The plane on the left is a mini blitz built from  a free magazine plan. Initially as depicted left i built it powered with a OS10 Max engine, It flew well but had the glide characteristics of a brick, once the engine stopped which was a slight problem as it has no undercarriage.

I decided to modify the plane with initial intentions of turning it into a slope soarer but then had the idea of dropping it from another aircraft. Its flat fuslage top and twin fins make it ideal to fit under the  fuslage of another plane, see  below.

The drop mechanism simply tie wraps or elastic bands on to the drop plane. The servo is operated from the delta via a plug that goes to the throttle channel, this detaches when the plane releases. The arm of the servo goes through a slot in the top of the delta and rotates 90 degrees to lock the delta on. The slot at the back of the mechanism fits a tab further back on the delta to prevent it rotating in flight.

Above a second mini blitz was bought from a swap meet for 50p which i modified in a  similar way to the first.

Having now got two planes the next logical step was to devise a method of dropping both at once. I built the mechanism below. The servos are on a y lead both released by one delta pilot they have to be set so one releases fractionally before the other as there is no power to the servos when the one connected has gone. An Initial go wasn't to successful as both pilots thought they were flying the same plane resulting in one crashing, it was rebuilt and some distinguishing colour added. There have been several successful drops since from a Flair Piper Cub.

A fun use to put this mechanism to would be head to head competitions such as spot landing and longest glide etc.

Left along the same lines i have built a cradle on top of my long cabin. The release mechanism is similar a servo arm lock the plane on and rotates 90 degrees to release, instead of  gravity elastic bands keep the plane tensioned against the servo and  eject when released. the most force being applied to the front, once the nose is lifted the prop wash and wind do the rest. worked successfully with a depron ducted fan jet. i have also dropped a small epp slope soarer from it. and a similar glider called a pixie depicted on the right