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Photo Record of Extended Wing Build

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Posted

In case someone is interested in building a set of extended wings for an Avid (or KF)  This is the photo record of what I did.  These wings built to the Avid Magnum dimensions by extending a set of Avid HH wing spars by 16.5" and the flaperons by 18".  The spar inserts are strengthened by laminating the stock 18" microlam plywood insert to a 36" mirolam plywood section and also adding top and bottom 1/8" x 3/4" aluminum flanges epoxied and riveted together.  The aluminum drag tubes in the inner two bays beyond the tanks have been replaced with 4130 chrome molly drag tubes.  The lift struts have been extended and doubled in the center sections with 4 foot  1" X .058 4130.  The front to rear tube lengths have been adjusted to reduce the overall washout to 7/8" and the wings built to this washout.  The lift strut brackets have been moved out one bay and additional rivets have been added per the magnum build manual.  The flaperon hanger rib tails have been reinforced with laminated and riveted aluminum sideplates.  They have aluminum skins in the top from the leading edge back 18" and have the Kitfox cuff and VG's at 1.5" back from the leading edge and 36" x 6" tip fences. The wing tips have been semi squared to support tip fences and the trailing edges moved back an additional  1/2".  The wings are covered with Oratex fabric. 

I use this plane for hunting so I haul pretty heavy loads in it.  This additional strengthening adds weight and might be more that needed by many folks, but the added length also adds additional bending stress to the wing and this can be a problem with the flexure binding the flaperon movement.  These wings do not have any problem with that.

Hopefully someone else can find some useful information here.  It is kind of fun to scroll through the pictures and see them take shape.

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Posted

A lot of work but an excellent job!

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Posted

This is awesome Randy! Thanks for taking the time to put up all those pictures. Now that you have flown them for a while are you still really liking them? Is there a penalty in turbulence with the lower wing load? 

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Posted

Hi Kenneth,  Yes, I really like them! The most noticeable difference is that I can keep it just above the big sink rate (stall) with a lot less throttle input, so I can make my landing approaches slower and more stable.  The other biggest change is it gets off much faster when loaded heavy.  These seem normal now but the differences stand out when I fly Jack's plane with the standard HH wings.  I can't say that I can tell any difference in turbulence between the wings.

I am seriously thinking about adding slats to these wings now.  Randy Apling (Carbon Concepts) is making them for Cubs up here now.  More to come on that, probably a couple of months out before I can get them since he is busy making skis right now and also has some back orders on the slats.  He is also developing a carbon flap for cubs that has a flexible mid section and uses small electric actuators on each flap to warp the rear half of the flap down or up.  with flaps deployed and fully warped down they are at 75 degrees.  They also relex up to 5 degrees and add about 4 to 5 mph to the cruise speed.  pretty cool stuff!

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Posted

Outstanding build and workmanship Randy!

Is this a standard Magnum fuselage and landing gear?

paul

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Posted

Randy, interestingly enough I sent him a message a few days ago about slats for a Kitfox. He has already been working with Steve Henry on the slats for Just aircraft. Steve supposedly had a reduction in stall speed by 6.5 mph on his Higlander. They are pricey though at $500 per 4 foot section with hangers. For you guys that do a lot of off field work I can imagine that translating to being worth it in the long run to get you into and out of areas easier. 
 

I can’t wait to see what they bring you once you get the, installed. 

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Posted

Hi Paul,

The fuselage is an Airdale Avid Plus.  I had Steve Windner add a third mounting point for the gear to make it stronger and then built my own gear that is 5 1/2" taller than the Airdale wide gear, plus substantially beefed up.  He also opened up the baggage area so I can sleep in it if needed (6' from front seat truss to back of baggage).  It has really been a great plane for my use.

Randy

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Posted

Hi Kenneth,

Yes, he said that he built a set for Steve Henry for YeHaw 7 and Yehaw 6.  As you say, they are not cheap but I don't think they are likely to get any cheaper and it is something that I am really interested in trying.  It looks like I will have to have him make 3 sections for each wing, each at a different length.  I can mount the supports to each rib except at the tanks and will plan to glue those supports on.  This will leave about 12" with no slat between the fuselage and the first slat.  On the cubs they have found that if they leave a gap in this area (about 18" on the Cubs) they have a lot better cruise performance and don't sacrifice much low end performance.  They do slow the cruise down by 4  to 5 mph though. They also found that mounting the bottom front of the slat even with the bottom of the wing give minimal sacrifice to cruise.  Mounting 1" below the bottom of the wing maximizes the low end performance but really kills the cruise speed.

Randy

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Posted

I have patterens for slats that im thinking of makin i got from a buddy, the patteren is from a Stol King. A good friend of mine here built a whole bird from patterens, and he has all the jigs still too boot, said i could also borrow them, ive been giving the Stol King some thought. Guess there is almost 600' of tubing just in the fuse if i remember right. 

