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I've seen these (note the parts pointed to by the red arrows in the image) on the landing gear struts of Super Cubs and plenty of other STOL bush planes with large tundra tires. It looks like maybe just an aerodynamic fairing on the gas tube/strut of the landing gear but I'm wondering why on every example I've seen of this, the aerodynamic shapes are angled differently (one is more "up" than the other). What is this if I'm wrong about what it is and most of all why are they always angled differently? Is this to try and help with adverse yaw or something?

You can also see them in this video here (note that they, too, like all I've seen, are angled differently): FlightChops Super Cub

Sweet Super Cub

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  • $\begingroup$ You say they are always angled differently. Is this difference always consistent with the direction of the spiral of the slipstream? In this photo, it is. If the trend is consistent, someone might want to include that observation in an answer. An answer has already noted that they are loose fitting and free to move slightly. $\endgroup$
    – quiet flyer
    Nov 16, 2022 at 12:25

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Those are not specifically STOL hardware, they are bungee covers that happen to have an airfoil shape.

Aircraft like the one in your picture use bungees (also called "shock cords") to absorb the force of landing: As weight is transferred to the gear the bungees are stretched. The installed bungees look like this:
J3 Cub Bungee installation/removal

The bungees are literally just "aviation-grade" bungee cords, and would be quickly deteriorated by weather if left exposed, so they are usually covered. The most basic covering is a leather or plastic boot:
"Bungee boots"

The boots are not much more aerodynamic than the exposed bungees however, so some aircraft (including many with STOL kits) have a cover with an aerodynamically favorable shape to reduce the drag caused by the bungee bulge. That style of cover is what's shown in your picture.
Here's a closer look:
Airfoil bungee covers

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    $\begingroup$ Any idea why each of the aerodynamic covers are ALWAYS at a different angle from the other? $\endgroup$
    – Pugz
    Sep 26, 2015 at 4:36
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    $\begingroup$ @Pugz they aren't always at a different angle from each other - in fact they should be at the same angle (so the "fat" end of the fairing is aligned with the relative wind in cruise flight - splitting the airflow around the bulge while creating the least amount of drag). They may appear to be at different angles in photographs (particularly those taken at an angle) or be slightly offset on the ground if the gear is uneven though. If I could find a good head-on eye-level shot of an installed pair it would be a better illustration but that's not a popular photographing angle. $\endgroup$
    – voretaq7
    Sep 26, 2015 at 5:13
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    $\begingroup$ The covers are a loose fit over the bungee and strut and are free to rotate a fraction of a turn. $\endgroup$
    – Wirewrap
    Sep 26, 2015 at 6:50
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    $\begingroup$ Those have wing airfoils, so it has to do something with increasing lift. Haven't seen you Pugz in about a month. $\endgroup$
    – Ethan
    Sep 28, 2015 at 2:22
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    $\begingroup$ ;-) It feels so good to be baaaack!!! $\endgroup$
    – Pugz
    Sep 29, 2015 at 19:16

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