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Wing Tip Shape Summary

In regards to the poor fit of the Wag tip, you would think after selling the same wing tip for 36 years they would have fixed their mold. Its the kind of quality you come to expect from them. Those tips are pricey for something that "almost fits".
 
One would think so. Flew the cub, disappointed in the handling, may not be just the tips the cub has no roll stability it did not have much before with the droop tips but better than what it has now. I suspect that the fact that I have no dihedral is the major problem. When one stretches the string from tip to tip and it lays flat, that's not good.§
 
Question, using the Dakota tips on stock PA 18 wing, however building as an experimental, can you cut the wing and shorten it to the aileron, or is it best to replace the tip rips with full length ribs and extend the wing? Then if you do extend the wing, and want to extend the aileron, how do you extend the stock aileron, or do you have to build new ones? The tips I bought used with no instructions, just the fiberglass tip and full size solid wood rib that the tip screws to. The tips are light, but the solid wood end rib is very heavy. Any help would be appreciated. Thanks
 
The Dakota Cub wing tips are designed to attach to a full rib. You can buy a metal rib to attach them to if you prefer. I might not be following all of your questions full, but I do remember how the tip is designed to be attached and hopefully that helps.

DCA does have instructions for the wing tip installation. I don't see them listed on the website currently (they might be getting updated) but if you give them a call they can email you the instructions.
 
Hi. I am bumping this thread to see if any new thought juices have flowed on the topic since 2014.

Also, I will post photos in a couple days of a Cub tip shape I had never seen before. It is purported to be a John W. Thorp installation associated possibly with STC SA2490WE, of which I can find no record.

It looks like an original Cub tip bow at the front that transforms to a squared tip at the trailing edge. Aileron span appears to be stock.

Anyone seen this before? Thanks for any replies. This happens to be on a -14 refurbed in Fairbanks in 2004.

Also, can someone find Jerry Burrs discussion and thread of wing tip shapes and link it here? I and the “search” function seem to speak different languages, but I will give it a try. d
 
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Wasn't this PA-14 recently for sale with the note the tips had to be removed for some reason? It used to be at Bradley's I believe and I recall seeing it. The idea of the tip design was the length of the wing's rear determined the best lift, something like the Britten-Norman Islander's tips but not upturned just flat.

Gary
 

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Gary, yes, that -14, and tip shape looks like the Islander without upsweep.

No joy with search function. I found a link to Jerry Burrs discussion, but was redirected to sc.org homepage several tries.

Any help is appreciated. Both with the search and also the referenced John Thorp STC

THANKS. d
 
Do the CD 337 records on file describe the tip mod? They used to just say installed blah blah. I also recall reading about that tip design years ago but not sure where. Thorp's design? Have a look at them and the T-18 appears similar.

Where did you get the STC#? If it's no longer active can the issuing FAA office provide something like ICA or prints?

What's the concern now? Rear spar loading or simply no documentation of a benign design? The plane I saw was flying earlier than 2004 - as I recall.

Gary
 
b0be1453a2843509ddceccc54706eb98.jpg


This is a NorthStar home built... The wing tip design is what I think you are describing... I do not know of any STC that would approve this style tip in a Cub series...

Brian


Sent from my iPhone using Tapatalk
 
Gary, the 337 record for this aircraft reads something like “...reference STC SA2490WE. Installed 0-360 etc etc and modified wing tips in accordance with John w Thorp installation instructions dated etc etc...”

no field approval in that block. IA approved

I cannot find anything, and havent checked with fsdo yet. Figurd I would rely on sc.org local knowledge as an easy first step

Brian, it is similar to Northstar, but seems Piper bow at front and at greatest point of span runs straight back. Northstar appears to “sweep” for the whole curve
 
Dave Calkins said:
Gary, the 337 record for this aircraft reads something like “...reference STC SA2490WE. Installed 0-360 etc etc and modified wing tips in accordance with John w Thorp installation instructions dated etc etc...”

no field approval in that block. IA approved
Click to expand...

Well that's how things used to be done in my experience as an owner non-A&P who kept the paperwork. Someone now must have taken an issue with the alteration. Who did the 337 and in what year? - no need for exact name here - maybe airport or town/State location? Sometimes those signing the form or the owner at that time are still available for a short talk or may have paperwork filed away. I wonder if the STC's issuing FAA regional office can be asked like I mentioned earlier? If you can confirm compliance with the installation instructions that might help.

Gary
 
I am not a full time mechanic, and yet I see IA approved major alterations all the time. I corrected four this year alone. A lot of IAs think they can approve stuff by filling out a 337.

