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How to Calculate Wing Size for Plane Weight

#1
Does anybody know of a good method for calculating the wing size (wingspan / area) needed for a planes overall weight. Is there a simple formula that can be used to work this out?
Google'd a few sites but they seem to either contradict each other or explain it in a way even a NASA engineer would have difficulty understanding.

Thanks
 

Hai-Lee

Old and Bold RC PILOT
Mentor
#2
Wing loading is as variable as is plane design. Slow flying aircraft have low wing loading and racing planes have high wing loading and there is a myriad of different wing loading figures in between.

Also there is the Re number to consider. Basically that means that large wings, (large cords), are able to have higher wing loading and can be considered as more efficient.

If you are just starting out in designing your own I would suggest that you find a similar existing design and use the same figures, (weight, wing loading, power required, Etc.), as a starting point and adjust the figures to suit your exact requirements.

Without any figures as to weight, size, and flight envelop required you question is simply too broad to narrow down to a single paragraph.

I am willing to assist but further information would be required to give a set of figures which is what it seems you require.

Surely someone else will give you a range of figures which will work but then you will still need to make decisions for yourself within the range of figures given.

Have fun!
 

Craftydan

Hostage Taker of Quads
Moderator
Mentor
#3
I'd say it depends on the NASA engineer ;)

First off, the descriptions are complicated because it's complicated. Change the airfoil shape, airspeed, wing cord, or angle of attack, and the needed area to stay aloft changes. In flight we commonly change airspeed and angle of attack to rise or sink in the air. On airplanes with flaps, "changing the airfoil" is exactly what flaps are doing to trade drag for a lower stall speed.

Kinda makes it hard to say "I want a plane that can carry X" and get exactly there without hitting some nasty concepts along the way.

But this is like hand grenades and horse shoes -- close enough counts. The easiest way to get close . . . Wing loading. How much weight per area of wing:

Gliders: < 10 oz/sq.ft

Trainers: 10-15 oz/sq.ft

Sport planes: 15-20 oz/sq.ft

Warbirds and heavy scale planes: 20-25 oz/sq.ft


There is a method called cubic-wing-loading that's a bit more accurate in following these trends as the airframe scales up and down(because the air doesn't), but I find that more useful when approaching extremely big (giant scale), extremely small (peanut scale) or comparing performance between two that are close in loading, but different in size -- Raw wing loading estimates are a suitable pace to take a first guess at your weight allowances and wing area.
 
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#8
Thanks guys.

@Craftydan... after looking up cubic-wing-loading I found this... http://www.flyrc.com/wing-load-calculator/

Comparing the results shown by this to models of similar weight / wing size I'm looking to design it seems about right. Although not fully understanding the math ( I can research that more later) its given me some good ball-park figures to play around with.

Looks like I need to be thinking around the 308 sq.in area.

Again, thanks all for the replies :)
 
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