Braced mid-wing landing gear

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Wanttaja

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For a little more inspiration, here is some detail on the last Farman Moustique model actually built in any numbers, the single-seat F451 selected as one of the winners of a 1938 Aviation Populaire contest to encourage private flying in the lead-up to the expected conflict that would become WWII.

Specifications (F.451)
...
Gross weight: 285 kg (628 lb)
Reading one of the images, it looks like it says "Poids Total 249 kg."

Ron Wanttaja
 

cluttonfred

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Reading one of the images, it looks like it says "Poids Total 249 kg."

Ron Wanttaja
Different sources, different models...I am not sure which is correct. I wouldn't be copying the actual structure in any case, just looking for inspiration. Note that the F.451 info I just posted is all the single-seat model, not the one and only red and silver F.455 two-seater that hangs in the museum at Le Bourget that was the real inspiration for my two-seat concept.
 

cluttonfred

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A related question on wire-braced wing structures...I noticed that Steve Wittman’s V-Witt and some of his other racers use wire bracing to that main spar only. For a modern Moustique, would it be workable to use a torsionally stiff wing design (diagonal ribs like an Ercoupe or maybe geodetic wings) and wire bracing to the main spar only? That and cantilever tail surfaces would, I think, greatly simplify the build without losing the retro feel.

1C680313-2253-44EA-A076-4AF3D6AB1751.png 95FD4FCD-D54E-4977-A6C0-D9AC0B933A23.jpeg
 

Lois

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Just a thought...

On a Moustique, where the spar-- or carry through-- for the mid-wing is right above the pilot's thighs or so, landing wires could be supported by a central inverted-V pylon and flying wires attached to a fuselage carry through. Like Fly Baby but at the bottom of the cockpit. Then a split axle, bungee-- or other-- shock absorbing, landing gear could attach to the fuse and be totally independent of the wing and its support.
 

Wanttaja

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A related question on wire-braced wing structures...I noticed that Steve Wittman’s V-Witt and some of his other racers use wire bracing to that main spar only. For a modern Moustique, would it be workable to use a torsionally stiff wing design (diagonal ribs like an Ercoupe or maybe geodetic wings) and wire bracing to the main spar only? That and cantilever tail surfaces would, I think, greatly simplify the build without losing the retro feel.
Seems like going to a torsionally stiff wing from a classic ragwing setup would make the design more complex, not less. You'd need something closer to a cantilever design (though not quite as complex, admittedly).

You'd also have to seriously beef up the remaining wire braces. Fly Baby uses four 1/8" cables per wing, two to each spar. Eliminate the pair to the aft spar, and you'll need 3/16" cable instead. Going to be much more difficult to bend the cables for nicopressing, and you'll need the larger AN-135-46 turnbuckles as well. Probably easier to go with swaged fittings, but that'll raise your cost.

The final factor is the ability to adjust the trim of the wing. Easy enough with brace cables to each spar, but with only cables to the main spar, it'll have to be implemented like a cantilever-winged aircraft.
brace.jpg
Ron Wanttaja
 

ragflyer

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+1 on RW. Double braced is simpler and less exacting (because it is more adjustable) than building a torsionally stiff wing. The simplest way to make it single braced and torsionally stiff would be a plywood d nose. All in all though a full fabric double braced wing would be simplest to build and will look the part.

To clarify, from a design perspective d nose and cantilever wings are simple enough to design but in the actual building the double braced are significantly easier.
 

rotax618

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The Flybaby’s design, having the critical flying wires attached to the axle so close to the ground is not an ideal solution, and to my mind should be avoided. When struts are suggested to save weight in high wing design, certain members maintain that cantilever is just as light, this is patently nonsense, but I believe a low wing should be cantilevered to avoid tension struts/wires (ties) being attached to the LG, or slender struts in compression as in the VP.
 

TFF

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Cantilever requires much more complicated designing. If you look at a skywalker. The wood spar is about 6” thick at the root. Lots more going on. A lot harder to build and a lot more expensive. I bet at this size verses utility, it’s heavier.

These are 30 minute planes with an occasional adventure. They are not day and in day out fly for profit quality airplanes. Basic as basic gets. If you are not going anywhere with anything else, it is better than some dream that never gets made.

A Flybaby or a MiniMax is way ahead of some sketchy gyro, powered parachute, or some other dreamed up kite. Perfect, no, but I don’t think the gear has ever been the problem as wooden as they are.

You might not like it, but why be snooty about it.
 

Wanttaja

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The Flybaby’s design, having the critical flying wires attached to the axle so close to the ground is not an ideal solution, and to my mind should be avoided.
While the Fly Baby has had than its share of wing issues (13 out of 51 accidents), the attachment point for the flying wires doesn't seem to be one of them.

Half of the wing failures occurred during aerobatics...which Pete Bowers approved of, but I do not.


Of the remainder...

- In May 1971 (NYC71FNE34), a flying wire turnbuckle failed due to corrosion.
- Also in May '71 (FTW71FPM29) a nicopress fitting pulled through.
- December 1971 (MIA72FKG60), NTSB report says "CABLE EYES SPLICED IMPROPERLY."
- August 1975 (OAK76FVM05) an owner damaged the landing gear in a hard landing...and took off again, fifteen minutes later. On a Fly Baby, the landing gear is a part of the wing support structure. In this case, a bent axle messed up the flying wires and they were slack.
- June 1976 (MIA76FKT81) wing carry-through rotted out.
- May 1990 (MKC90LA116), the wing spar pins were not re-inserted after unfolding the wings.
- June 1991 (CHI91DEP09), another case of wood rot at the spar carry-through. This case also involved aerobatics.
- May 1999 (ATL99LA092), the original builder had modified the plane to use solid tie rods (instead of cables) and these caused vibrations to be channeled into the wing anchors, which eventually fatigued.
- May 2000 (NYC00LA134), the suspected cause is that the flying wires were not evenly tightened.

I summarize the accidents at:


The stock system of attaching the flying and landing wires to the wing isn't ideal, but it seems to be sufficient as long as cables/turnbuckles/thimbles/shackles are used. There is an alternate method of attaching the wing that I'm pushing folks toward. This can be found:


I provide more detail on this in the first PB100 Companion Guide:


Ron Wanttaja
 
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