One guy even approved a Whirlwind prop on an old Chief!
 
I didn’t see Aviat Husky upsweep tips. Also the J-3 Float tips that are square plywood on the tip. Here is a pic of my Husky.B66DBA3B-A39D-46A5-AA1C-3F67135D979E.jpg
 

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2CD5367C-2E72-423D-95A4-3C46AF84AC1E.jpgBetter pic
 

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thanks for your replies guys.

Seattle ACO called me this morning and are doing what they can to make sense of that STC SA2480WE. MAYBE ITS A TYPO
 
a couple of photos
 

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Gary. thats my thought. They look great!

the assembled plane is not mine
the wings on the trailer are.

The workmanship is beautiful and if I can document them I will fly em.

I will attempt to contact the other plane’s owner to see about documentation. My documentation seems bogus or has a typographical error on the 337. Seattle ACO is also on task and communicative, which is heartening!
 
Dave those look very nice. Hopefully you can get the paper squared away. One of our fellow members is fixing up a J-3 on floats which is needing wing tip repair. This looks like it would be a nice improvement for him if possible. Are the spars still tapered as the original?
 
So there's a couple of examples at least one of which has successfully flown and proven the concept. Was there a one-time or multi approval? You noted an STC (Thorp?) which has since been withdrawn. Maybe the ACO can support the alteration. Is there adequate inspection access to document the components - if so are they the same for both sets?

As I mentioned I'd seen a plane with them here (Fairbanks-North Pole) years ago. That one flying used to be in McGrath and Cordova from the number.

Can't be structurally that much different than the common extensions that are supported and proven.

Gary
 
Guys....Cheers and Thanks to the Seattle Aircraft Certification Office.

This was a field approved alteration and I know the mechanic and the ASI that signed the approval. Many other Anchorage area folks will know them as well.

Seattle ACO provided this info and I have a clear direction for properly documenting the alteration.

I will move forward with Anchorage FSDO on this and report back as to performance of this style tip.

Pete.....the front spar and leading edge are as original Piper round tips. The new tip bow is aluminum tube. The rear spar has a spliced extension. The trailing edge is folded aluminum.
 
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Was the overall span increased beyond the stock wing or just the trailing edge? Was/is there an STC (STC SA2490WE) or was that just a reference to a particular "style" of tip?

Gary
 
Gary. the span really doesnt appear to be increased. I have not measured, but it is very close to stock-appearing in span.

STC SA2490WE does not come up.

In the records the verbiage......”...reference STC SA2480WE, Installation of Lycoming O-360...........blah blah blah......and modified wingtips in accordance with John W Thorp Installation Instructions.....”

so, It is a laundry list 337 with less than proper documentation. The IA before I owned this wasn’t buying it......so I got lucky to acquire this bird.
 
There is one flat-bottomed ultralight wing that will almost hang with the undercambered Quicksilver types: Kolb. Homer Kolb put a lot of effort into testing tips, and he wound up with something like this, except the tip bow stays down in the bottom surface plane. Lightest way to put the span where it counts. Simple radius up front and a straight run back.
 
The Kolb ultralight designs are enduring and seem to hold their value

I had always thought they would be super neat if I lived in warm climate
 
Dave Calkins said:
….Cheers and Thanks to the Seattle Aircraft Certification Office.
This was a field approved alteration and I know the mechanic and the ASI that signed the approval. Many other Anchorage area folks will know them as well.
Seattle ACO provided this info and I have a clear direction for properly documenting the alteration. …...
Click to expand...

I'm glad you had a good interaction with the SEA ACO.
We've had less than stellar results from our man at the SEA FSDO.
Are they really so busy that a simple field approval has to take 10 months?
(so far, that is-- it's getting closer but not approved yet!)
 
Skywalker said:
There is one flat-bottomed ultralight wing that will almost hang with the undercambered Quicksilver types: Kolb. Homer Kolb put a lot of effort into testing tips, and he wound up with something like this, except the tip bow stays down in the bottom surface plane. Lightest way to put the span where it counts. Simple radius up front and a straight run back.
Click to expand...

One story that made the rounds back in the ultralight days, was the 7:5016 airfoil on the Quick. Called that as it was derived from bending the 1/2" tubing using a pickup truck tire that size. NOT a knock, it worked!
 
I did my pa-12 a couple of years ago..., it had Madras tips that I removed (still have 'em). I used Ron's Night and Day STC to install long flaps and move the ailerons out. I bought a set of Super Cub ailerons with flap hangars from Dakota. There is no gap between the aileron tip and wing tip. The tips I got from Ron are Carbon Fiber and very light. It all came together real well.
 
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