美公司推出仿真蜂鸟侦察机

A California company that makes unmanned drone aircraft for the U.S. military has unveiled a tiny flying drone that looks like a hummingbird.  The airborne spy is part of a new kind of military technology that also has civilian uses.

Several years in development, the so-called nano-hummingbird is a smaller and more maneuverable version of drones now used by the U.S. military in Iraq and Afghanistan.  It looks like a real hummingbird with quickly flapping wings, and just like the real bird, can hover in mid-air and fly backwards.

The company that created it, AeroVironment, develops and tests drones outside Los Angeles.  They give observers an eye in the sky, and spot objects and track people on the ground.

The tiny bird-like drone has a camera and transmitter and a wingspan of just 17 centimeters.   It is operated remotely and flies by moving its wings, says project manager Matthew Keennon.

"It's being manipulated and controlled to allow the forward and backward flight, the rotation and also the side-to-side flight.  And all that's happening by just changing the curvature and the shape and different aspects of the wing movement at a very high speed," noted Keennon.

The tiny drone is still experimental.  The challenge and the funding came from the Defense Advanced Research Projects Agency, which asked for an airborne vehicle that would mimic something in nature.

Project manager Keennon says the challenge was huge and the work has been exciting.

"Because every time we made an improvement, got better, we were just so amazed," added Keennon.

While the company is developing some of the world's smallest drones, it is also testing one of the largest.  Called Global Observer, this unmanned craft is thin and sleek but has a wingspan almost equal to a Boeing 747.  It is powered by liquid hydrogen and can hover in the stratosphere, says AeroViroment's Steven Gitlin.

"And it's designed to fly for up to seven days at a time at about 65,000 feet [20,000 meters] altitude and carry a payload that either helps somebody see what they want to see or relays communication from one point to another," explained Gitlin.

The company spokesman says airborne drones are used for military surveillance, but also have civilian uses.

"Applications like first response, search and rescue, law enforcement, border security, even facility security and event security - anywhere a bird's-eye view in the sky in real time can help somebody do their job more effectively and more safely is a potential application for this technology," added Gitlin.

And the new nano-hummingbird will go places that larger drones cannot.

AeroVironment engineers say the device will still be in development for the next few years, and may not reach the market in its present form.  But they say the technology developed for the device will be used in future products.