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Wing weights

by gaming_addict
Tags: weights, wing
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gaming_addict
#1
Jun25-07, 03:30 AM
P: 59
Can anyone give me some listing or a table for roughly estimating wing weights per structural material used.

I'd like to have an estimate of the weight of the wing only, not the whole aircraft itself

Like for example:

A wing with chord a, span b, thickness c, material d(like aluminum or CFC), rated maximum wing loading of e, and sweep angle of f will have a weight of this...

I'm entering a design competition for X-Plane 8.6 again. This time, I'm pushing for more realism with aircraft empty weights :)
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Danger
#2
Jun26-07, 11:43 PM
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This is the first time that I realized that you aren't a real aeronautical guy; game simulators just don't make it, no matter how good you like to think they are.
For the weight of a wing, you take the volume of all parts, including spars, then add in control surface actuators, hydraulic lines, fuel tanks if applicable, and any other thing that is going to be crammed in there. You have to know the exact design before even beginning to make an estimate. Your best bet would be to take the input of the experts, which in this case would be FredGarvin, Rainman Aero, and RussWatters. They deal with these things professionally; I'm just an interested ex-pilot.
ank_gl
#3
Jun27-07, 12:05 AM
P: 735
Quote Quote by Danger View Post
I'm just an interested ex-pilot.
you are a pilot.
so cooooooool
i also wanted to be a pilot

gaming_addict
#4
Jun27-07, 03:32 AM
P: 59
Wing weights

Quote Quote by Danger View Post
This is the first time that I realized that you aren't a real aeronautical guy; game simulators just don't make it, no matter how good you like to think they are.
For the weight of a wing, you take the volume of all parts, including spars, then add in control surface actuators, hydraulic lines, fuel tanks if applicable, and any other thing that is going to be crammed in there. You have to know the exact design before even beginning to make an estimate. Your best bet would be to take the input of the experts, which in this case would be FredGarvin, Rainman Aero, and RussWatters. They deal with these things professionally; I'm just an interested ex-pilot.
Well, I could tolerate up to 20% error. I believe there must be a way when I read that German aircraft companies back in WW2, that submitted early designs without plans for internal structure, they gave good weight estimates. I believe other than table it's backed by experience.

Actually, the X-Plane simulator I used is good enough for testing designs, especially concept designs. The best aeronautical engineering schools in my country and a few others use it for educational purposes, even for validating design studies(after it has gone thru wind tunnel testing of course!) =)

I also use it to help me design small scale gliders(for real) some of which had unusual wing shapes or mixed sweep and they flew, I always test their stall behavior, spin characteristics and compare it to the simulator model - I guess that's the closest I got to real life aviation.. With you being a pilot, I envy you!
caslav.ilic
#5
Jun27-07, 04:45 AM
P: 87
Well, I could tolerate up to 20% error. I believe there must be a way when I read that German aircraft companies back in WW2, that submitted early designs without plans for internal structure, they gave good weight estimates. I believe other than table it's backed by experience.
There are statistical formulas that can be quite precise, but as statistic goes, providing that your design stays within the general bounds of existing designs. The first such widely available reference that comes to mind is Raymer's "Aircraft Design: A Conceptual Approach". It splits the airplanes into three categories -- general aviation, transport, and fighter -- and gives statistical formulas for many configuration elements of each of these categories. For example, as you need it, in these formulas the wing structural weight depends precisely on thickness, span, aspect ratio, sweep, loading, etc.

However, if the design is an "outlier" (you're designing something "strange"), then the statistical formulas have to be supported by many "fudge-factors", based on designer/company experience and internal data. For example, these formulas beeing assembled during 80's, the book itself says something like "if the wing has considerable amount of composites, multiply weight by 0.80". Or, if you have forward sweep, you'd have to increase the weight compared to the same-sweep backward swept wing, because forward swept wings are unstable to some dynamic loads and will have to be stiffer inside -- the factor? X-29 designers would surely have one in mind :)

--
Chusslove Illich (Часлав Илић)
gaming_addict
#6
Jun27-07, 05:31 AM
P: 59
Wow! Thank you Chusslove! That's exactly what I need. I'm glad, such formulas exist. Will look for the book!

My design shouldn't be an outlier, but I may experiment with mixed sweep. Forward sweep from root to 1/3 of wing then swept back all the way to the tip. In the interest of having the high speed performance of swept wings with lesser torque loads of a swept back wing, thus reducing weight, if I thought of it correctly..


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