Unispray have developed a new centrifugal energy nozzle, the "Unimiser", for the aerial application of

pesticides. The new nozzle is designed to substantially resulting from the

aerial application of pesticides in the cotton industry. The nozzle was designed to generate a very low

range of droplet sizes, (having a relative span of less than 0.8 compared with 1.2 -1.6 for most

currently available nozzles) and a volume median diameter of 250 pm,

Testing of prototype models have demonstrated that that the Unimiser nozzle is able to generate a

narrower range of droplet sizes, as indicated by a lower span, than any other commercially available

alternative. It is expected that drift from this nozzle is likely to be lower than for other nozzle used on

aircraft in the cotton industry.

During the course of this project Unispray decided to initially concentrate on a Helicopter version of the

initial prototype. The results from the single flight line deposit measurements showed that there was a

consistent area of low deposit beneath the centre-line of the helicopter. Since it was impractical to

mount an air driven rotary nozzle in the slow moving air close to the airframe beneath the centre line of

a helicopter, a small number of additional hydraulic nozzles were fitted. This small modification

improved the uniformity of the deposit. The tests showed that more uniform ground deposit patterns

were obtained when three Unimiser nozzles were operated on each side of the helicopter.

Based on results from the wind tunnel studies, pattern testing and market requirements, Unispray

decided to concentrate on a "retro fit" version that can easily be added to existing Micronair units.

Droplet size was measured over the range of nozzle rotational speeds, liquid flowrates and airspeeds

that are likely to be encountered in the field. Testing was initially undertaken with water only but was

later repeated with a Water + 0.1% Agral mix. The Agral was added as it is oflen considered to be

more representative of an actual tank mix. In general a slightly larger range of droplet sizes (larger

span) was generated with the Water + Agral mix. From the measurements a regression analysis was

undertaken to enable prediction of droplet size using the range of variable tested in the wind tunnel

From this analysis an EXCEL based "nozzle calculator" was developed and a full working copy of the

calculator has been included with this report.