Ref the requirement for data loggers in over 25kg models, here's two units I've used previously that will satisfy the requirements, the SM Modelbau GPS logger https://www.sm-modellbau.de/GPS-Logger-3 and Aerobtec Altis GPS unit https://aerobtec.com/altis-gps/ both units will log the full flight path with speed, height and position etc. In addition they work on the telemetry on most radio makes, I've used them with Multiplex, Jeti and set them up on Futaba, so in addition to acting as a data logger you get live feedback in flight, so can use them to set say height alarms or in the case of Jeti in conjunction with their LUA boundary alarm. If used with a system that logs data on the transmitter you will store the flight data on both the unit and in the transmitter.
The SM Modelbau units are only available direct from them in Germany, the Aerobtec units are available from UK suppliers, e.g. Hyperflight https://www.hyperflight.co.uk/products. ... ltis-gps-2
