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Sonex Wingtip Extentions

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Daleandee

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The video really doesn't show much but you'll get the drift. There is no company that I could find and only an email address for contact.

I'm not interested in these personally but they are said to increase the rate of climb, better cruise, decrease stall speed, etc.

They look pretty good on the airplane but I'd be concerned if there was any real testing as to the effects of bending on the spar, load transfers, and such. Anyway ... appreciate any and all valued responses, opinions, comments, and thoughts on such an idea. If it's received by the designer like the Corvair wasn't then they will have to rename their airplanes and wear a mask to Sun-N-Fun even after the Corona threat is over. :eek:

 
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Victor Bravo

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The tips on the red airplane at the end of the video would have a very very high likelihood of working. I can't vouch for the little mini winglets on the other one, but I will absolutely bet on the tapered tips on the red airplane. I'd bet on a measurable improvement in performance. Partly from the increased span, partly from the swept back "Scheumann" style planform moving the pressure field around, and partly from the sweep being able to throw a vortex to add energy to the BL.
 

Mcmark

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I have seen that reversed Wittman tip on several RV airplanes.
Hearsay is they work as well as the those on the Tailwind/Buttercup airplanes.
There is a Tailwind group in Switzerland that are adding winglets to theirs for more benefit. Looks like a shark fin.
No first hand knowledge from me.
 

TFF

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Not that you can’t get it wrong, but tips are pretty known entities. compared to the standard wing, they are huge span increases. Eyeball 3-4 ft more. General shape is almost textbook. Helps with less induced drag and probably better aileron control because of smaller wing tip vortices. Flying fine in the video. The only real question is where it places it’s loading for the spar.
 

gtae07

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I’ve seen swept/pointed tips on an RV-6 before (it was Paul Lipps’s airplane), for the same benefits (better climb/cruise). However such tips are going to increase bending moment on the wing; I would expect at least a reduction in max G load and consequent reductions in Va and Vno. And as noted, how are the loads being reacted into the rest of the wing?

OTOH something like this might be just the thing for a lower-powered Sonex if you aren’t as concerned about aerobatics.

I’ve also thought about making a set of quick-change tips for my RV-7, to have an extended set for travel and the “stock” tips for fun flying. But I don’t think the performance gains would offset the time and money to fabricate. Would be fun, though, and a good challenge.
 

BJC

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I’ve also thought about making a set of quick-change tips for my RV-7, to have an extended set for travel and the “stock” tips for fun flying. But I don’t think the performance gains would offset the time and money to fabricate. Would be fun, though, and a good challenge.
Glasairs have optional extended wing tips. They increase the span, increase high altitude cruise speed, lower stall and landing speed, and can be built “wet” for an additional 10 or 11 gallons of fuel. Some builders have bonded them on permanently. If built to plans, it takes 3 to 5 minutes per tip to swap them.

They do significantly reduce the roll rate. The wing structure still meets the advertised Vne and +/- g as the short wing.


BJC
 

Daleandee

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The tips on the red airplane at the end of the video would have a very very high likelihood of working. I can't vouch for the little mini winglets on the other one ... "
I can't be absolutely certain but it appears that both airplanes are sporting the same type of tips. Here's a photo from the video that appears to show that ...

1589922898034.png

Here's a link to some install photos (follow the link mcrae0104 posted above): SonexFlight Podcast: Episode 69 - AllenFlight Extended Wingtips
 
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jedi

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Death of CEO Jeremy Monnett, in the crash of June 02, 2015 near Wittman Regional Airport
(Sonex, N123SX, Sonex Aircraft LLC: Fatal accident occurred June 02, 2015 near Wittman Regional Airport (KOSH), Oshkosh, Wisconsin} inspired a report on raked wingtips as a safety and performance improvement on the typical Hershey bar wing.
Sonex expressed absolutely no interest in the proposal. The attachment shows the proposal on an RV. Anyone interested in continuing development of the proposal should create a new thread on the subject.

RV.jpg
 

Vigilant1

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Death of CEO Jeremy Monnett, in the crash of June 02, 2015 near Wittman Regional Airport
(Sonex, N123SX, Sonex Aircraft LLC: Fatal accident occurred June 02, 2015 near Wittman Regional Airport (KOSH), Oshkosh, Wisconsin} inspired a report on raked wingtips as a safety and performance improvement on the typical Hershey bar wing.
Sonex expressed absolutely no interest in the proposal. The attachment shows the proposal on an RV. Anyone interested in continuing development of the proposal should create a new thread on the subject.

View attachment 96974
Well, since it is in this thread--
". . . Inspired a report on raked wingtips"? Do you have additional info on the entity that was 'inspired' to write the document?

Noting the illustration--was Van's also not interested? Did Piper change the Cherokee wingtips?
 
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Victor Bravo

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The original research and experimentation was done by Wil Scheumann, using a modified AS-W12 sailplane. A groundbreaking artile in Soaring magazine in the early 1980's was the first time anybody had done this (in the modern era).


Based on Scheumann's results with the clip-wing '12, the late great Klaus Holighaus developed the Schempp-Hirth Discus sailplane, which came on the scene in 1984 or 85 IIRC. It was an immediate hit and rewrote the record book in its class. Since then, almost every new sailplane design has used some variation of a swept or raked wingtip, with or without the "full" Scheumann multi-sweep main wing planform.

