Aileron spades

Although more reminiscent of a lunch tray, they’re named spades because of their shovel-adjacent appearance. Spades are mounted on ailerons with a small metal pylon that bends to position the spade ahead of the aileron’s hinge point.

They’re affectionately referred to by pilots as “power steering” because spades do exactly that—reduce the amount of force a pilot needs to apply to the controls to move the ailerons. When a control surface moves, the spade moves with it, generating a force that acts complementary to the control surface’s motion.

Let’s say we want to roll right, and so we turn our stick or yoke to the right. The right aileron will start deflecting upward, and the spade will deflect with it into the wind. The spade is met with the airflow that creates a force that helps in deflecting the aileron farther.

With the aileron straight, the spade is in line with the airflow and won’t affect the aileron.

Overall, these small forces are significant enough on ailerons to make it much easier to maneuver the controls, especially at higher speeds, which is why spades are such a popular feature on aerobatic aircraft. Large and fast deflections of the ailerons without as much stick force are critical to executing the maneuvers you see at airshows, making the spade an indispensable tool.

That being said, “power steering” can be helpful on a variety of airplanes. Some high-wing aircraft, like the American Champion Citabria, also feature spades to reduce control input required on the ailerons and to provide yet another great opportunity to hit your head on something.

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