Not all that surprising. Looking at the inlets on the F-22 and F-35, one of the clearest defining differences, both in a visual and an aerodynamic sense, comes from the latter having Diverterless Supersonic Inlet, which Lockheed Martin had only invented (and patented) a few years prior to slapping it on the X-35.

NB — Code One is a publication from Lockheed Martin.

The DSI traces its roots to work done by Lockheed Martin engineers in the early 1990s as part of an independent research and development project called the Advanced Propulsion Integration project. The concept was developed and refined with Lockheed Martin-proprietary computer modeling tools made possible by advances in Computational Fluid Dynamics, or CFD.

The DSI concept was introduced into the JAST/JSF program as a trade study item in mid-1994. It was compared with a traditional "caret" style inlet. The trade studies involved additional CFD, testing, and weight and cost analyses. The new inlet earned its way into the JSF design after proving to be thirty percent lighter and showing lower production and maintenance costs over traditional inlets while still meeting all performance requirements.

The DSI inlet used on the JSF has evolved through several design iterations. The shaft-driven lift fan on the STOVL JSF required the use of a bifurcated duct with one inlet on each side. The initial version was essentially the same design used on the lower surface of the F-16 rotated up onto either side of the JSF forward fuselage.

This design had a cowl that was symmetrical about the centerline of the bump. This version of the inlet appears on the X-35 demonstrator aircraft. Later CFD analysis and testing led to refinements of the design to improve its performance at high angles of attack by shifting the upper and lower cowl lips to take advantage of the side-mounted location and to improve high angle-of-attack performance. This later version has been fully tested in the wind tunnel and will be used on the EMD and on production aircraft.

Engineers made enough technical advances during this period that two US patent applications were filed, one dealing with the overall design and the second dealing with the integration process of the new technology. Both patents were granted in 1998.