Elevating a fixed wing drone with a multicopter drone to achieve secure flight altitudes

Working with fixed-wings in tropical forests is no easy job. Launching and landing a fixed wing in the reduced space of the dense forest is a real challenge. To worsen the situation, the first commercial fixed-wings still had quite basic take-off control systems, not enough to assure a secure ascension of the drone through the canopy.
In 2013, we carried out mapping missions in the dense forests of Suriname to analyze the impact of different logging methods. The fixed-wing drone we used at the time was the Swinglet Cam, the first drone of the Swiss company SenseFly. At the time, this drone did not have a fully controlled ascension mechanism, which, at one point during the mission, resulted in a crash into a tree during take-off, leading to the burn of the motor. Luckily, we were able to repair the drone, but did not want to risk a second time.
Hence, we came up with the idea of using a second multicopter drone we had brought to the field to serve as an elevator of the fixed-wing drone, in order to elevate it to secure flight altitudes, far above the forest canopy, before releasing it to start the mission.
The video you see here is one of the tests we did in an open space.
As a result of the poor take-off performance of the Swinglet Cam drone in such a difficult forest environment and based on our reports, SenseFly developed a much more sophisticated ascension mechanism, which is being used in their fixed wing drone systems until today.