New class of UAVs look more like UFOs

Most Unmanned Aerial Vehicles (UAVs) employ a fixed wing design like that of a traditional plane. But these designs offer limited maneuverability and payload capacity, require a runway to takeoff and land, and are unable to hover. Vertical Take Off and Landing (VTOL) UAVs get around these problems, usually by employing rotors like a helicopter. Now UK-based company AESIR has developed a VTOL UAV that has no external rotating parts, instead relying on a phenomenon known as the Coanda effect to generate lift.

The Coanda effect is the tendency of a fluid jet to become ‘attached’ to a nearby curved body instead of following its original path. The effect can be seen by placing a can in front of a lit candle. If you blow directly at the can, the air will bend around it and extinguish the candle – that’s the Coanda effect. It was used in the design of the pedal powered submarine we looked at earlier this year and, because the fluid jet can be a liquid or a gas, AESIR have been able to utilize the effect in the UAV.

The Design

In the case of the AESIR UAV, air velocity is created in the center of the craft using a fan and then directing the air flow through an outlet so it follows over the curved surface. The amount of lift generated is dependent upon the velocity, mass and density of the air. To help reduce the weight of the craft and maximize durability the craft are made from carbon fiber.

Since the rotation of the fan causes the body of the UAV to rotate in the opposite direction, AESIR placed a series of vanes in the airflow around the outside of the body to neutralize this effect. Moveable flaps on sections of the lifting surface provide yaw control to allow the UAV to turn left or right. And flaps on the outside of the craft use the lift airflow to provide directional control, causing the craft to tilt and move in the direction of the tilt.

AESIR say their designs have inherent stability as a surveillance platform, thanks to a sustained hover capability, and can survive low speed impact with the ground, buildings and other fixed objects. They also have a large payload capacity when compared to similar sized fixed wing craft and have been designed to be flexible using “plug-and-play” payloads.

Read more . . .

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Tags: Carbon fiber, Coand? effect, Coanda, Fixed-wing aircraft, Helicopter, Unmanned aerial vehicle, VTOL

This entry was posted on Tuesday, September 22nd, 2009 at 7:07 pm and is filed under Consider This, Innovation, gizmag. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.