Stealth Questions: What's the Difference Between F-35A and F-35B?

Charlie Gao

Key Points: The F-35B is worse.

Often times, the F-35 has been colloquially referred to as one aircraft in the media, or various versions of the F-35 have been conflated with each other. However, despite their shared “program,” the standard F-35A and the VSTOL F-35B are very different and even feature different fuselages in addition to the additional complexity introduced in the B variant.

The primary difference between the two jets is that the B is less nimble in general. There are a multitude of reasons for this, many of which stem from the necessity for the B to have VSTOL capability.

The B variant is considerably “fatter” and bulkier than the F-35A as a result of the integration of the lift fan. This image overlays the fuselage shape of the F-35A over the F-35B, with the B being in orange. As a result of the increased frontal profile, the B has more drag.

This makes it slower to accelerate and harder to turn. Practically, the F-35B takes approximately eighteen more seconds to accelerate from Mach 0.8 to Mach 1.2 compared to the F-35A.

The increased profile and different weight also affects the potential turn rate, but practically, the F-35B is limited to pulling 7Gs maximum to avoid damage to internal components.

The B also has less internal fuel, but this is to be expected as it has additional parts that take up space in the fuselage that the A doesn’t. This limits its effective combat range versus the A, but it still is far superior to the other VSTOL aircraft that preceded it.

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