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Posted


Hey Buckey, that would be a great project  I might be well worth it to build the slats out of aluminum if you have the patters and it is probably considerably cheaper.

  I will let you know know what I think of these when I get them on and working.  It will probably be around Feb / March when I get them.

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Posted

Hi Kenneth,

Yes, he said that he built a set for Steve Henry for YeHaw 7 and Yehaw 6.  As you say, they are not cheap but I don't think they are likely to get any cheaper and it is something that I am really interested in trying.  It looks like I will have to have him make 3 sections for each wing, each at a different length.  I can mount the supports to each rib except at the tanks and will plan to glue those supports on.  This will leave about 12" with no slat between the fuselage and the first slat.  On the cubs they have found that if they leave a gap in this area (about 18" on the Cubs) they have a lot better cruise performance and don't sacrifice much low end performance.  They do slow the cruise down by 4  to 5 mph though. They also found that mounting the bottom front of the slat even with the bottom of the wing give minimal sacrifice to cruise.  Mounting 1" below the bottom of the wing maximizes the low end performance but really kills the cruise speed.

Randy

That is great information. I do think they would not be too hard to build. 

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Posted

I took a good look at his flyin Stol King slats and man it sure looks nice and easy to build, just have to figure out if the mountin system would work or what mods it would need, easy to do,  there no way i can afford $500 for each piece if it takes 3 to do each wing. But the Carbon Concepts carbonfiber skis sure r NICE!!!!! But i think my next project right now tho is going to b a cargo/belly pod for the KF,  or im leaning towards the wifes 1952 ford panel hotrod. Hahahahahaaaaaa 

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Posted

Wow, usually it is too much resin making fiberglass or carbon weak. Sounds like they weren’t attached well either. 

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Posted

Wow, usually it is too much resin making fiberglass or carbon weak. Sounds like they weren’t attached well either. 

Dry layups are much worse than overly wet ones.  Overly wet ones are just excessively heavy, but not dangerous.  Overly dry, the glass/carbon layers work independently instead of as a unit and are only as strong as the strongest layer, which in compression is basically zero.

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Posted

Wow, usually it is too much resin making fiberglass or carbon weak. Sounds like they weren’t attached well either. 

Dry layups are much worse than overly wet ones.  Overly wet ones are just excessively heavy, but not dangerous.  Overly dry, the glass/carbon layers work independently instead of as a unit and are only as strong as the strongest layer, which in compression is basically zero.

Great description of it. I was aware of both but just shocked to see that it was something laid up that dry. 

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Posted

It may be in a different video but I think it's in  this one, Mike talks about how if you have too much resin and the layers aren't compressed really tightly the resin can start cracking as the structure works/ moves and then the shards of resin start  cutting fibers.

So it's a very fine balance. 

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Posted

There would have to be a LOT of excess resin for that to happen!  The biggest hazard of wet layups is weight.  One of my other (very) long term projects is building a Cozy (Rutan Canard).  Since the entire airplane is moldless layups, even a little excess resin on each layup can add up to a lot of extra weight.  Excessively wet layups mean the part is too heavy, but usable.  Post cure evidence of a dry layup (white spots usually) means you either remake the part if possible, or cut out the dry section and repair it.

 

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Posted

Hey Randy, looking at your wing build I noticed that you made provision for the flat plate on the wing tip but did not see it in the completed pictures.  Are you flying with it now and if so what results are you seeing.  Also I'm curious if you considered other shapes for the wing tip with your build or simply a flat plate on the final rib like I've seen on other planes.  The Avid wing tip seems to offer little beyond the fact that it is pleasing to the eye but maybe I'm missing something.  I'm considering building Hoerner style tips for mine but have not made the final decision although I have ordered some nicrome wire so maybe closer than I think.

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Posted (edited)

Hi Paul,

I am currently flying it with the wingtip fences on as you can see in the pictures below.  I made them so I can put them on and off easily with just screws.  I put a plate in the fiberglass wingtip behind the marker lights screw into in the front and some small aluminum angles riveted to the fences at the support tube that extends from the rear spar to the wing tip and the trailing edge let me attach them with pan head sheet metal screws at those locations.  I cannot say there is any substantial difference that I can tell but it seems like there might be a small improvement at slow speed and no change at cruise.  I have not pulled them off since putting them on over a year ago so I really should do that; sometimes I notice things more when I take them off than when I put them on.

Randy

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Edited by SuberAvid
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Posted

Randy, it looks like you need a tail ski! If you do have one that must be pretty soft snow! Of course I have never been on skis in a plane but that looks like your tail is sure down a ways. Looks like fun to me! 

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Posted

Yep, I have a tailwheel ski but didn't have it on in this picture since it is a 1 1/4" and the T3 suspension is made for a 1 1/2".  I didn't have an adapter built yet.

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