Nice project. Good luck. A few comments: Be very aware of the increasing power interfering with other components on the hardware if you use the higher power transmitters. I have noticed much slower GPS lock when I dialed the power up to 100mW on an experimental plug and play GPS/telemetry system. At times it will not obtain fix at all. That indicates that the front end is being swamped by the local telemetry Tx. I dialed the power back down and the situation improved markedly, although it still would have been affecting the time to lock and possibly the DOP. Also, I have had an on-pad deployment event occur when some telemetry keyed up a 1W transmitter. The RF got into the deployment electronics and triggered it as I walked away from the pad I would suggest getting the telemetry antenna well away from the GPS if using higher power. If it were me I would probably run a skinny coax for the Tx (or you could do something with the GPS antenna/receiver) to get the separation up. Here is a suggestion also. Please provide some extra channels for inputs from other electronics. The TeleMega I use has four extra inputs and I can use them to monitor the battery and pyro voltages on my other altimeters. That means there is no guessing when it is on the pad if there is enough juice for the flight, especially after an unplanned extended pad time. Also provides direct indication of nosecone separation .