Booyco Engineering successfully completed the fast track development of an air conditioning system for the second generation vehicle mounted mine detection (VMMD) unit, designated Husky 2G, for local OEM RSD.

“Booyco Engineering was responsible for the engineering, manufacturing and supply of the air conditioning system on the original Husky VMMD machine launched several years ago, and it was logical for the company to engineer the system for the new generation vehicle,” says Grant Miller, project engineer at Booyco Engineering.

The Husky VMMD vehicle, operated by one person, facilitates fast and efficient route clearance to ensure safe passage for military and civilian personnel and vehicles. With the increasing length of route clearance missions, RSD identified the need for a vehicle that could carry two occupants to allow for the tasks to be split between a driver and an operator of the detection equipment.

The Husky 2G has the same protection, survivability, frangibility and reparability as well as similar mobility characteristics to the Husky MK III.

“With increased cabin space and two occupants instead of one, the ambient temperature control needed to be enhanced and Booyco was tasked with developing an air conditioning system that could increase the cooling requirements in the cab,” says Miller.

High demands on cooling and heating functions

Apart from the cooling requirement, there was also a need to provide heating, using a hot water coil. “The heating capability also allows for a demisting option to be included in the system, which is a vital function in inclement weather if one considers that visibility in mine detection is extremely important,” Miller explains.

The cab of the Husky 2G vehicle mounted mine detection vehicle is extremely small and accessed via a hatch in the roof, since there are no doors on the front, back or sides. There are armoured fixed pane glass windows in the front and sides of the cab. This results in the driver and operator being exposed to extreme heat when the vehicle is operating in hot, sunny places, thus necessitating additional cooling.

“Space is extremely restricted, and this did present challenges in terms of where the air conditioner could be installed. While the most appropriate solution appeared to be placing the air conditioner in the front portion of the roof this created additional challenges as the unit had to be extremely compact to allow sufficient space for the operator to enter and leave the cab,” says Miller. “Another challenge faced was that the mine detection equipment on the vehicle is highly sensitive to electromagnetic interference. This meant that we were unable to use conventional components to control the air temperature, as this would create interference on the mine detection system”

A “cool” idea

To solve this problem, the company used a refrigerant compressor with a variable swash plate, allowing the system to vary the amount of cooling capacity provided. This prevented the system from cycling during operation. In mine detection mode, there is a constant field established in the clutch, eliminating spurious signals to the operator. Should the system trip, the clutch will not re-engage, preventing spurious signals as well as alerting the driver to the compressor trip.

Husky mine detection vehicles are deployed in a number of countries in the world, with varying temperature ranges. To ensure a comfortable environment under all conditions, the air conditioners were designed to provide cooling at a maximum ambient of +55°C as well as heating in a minimum ambient of -40°C external to the vehicle.

The new system is mounted in the same position as the one in the single cab Husky, in the roof above the driver and his operator, although it is obviously larger to ensure that appropriate cooling and heating can be provided. The Husky 2G incorporates Booyco Engineering’s custom designed electronic controller, programmed to accommodate this vehicle’s mine detection requirement.

Tested for reliable performance

As with all custom-built air conditioners, these units were comprehensively tested by Booyco Engineering prior to delivery. These tests included thermodynamic performance, endurance and accelerated vibration testing. All tests are aimed at meeting stringent quality specifications, as reliability and performance are critical in this type of vehicle. In addition, all units underwent a factory acceptance inspection and test to prove that each unit is defect free prior to delivery.

“We were tasked with providing a fast track solution to a very challenging design application and we were able to present RSD with a tailor-made temperature control system that will ensure the comfort of both the driver and the operator of the Husky 2G,” Miller concludes.