The sporty, red-and-white helicopter is flown using a radio signal from a hand-held controller that closely resembles controllers for miniature hobby aircraft. When the helicopter is in the air, the entire vineyard is considered an emergency-landing site. Should the helicopter lose the radio signal from the controller, the built-in safety system will cause it to immediately pause, hover and then slowly land.

Currently, only water is being sprayed on the vineyards as the researchers explore how well the aerial applicator would cover the vineyard. Water-sensitive test papers are spotted at specific sites throughout the vineyards. Water droplets from the helicopter spray system leave on the paper tiny blue dots that, when recorded and computer analyzed, provide valuable information about where the spray is landing.

The helicopter is equipped with one eight-liter tank on either side of the fuselage, giving it the capacity to carry 16 liters, or slightly more than four gallons, of water or liquid spray. The aircraft has a recommended maximum spraying speed of approximately 15 mph, as it methodically moves up and down the vineyard rows.

So far, the data indicate that the helicopter is providing thorough coverage across the vineyard and that the air currents stirred up by the helicopter rotors are causing the spray to reach even the undersides of the grapevine leaf canopy. Furthermore, the researchers have been impressed by the stability of the helicopter, even in gusty winds.

Eventually, the research team plans to conduct application tests with commonly used agricultural pesticides and herbicides. They will explore how well the helicopter compares to a tractor-drawn spray rig in terms of operator safety, cost and efficiency. They also are expanding the test flights to some almond orchards in California's Central Valley.

The results of the study — expected to be completed late this summer – will help determine where and how the mini-helicopter might play a role in U.S. agriculture.  In Japan, where rice fields average about five acres and are often surrounded by residential or commercial development, the helicopter provides a safe, efficient method for applying agricultural sprays.