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Therapy Project

Those are wing root fittings. He's trying to duplicate strut attach fittings that also hold a compression member.
 
Those are wing root fittings. He's trying to duplicate strut attach fittings that also hold a compression member.
Right. Wag used to have them...I saw them in an old catalog. They quit stocking them, probably because they were hard to make. I ran across some references about cracks showing up in the bend-- -- the radius was just too small for 4130.

I spent most of the day fabricating a stout pattern from some scrap railroad rail. I ran out of steam drilling bolt holes, plus I had to tend to a flat on my pickup. But I think I'm on course.

Sent from my SM-J320V using SuperCub.Org mobile app
 
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RV

I MIGHT have a set that came with an old Wag 2+2 kit project I bought years ago. I'll check............. Might save you a little grief.
 
also a clue when bending short sides like that, is to cut over size, bend, then trim to size.... i use that quite allot.... also for when rolling things like cowl doors.... form, then cut to final size..
 
RV

I think I may have located them.............. in a neighbor's hangar...……. We did some "swapping" years ago. Should find in a day or two. All brace wires and compression struts should be with them if interested. They are the WAG version of the J3 wood spar parts. I'm sure they will need bead blasting and priming/painting.
 
RV

I think I may have located them.............. in a neighbor's hangar...……. We did some "swapping" years ago. Should find in a day or two. All brace wires and compression struts should be with them if interested. They are the WAG version of the J3 wood spar parts. I'm sure they will need bead blasting and priming/painting.

Yes, I'd be interested in the whole lot. PM me when you uncover them.

Thanks!

Vic
 
Laying out ribs

Just to show that I'm still doing things, a photo of the beginnings of a wing.


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I wish I could say I've been putting in good time on the project, but out-of-control circumstances in my work have really messed with my free time.

I keep saying, "wait until end of December...." Except now it is "wait until February." In any event, things have to loosen up in a couple months.

The point of the layout is for me to get a 3-D feel for how the flaps and ailerons will be placed. Then I'll trim up the ribs and make the appropriate shapes for trailing edge coves.

Vic
 

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I have just disassembled a set of wood wings. Most parts are now surplus because they won't fit new aluminum wings. Let me know if I can help you with steel parts. Also four 17-gallon fuel tanks with electric senders.
 
That was my first post above. I've been glued to this site for two months, and the good information has been overwhelming. I finished my Super Cub clone in 1986. Wood wings, flaps, four 17-gallon fuel tanks. Overhead structure same as a Super Cub. (Some wing parts came from 1960 SC that was destroyed two weeks after i sold it. O-320 on dynafocal mount. (Thought dynafocal rings were too expensive, so I pressed out my own parts and scratch-built the mount.) Plane was caught outside at the farm in the massive snow year of 95-96. Wound up chroming the cylinders and regrinding the cam shaft and lifters. Plane has sat in a heated hangar for over ten years, so I decided last winter to get it going again (TT 250 hours). Couldn't stop disassembling it as I found a long list of deficiencies. (My other aircraft: Travel Air 6000, Bucker Jungmann, and homebuilt Bucker Jungmeister.)
 
That was my first post above. I've been glued to this site for two months, and the good information has been overwhelming. I finished my Super Cub clone in 1986. Wood wings, flaps, four 17-gallon fuel tanks. Overhead structure same as a Super Cub. (Some wing parts came from 1960 SC that was destroyed two weeks after i sold it. O-320 on dynafocal mount. (Thought dynafocal rings were too expensive, so I pressed out my own parts and scratch-built the mount.) Plane was caught outside at the farm in the massive snow year of 95-96. Wound up chroming the cylinders and regrinding the cam shaft and lifters. Plane has sat in a heated hangar for over ten years, so I decided last winter to get it going again (TT 250 hours). Couldn't stop disassembling it as I found a long list of deficiencies. (My other aircraft: Travel Air 6000, Bucker Jungmann, and homebuilt Bucker Jungmeister.)

Glad to see you on board. I'm not far from Kalispell and should get out of my little world and over there sometime. Thanks for the info.

Vic
 
Glad to see you on board. I'm not far from Kalispell and should get out of my little world and over there sometime. Thanks for the info.

Vic

Likewise, welcome to sc.org, Hank! Looking forward to seeing your “fleet” at a fly in next summer!

MTV
 
Still plodding along….

Lately I've been mocking up flap ideas. I've decided to not go with the double-fixed-position-slot I was playing with (and discussed on this thread: https://www.supercub.org/forum/show...-and-Big-wheels-any-suggestions-on-kits/page4 )

I've decided to stick to a simple slotted flap design. I was getting bogged down in stress calculations and permutations--and I was sort of getting scared of going too far astray.

So, given that I don't want to take the time to learn CAD and model things the modern way, I rigged up a 3d mockup to look at things.


I was moderately please with myself, noting the gap to fall within the .01-.02 chord length I see stated in various tomes, but then I looked at that thread above an saw Pete (skywagon8a) mentioning how the slot isn't really needed until higher deflections of the flap deployment. It sounds right to me. I'm thinking I have the gap opening too early in the video.

