I used to do a fair amount of hobby rocketry. I've since moved on to building my own rocket engines and publishing on rocket engine design. I was always interested in more advanced methods. One report that got my attention was this:
It is available here: https://blastzone.org/nar/narts/ This report uses an arrangement of photocells in a control system to guide the servos.
The Wii camera can track the sun as well. We can use this to accomplish the same task, but in a slick new way (of course, the old way is really nice and elegant which is awesome too).
This is where my Wii Rocket has come from. It has yet to fly, but it is close. Don't worry, this can't be used for anything nefarious. The Wii camera is not heat-seeking. That is very low frequency (long-wave) IR. The Wii camera views near-red infrared (short-wave). Infrared covers a very large frequency range so it is important to clarify what type of IR you are talking about. The sun works for tracking because is it blasting out a whole range of light.
I will add updates as this continues.