What is a gyrocopter?
A gyrocopter (also called autogyro) is a rotary-wing aircraft that flies by means of autorotation. Unlike a helicopter, the rotor of a gyrocopter is not powered directly by a motor, but turns by the action of the relative airflow on the blades. The first flying autogyro was invented in Spain in1923 by Juan de la Cierva, but it was soon superseded by the invention of the helicopter. Nevertheless, autogyros have gained great popularity especially in recent years for use as a sporting aircraft. By the end of 2013 there were over 500 licensed autogyros in Germany alone.
Due to its exceptional properties, the gyrocopter has a high potential for use in parapublic missions, such as: police operations, border control, coast guarding, emergency management, or for agricultural purposes.
Picture 1: Comparison of a horizontal flight of an autogyro and a helicopter
The gyrocopter – an aircraft with outstanding performance
Picture 2: MTOsport
The gyrocopter’s main advantages originate in it being a microlight driven by autorotation. Therefore, it is able to fly extremely slowly while being very agile. In addition, due to the rotating blades it is impossible to stall. Short take-off and landing distances (10 to 50 meters) enable the gyrocopter to take-off almost vertically and also to land with high approach angles.
The gyrocopter is thought to be one of the safest aircrafts in the world. Should the thrust-generating propeller fail, the rotary-wing stays in autorotation. This allows the pilot to slowly and safely land the gyrocopter. In fact, landing the gyrocopter in an emergency situation is exactly the same procedure as landing it under normal conditions.
The gyrocopter can be flown safely and steadily under both strong wind and turbulent conditions.
In addition to the good handling qualities, the operating and maintenance costs of the gyrocopter are of a much lower level, especially when compared to a helicopter. This results from the simplified mechanics of the aircraft; the basic rotary-wing system and the cost-efficient propeller-driven engine. When the rotor is dismounted, the gyrocopter requires little space and can be easily transported on a trailer.
The growing popularity of the autogyro and its attractive flying characteristics have also captured the attention of the Institute of Flight Systems where research into the flight dynamics of the autogyro is being performed.
Over the past few years the DLR has been able to make great advances in exploring the gyrocopter’s flight qualities, while also building up unique research facilities at the same time. This has all been made possible through the use of simulation models and flight data that were gained from flight experiments. The following technical aims are being researched:
The Institute of Flight Systems operates two autogyros manufactured by AutoGyro GmbH located in Hildesheim (Germany). Both autogyros are stationed at Braunschweig’s research airport.
The Cavalon GTD (Gyroplane Technology Demonstrator) aircraft has been used since 2013. It has a significant role in flight experiments for the project: “Use of autogyros in emergency management and rescue operations“ undertaken in cooperation with the THW (German Federal Agency for Technical Relief). The aim of the project is to address how the gyrocopter can be routinely operated for parapublic use.
The second aircraft, an MTOsport autogyro is also operated by the DLR flight operations group (http://www.dlr-fg.de). It was previously used for flight measuring programs in 2010 and 2012 for the validation of simulation models and in addition to produce flight data to study autogyro flight dynamics.
The rear seat of this aircraft was removed to equip the gyrocopter with the necessary measuring instruments. An inertial platform provided information for the angles of orientation, rotational velocities, and accelerations of the fuselage. At the same time other instruments recorded more additional measurement data.
A special feature was the installation of two laser sensors at the mast to measure the position of the rotor blades in the plane of rotation and their blade-flapping angles.
Additionally, an air data boom of two meters in length was installed at the airplane’s nose to measure the angle of attack and sideslip angle in free stream air without the disturbances from the fuselage and rotor.
The manoeuvres flown helped to create a valuable database to analyse the flight dynamics of the gyrocopter, and to validate the simulation models. A point of special interest was to explore the flapping movements of the rotor blades in all possible flight situations as well as on the ground.
Rotor handling on the ground
Horizontal flight at 40-180 km/h
Climb and descent
Descent with engine on
Dynamic roll, yaw, and pitch stick inputs
Alternation of load
Flight at 10.000 ft.
Sideslip at different flight velocities
(until rudder is fully deflected)
Sideslip with engine turned off
Horizontal flight at 40-80km/h
Blade flapping on the ground
Spiral dive to determine the maximum load factor at 2.000 and 8.000 ft.
The project “Gyro Train” was supported by the Innovationsfonds of Lower Saxony from 2009 to 2012. Its aim was to study the effectiveness of flight simulator training for a gyrocopter. During this research a real-time simulator model was developed. In addition, different simulation models were developed using Simulink for the purpose of research into: offline-simulation, linearization, and parameter estimation. As a result a prototype of a training-simulator for the MTOsport was built and validated against real data gained from flight test.
An improved version of the prototype is now being used for pilot training, and also to study different and dangerous flight manoeuvres to capture the gyrocopter’s response. Furthermore, the flight qualities of a gyrocopter in new configurations can be tested, for example the effects of adding wings can be investigated.
At present the important task of better understanding autogyro flight dynamics has progressed, however, there remains further research to be performed in order to fully understand the aircrafts performance. Within the Institute of Flight Systems this task has been recognized and is being addressed by ongoing research, optimization, and development to maximise the benefits from this type of aircraft’s high potential.
Therefore, the cooperation with the THW is being continued to prove the gyrocopter’s suitability for use in disaster areas and parapublic applications.
The simulation models are being used in current projects to support the design of a future autogyro, for example in an ongoing concept study of a twin-engine autogyro. As a result, existing models are being equipped with additional wings, a second engine, or an increased weight to test different aircraft manoeuvres such as a jump start. In addition, these simulations are also helping to prepare future flight experiments.
Picture 8: Concept study of a twin-engine autogyro
Simtec Systems GmbH
Universität der Bundeswehr München