The plan at this point is to go with longer than stock flaps (84 inches vs 63 inches or thereabouts), and increase the chord to 15.5 inches from the 13.25 inches. I chickened out on doing anything too radical because I'm working with a wooden wing and I'm not quite accomplished enough to push the envelope very far. I'm pretty sure I'll never enter a serious STOL contest anyway.

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I wonder if there's any advantage or downside to forming a flap like a small wing with an upper (and/or maybe lower) upward camber? There are constraints at the rear wing cove that determine the frontal shape, but after that to the trailing edge would more of a wing shape be good? Or at least maintain the wings upper camber to the training edge. Another consideration might be to extend the cove shape and incorporate the Piper add-on fairing into the main wing like Maule and Cessna did. This probably has already been tried and decided.

Another tome: http://naca.central.cranfield.ac.uk/reports/arc/rm/3681.pdf

Gary
 
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more of a wing shape
Near the trailing edge the top and bottom contours of the wing are very nearly linear. So there's really no shape to play with there. If I'm understanding you correctly - - -
 
Yes Gordon there's probably not much to play with and I suspect the final shape is often dictated by ease of fabrication. But look at a Cessna flap (similar to the classic 2-h in A&V-D; p. 212) and unlike Piper the forward shape is more of an airfoil and the wing trailing edge more of a shaped cove that extends rearward to both accommodate the seal in cruise and then the upper energizing flow when extended. Still....an under camber somewhat paralleling the upper might be an interesting experiment. Might act similar to Gurney flaps by redirecting the trailing edge flow down more than a normal flat flap bottom (but at the expense of added drag in cruise).

Gary
 
Personally I would model the flaps shape following what Cessna has done as Vic is leaning to. Their sliding pivots are nice but in Vic's view not easily achieved in his build such that a simple pivot is the way to go. Heck even I am utilizing simple pivots in my considerably more complex build.

The 15.5 cord is right in line with the general feeling that .25c is right for the flaps. This is conservative and safe engineering.

I myself would not utilize a Gurney lip but would prefer a blunt trailing edge should the effect the lip offers be desired. The blunt trailing edge would just be cropping off the the aft end leaving something like a ¼" or less flat end with sharp edges. This does not have the drag the lip has.

But that said another personal opinion, I would stay close to the original airfoil unless you are ready for the can of worms that altering the TE can lead into.

I would spend time working with "paper dolls", as in cut out the parts in cardboard and pivot them on a push pin. This work all done on a table allows to very fast alterations with quick measurements. This allows fast visualizing of the changes.
I would not go to wood mockups till it really feels right.

My wife marvels at how much I scrounge thin cardboard like what shirts used to get folded over and what pizza boxes were once made from. Rosin paper works well too.
Yah the CAD program lets you see allot but I also model in cardboard as well as cut out my "dolls" in Masonite on a Gerber router. These parts are impressively accurate but do "move" with humidity.
 
Food for thought.
No flaps:
https://www.youtube.com/watch?v=E19812NHEmE
https://www.youtube.com/watch?v=6UlsArvbTeo
With hinged flap: Slotted flap starts at 7.38
Notice what happens to the flow along the bottom of the wing as it moves up through the slot. At 8.04 notice the dead air space directly behind the wing in the slot. That is created by the shape of the curve transition from the bottom of the airfoil up into the slot. The radius of the curve in this video is too tight as is yours. It is actually creating a small aerodynamic dam reducing the smooth flow up through the slot opening. The whole idea is to have high velocity smooth flow through the slot opening. This high velocity maintains flow attachment on the top surface of the flap through higher deflection angles. There are some good views of leading edge slat flow at the end of this video. The principles are the same.

Look at the bottom of a Cessna wing. Notice the shape of the surface as it transitions up into the slot. Years ago there was an STC kit which closed this opening when the flaps were up with the claim of higher cruise speeds. Cessna marketing wanted some speed changes for the new model year on the 206. So they closed the gap. This decreased the cruise drag by the amount that allowed the airspeed needle to move from one side of the marking line on the indicator to the other. It also increased the stall speed by the same amount. The test pilot who did these tests told me of this. Your Cub will not be anywhere near the speed of a 206 where the drag component has more effect.

Vic, change the shape of the bottom corner of your wing rib to a much larger radius. Eliminate that dead air pocket when the flaps are down.
 
Here's some examples of a flap on the Arctic Tern or earlier Interstate. Note the cove and hinge forming an extension and gap. This is very close to the flap 2-h design on a 23012 airfoil in A&V-D I noted above.

Gary
 

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Here's some examples of a flap on the Arctic Tern or earlier Interstate.

Gary

I had forgotten they had a good flap system. Vic I consider what Gary is showing here a great guideline for you to study. The brackets and cove shape are pretty darn easy to fabricate.
The brackets could be steel or aluminum.
 
Here's a screen grab of the Cessna flap and cove cross section. Note the upper overlap lip extending aft over the flap and the design to the forward curved intake to the cove.

Gary
 

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