oct 2016 by EDMO

[lostman 198]

Trust me, 150 feet off a ground roll after the fan quits turning is HUGE!! I know, I've had three engine out and off field landings in my career. I've managed to walk away from them all but the first one wouldn't have ended with me getting 25 stitches to the forehead if I could have stopped that much quicker. To me it's not just about the STOL  abilities, it's about the engine out safety factor as well. Of course the STOL ability is really cool, but it's secondary to the engine stopping. 

[akflyer 1427]

So what exactly do the green strips in the middle of the wing Do, other than look really neat,

its a STOL fence.  It helps keep the air from spilling off the end of the wing when your flying low slow and uncoordinated.  I doubt it adds much drag, but it is a part of many of the STOL manufactures kits.. I think it does more for you than a leading edge cuff with no drawbacks.

 

[dholly 718]

Buddy of mine just bought a 182 Wren Conversion. Now that thing has some funky looking fences. Not to mention that crazy canard. 

[Bandit 286]

I do understand the concern, but why fly a airplane that glides like a rock ? That's why I like my Bandit simple and lite. It should glide as good as anything in a engine out situation.