In the near future we may see electric vertical take-off aircraft taking passengers to their destinations as aerial taxis high above traffic jams. But the flight system controls for these aircraft still represent a major challenge. Researchers at the Technical University of Munich (TUM) have applied their enormous expertise in this area to develop a control technology which is now being used in the prototype V600 from AutoFlightX.
Helicopters and multicopters can take off and land vertically, but they are not very efficient when it comes to cruise flight. Classic cruising aircraft on the other hand are efficient over longer distances, but they require a take-off and landing runway. A transition aircraft combines the respective advantages: Propellers are used to take off and land vertically; at the same time the aircraft has fixed wings for the transition to efficient cruise flight.
During vertical take-off the transitional aircraft is in hover mode. This is followed by the transition mode during which the aircraft goes from hover mode to the third mode: Forward flight, technically referred to as cruise flight.
The company AutoFlightX, located in Gilching near Munich, is collaborating with the TUM Chair on the development of its flying taxi prototype.
“We want to build an air taxi which is easy to launch and land vertically, but which is still capable of the most efficient possible longer distance flight. The biggest challenges here are flight control and flight stabilization, making sure the aircraft stays airborne even under difficult conditions.”
Matthias Bittner, Chief Operating Officer
Three Flight Phases, One Control Law
This is where the development activities of the TUM researchers come into play.
“We can teach the flight system how it should behave during the various flight phases. This is a special challenge with a Vertical Take Off and Landing vehicle. Here we’re using a complex control system that has not yet made its way into industrial use.”
Franz Sax, TUM Chair of Flight System Dynamics
Established solutions already exist for both hover mode and cruise flight. In the control system now being configured for the flying taxi, one control law handles all three flight phases. This means the aircraft can also be kept under control during the transition phase.
The controller evaluates data supplied by sensors, for example on the position and speed of the aircraft. It also receives input from the pilot. Its algorithm uses the data to calculate the actions necessary in order to achieve the desired flight behavior. These calculations are also impacted by physical effects which however can vary according to the respective flight phase. The control system also has to react to these changes.
Proven Technical Viability
The flight system control developed at TUM is now being applied in the prototype AutoFlightX V600. The aircraft was presented to the public for the first time at the AERO EXPO in Friedrichshafen, Germany, with a wing-span of 8.50 meters and a length of 7.60 meters. The V600 resembles a Rutan Long-EZ, a canard layout aircraft with a forward-mounted control wing. Several propellers make vertical take-off and landing possible, pointing downwards like those of a multicopter. The V600 prototype will be flown by a pilot from the beginning onwards.
With the V600 the developers have now shown that the construction of the aircraft is technically feasible. However, it will be a while before the flying taxi takes off with its first passengers.
“Experts assume that the technology will be ready for the market in 2025.”
Photo Credit: AutoFlightX