I've started to look into making a rocket engine gimbal. I need it to be light, slim, and reliable, so I'm trying to do it without servos. I've decided that I want to try to do it using solenoids and magnets. In the picture above, you can see a crude rendition of the concept. The engine will be mounted in a spring, and the spring will be affixed to the housing just at the very top. This will keep the engine straight normally, but allow the engine to flex side to side. There we be four magnets at the bottom of the engine, equally spaced around the diameter. There will be 4 corresponding solenoids surrounding the motor. But running a current through them, the engine should bend in the direction of the solenoid.

I used some homemade lab masses (paperclips) to figure out how much force is needed to deflect the spring 5 degrees. My friend Zach imparted me with some physics wisdom so I could figure out how to calculate the EM forces for some different configurations of solenoids and magnets. Doing the math beforehand rather than blindly testing it should save some time and money.

This design for an EM gimbal, as far as I know, is a novel idea. The idea of working on something that hasn't been done before is both exciting and daunting, but will make for a fun challenge.

Also, I've been playing around with ignition methods. I finally found one that worked. A small length of nichrome wire, bent into a loop at the end, dipped in clear nail polish, and then coated in a bit of ground up matchhead paste works reliably and is pretty cheap to make. Two of them can be ignited simultaneously with a single 9v battery