Yes, this is a missile. Sorry about that. But it turns out the AIM-9 Sidewinder is the only well-documented example I can find, on the web, of a machine that employs these interesting little widgets called “rollerons.” See the little metal pinwheels at the trailing corners of the fins? The rolleron is basically an air-driven gyroscope, as Tom Harris explains over on HowStuffWorks:

[A] spinning wheel resists lateral forces acting on it. In this case, the gyroscopic motion counteracts the missile’s tendency to roll — to rotate about its central axis. The simple, cheap rollerons steady the missile as it zips through the air, which keeps the seeker assembly from spinning at top speed. This makes it a lot easier to track the target…

Cool, neh? And there could certainly be nonlethal applications for all you hobby rocketeers out there. [Thanks, Lewis!]