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This is a good example of the type of ultralight I am trying to build:

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How might the airfoil be constructed in this plane?

My guess was that it's mostly created by the cables that suspend it, but then again, one like this:

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Doesn't have those cables, so how are the wings constructed?

If you could link me to some sort of visual it'd also be much appreciated.

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There are various ways to build a wing like this. Ultimately you need something to shape the rigid form which you then pull fabric over. The cables do not provide the wing shape they provide support for the length of the wing. This goes back to the fairly early days of aircraft design for heavier than air flight,

In 1909,Frenchman Louis Bleriot produced an aircraft with notable design differences. He built a successful mono-wing aircraft. The wings were still supported by wires, but a mast extending above the fuselage enabled the wings to be supported from above, as well as underneath.

Mast/cable wings fell out of popularity as spar supported wings became viable in the early days of heavier than air flight.

As early as 1910, German Hugo Junkers was able to build an aircraft with metal truss construction and metal skin due to the availability of stronger powerplants to thrust the plane forward and into the sky. The use of metal instead of wood for the primary structure eliminated the need for external wing braces and wires

You can use wood like this. Or wood with a foam core. enter image description here

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You can also achieve the same goal with a metal rib assembly.

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If you have the budget carbon fiber is also an option.

There are a few ways to cover the wing frame once its complete but ultimately the fabric must be pulled over the form and, in some capacity, shrunk to make it taught.

Fabric covered wings have lead to some of the most successful airplanes in history. There is quite a bit of info out there on how to work with fabric in relation to aircraft. The FAA has a nice handbook on it here and more info here.

If you intend on building something I would take a look at this site about building a Breezy. It looks like you can even get a full kit for one here.

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  • $\begingroup$ Thanks for the detailed response and I apologize for taking a week to respond. My follow-up question for this would be (since ultralights in the US are defined as being less than 254lbs and seat only 1) is wood a viable option for making a plane this light? I have to create an entire chassis and hold an engine and a propeller so that's why I was worried about the weight of wood getting in the way. The breezy is a two seater, so I can't follow it exactly, but otherwise its design is what I'm going for. Since you didn't say anything about the helium bag option, I assume it's not viable? $\endgroup$
    – TrapAlcubierreDrive
    Commented Feb 19, 2018 at 20:25
  • $\begingroup$ @TrapAlcubierreDrive I dont know much about the helium bag style design so I refrained from commenting. You could always go for a single seat breezy. Balsa wood is not terribly heavy and if weight is a concern, carbon fiber is an option. There are lots of designs and kits out there for this you may want to start off with a kit to get an idea of how these things are built. $\endgroup$
    – Dave
    Commented Feb 19, 2018 at 21:12
  • $\begingroup$ Yep I found a good PDF showing the construction of an ultralight on this page. (link: grabcad.com/library/ultralight-airplane) It's the PDF labeled Fighter. Regarding balsa wood, I've see it used in model airplanes, but for the most part I thought it was pretty weak and so I'm wondering how well it would stand up to being on an ultralight. Is there any variety of it that you might recommend or that is used often in airplanes? I don't have the money for full carbon fiber construction, though I may make the spars out of it, since they don't use as much material as airfoil pieces. $\endgroup$
    – TrapAlcubierreDrive
    Commented Feb 19, 2018 at 23:42

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