Some time ago I got one of those awesome little IR controlled helicopters, a Syma S107.
Then, I saw a guy on eBay selling keychain video recorders, similar to this one. Of course, I thought I maybe could mount the guts of the micro video camera under the helicopter, and record my flights.
First, I dis-assembled the video camera. It isn't hard, there are 4 screws, 2 on the outside and 2 on the inside. Then the board pops out of the shell.
I also partly disassembled the helicopter, to get to the power wires.
Next, I cut the original battery leads on the video camera. Both batteries are 3.7V, so the helicopter battery will run the camera.
I soldered the power wires together, red to red and black to black, to form a parallel circuit. I wrapped the joints with a little electrical tape, to make sure there wouldn't be any short circuits.
Then, I put the helicopter back together. I slung the camera pod under the body, slightly forward of center, and used a rubber band to hold it.
One problem I found was that the camera vibrated wildly on its ribbon, and needed support. I glued a short bit of coated wire to the board, bent the end, and glued that to the back of the camera.
Here's a short sample movie, of me flying it around my small laundry room. The camera gives reasonably good video (cell phone quality) in bright light. The sound is interesting, you can gear the whir of the helicopter gears and the wind noise from the rotor wash.
The toy still flies reasonably well, though the added weight does make the helicopter noticeably slower to react. The weight bias is slightly too far forward, the way I have it, so copter tends to drift forward, and I need to add some weight to the rear to balance it better. You can't mount the camera pod too far to the rear, because if it blocks the view of the IR sensor (which is located between the rear tail struts) your helicopter will lose touch with your controller frequently.
The effect on runtime is significant... my stock helicopter would fly for around 5 minutes or so (I never really timed it carefully). The modded helicopter will fly for around 3:00 or so. I blame two factors: the weight of the camera causes you to use more throttle (and more main rotor), and the drain from the camera recording.
My next step is to locate a small, easy to detach power connector, and install it, so I can easily remove the camera pod if I don't want to record.