The propulsion consists of 4 sets of contra-rotating disks, each set driven at the same rpm by a conventional aero-engine. The disks are surrounded by blades whose angle of attack can be altered by offsetting the axis of the rotating disks. As each blade can be given a different angle of attack, the resulting main thrust can be in any required direction in 360° around any axis.
This allows the craft to launch vertically, remain in a fixed position in the air, travel in any direction, rotate in any direction like a football, and thrust upwards thereby ‘gluing down’ on landing. The basic idea was the development of an aircraft which combines the positive flight characteristics of both rotorcraft and fixed wing air vehicles and has the potential to operate in environments denied to conventional air platforms.
Only very slight movements of the offset are needed in order to achieve a quick respond and high agility. This permits reverse thrust in within a fraction of a second and allows D-Dalus to cling onto flat surfaces to protect it against sliding on movable platforms or when landing on inclined surfaces.
There is a complex aerodynamic advantage in forward flight when a certain amount of the vertical thrust is created by its winged body.