First robotic flying insect

The first robotic flying insect was the insectithopter, an artificial dragonfly that measured 6 x 9 x 1.5 cm (2.3 x 3.5 x 0.5 in) and was cable of controlled flight over distances of up to 200 m (656 ft). It was designed and built for the United States Central Intelligence Agency (CIA) at the Vought Advanced Technology Center in Dallas, Texas. Work began on the project in the early 1970s and concluded some time after 1974.

Although it was designed as a surveillance tool, the insectithopter did not carry a microphone or transmitter. Even the state of the art for the 1970s would have been far too bulky and heavy for this application. Instead, the insectithopter was designed to work as part of a laser-based recording system that allowed all this equipment to be located far from the location being monitored.

This system, which was independently developed by several intelligence agencies during the cold war, worked by shining a laser onto a reflective surface close to the surveillance target. The sound of the target's conversation would create tiny vibrations in the objects nearby, including the reflector. This vibration would distort the reflected light, and from these small fluctuations it was possible to reconstruct the sound that caused them.

Although impressive-sounding, this technique was only marginally usable, and even then only under very specific circumstances. It required a stable, highly reflective object close to the target, and the laser had to be positioned so as to hit the object dead-on in order for the light to be bounced back to the receiver. Even in the situation this system was best suited to (recording indoor conversations by shining a laser onto a window) it still required the operatives to secure covert access to the building directly opposite the target room with enough time to calibrate all their systems.

The insectithopter was designed to extend the usability of this system by providing a reflector that could be positioned where it was needed straight away. Each shiny eye of the robot bug was a device called a "retroreflector" which used concave surfaces to bounce light back in the direction it came from, regardless of orientation. The idea was that operatives in the field could fly this unobtrusive bug over to where a target was speaking and then shine their laser towards it.

Propulsion was provided by a tiny device called a fluidic oscillator, which used the gas given off by lithium nitrate crystals to generate thrust. Some gas was diverted to flap the wings, but this was mostly for cosmetic reasons. The actual mechanism of flight was more or less like a conventional aircraft – the wings provided lift while the rear-facing exhaust vent provided thrust.

As there was no room on board for electronics, control was achieved using a laser and some clever metallurgy: by varying the power of the laser beam, the insectithopter's rudder-like tail could be made to bend to the left or right, and if the laser was shut off, the cooling of a metal backplate would shut the exhaust vent and cause it to land.

The project was overseen by CIA technologist Charles Adkins, but the majority of the work was carried out by a single extremely inventive engineer (whose name remains classified) at the Vought ATC. This engineer was an amateur watchmaker and entomologist, who went as far as to built a tiny wind tunnel to test his invention.

Ultimately, while it performed well in a highly-controlled test environment, the insectithopter proved impossible to fly outdoors, where the slightest breeze would send it tumbling to the ground. The project was mothballed in the mid-1970s without ever seeing operational use.