Lockheed Martin is building three new F-35 test aircraft for the US military

Published: 2026-04-26 07:01:07 ET LMT

Published on 04/26/2026 at 07:01 am EDT

Key takeaways

The US military has awarded a contract modification worth 177.5 million dollars (around 151 million euros) to Lockheed Martin for the design and construction of three new F-35 test aircraft. The initiative aims to bridge a potential testing gap and prepare the programme for the forthcoming major upgrade, Block 4.

Each F-35 variant will receive a dedicated test aircraft: the conventional F-35A for the Air Force, the short take-off and vertical landing F-35B for the Marine Corps, and the F-35C carrier variant for the Navy. The project is scheduled for completion in April 2031.

Sources of funding

Funding for this project comes from multiple sources. The Air Force and the Navy are each contributing 18.8 million dollars (16 million euros) from their research, development, test and evaluation budgets. International partners taking part in the F-35 programme are providing a further 8.4 million dollars (7.2 million euros).

The work on these new test aircraft will be spread across seven locations in three countries: Fort Worth, Texas; El Segundo, California; Warton, United Kingdom; Orlando, Florida; Nashua, New Hampshire; Grenaa, Denmark; and Baltimore, Maryland.

Flying laboratories

These specialised aircraft are not intended for combat, but serve as flying laboratories. They are equipped with advanced instruments to measure and validate the F-35’s aerodynamic, structural and performance characteristics across the entire flight envelope. When major software or hardware upgrades are under development, these test aircraft provide a controlled environment for data collection. That data is essential to certify upgrades for operational use.

The original flight sciences aircraft used in the F-35 programme have been in service since the early development phases. After more than a decade of extensive flight testing, they are nearing the end of their operational service life. This contract is intended to prevent a capacity gap. Without dedicated test assets, the programme would be unable to support ongoing and future flight tests.

Block 4 testing

Replacing these ageing aircraft ensures continuity as the F-35 programme moves into extensive testing of Block 4 capabilities. Block 4 represents a major upgrade effort, with substantial software and hardware improvements that will significantly enhance the aircraft’s weapons capacity, sensor integration, electronic warfare performance and pilot interface.

This upgrade has been in development for years and is being rolled out progressively across the fleet. Many advanced features still need to be validated through structured flight tests before they can become operational. The new flight sciences aircraft provide the means to conduct those tests, without the constraints of ageing test platforms.

Maintaining a robust test infrastructure

The F-35 programme is the largest defence procurement effort in US history. A robust testing infrastructure is crucial to its continued success and longevity. With more than 1,000 jets delivered to operators in the United States and partner nations since production began, the programme is expected to run into the 2030s.

Without instrumented test aircraft to validate new capabilities, the upgrade pipeline would grind to a halt. Operators waiting for approved software or weapons integrations would be left without improvements they have already funded.

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