FPGA/DSP Unmanned Aerial Vehicle

If you hadn't the size constraint I would have suggested one of the standard development kits and use a prototype HSMC board such as this one (http://www.bitec-dsp.com/hsmc_proto.html) to put your ADC, servo drivers and serial interfaces.

For a smaller size the DE0-nano is a good solution. There is also the bemicro (http://www.arrownac.com/offers/altera-corporation/bemicro/index.html) that has a 80-pin contact and can be flashed so that you don't need the USB connection, if I remember correctly. It uses a non standard RAM though, and you need to buy a license to use it.

Without more details about the DSP you require and how you need to interface it to the FPGA it is difficult to give any ideas on this part though.