Engineering and military technology company Braddick Defense Systems is developing a high-speed, long-range, mobile deployment unmanned aerial vehicle for surveillance and attack-mission augmentation in collaboration with aeronautical engineering company Marenco Engineering Technologies Africa.
Braddick Defense Systems CEO Adam McCallum states that the lock-wing drone was originally going to be a quadracopter; however, while conducting research for the project, Braddick contacted Marenco Engineering, as the company is an expert in this field, and the idea of a lock- wing drone came to fruition.
The first prototype of the drone recently completed a full autonomous mission, equipped with a camera. The second prototype, which will be completed this year, will be a one-sixth-scale model.
“We wanted to develop an aircraft that could support clandestine operations. It is an African-engineered device that will serve as an African solution to African problems, such as poaching and piracy,” he says.
Using global positioning system target coordination, the drone can be dismantled and reassembled in a field, deployed from an 800 kg trailer, loiter over a target and provide live surveillance feeds to deployed forces, who can then neutralise a target by dropping laser-guided ordnance from the vehicle, explains McCallum.
“The drone can be deployed by a two-man crew which can assemble the drone, put together the mission plan and augment the drone from any mobile location. The lock-wing drone has rotary vertical take-off and landing capabilities, combined with the efficiency and speed of a fixed-wing aircraft.
“It comprises two large- diameter single-blade rotors. The rotors are locked in position for an efficient high-speed-level cruise. The flight speed is not compro- mised by a large-diameter rotor as with the standard helicopter configuration, and a ducted fan enables both hovering when tilted downward and high-speed propulsion for level flight when in the horizontal thrust posi- tion,” says McCallum.
He further explains that the drone has two single-blade counterbalanced rotors for vertical take-off and landing that lock into position during cruise flight mode.
“The stub wings form part of a high- aspect-ratio cruise wing when the rotor blades are locked and the ducted fan rotates 90º to control hovering,” he states.
McCallum says it is difficult to design an efficient rotor that can also be used for flight propulsion.
“In horizontal flight, the thrust requirement is ten to twenty times lower than that of the hovering requirement. Therefore, the blade area required for hovering causes drag during forward flight.
“Reducing the rotational speed in forward flight can increase the propeller’s efficiency, but this also reduces the maxi- mum achievable speed.
“The lock-wing concept enables the ducted fan to be designed for high-speed cruise. As a result, the thrust requirements for hovering are small and efficiency in this case is not an issue. This is the most significant advantage offered by the concept with regard to tilt-rotor concepts,” he explains.
McCallum notes that, hopefully, the drone will achieve a flight time of eight hours.
“For surveillance, we hope to achieve a minimum flight time of between six and eight hours, with a full range of infrared and electronic war capabilities available. The balance of flight time also requires the balance of speed and payload.
“The quadracopter concept took too long to perfect. It could only loiter for short periods because of the flight time to and from the target area. With the lock-wing concept, we have higher speed capabilities during level flight or cruise.
“If the drone can get to a target area in a shorter time, it will be able to loiter over that target for longer,” he says.
McCallum states that the second proto- type of the drone is currently in production, with flight tests expected toward mid-April 2013.
“We expect the drone to be available to the military market in one year,” he concludes.