dennisb64

Hi to all,
what angles are in polyhedral wings ?, and where do they begin in the wing span ?; would this mean their are 2 root ribs in this wing design ?.

Bob Laine

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dennisb64......... A Polyhedral wing is a wing that has dihedral in the center of the wing, and then has another upward dihedral somewhere out from the "root rib".

dennisb64

would anyone know what degree of angle these might be of dihedral ? and how far is the secound dihedral location would be on the wing span ?.

Bob Laine

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There is no one degree of setting. I have seen polyhedral wing's that almost made a complete circle. I would think that on a 60-70" wingspan maybe the first 60% would have about 2," and the second 40% maybe 1 1/2 to two inches. Bob

dennisb64

Thanks Bob, I'm understanding that not all model aircraft designs are created equally, they all have their differences. I guess that's what makes this hobby so fun. Thanks for your input.

Dennis

BMatthews

Dennis, are you making a glider?

As you already have seen it's fairly open. More leads to better rudder response but it makes the wing less efficient. Less makes the wing more efficient but less responsive.

Generally the location for the outer panel breaks is chosen with an eye to making the front view of the wing sort of approximate 1/2 of an elliptical shape. This is also why a 5 panel poly setup has become more popular recently. A flat center, mildly angled mid-outer panels and then sharper upturned small tip panels. This keeps the major lift production in the center portion of the wing more efficient while moving the yaw to roll function of the dihedral out to the wingtips where it has more leverage.

Bob Laine

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You are welcome Dennis. I am in to process of building a "Gull Wing" 96" WS Spook. I learned to fly with this design back in the 50's. The "Gull" wing has dihedral for roughly the first 25% at about a 45 degree angle. From that point it only has about a 10 degree angle. The Polyhedral, and Gull,l wing were used almost exclusively for free flight models. The Gull wing adds a somewhat "Pendelum effect to the wing .
To put ailerons on a wing of this type would be almost useless, because of the wings inherent stability. Three channels seems to be OK for them. Rudder, Throttle, and elevator. All these old designs, really have a lot of character. Good luck with whatever your project is. Bob Laine

dennisb64

Yes, I would like to make a glider hand launch, with a simple fuselage design by George Chabot, you add your own wing. This would be rudder and elevator only. For just beginning sailplanes thought this would be good start. And thank you for your input too Bmattews.

SoCal GliderGuider

RES: Rudder, Elevator and Spoilpers:

11 to 15 degrees total one side using a horizontal line as a reference. So you make the inside panel 4 degrees at the fuse and the break between the inner panel and tip 7 degrees for the 11 degrees total. I prefer the 15 degrees for two meters while the 11 degrees seems to work better on larger 3 meter sailplanes. Single piece wing for two meters and three piece wing for three meters.

So the center section on the three meter would have 6 to 8 degrees from one panel to the other.

Most "modern" hand lauched sailplanes use a rather flat wing and with minimal dihedral and flaperons. A peg on one tip for a discus launch. If this is your first forray into sailplanes I would look at a two meter ARF and a hi-start.

marwen1

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Ain't this polyhedral stuff all fun?

I too, am working on something called the AIRHOPPER. A 1941 vintage.

GULLWING configuration.

Lots of enjoyment and mostly self-sastisfaction

My problem is that I get so involved with tis project, other more duties here at home get abandoned.

Oh, let me tell you how my sweetie gets on me for having too much fun! LOL

ENJOY your POLY

marwen