Tandem-wing LSA/microlight concept and poll

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Which tandem-wing configuration would interest you the most (pick one in each of four categories).

  • A1 - High wing forward, low wing aft (Flying Flea) OR

    Votes: 18 36.7%
  • A2 - Low wing forward, high wing aft (Quickie);

    Votes: 27 55.1%
  • B1 - Two-axis controls (no rudder pedals like an Ercoupe) OR

    Votes: 9 18.4%
  • B2 - Three-axis controls (with rudder pedals like a Cessna);

    Votes: 35 71.4%
  • C1 - Conventional (taildragger) gear OR

    Votes: 23 46.9%
  • C2 - Tricycle (nosewheel) gear;

    Votes: 21 42.9%
  • D1 - Tractor engine (engine and propeller at front) OR

    Votes: 33 67.3%
  • D2 - Pusher engine (engine and propeller at rear);

    Votes: 13 26.5%

  • Total voters
    49

Sockmonkey

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i think that one needs red stars and tail gunner. ;-)
Ah, I know the one you mean. The Sh-Tandem. Yeah, it does look like a clone of it, but I was initially working off a Deleanne design.
Rather than a rear gun I gave it a small cargo area and seating for two passengers.
 

Sockmonkey

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Umm, aren't the wings the wrong way around for Delanne? He was another "slot effect" guy so the front wing should be high and the rear wing low.
Yeah, but I switched them around because it looked better. Still viable.
Now here's some crazy.

Monowheel tandem with reverse dihedral on the rear wing.
I should probably bend the wingtips up a little.
 

mcrae0104

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Socks, you really should have a build thread featuring your menagerie.
 

Bill-Higdon

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Salem, Oregon, USA
Yeah, but I switched them around because it looked better. Still viable.
Now here's some crazy.

Monowheel tandem with reverse dihedral on the rear wing.
I should probably bend the wingtips up a little.
Sockmonkey this one for some reason reminds me a character from some Japanamation I've seen in my dark and distant past
 

Sockmonkey

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Sockmonkey this one for some reason reminds me a character from some Japanamation I've seen in my dark and distant past
I purposely made it a bit anthropomorphic.
You can imagine the character leaping, arms spread, cloak flapping, and feet extended forward for a dramatic landing.

A slight upturn of the wingtips and forward sweep of the gear leg increases this impression.
There is a narrow path for that which is cool, buildable, and functional.
I like to think I navigate that path pretty well.
 

cluttonfred

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I can't think of many successful non-fly-by-wire designs that can get away without any vertical (or at least 45 degrees or so) surfaces for directional stability. Yes, a few flying wings, but the Northrops were marginal without the down-turned tips of the early versions.

I was thinking of something more like the actual Payen designs but with a constant-chord canard and clipped delta wing for simplicity. At low wing loading the delta starts to look more interesting.

1624219226785.png

Certainly doable, though I did have aerodynamic stability reasons for offsetting them.
Usually so I can get away with eliminating the vertical tail.
 
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Tiger Tim

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I like the Flechair, I really do, in fact I like to imagine I have one in my hangar to commute to out-of-town work in or just generally show up in the nick of time in it to save the day like the dashing hero I am...

...but I’m not convinced that aft wing is doing a whole lot more than adding wetted area and drag. If you figure the CG is 15° aft of the main wheels and thus the total centre of lift also in that region, then it looks like the forward wing is doing the lion’s share of the lifting. “Oh, but something-something-delta-leading-edge-vortexes-and-STOL,” you may say. To that I’d like to point out that the Payen’s fore wing carries ailerons only AFAIK so any voodoo magic extra lift on the aft wing would just pitch the nose down.

Looks cool as all heck though.
 

Sockmonkey

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I can't think of many successful non-fly-by-wire designs that can get away without an vertical (or at least 45 degrees or so) surfaces for directional stability. Yes, a few flying wings, but the Northrops were marginal without the down-turned tips of the early versions.

I was thinking of something more like the actual Payen designs but with a constant-chord canard and clipped delta wing for simplicity. At low wing loadings the delta starts to look more interesting.
That's why I gave some of those deltas dihedral or anhedral, so they would work as V-tails in addition to being lifting surfaces like I did with this guy.

Even a flat delta gives some directional stability. The question is if it's enough.
I was placing the wings at different heights to reduce the overall length so it could be compact and sturdy. You can get away with that in a tandem. Just look at how short you can make a Pou.
I like the Flechair, I really do, in fact I like to imagine I have one in my hangar to commute to out-of-town work in or just generally show up in the nick of time in it to save the day like the dashing hero I am...

...but I’m not convinced that aft wing is doing a whole lot more than adding wetted area and drag. If you figure the CG is 15° aft of the main wheels and thus the total centre of lift also in that region, then it looks like the forward wing is doing the lion’s share of the lifting. “Oh, but something-something-delta-leading-edge-vortexes-and-STOL,” you may say. To that I’d like to point out that the Payen’s fore wing carries ailerons only AFAIK so any voodoo magic extra lift on the aft wing would just pitch the nose down.

Looks cool as all heck though.
It's the lift distribution. STOL has nothing to do with it.
The fore wing of a tandem needs a higher area loading than the rear wing for stability and to make the fore wing stall first.
That being the case, it's more efficient for the fore wing to be a higher aspect ratio and carry more of the overall weight than the aft wing.
You want the aft wing to be as stall-proof as possible, and making it a delta with a low load is an effective way to do that.
This also keeps the induced drag of the rear wing low.
You have slightly more skin friction overall, but that's more than made up for by the fact that your main wing doesn't have to be as big because it's being helped by the tail instead of having to fight the additional downforce of a conventional tail.
For these little one-man planes, you fore wing to be carrying all the engine weight, with the weight of the pilot being supported by both wingsets.
 

WonderousMountain

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You can get the tail up a bit for better landings if you tilt rail down 6 degrees.
Give it a little more depth than width that looks nice & build something Erkki!
 
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