Why is too much wing width a disadvantage?

[Thomsail1]

I can understand longer wings span for thermaling. Or a thinner chord for sliceing thru the air but a wider aspect wing would catch more thermal or Cause drag? I'm only talking about 25% more width.

[Lomcevak]

Drag. Higher aspect ratio=more efficient, less tip losses, etc.

[sailhigh]

A wider wing doesn't "catch" more thermals, infact a wing doesnt' know if it's in a thermal or not. An aircraft has to be in a parcel of rising air for it to climb. If you keep the wingspan the same and increase it's width (chord) you are reducing the aspect ratio. Low aspect ratio wings are less efficient, don't climb well and have high Lift to Drag ratios.

[11b2c]

In a perfect world, a thin, long, tapering wing would be the most efficient. This is because of wingtip vortices, horizontal tornadoes just beyond the tip of each wing where the low pressure air on top of the wing mixes with the relatively higher pressure air on the bottom of the wing. Less wingtip area or lifting surface near the tip means a smaller vortice. SO if the tip had a symmetrical airfoil and was very tiny, induced drag could be reduced to an absolute minimum. However...

Usually the wider aspect ratios you see on models versus fullsize is a function of the lower "reynolds numbers" our smaller gliders have. A reynolds number, roughly, is a ratio between the size of an object going through the air and the actual size of air molecules. In my understanding it makes more sense to stretch the wing planform width-wise as reynolds numbers get smaller with smaller-sized flying objects.

In my best "I barely graduated from Northern Arizona U." explanation, butterflies are smaller than albatrosses and have very wide wings. Albatrosses are larger than butterflies and have very thin wings. Evolution made it that way for a reason. We R/C glider guys are somewhere in the middle, dealing with the tradeoff as best we can.

Also, in some cases people make wider glider wings to get more thickness proportionally out of a given airfoil for a stronger wing.

Hope this helps.

[Ib Jensen]

The Condor and Buzzard are two extremely good thermal fliers that evolution has equipped with low aspect ratio wings for low speed thermalling. The Albatrosses is optimized for covering ground (water) at relatively high speeds.

Ib

[Ollie]

No system for only span or chord.

You begin by desiding what type of flight characteristics you want the plane to have (L/D vs Vmax vs Vlow, vs W, vs ?, vs ?, ...). Then you try to quantify and prioritize those characteristics. This data then becomes a standard against which you can judge the virtue of the many design decisions to resolve conflicting objectives that are involved. You can start with the characteriatics of the model that the equipment came from. Calculate its performance and deside how you want to modify it for "improvement." The process goes something like this: analyze, modify, reanalyze, judge results and consider new modifications. With sufficient iterations, the process should converge on your objectives.