Lift and carry
The payload sits in a locked composite bay under the fuselage, or on a tension-sensing winch. Never on an open hook. Load cells read the mass and the centre of gravity before the aircraft will arm, so a badly packed or over-mass load is caught on the ground. Without that, a delivery drone is a toy with a strap. With it, a 30 kg case moves sealed and time-stamped, opens only to an authorised code, and holds a cold chain from +2 to +8 C for blood or vaccines. The same bay and winch fit every airframe in the range.