Newbie advice on actuators - High Altitude Balloon Project

Hi, I was wondering if the community would mind suggesting an actuator for a High Altitude Balloon project that I am involved in. I'd like to actuate main parachute deployment at a given altitude by cutting/releasing a loop. I think I've settled on a pressure/temp sensor BMP280 which I'll be using to record ambient data and also initiate the parachute release at a given pressure (and therefore altitude).

I am so new to Arduino that I haven't ven bought the Dummies book yet! Any suggestions would be gratefully appreciated.

Best wishes

Phil :)

Google "arduino hab cut down" to see how others release their chutes.