It works in two ways. First, it re-arranges the local pressure distributions on the upper surface of the wing to oppose (delay) the formation of the wingtip vortex phenomenon. Second, the raked tip becomes a large vortex generator at high AoA. This vortex adds a significant amount of energy into the boundary layer and flow velocities, keeping the flow attached at higher AoA than would otherwise be possible.


Myself and others have written about this before... see post #196 here:
 
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jedi

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Well, since it is in this thread--
". . . Inspired a report on raked wingtips"? Do you have additional info on the entity that was 'inspired' to write the document?

Noting the illustration--was Van's also not interested? Did Piper change the Cherokee wingtips?
Both Glasair and Vans were approached but not heavily pressured. There is the "not invented here" barrier and the "our product works fine" attitude and the we looked at that answer.

Piper has after market wing tips.

My son and I wrote the report for the EAA founders innovation prize competition {EAA Founder’s Innovation Prize | EAA}. We found it interesting to note that the winners consistently focus on instrumentation and training to avoid the stall/spin rather than fixing the stall/spin tendency. Reference Henryk's Kasper Wing deep stall videos to see what can be done to avoid loss of control and spins.

We found that pilots are willing to accept the risks of LOC with existing designs and have concentrated our efforts on new clean sheet design proposals. As members here know that is a long road.

I am interested in working with anyone who has equipment and/or interest and would like to explore the concepts and assist with hardware development.
 
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AJLiberatore

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Anyway ... appreciate any and all valued responses, opinions, comments, and thoughts on such an idea.>
Thanks for the post Daleandee.

As someone fascinated with aero-design and by extensions wingtips 😂, the audio was pure gold.

Did anyone catch the 6 degree washout to try to achieve "Bell Curve Lift" and a Zero-Lift-Line at (iirc) cruise? Wow. I was smitten a while back by the Jodel D-18 and IIRC, their triangular tips have 7 degrees of washout and do not do much at cruise, but in the other modes is where they shine. I hear through the grapevine that one design that uses a like tip that some of builders add washout but nothing like these numbers.

It hit me a while back that the many aircraft that incorporate wing extensions like the Sea Bee are adding them out at the tip (not root) where all these flow issues start and imho you are moving them outward and your original wing is now working like it should, or so I speculate.

IIRC the Jack Cox article back in the day when Steve Wittman added his famous tip to his Tailwind it was noted for structural reasons he couldn't go with the trailing edge parallel and co-linear so it was swept forward where as in this Sonex modified tip it is parallel and co-linear with the trailing edge. I'd love to see some CFD on the Wittman tip as to what and where the vortices are going, I can't help but wonder are they starting to diffuse just outboard of the ailerons.

I stumbled upon a picture of a PA-14 that somehow received a 337 (I speculate) where the traditional Short Wing Piper tip was turned in to an almost 1/4 ellipse tip via extending the outer most point on the tip straight aft and merging with the extended trailing edge at 90 degrees. Again I'd love to know the changes / benefits.

Another question I have is can the Bell Lift Curve and or Prantl-D (Al Bowers) washout models be applied to many in the traditional configuration fleet with benefits.

My best,
Anthony
 

mcrae0104

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Death of CEO Jeremy Monnett, in the crash of June 02, 2015 near Wittman Regional Airport... inspired a report on raked wingtips as a safety and performance improvement on the typical Hershey bar wing.
Would you be willing to share this report, or at least summarize the safety benefits?
 

radfordc

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I would expect at least a reduction in max G load and consequent reductions in Va and Vno.
The Sonex wing is very strong to start with. Tested to destruction at around 11 g if I recall correctly. The broken test wing still hangs on the wall at the Sonex hangar.
 

BJC

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I stumbled upon a picture of a PA-14 that somehow received a 337 (I speculate) where the traditional Short Wing Piper tip was turned in to an almost 1/4 ellipse tip via extending the outer most point on the tip straight aft and merging with the extended trailing edge at 90 degrees. Again I'd love to know the changes / benefits.
Don't know about the Piper, but a wing tip mod that Steve Wolf made in morphing the Pitts wing onto the Wolf Pitts / Wolf Pro wings is similar, and has two significant benefits: It extends the aileron span and area out further, significantly increasing the roll rate and aileron authority at low speed, and it significantly reduces the induced drag during high g pitch changes (pulls / pushes to vertical, etc.) possible with much less speed loss, which makes vertical maneuvers much easier.


BJC
 

TFF

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The original Tailwind tips are 4130 frames bolted to the tip rib. I think they were such a success, he could not do without. Put the test part on just one tip and flew the pattern and it was a crazy improvement that he flew cross controlled the whole way. Put them on his race plane. He added them to his Buttercup in the mid 90s. He never built a W10 for himself. It was designed as an improvement for three friends, one of which was Clement. Most today build them the Clement integrated way extending the spar and making ribs and ply covering. There have been some that keep the bottom surface flat to the tip. Some the top surface flat. There is one with modified airfoil at the tip that supposedly will reduce the stall into LSA territory. I have seen similar trapezoidal tips on Aztecs.

If you look at RVs, the late tips get the end out from the ailerons more than the ,what I think are prettier, original. Not as far as it could, because Vans is conservative on looks, but moved in that direction.
 
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