Backpack drone that peers behind enemy lines
A HOVERING spy craft only 23 centimetres across could soon be flying behind enemy lines to conduct surveillance, or darting about inside buildings to help police find hostage-takers.
Micro Craft, an aerospace development company in San Diego, California, last week successfully tested the miniature vehicle (www.microcraft.com/UAV01.htm). It consists of little more than a ducted fan that rotates inside a protective cylinder. The fan is pitched at an angle so that its wash counteracts the slight spin the fan imparts.
"It performed great. It's very stable," says programme manager Allen Zwan. Even in high winds, the 1.4-kilogram craft managed to take off, hover, and move around at slow and medium speeds.
A small two-stroke petrol engine drives the fan. This provides enough lift to get the craft off the ground and allow it to hover and move from side to side. To travel at top speed, the vehicle turns sideways so that the fan points almost horizontally and the aerofoil-shaped edges of the duct provide lift. It can fly for about an hour on the 200 grams of fuel it carries. The aircraft was developed with funding from the US Defense Advanced Research Projects Agency (DARPA). The idea is that soldiers will carry the small, lightweight reconnaissance aircraft in their backpacks.
A remote controller tells the drone where to go and how fast to fly. On-board electronics keep the craft flying, adjusting the speed of the fan and the angle of the control vanes. The test vehicle last week carried a video camera that transmitted images back to the ground. But it could also support communications relays, or even a laser that would "paint" a target with light to guide in missiles from larger craft.
Author: Kurt Kleiner, Toronto
New Scientist issue: 21 October 2000
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