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Another Ultralight-ish High Wing Idea

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RJW

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I like the cantilever design. Would you be willing to share your thoughts about the wing, ribs attach, etc?
Not much to share about the wing right now. I'm not certain yet what it will be made of (metal or composite). If I go with metal it will be pretty standard--sheet spar web with extruded angles and flats to make up the spar caps and metal skin on the leading edge to make the d-tube. The aft part of the wing will be fabric covered. Look up Earthstar airplanes to see a similar wing design.

The airfoil is a modified Riblett 30A618. It has been changed slightly to fit 90-degree extruded angles to the spar at .3c without creating a discontinuity. Also since the mod makes the bottom surface flat from .25c aft it will be easy to build on a flat table.

Rob
 

RJW

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What do folks think of this? I don't really need folding wings but it would be nice to fold it up and stick it in the corner when not flying it. Would make it easy to trailer too. All folded up it's 17.5 feet long and 8 feet wide.

The "swing wing" center section (like the wing on the Backyard Flyer) adds almost no additional complexity and just a few ounces of extra weight. The Flying Flea style folded outboard panels add some complexity but only a little extra weight with the additional hardware located so far out on the wing.

How tight can you bend a teleflex cable? Wondering if it's possible to use these cables for the ailerons so nothing has to be disconnected when the wings are folded.

The prop in the drawing is 68 inches. Just wanted to see if it would fit. Wouldn't be able to use a four-blade prop though.

Also redrew the cockpit. Made it a bit longer with a better seating position. Hopefully this arrangement will make it easier to get in and out of it.

Rob

CL 5.jpg
 
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BJC

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What do folks think of this?
... The "swing wing" center section (like the wing on the Backyard Flyer) adds almost no additional complexity and just a few ounces of extra weight.
That surprises me.


BJC
 

RJW

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That surprises me.
The Backyard Flyer has one additional small bolt about which the wing pivots. The 4 bolts that retain the wing on the Backyard Flyer are inserted vertically and are in tension rather then a more conventional setup where the bolts are in double shear. Very little difference in complexity. Being in tension the retaining bolts and brackets might need to be a bit heavier. Don't know for certain since I haven't analyzed the two arrangements yet.

Rob
 

cluttonfred

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For minimalist ultralights, I am often surprised that we don't see more designs take the Sky Pup approach...a conventional tractor monoplane with two-axis rudder/elevator controls and no ailerons at all. No control runs to worry about at all so all kinds of wing folding techniques become a lot easier. Give it rugged tricycle gear and just land crabbed like an Ercoupe. Fly gently and smoothly and it will coordinate itself.

sky pup farm strip.jpg
 
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RJW

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I really like the Sky Pup. But I live in North-Central Kansas apparently right where all the big weather fronts like to meet up and hang out. The wind never stops blowing pretty much from any direction it feels like. And rarely right down the runway. ;--)

Rob
 

wanttobuild

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Pretty nice, always liked the swing wing. I have 3 designs going at once, and I hand draw them on vellum.
I use the eraser shield and eraser, more than the .5 pencil.
Teleflex cable could be bent pretty tight, I don't have a specific radius in front of me, but I believe it could be made to work for the wing flip app. I do wonder about the wing flip though? you might be able to insert a bent pipe handle when the hinge gets wide enough
 
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cluttonfred

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I have not heard that the Sky Pup is any more limited in terms of crosswind conditions than any other ultralight of similar gross weight and wing and power loading.

What I'd really like to see is an aluminum tube (or angle) and gusset design like the Sky Pup but with two seats, tricycle gear, and a VW engine or similar engine. It doesn't have to be a high wing, either!

low wing sky pup on skis.jpg
 
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RJW

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I do wonder about the wing flip though? you might be able to insert a bent pipe handle when the hinge gets wide enough
Thanks. And you're right. There's a lot of curvature to the top of the wing. I haven't given any serious thought just yet to an actual hinge design. I'll think about it and look at what others have done in the next few days.

It is nice to be able to sketch these ideas on the computer. There is a downside though. In the years since I've had this software I have drawn about 800 objects! Many are simple like this airplane but others very thoroughly worked out with hundreds of parts. It can be a huge time-suck! I probably could have built a half dozen airplanes in the amount of time I've wasted drawing stuff. It is kind of fun though.

Rob
 

wanttobuild

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About 6 years now, I have been reading, and looking at designs. Easy to criticize a design until you start "fixing it" with your pencil!
Until most recently I have been unable to accomplish any real gain, whether that be performance, aero improvements, ease of construction methods, aging materials (a big one, imho).
But I have "gotten religion" now.
Really High Performance Materials will allow a measurable gain, (and there aint no doubt about it).
Ben
 

lr27

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Seems like a low wing with extra dihedral would solve the stick linkage problem without flying much different. Probably requires some attention to a decent roll cage. This configuration could allow the fuselage to be mostly a long stick. It might have better visibility, too.

Seems like your pilot ought to have hearing protection and a helmet.
 

RJW

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To be honest I'm not a big fan of high-wing airplanes. I prefer low-wing ships. But a low-wing airplane would be more complicated than this simple machine. Just building a wing with dihedral adds a bunch of work/parts. The main motivation for me is the simplicity of the concept. Also of importance to me is being able to use up a lot of stuff I already have on hand.

I agree with those who suggest I will not end up with an improvement over similar aircraft. That hasn't been my intention. I'm simply looking to use up some of my airplane junk on a plane that doesn't have a million parts.

I need to make a few small changes to the fuse in the next few days. If all goes well I'll start welding it up after Thanksgiving.

I'll see what I can do about a helmet for the pilot. :--)

Rob
 

RJW

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Tacked up the cockpit floor yesterday. It doesn't look like much but I gotta start somewhere. I'll try to get the top stuck together today. Then I have to jig the top and bottom in 3 dimensions and tack the sides on.

Rob
C Floor.jpg
 

RJW

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I ordered some $20 4.00-6 wheeliebarrow wheels and tires. They should be here in a few days. Thought I'd waste some time drawing them on the model to see how bad they look. They look kind of goofy but I like it. Had to get all three the same size because I'm cheap. They weigh 5 pounds each. Maybe I'll drill them full of holes to save some ounces.

CL8.jpg

Rob
 
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