Karlsruhe, Germany in March 2016.
Since 2013, the German Ultralight Flight Association has been testing the Volocopter on behalf of the Federal Ministry of Transport and Digital Infrastructure. In February, the Association granted Karlsruher e-volo GmbH a provisional certificate for its VC200 as an ultralight aircraft (certificate number (VVZ) (D-MYVC). e-volo aims to have its Volocopter certified as an ultralight prototype and, hence, pave way for series production of the 2-seater. The completely new, vertical takeoff aircraft is extremely easy to fly, quiet, and emission-free. A comprehensive redundancy concept in all its electronic components ensures its safe landing, even if one or more drives were to fail. The Volocopter is controlled with one hand using a joystick. The zero emissions have been made possible by its all-electric drives and rechargeable batteries that can be swapped very quickly and easily.
Unmanned test flights prior to the certification:
The certified VC200 can also be operated remotely for unmanned test flights. This reduces the usual “launch risk” of a new aircraft. The e-volo team conducted more than 100 unmanned test flights as part of the preparation to have the VC200 certified for unmanned flights. With professional remote control, the team was able to conduct stress tests on the entire system, its different modules, and the individual components. For instance, they would switch off motors, disconnect some of the batteries or flight control electronics, etc. They also fed wrong information, e.g., with “defective” sensors into the aircraft’s control system. In addition, unmanned test flights were also conducted under turbulent weather conditions. The e-volo team, together with Jörg Seewald, the association’s representative for the test program, were extremely impressed by the way the VC200 was able to stabilize itself in adverse weather conditions as well as compensate for the loss of rotors without any intervention from the pilot.
Manned test flights:
The manned test flights are planned in three phases. In the first phase, the test flights will be at low altitudes and restricted to a maximum flight speed of 25 km/h. In the second phase, the emphasis will be on flight maneuvers with a flight speed of up to 50 km/h at an average altitude. The third phase is aimed to validate the system at higher altitudes and in the full speed range of the VC200 (up to 100 km/h).
Videos of the test flights are available at www.volocopter.com or on YouTube.
Technical description of the Volocopter
The Volocopter is made of a light-weight, fiber composite material. In addition to cruise flights, it can also take-off and land vertically as well as hover in the air. The VC200 Volocopter runs on all-electric motors. The electric motors of its 18 rotors are powered by nine independent batteries. When in a floating state and with a 450 kg take-off weight, the VC200 requires about 45kW, depending on the air pressure / temperature. Its redundancy concept ensures stability, even if parts of the system were to fail. This principle is used in all system components that are necessary for safe flights. The necessary thrust required to provide buoyancy is achieved through several independently driven rotors, each with two fixed blades. Unlike a helicopter, the blade angle on the VC200 cannot be adjusted. The amount of thrust produced depends solely on the rotation speed of the different rotors.
Appropriate combination of the torques around the axis (roll and pitch), which are produced by the speed differences of the different rotors and that are perpendicular to the axis (yaw), as well as alterations in the total thrust produced by all the rotors enable the Volocopter to maneuver in all three rotational degrees of freedom (pitch, roll, and yaw), whereas the fixed setup of the rotors allows for translational movement (vertical, “up/down”). In combination with the position angle, the Volocopter is able to make flight movements in all six rotational and translational degrees of freedom as well as indirect horizontal movements (“forwards/backwards” and “rightwards/leftwards”).
Although the Volocopter initially exhibits what would seem to be unstable flight characteristics due to its relatively high number of rotors that have a fixed blade angle, its multi-redundant flight control system ensures precise altitude control and positioning stability. It is actually much more stable than conventional aircraft. It adheres to the pilot’s specifications and compensates for external effects independently. This makes flying it much easier, and the pilot can control the Volocopter safely, even in adverse environmental conditions.
The flight control system comprises of several completely independent units. Each flight control unit contains a complete set of positioning sensors that consist of pressure gauges, gyroscopes, accelerometers, and magnetometers for all three spatial axes. Theoretically, each of the flight control units can control the VC200 independently. The Volocopter is operated with one hand using a joystick. The pilot intuitively controls all flight axes through rotational movements of the joystick’s axis. Rising and falling commands are given through an altitude control thumb button. In order to land, the pilot only needs to press and hold the button down until the Volocopter is on the ground. Once it nears the ground, the control system automatically slows down the Volocopter to ensure a gentle landing.