Leonardo solved an overheating issue with its miniaturised P5 Combat Training System (CTS) internal subsystem on the Lockheed Martin F-35 Lightning II Joint Strike Fighter (JSF) by installing a radiator with the liquid coolant down the middle.
Chris Lettiere, Leonardo's vice-president for engineering, told Jane's on 11 December that the repacking of the pod into an internal form factor for the F-35 was a challenging redesign and repacking effort. The baseline externally carried podded system is about 63.5 kg and 76.2 m3 , while the F-35 variant is an internally mounted unit one-quarter the size and weight of the podded system. Installing the subsystem in the aircraft subjects it to high temperatures that it would not experience in a wing pod.
Lettiere said although both systems face difficult environments such as shock, vibration, and temperature, significant differences in those environments drove very different design and qualification approaches. Furthermore, he said, the redesign and repackaging into a significantly denser form factor required multiple proprietary engineering innovations.
Lettiere said the functionality and capability of the two variants are equal, with only two exceptions: the F-35 subsystem incorporates a National Security Agency (NSA)-certified Type-1 encryption unit for secure datalink communications and the externally carried pod incorporates its own GPS/inertial navigation system (INS) while the F-35 internal variant obtains tracking information from the host aircraft.
The proximity to heat was one of two technical challenges Leonardo faced when compressing P5CTS for the F-35. Lettiere said on 6 December that the other was the difficult shock and vibration environment the subsystem faced being on top of the aircraft's 25 mm gun. The F-35A has a General Dynamics GAU-22/A four-barrel gun in the port engine air-intake trunk upper surface. The F-35B and F-35C each has a 'missionised' GAU-12 cannon in externally mounted, low-observable pods.
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