My Flycycle - barely more than a sketch

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Tiger Tim

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While thinking on how to work my way through tail volume coefficient last night I gave my preliminary wing design a bit of a work-through. The taper is gone to help keep root chord reasonable and while I had originally gone with a 5 foot MAC in the redesign I bumped it to 5.5 feet so the leading and trailing edge tubes can be no longer than 12 feet while still reaching my target wing area. There’s a lot to go on the wing yet, and a couple things materializing that I don’t like, but area, MAC and span were needed for tail calculations so this will be a good enough place holder for now.
D7096698-D467-4BF7-97C6-C8C0614B4F82.jpeg

Here’s my tail surface area calculations using the method in Stan Hall’s article linked above and copying the tail volume coefficient of a J-3:
0AA3B2B8-8E42-42AB-90D5-CA1101648F2B.jpeg

The vertical tail area is down to 7.3 square feet from the 16.7(!) I got from the other method. This new number ‘feels’ much more correct.

Curiously the horizontal tail area has actually gone up using Hall’s method, from 23.2 to 26.2. Both of those still seem way too high but again I’m copying the volume coefficient of a J-3 which has a wider CG range than I think I’ll need. When I get home I’ll consult my Baby Ace D drawings to determine its horizontal tail volume coefficient, which is perfectly acceptable and I’m assuming to be smaller than a J-3s. We’ll see how that goes.
 

Tiger Tim

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I might suggest calculating minimum thrust needed for a safe rate of climb in warmish, humid conditions, at 150% of gross weight, and wing loading.
Oh for sure. This thing will be designed to be more than sufficient in all respects, and if we’re being honest will probably never be built anyways.
 

TFF

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That’s a pretty wide wing when it comes to covering with cheaper non certified fabrics. Just a thought. I would “fake” the taper with the ailerons for style.
 

Tiger Tim

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That’s a pretty wide wing when it comes to covering with cheaper non certified fabrics.
That’s a good point. I’ve been so hung up on reasonable tube sizes I didn’t even think about available fabric.
 

Tiger Tim

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I know I said I’d keep going but I think I’m going to wrap the thread up here. Some spar tube sizing issues became apparent and looking ahead a bit I didn’t really like where things were going to go with regards to bracing the wing.

I’m okay with this, it was only ever going to be an academic exercise and I learned plenty. Next time I want to sketch up something with an enclosed fuselage, perhaps a little biplane or a modern re-think of something from the old Flying and Glider Manuals. Wouldn’t a tube and gusset Gere Sport or Heath Parasol be neat?
 

cluttonfred

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Thanks for sharing your thought process nonetheless. On those old F&GMs, I’ve long thought that an updated aluminum tube and gusset Alco Sportplane would be great fun. Maybe an industrial V-twin with an Ace redrive for the size of the original or scaled up a little for 1+1 motorcycle-style tandem seating with a basic VW….

F1715BBE-6053-4A1B-BDB7-69B65EB034D6.png35BBFCBA-1F92-43D8-9B72-C5ED5A70236C.png4A3AAB6F-6B70-4113-815F-36B780E5EEE8.png

Wouldn’t a tube and gusset Gere Sport or Heath Parasol be neat?
 
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cluttonfred

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I agree that cockpit access is a bit of a stumper. The photos in the EAA reprint show the right side “door” completely blocked by a diagonal fuselage member and the left side by a horizontal one. I suspect the left side was worked into a door of some kind but it’s not at all clear.

F4CC3E63-A754-45D8-83AA-EF1C1A4153D6.jpeg D6F93C3C-DE8D-4170-981D-A8E2A7EFF570.jpeg

The unbraced forward vertical supports to the wing make me a little nervous though they are probably fine. You’d have to do a new stress analysis to do the design in aluminum tubes anyway. I’d probably take the opportunity to simplify that area by carrying to top longerons toward under the wing. Then those door bays could have single diagonal struts top to bottom leaving a triangular door or corner braces for a roughly rectangular door.

