General Atomics UAV cooling solution

The MQ-9 Reaper, used by the United States Air Force, provides reconnaissance, surveillance and precision striking capabilities. This unmanned aerial vehicle (UAV) gives a tactical advantage for U.S. forces around the globe, but the sensitive electronics require proper ground thermal management prior to takeoff. Inadequate cooling can force mission critical operations to abort.

General Atomics, a San Diego-based defense company and industry leader in remotely piloted aircraft solutions, required a flight line ground support cooling system for MQ-9 UAVs. Our Air Rover engineers, leaning on experience with precision-engineered environmental control units (ECUs) and military application integrated systems, rose to meet the mission critical challenge.

Sensitive aeronautical electronics require thermal management

Electronics in the avionics bay of the MQ-9 Reaper tend to overheat. Proper ground thermal management is necessary to mitigate this issue and ensure optimal operating conditions are maintained. Otherwise, cameras and radars in the intelligence surveillance reconnaissance (ISR) system can become unable to operate, or batteries can fail to charge prior to takeoff and lead to a mission failure.

Additionally, remote piloted aircrafts (RPAs) often operate in isolated desert climates where resources may not be readily available to repair support equipment. Warfighters depend on ECUs to cool effectively and perform reliably, without needing assistance from resources that are potentially hours or days away.

The scope of the project consisted of developing, building and testing a turnkey integrated flight line ground support cooling system for the UAVs. An integrated system is necessary for the cooling system to easily and efficiently reach the UAV on the tarmac in between missions. The package needed to include a ruggedized ECU with ducting (for heating, ventilation and air conditioning) and a power generator mounted on a runway-certified, tactical trailer.

Air Rover assigned a team of engineers, sheet metal designers, a senior QA/contract manager and an account manager to work through General Atomics’ RFP. In the span of five months, we designed a precise and reliable cooling solution for this critical aerospace application.

Solving airflow and control panel challenges with a consultative engineering team

Right away our engineers were collaborating closely with the client, learning the demands and constraints of the MQ-9 Reaper’s cooling needs and identifying difficult spec items early in the process.

The first challenge we faced was the airflow specification, which required 2,000 CFM of air to move over 40 feet of 16 inch diameter ducting that then reduced to 8 inches in diameter to fit a specialized aircraft duct connector. Without enough airflow capability, adequate cooling can’t be achieved, no matter how many tons of cooling you provide.

We overcame the airflow challenge by selecting a natively motorized, higher horsepower reverse-inclined impeller in lieu of a standard forward-inclined centrifugal blower with AC motor assembly. The more powerful motorized impeller met the airflow requirement against the duct restrictions and provided added reliability as well.

The application also required a single integrated control panel for both the ECU and the power generator, which posed another challenge. Our standard ECU comes with a separate remote control box and control cable interface, but to meet the customer’s needs we eliminated the standard remote control box. Instead we redesigned the power generator control panel’s layout to create enough space to integrate the ECU components (controllers, switches and indicators) and hard-wire the ECU control cable directly to the new generator control panel. This resulted in a control panel tailored to their exact needs.

Other customizations included a return air louvered grill (instead of the standard return air duct) to provide 100% outside air for the open-loop configuration. We also added a limit switch to the generator power transfer switch to allow for rapid system shutdown (ECU and power generator) in the event of an emergency on the tarmac.

Finally, with a custom production facility on-site, our engineers diligently worked with sheet metal designers to streamline the engineering and building process.

Integrated ground support cooling system for the MQ-9 Reaper

Following the design stage, we tested the product (verifying metrics such as thermal and air flow performance, trailer maneuverability and towability) to ensure the product was field-ready. After the unit successfully passed testing parameters, the unit was ready to guarantee reliability in even the most demanding UAV operating environments.

The project took approximately five months from start to finish, and resulted in an integrated flight line ground support cooling system with 5 tons of cooling capacity for their MQ-9 Reapers. Additionally, General Atomics was so impressed with the flight line system that they began using it to cool their MQ-1 Predators, too. With this precision engineered system, the RPAs can reliably perform mission critical strikes, coordination and intelligence reconnaissance.


Achieve reliable, precision-engineered solutions

Your engineering team faces complex cooling challenges – but not impossible. Our experienced and flexible team will design ECUs to meet even the most demanding environments, and can work through previously unsolved (or unanticipated) challenges in your mission critical application.

Take the next step towards your precision-engineered ECU solution and speak with an Air Rover engineer today.