That's going to be one big parachute to safely lower a plane. Having flown model rockets for 30+ years, one rocket at 16 ozs uses a 18 inch diameter chute. It slows it down, but still falls at a good rate. Now take a 7lb plane at let it fall at that same rate, the chute would be approx 126 inches in diameter. Add forward velocity to the equation ?? I would love to see this happen, but some how rockets + parachute = tree tops or powerlines even if both are 1/4 mile away and upwind. OHHH I keep forgetting about everybodys "friend" MURPHY! Seriously good luck and keep us posted this is an interesting comcept.