This Instructable showcases a couple of example projects I made to test out if I could take advantage of this unused "Turbo Mode" and operate a gun turret remotely. I built two vehicles - one using a fully automatic battery powered Nerf gun and another using a battery powered squirt gun with an electric pump.
EDIT: I originally titled this "Hack an RC car's unused 5th channel!" but I've since been informed that it's actually just three channels. The forward/backward and left/right controls are just two channels! If you see me refer to a 5th channel, just imagine I said three, okay?
EDIT #2: (5/28/13) I recently made another project and Instructable very similar to this one. I mounted an Airsoft machine gun on the top of an RC car! Here's the link to see a full video tutorial to make it: http://www.instructables.com/id/Airsoft-Gun-on-an-RC-Car-Hack/
- I was helped greatly by this Instructable by techbitar: "Use Arduino with TIP120 transistor to control motors and high power devices"
- I also found some great information from this tutorial: "Using a transistor to control high current loads with an Arduino"