Aircraft Electronics Packaging

Liquid-to-Liquid Heat-Exchanger :

For this project we used our mechanical design expertise to repackage an off-the-shelf liquid heat exchanger into a smaller unit for a 300% reduction in overall volume. This unit required size reduction in order to fit into the electronics rack of the HSRL2 Environmental Enclosure.

The heat exchanger is used to keep the HSRL2 laser temperature under control by first running coolant through the laser, then through radiators (liquid-to-air heat exchangers) that dump that heat into the air inside the enclosure. This was done because the electronics could get cold in the high altitude of the ER-2 aircraft.

The Liquid-to-Liquid Heat Exchanger consists of a custom-designed coolant reservoir, a water pump, a heat exchanger, a heater, numerous custom bent copper pipes with fittings, PVC pipes and fittings, electronics, switches and gauges, and removable external panels. The custom coolant reservoir is unique in that it serves as a structural component of the box, forming the external shape of one third of the entire rack mounted shape. All of these components are combined into a 17-inch (43.2-cm) X 5.25-inch (13.3-cm) X 17-inch (43.2-cm) enclosure.


To reduce the size of this unit sufficiently, WMD had to rethink the original plastic coolant reservoir.

That reservoir required a large amount of volume that would no longer be available in the new design. To overcome this difficulty, WMD engineered an aluminum coolant reservoir that is integral to the structure of the assembly itself. This, combined with corner posts and the exterior panels, creates a rigid structure for mounting the remaining components.

ER-2 Doppler Radar System Enclosure :

The Electronics Enclosure was designed and built for a Doppler Radar instrument that is housed in the nose of the NASA ER-2 high altitude research aircraft. The system had a previous design for an enclosure to hold its data processing electronics. The old design was difficult to install, did not provide an adequate thermal environment for the electronics, and was not aesthetically pleasing.

The old design had an outer skin that was bolted to hard points in the nose of the ER-2. The electronics were then slid into and bolted to the outer skin. The new design shown is built around a standard off the shelf card rack (shown in orange in the middle of the enclosure). The main body of the enclosure is 19.9 inches (50.5 cm) wide x 11.9 inches (30.2 cm) tall x 12.25 inches (31.1 cm) deep to approximately match the existing enclosure. The mounting "ears" on the side increase the overall width to 23.9 inches and these attach the enclosure to the mounting points in the ER-2 nose. This design allows all of the electronics to remain enclosed and gives easy access to the mounting points.

The previous design continuously pulled very cold air into the box from the outside environment. This was done in anticipation that the electronics would need to be cooled and if they needed to be heated, approximately 100 W of heat could be added to the incoming air through heaters. However, it was learned that the electronics were being cooled below freezing even with the extra heating. This was not a problem during operation since there is little moisture at the operating altitude above 60,000 ft.

However, as the aircraft descended, the cold electronics would allow water to condense. This could cause electrical short circuits. The new design seals the internal electronics from the outside air. The internal air is very well circulated in order to cool hot spots and heat cold spots using convection. The new design should keep the electronics warm enough to eliminate the previous condensation problems.

The customers for this project are pleased with the appearance of the new design. Therefore, the aesthetic requirements have been met.

Cloud Radar Data System Enclosure :

The Cloud Radar System was designed to fly on the NASA ER-2 aircraft. We designed an enclosure for the data system electronics cards, power supply, and hard drive. The design needed to fit into the tight space of the ER-2 Super-Pod mid-body.

Similar boxes had problems with condensation forming on their electronic components: the electronics cooled to below freezing when the ER-2 flew at a 65,000-ft (19.8-km) altitude, and water condensed on the electronics as the aircraft descended to a warmer and more humid altitude. To address these problems, we designed a sealed enclosure with twelve fans that continuously circulated air inside. This evenly distributed heat from the electronics to other areas. Hot spots were cooled and the system stayed warm enough to prevent condensation.

Since a sealed enclosure could cause overheating during operation on the ground, we designed adjustable vents that allow outside air to be pulled into the box, blown across the electronics, and vented outside. If necessary, the vent area could be adjusted so that outside cooling air entered the box during flight.

We also designed a new handle for an existing sealed hard-drive enclosure. This new hard drive used a cam-mechanism to reduce the force required to remove the hard drive from its connector.