Imagine an aircraft small enough to fit in the palm of your hand, yet able to fly into damaged buildings to search for survivors or on to battlefields to detect toxic chemicals.
The idea is being researched with help from funding by Darpa, the US defence agency for advanced research projects, under the new Micro Air Vehicles research programme.
Engineers at the Georgia Technology Research Institute, Atlanta, are looking at innovative control methods that can be applied to flying vehicles of such small size.
Conventional techniques for controlling flight direction, such as motors and hydraulic actuators that move the wing and tail fins, cannot be scaled down.
Dr Sam Blankenship, coordinator of GTRI’s MicroFlyer programme, says designers may need to study birds and insects for information.
The specification is for a wing span of 150mm and an upper weight limit of 50g for the vehicle and its payload.
Cost is a vital part of the equation. An upper price of $1,000 takes into account the disposable nature of the vehicles – they may need to be destroyed if contaminated from hazardous substances while on a fact-finding mission.
It is not just the scaling of aerodynamic principles at issue. Relatively severe weight restrictions require new types of flight controls, power sources, propulsion systems and avionics.
At GTRI, research engineer Robert Roglin is looking at ways to control aircraft lift by harnessing the bellows effect of piezoelectric sensor technology that enables a device to deform physically when triggered by an electrical actuator.
Roglin’s work, embracing propulsion concepts, is one of a number of projects. Others include the development of tiny jet turbine engines, pulse jets and ducted fans.
Batteries, guidance and navigation systems and tiny payloads such as TV cameras and sniffers are also being investigated, as are safety aspects such as the effect on humans who come into contact with rotor blades.
Multiple function chips that integrate image acquisition, processing and data compression are well into development. And integration, necessary to keep the parts count and space to a minimum, is being extended to complex on-chip sensor systems covering optical, chemical and biological functions.
`We are not sure what will turn out to be the most difficult challenge,’ says Blakenship. But he is certain that only companies with broad interdisciplinary skills will be capable of developing these tiny airborne wonders.