The aircraft passed the Functional Test Flight ahead of an extensive flight test campaign, paving the way for the Block 4 upgrade.
On Jan. 6, 2023, the 461st Flight Test Squadron conducted the first flight of an F-35 in the Technology Refresh 3 (TR-3) configuration at Edwards Air Force Base, California. The first aircraft chosen to receive the TR-3 upgrades is the first production-model F-35 delivered to the Air Force, better known as AF-7, which is also specially instrumented for developmental flight testing.

Maj. Ryan “BOLO” Luersen, a U.S. Air Force experimental test pilot, executed a functional check flight (FCF) profile to verify aircraft airworthiness and system stability after the upgrades. The 50-minute flight, which took the jet to 35,000 feet at speeds just shy of the speed of sound above the Mojave Desert, marked the start of an extensive flight test campaign. The Air Force says that developmental and operational test flights will continue through 2023 to ensure safety and prove warfighting capabilities.

“This is a significant achievement for the F-35 program,” said Air Force Lt. Gen. Mike Schmidt, program executive officer, F-35 Joint Program Office. “TR-3 is the F-35’s critical computer processing electronics upgrade that will continue to provide all our pilots with the capability they need to be successful against any adversary. There is still a lot of work to do and I am confident that our industry partners and government team will get the job done.”

Here is how the Air Force described the Technology Refresh 3 in the press release:

TR-3 provides the computational horsepower to support modernized Block 4 capabilities for the F-35 including: new sensor suites, more long-range precision weapons, improved electronic warfare features, more powerful data fusion, and increased cross-platform interoperability. These capabilities provide the warfighter a combat-edge to identify, track, engage, and survive against advanced air, ground, and cyber threats. TR-3 significantly updates core processing power and memory capacity, which will allow the F-35 to run advanced software packed with state-of-the-art warfighting capabilities.

“The F-35 Integrated Test Force at Edwards AFB is proud to have executed yet another first-flight within the F-35 program,” said Air Force Lt. Col. Christopher Campbell, commander of the 461st Flight Test Squadron and director of the F-35 Integrated Test Force. “Technology Refresh 3 modernizes the computational core of the F-35 air vehicle. Therefore, new TR-3 hardware and software affect nearly every aircraft feature. Today’s event was just the start of a comprehensive flight test campaign that will both verify and improve the safety, stability, and performance of the whole F-35 weapon system in this new configuration.”

An F-35A takes off from Edwards Air Force Base, California, on January 6, 2023. A developmental test team from the 461st Flight Test Squadron conducted the first flight of an F-35 in the Technology Refresh 3 (TR-3) configuration at the base. (Courtesy photo – F-35 JPO)

As we already reported, Tech Refresh 3 is considered essential in order to deliver the Block 4 upgrade and the future ones, being described as the IT backbone for all future improvements. TR-3 will be installed in all new production aircraft and retrofitted on all the F-35s already in service back to Lot 10. The retrofit, which requires 14 days of downtime, will be performed during scheduled maintenance. This way the F-35 will migrate to the open-system architecture and exploit all its advantages, like adding new or improved capabilities on operational aircraft very quickly and at a reduced cost.

The TR-3 program has overcome technical complexity challenges with hardware and software, and is now on-track to deliver capability to the U.S. and its allies starting in 2023. The government and industry team continue to find innovative ways to ensure delivery of critical capabilities to defeat future threats. Lessons learned in the execution of the TR-3 program will be applied across the entire Block 4 modernization program, says the press release.

Over 75 major upgrades expected to be included in the upcoming Block 4 F-35. Among the upgrades there are enhancements of the Electronic Warfare capabilities, radar and electro-optical systems, weapons, cockpit and navigation systems. Some of these upgrades will be delivered in increments until the final configuration, for which an engine upgrade might be required in order to provide more power to all the systems.

Among the unclassified upgrades there are a next generation Distributed Aperture System, a new Integrated Core Processor, cooling systems enhancements, new Electronic Warfare processor and antennas. Unclassified slides from Lockheed Martin also show Auto Ground Collision Avoidance System integration, a new Open System Architecture, Multi-Domain Operations and Missile Defense capabilities, Manned-Unmanned Teaming and extended range with the use of external fuel tanks.

A recently confirmed upgrade that will come with Block 4 is the new APG-85 AESA radar, which will replace the current APG-81. The majority of the details about the Block 4 upgrades, however, are classified. Often considered the F-35’s most ambitious upgrade, the Block 4 is meant to help keep the Lightning II’s fighting edge over potential adversaries through 2070.