The keys to the Alco look are the straight wing without dihedral, the top longerons straight back from wing to tail, and the straight axle gear with wire wheels. Given the likely lousy view from the back seat with motorcycle seating, I’d now say make it a single-seater or fatten the fuselage to make a side-by-side two-seater.


The ALCO is neat but I can’t for the life of me figure out how you get into it.
 

Topaz

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The ALCO is neat but I can’t for the life of me figure out how you get into it.
From the lighting in the cockpit area, it looks very much like there's an open bay in the wing over the cockpit. No "roof", as it were. So you probably get in from the top. Not practical, but better than trying to crawl in through the side windows. ;)
 

Tiger Tim

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I was thinking about this thread again today and looking back on how much I learned in just a couple days of crunching numbers. Perhaps my biggest take-away was just how clever some of the existing popular UL aircraft really are.

Staying on the subject of a single tube semi-scale plane, how about a shrunken-down version of the Boeing YL-15; a UL-15 if you will…


It could have a lot of the features other people think they want like a skinny fuselage, STOL performance, folding wings, and probably the provision for some weirdo to hang a second engine for a push-pull arrangement.
 

Sockmonkey

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I like the construction technique of that one, but the configuration seems like it's trying to make unneeded allowances for something.
 

Bill-Higdon

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From the lighting in the cockpit area, it looks very much like there's an open bay in the wing over the cockpit. No "roof", as it were. So you probably get in from the top. Not practical, but better than trying to crawl in through the side windows. ;)
That was my thought also
 

Riggerrob

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To the rear for the guy in the back seat yeah, but that's only useful if you're trying to do a specific job like aerial surveying or something.
They were originally designed for spotting and correcting artillery fire.
Another motivation was the desire to fold it small enough to fit on a typical 2.5 ton Army truck.
 

Riggerrob

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Historian here.
The original Piper Skycycle cockpit was built inside a center drop tank from an F4U Corsair. Surplus drop tanks were a diem a dozen at the end of WW2.
Piper - and the next dozen manufacturers - were overly optimistic about the market for light, civilian airplanes in the after-math of WW2.

Lockheed built and test-flew the similar Little Dipper. A few years back, an American built and flew a full-scale replica of a Lockheed Little Dipper starting with little more than a few photographs. He had to re-calculate all the skin thicknesses, etc. to ensure that it was strong enough.

Finally, look up the Carlson SkyCycle which was another replica of the Piper SkyCycle. Carlson used a molded fiberglass fairing around his cockpit. Demand was low, so Carlson donated his only prototype to the Piper Museum and later sold his entire Sparrow and Cricket line of ultra-lights to Team Mini Max.
 
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challenger_II

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Considering the YO-15 was designed for aerial observation, I would think the rear seat visibility would be obvious?
The Alaska Fish and Game Service used the YO-15's for spotting, also.


To the rear for the guy in the back seat yeah, but that's only useful if you're trying to do a specific job like aerial surveying or something.
 

Lucky Dog

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Here's a simple concept I was working on a few years back, based upon a cantilevered sheet-metal wing. The weight of the engine dictates that the pilot's position overlap the engine compartment a bit (similar to Minimax and Aeronca C3). I worked out a simple fairing for it that looks pretty good. I still want to build it, but I would feel better about the design if I could incorporate a lightweight, yet effective roll bar. High wing designs are safer, but the view is so boring.
 

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Sockmonkey

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Considering the YO-15 was designed for aerial observation, I would think the rear seat visibility would be obvious?
The Alaska Fish and Game Service used the YO-15's for spotting, also.
Sure, I'm not questioning the design being used for the thing it was made for.
I'm saying you wouldn't need to bother copying that form for a single seat LSA homebuilt.
 

Tiger Tim

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Sure, I'm not questioning the design being used for the thing it was made for.
I'm saying you wouldn't need to bother copying that form for a single seat LSA homebuilt.
We don’t need to bother doing a lot of stuff.

In this particular case, the scale YL-15 could be a structurally efficient way to lay out the pieces of a pod and boom light plane. It would be similar in a lot of ways to a Kolb Ultrastar, except the engine is on the front.
 
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