Why You Need Front Weight on "Flying Wing" Gliders, and What to Use
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New: If a video would be helpful for figuring out front weight, then skip through this video until 6:32 (or 6:10 if you are unsure about folding angles too).

I do not include weights when I send boxes of foam sheets because the sheets can be made into various gliders, requiring diffenent weights. But don't worry. You can easily make your own weights at no cost or almost no cost.
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Why you need front weight.

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Mosquito, Jagwing and other "flying-wing" type air-surf gliders--that are all wing and no tail--are the best to fly as walkalong gliders. Since they do not have a tail, they need weight in the front and flaps in the back for stable flight. Here’s how it works: If you drop the glider without any weight in the front, it just stalls and waffles, out of control.
If we add a front weight, the glider moves forward. But then the front weight also makes the front dip down and dive to the ground--not good. So we bend flaps (elevons) in the back of the glider, up at an angle of about 45 degrees. Then, when the glider starts to dive toward the ground, the air flowing over the glider (called relative or apparent wind) is diverted up by the back flaps. As per Newton’s 3rd law of motion (action and reaction), when air is forced up by the back flaps, the reaction is that the back of the glider is forced down, which is the opposite of a dive. When you get it adjusted correctly, the front weight and back flaps balance out each other perfectly. The weight prevents stalling and the flaps prevent diving. The result is efficient, stable, elegant gliding!

What to use for front weight: paper, aluminum foil, copper strands

I usually send sample ready-to-fly gliders along with packages of foam sheet, and these have very thin copper wires for weight, for several reasons. The wires are recycled from electrical cords (see below), but that can be a lot of work if you have many. Consider these other options:

You can use paper, and it is everywhere...

The patterns for Mosquito, Mama Bug and Jagwing gliders include patterns for paper weights for the front. The fact that paper works well for weight goes to show how heavy it is--about 8 times heavier than the same surface of foam.

Front weights of paper are easy, but beware of two things: First, in humid weather paper can become limp, so it does not hold its shape. If that happens, aluminum (below) is a good alternative unaffected by humidity. Second, a strip of paper can interact with air in a bad way (drag). If it hangs below the glider, it can cause diving. But in the picture to the left, you can see two ways manage the problem. Bending the strip in the middle seems to alleviate the problem (left glider). Even better, crushing and rolling the paper so it presents a thin profile to the air (glider on right) cuts through the air better.

Although paper is already on the pattern, if you bring aluminum foil it is even better. We think of aluminum as a lightweight metal--and it is compared to other metals--but it is still over twice as dense as water.

A strip of aluminum foil about 13 mm (1/2") wide, then crushed and rolled into a sort of wire, is an excellent front weight. Aluminum is not affected by humidity, it's more rigid than paper, is fun to form and holds its shape. I think it makes the best all around weight.

Tiny copper strands have two advantages: they are recycled; and when pushed against the foam wings, they do not hurt the foam. But they can be a lot of work if you are making lots of gliders.


As you can see in the middle there are lots of thin copper wires inside the insulation of electrical cords, and they are usually thrown away when an appliance breaks. But you can recycle them into good front weights if you have patience. There are lots of different kinds of wire strippers, from simple and inexpensive to complex and expensive. If you strip the wires when the insulation is warm, then it will be easier and not as likely to break wires. I even put the wires in hot water. You will find that some electrical cords are easier to strip than others. Electrical cords that carry lots of amperage use thicker strands.

For North American foam Mosquito gliders, I use copper wires that are 16.5cm (6.5") long, bent into a V shape so it's really like having two. You can use a single wire half as long for Asian foam because the foam Asian foam is lighter and needs less weight.

The easiest way to adjust front weight

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Getting “flying wing” gliders adjusted will become intuitive and easy, but it can be confusing at first. I suggest starting by:
1.) Bend the back flaps (elevons) to about 45 degrees up, then…
2.) Add weight to the front until the glider does not stall in test flights. But it the glider dives, you might have too much weight. Then, when you are close...
3.) If the weight is long and thin, you can micro-adjust by bending it more forward if it stalls, or more back if it is diving. This shifts the "center of gravity" or balancing point of the glider. Bending forward is just like adding more weight. Bending backward is just like cutting off weight.

 

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