Running the APG-85 more than doubles the cooling needed for the entire aircraft — from roughly 30 kW today to a future requirement of 62 kW to 80 kW.
APG-85, the F-35, and a surprising thermal signature
Lieutenant General Greg Masiello told the Senate Armed Services Committee that the Northrop Grumman APG-85 radar destined for US F-35s imposes dramatically higher cooling demands. He said the radar’s “full capability” could not be exploited without planned engine upgrades and a “complex cooling system.” The program expects upgraded engines in 2031, while the cooling upgrade will arrive “a few years later.” Masiello also disclosed that F-35Bs have been delivered to the US Marine Corps without radars, and that the APG-85 is not interchangeable with the current APG-81 and will not be exported to other countries.
Why the cooling figure matters: power, waveforms and HPM
The jump in cooling requirement is notable because it implies a large increase in transmitter energy. High-power microwave (HPM) systems are a form of directed energy that attack radio‑frequency devices — radars, communications radios and passive receivers — with pulses strong enough to force systems offline or cause physical damage. The source notes that a radar needing far more cooling “must be pumping remarkably greater energy out through its antenna,” and that such power levels point to HPM capability rather than conventional sensing or jamming alone.
Technical lineage: APG-81, gallium-nitride and CHAMP
The APG-85 follows an evolution noted in the source material. Reports have previously suggested that the baseline APG-81 radar on the F-35 has an HPM-like mode. The APG-85 uses gallium-nitride technology, which the source says is more efficient than the APG-81’s gallium-arsenide: “more energy on target for the same input power,” and broader frequency-band operation, attributes pertinent to attacking a variety of HPM targets.
Longstanding US work on HPM is also cited. Boeing’s Counter‑electronics HPM Advanced Missile Project (CHAMP), built for the Air Force Research Laboratory, demonstrated in 2012 a missile that could disable multiple electronic targets in a single sortie. CHAMP became a congressional favourite after that demonstration, but a senior Air Combat Command leader said at a 2015 conference that it “cost way too much.” Presenters at the same event mapped a path toward more compact, beam‑steered, efficient HPM systems and “smart waveform” weapons, including concepts mounted on uncrewed aircraft.
International programmes: Britain, Typhoon, and GCAP/ISANKE
The United States is not the only actor. British government and industry researchers, including Leonardo (formerly Ferranti), have worked with HPM since the 1990s. QinetiQ commissioned an HPM test facility called Orion in 2002; in 2006 there were reports of a proposal to test a reusable HPM generator on a Northrop Grumman BQM-145 drone. In 2007 an Advanced Radar Targeting System (ARTS) was tested on a Tornado; hardware from that work fed into an experimental Bright Adder radar and eventually into the ECRS Mk 2 radar for upgraded Royal Air Force Typhoons. The source calls ECRS Mk 2 “unique to the RAF and costly,” and links that cost to the perceived importance of its hinted-at electronic-attack modes.
The multinational Global Combat Aircraft Program (GCAP) is also described. Its sensor suite, ISANKE (Integrated Sensing and Non‑Kinetic Effects), and the GCAP concept include “two megawatt-class integrated generators on both engines” and an emphasis on cooling. The Excalibur testbed, a modified Boeing 757, carries large electronic warfare apertures as part of that development work.
Testing, effects assessment, and operational constraints
Speakers at a US air power conference in May — the author notes the event was held under Chatham House rule — highlighted practical constraints. Some nonkinetic effects are “fragile,” meaning they could be countered if their mechanisms are revealed. Testing HPM in the continental United States is difficult because of “wide-ranging effects” and uncertainty about how signals might “spill out”; one speaker warned of possible interference with GPS satellites and suggested even ground-reflected signals could harm satellite receivers, adding that “the burden is on us to prove the negative.” Another speaker conceded, “We don’t know how to do BDA (bomb damage assessment),” noting adversary systems can be programmed to feign damage or restart after transmissions cease.
What this means for the US Marine Corps, policymakers, and technologists
- US Marine Corps: The disclosure that some F-35Bs were delivered without radars will focus attention on operational gaps until APG-85 installations, engines and cooling upgrades are fielded.
- Policymakers and procurement leaders: The APG-85’s non-export status, late deliveries, and cascading upgrade timeline (engine upgrade expected in 2031; cooling a few years later) raise schedule and acquisition questions that will bear on force plans.
- Technologists and test engineers: The drive toward gallium-nitride transmitters, higher onboard power generation, and large cooling budgets highlights technical trade-offs between sensing, directed-energy effects, and the platform’s thermal and electrical architecture — and underscores how hard testing and BDA remain for HPM effects.
The record in the source indicates a long, deliberate arc from experimental HPM demonstrations to sensors built with HPM-like attributes, but also a technology still bounded by cooling, power, testing and assessment limits. The APG-85’s cooling numbers — 62 kW to 80 kW versus today’s ~30 kW — and the stated sequencing of engine and cooling upgrades crystallise the dilemma: designers appear confident enough to push radar power toward directed-energy regimes, yet the infrastructure and assurance required to employ such effects safely and reliably remain works in progress.
