- Lockheed Martin received a $177.5 million contract modification on April 23, 2026, to build three new F-35 flight science aircraft, one per variant.
- Work spans seven locations across the U.S., U.K., and Denmark, with completion expected by April 2031.
Lockheed Martin has secured a $177.5 million contract modification to design and build three new F-35 flight science aircraft — one for each variant of the jet — as the U.S. military moves to prevent a testing capability gap and prepare the program for its next major upgrade block.
Naval Air Systems Command awarded the modification on April 23, 2026, at Patuxent River, Maryland. The deal is a modification to an existing cost-plus-incentive-fee contract and covers all touch labor and reach-back engineering needed to produce the three replacement aircraft. One jet will be built for each F-35 variant: the Air Force’s conventional F-35A, the Marine Corps’ short takeoff and vertical landing F-35B, and the Navy’s carrier-capable F-35C. Completion is expected by April 2031.
Funding for the award draws from multiple sources. The Air Force and Navy are each putting in $18.8 million in fiscal year 2025 research, development, test and evaluation funds. F-35 cooperative program partner nations are contributing $8.4 million. Of the total obligated at award — $37.7 million — the entire amount expires at the end of the current fiscal year. T
Work will be distributed across seven locations in three countries. Fort Worth, Texas, where Lockheed Martin’s F-35 production line sits, will handle the largest share at 30 percent. El Segundo, California, accounts for 25 percent of the effort. Warton, United Kingdom — home to BAE Systems’ F-35 work — picks up 20 percent. The remaining work is split between Orlando, Florida at 10 percent, Nashua, New Hampshire and Grenaa, Denmark at 5 percent each, and Baltimore, Maryland at 5 percent.
These are not combat jets — they are purpose-built or purpose-modified airframes instrumented to measure and validate aerodynamic, structural, and performance characteristics across the flight envelope. When a major software or hardware upgrade enters development, flight science aircraft serve as the controlled test beds that generate the data needed to certify it for operational use. They fly edge-of-envelope profiles that would be too risky or too instrumentation-intensive for standard production jets.
The original flight science aircraft supporting the F-35 program have been flying since the program’s early developmental years. After more than a decade of intensive test flying, those airframes are aging out. The contract explicitly cites the need to prevent a capability gap — a period during which the program would lack the dedicated test assets required to support ongoing and future flight test campaigns. Replacing them now ensures continuity as the program pivots toward what the contract describes as holistic testing of Block 4 capabilities.
Block 4 is the F-35’s current major upgrade effort, a sweeping package of software and hardware improvements that significantly expands the jet’s weapons carriage, sensor integration, electronic warfare performance, and pilot interface. The upgrade has been in development for years and is rolling out incrementally across the fleet, but many of its capabilities still require structured flight test validation before they can be cleared for operational use. New flight science aircraft give the program the tools to run those tests without being constrained by the limitations of aging test airframes.
The F-35 program remains the largest defense acquisition in U.S. history by total projected cost. More than 1,000 jets have been delivered to the U.S. and partner nation operators since production began, and the program is expected to remain in production well into the 2030s. Sustaining robust flight test infrastructure is not incidental to that timeline — it is foundational. Without the instrumented test aircraft to validate new capabilities, the upgrade pipeline stalls, and operators waiting on cleared software or weapons integrations are left without the improvements they have already funded.