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Wing weight

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NeedHelp12

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Hi,

I was just wondering whether there are some rules for how heavy an airplane wing must be at least and at most relative to the whole airplane weight in order for it to fly?

Thanks in advance
 

wsimpso1

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Rules on how much something must weigh? You mean like regulations? Nope. What good would a min and max weight do for this purpose? In airplanes WEIGHT IS THE ENEMY. We design to carry all loads at something approaching min weight that will do the job.

CFR 14 Part 23 tells us what a certified light plane must have and how strong it must be. In Experimentals, we do not have to follow these rules, but following them is still a really good idea. You can look up the "old" version, it has more guidance.

As to reality, the entire airplane must carry limit loads with suitable factor of safety, including wing structures. This can be met many ways. A variety of design features will drive weight. Airplane weight, wing area, aspect ratio, degree of internal bracing, Vdive required, material set used, and other factors all influence how much weight will result when the wing is designed to carry the loads and stay on the airplane.

A number of authors (Raymer and Thurston come to mind) have tabulated many designs and come up with guidance on expected weights of many systems relative to gross weight, so some rules of thumb do exist, but these are for estimates in initial planning. Once the design work starts, wing design is a particularly prominent one, and suitable effort in design will result in a close to minimum weight structure that will do the job. If someone just has to have a certain wing area, wing loading, aspect ratio, degree of external bracing, and material set, that will drive the weight of the wing.

Billski
 

Mad MAC

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There is a whole book about it (its quite useful and you have somewhere to write / paste all your weight notes)
Airplane Design Part V: Component Weight Estimation

or one of raymers books (there is atleast a chapter in each on the sump
Simplified Aircraft Design for Homebuilders by Daniel P Raymer
Aircraft Design: A Conceptual Approach

There is also the article on weight in the Roncz series of Aircraft design articles in the EAA mag

You can also find that type of information on the NASA tech Sever
https://www.sti.nasa.gov
 

Speedboat100

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I am wondering if I can estimate the wing weight by making 1 metre wide part of the wing ?

Also if I stress this piece with weights...can I estimate the g-loads for the whole wing ?
 

proppastie

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I am wondering if I can estimate the wing weight by making 1 metre wide part of the wing ?

Also if I stress this piece with weights...can I estimate the g-loads for the whole wing ?
Should not need to build it to calculate the weight.
If you can not do that probably you will not be able to estimate g loads for the whole wing.....
 

Rockiedog2

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Spruce and Wicks catalogs both have material weights. Easy to get pretty close with a preliminary design. Just takes a little time.

I know a certain designer who after building his prototype wing panels put one in a fixture and loaded it with bricks to 5Gs. The fixture broke but the wing stood it. Said the wing sagged several inches seems like 5 but I may have that wrong. 12 ft panel.
Put it on the plane and it's still flying.
 
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Speedboat100

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Should not need to build it to calculate the weight.
If you can not do that probably you will not be able to estimate g loads for the whole wing.....
I see...what If I just do it anyway ...to see how well the details work out in smoothness.

If the mid piece of the wing is 1/6 length of the the wing..how do I do the math for the g-load stress test..or does it show anything at all ?
 

Speedboat100

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Spruce and Wicks catalogs both have material weights. Easy to get pretty close with a preliminary design. Just takes a little time.

I know a certain designer who after building his prototype wing panels put one in a fixture and loaded it with bricks to 5Gs. The fixture broke but the wing stood it. Said the wing sagged several inches seems like 5 but I may have that wrong. 12 ft panel.
Put it on the plane and it's still flying.

So do you suggest to build the whole wing panel at the same time..while at it ?
 

Lendo

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Wing Weight is difficult, without experience it difficult to evaluate all the components that go into a wing like control tubing and mechanisms, wiring, sealing fuel cells, fuel, nuts and bolts, Paint, the list goes on and on. I'm always asking people if they know their wing weight, it would be nice if there were a sq./ ft. or sq./m estimate, but sadly I don't know of one. It could be as low as 100 lbs. for a semi-span to 200 lbs.

Jim Marske suggests that the Wing Carries it's own weight, but when pressed, he suggested maybe not the Fuel. Jim deducts the wing weight from the Max TOW, for calculations. However he designs and manufacturers mainly Gliders.

I can give no other suggestion I'm sorry. Let us all know if you find something conclusive.
George
 

wsimpso1

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Weight estimation is calculating the volume of each piece times the density of each piece and adding them up. Yeah it is a bit tedious, but when you have a design, it is straightforward.

The hard part of figuring out how much a wing will weigh is getting the structural design. Making it strong enough while keeping it reasonably light is either an engineering tour-de-force or science+art or a combination of the two.

For airplane configuration, Raymer and Thurston and other authors have a variety of ways to get starting points.

Billski
 

proppastie

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I see...what If I just do it anyway ...to see how well the details work out in smoothness.

If the mid piece of the wing is 1/6 length of the the wing..how do I do the math for the g-load stress test..or does it show anything at all ?
building a panel to learn how is not a bad idea....yes properly done the stress test of a single panel will tell you how strong the whole wing will be..... you would need to learn some basic stress analysis and algebra to do the calculations. .....if you are to copy ALL the details of a successful design and stay under the weight of the airplane you are copying you probably would not need to do any of it....or better yet build a successful design to learn how to build and get useful experience needed to design your own. ....Frati "The Glider" has the most simple method (but not exactly the most accurate, certainly good enough though) to calculate the wing loading. Basic Glider Criteria from the FAA has samples of test loading .....both are free "google is you friend"
 
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