since 2005 we are building drones,

2005 till now the very robust SUSI (Save Universal Sensor and Instrument carrier)
2008 – 2014 fixed wing drones with autopilots
2014 VTOL fixed wing drone „SONGBIRD“ (now produced by germandrones gmbh)
2014 the GEO-COPTER for surveying
2018 VTOL fixed wing drones for transport

very easy to transport – small box
very robust
very easy to fly
very safe – parachute
2-stroke engine – 5.5 hps
steel frame & parachute wing
payload 8kg – total take-off weight 17kg
max speed 55 km/h
up to 3h flight time
2 different parachutes of different wind conditions
gimbal mounted sensor carrier
SUSI was a great success because it was very simple, just three servos were needed
very easy to operate, everyone could learn to fly within one day
very safe – if something fails, just switch out the engine and SUSI came down with a sinking rate of 2m-3m per secondthe frame was mounted within 20 minutes – just to put the steel tubes together with the alloy joints
due to the 2-stroke engine no batteries have to be charged – just 2 jerry cans each with 20l fuel and you could fly for 20hit was easy to repair, the junctions of the frame were made from alloy – if they had been bended they just had been replaced
frame was as well weldable and a punktured parachute could be fixed with tape8 kg of payload gave interesting options for operating different sensors at the same time

the low air speed allows high overlapping images along flight track even if the cameras need a couple of seconds to write the images to the storage card (big issue in 2005!)
the vibrations of the engines where damped with special rubber silent blocks
due to the insensitivity for the correct position of the point of gravity the change of the sensors were very easy

the disadvantages:
demand of a proper runway in the field for take-off and landing
low max speed of 55 km/h which allows operations only up to 6 m/s windspeed
used 2-stroke engines must be transported in airplanes as dangerous goods