Vulture 2 battery connection
A suggestion for attaching electrical connections between the plane and the truss.
For each connection a short length of backward facing copper tubing would be fixed to the plane (or even inside the body with the tail end of the pipe outside). The front of the copper pipe is soldered to the internal wire.
On the truss a cable hangs down to the plane with a small piece of steel wool soldered to the end. To make the electrical connection the steel wool is then pushed into the copper tube on the plane. The springyness of the steel wool will hold it in place but should slide out of the tube as the plane launches.
The amount of grip needed inside the tube can be varied by soldering more or less steel wool to the end of the wire. Install one tube/wire combo for each required connection.