Military Aviation


By eliminating radar reflections between the diverter and the aircraft’s skin, diverterless supersonic inlet crucially improve the F-35’s very-low-observable characteristics

The interesting photos in this post show an F-16 modified with diverterless supersonic inlet, or DSI, developed for the Joint Strike Fighter (JSF) – now the F-35 Lightning II – program. At high aircraft speeds through supersonic, the bump in the inlet works with the forward-swept inlet cowl to redirect unwanted boundary layer airflow away from the inlet, essentially doing the job of heavier, more complex, and more costly diverters used by several current fighters. The flight test program consisted of twelve flights flown in nine days in December 1996.

Initial research into the DSI was done by Lockheed Martin in the early 1990s. The first Lockheed DSI was flown on Dec. 11, 1996 as part of a Technology Demonstration project. It was installed on a F-16 Block 30 fighter, replacing aircraft’s original intake diverter. The modified F-16 demonstrated a maximum speed of Mach 2.0 (Mach 2.0 is the F-16’s clean certified maximum speed) and handling characteristics similar to a normal F-16. It was also shown that subsonic specific excess power was slightly improved.

The DSI concept was introduced into the Joint Advanced Strike Technology (JAST, which later became JSF) program as a trade study item in mid-1994. It was compared with a traditional “caret” style inlet. Than a DSI was incorporated into the design of the Lockheed Martin F-35 Lightning II after proving to be 30% lighter and showing lower production and maintenance costs over traditional inlets while still meeting all performance requirements.

Traditional aircraft inlets contain many heavy moving parts. In comparison, DSI completely eliminates all moving parts, which makes it far less complex and more reliable than earlier diverter-plate inlets. The removal of moving parts also reduces the overall weight of the aircraft.

DSIs also crucially improve the aircraft’s very-low-observable characteristics (by eliminating radar reflections between the diverter and the aircraft’s skin). Additionally, the “bump” surface reduces the engine’s exposure to radar, significantly reducing a strong source of radar reflection because they provide an additional shielding of engine fans against radar waves.

Analysts have noted that the DSI reduces the need for application of radar-absorbent materials (RAMs).

This print is available in multiple sizes from – CLICK HERE TO GET YOURS. F-35A Lightning II 56th OG, 61st FS, LF/12-5050 / 2014

Photo credit: Lockheed Martin

Artwork courtesy of

Dario Leone

Dario Leone is an aviation, defense and military writer. He is the Founder and Editor of “The Aviation Geek Club” one of the world’s most read military aviation blogs. His writing has appeared in The National Interest and other news media. He has reported from Europe and flown Super Puma and Cougar helicopters with the Swiss Air Force.

Recent Posts

Did you know that even though the A-3 Skywarrior didn’t have a bombsight was the most accurate dive bomber during the Vietnam War?

The A-3 Skywarrior The Douglas A-3 Skywarrior was designed as a strategic bomber for the… Read More

7 hours ago

Unique SR-71 Cockpit photos show why no cockpit demands as much intense focus as a Blackbird’s

The Blackbird The SR-71, unofficially known as the “Blackbird,” was a long-range, Mach 3+, strategic… Read More

1 day ago

Two B-52 Stratofortresses land at civilian airport to test their ability to operate in austere environments

B-52 Stratofortresses land at civilian airport A pair of B-52H Stratofortresses from the 20th Bomb… Read More

1 day ago

Anatoly Kvochur, test pilot who ejected 2 seconds Before the Crash of his MiG-29 and first to land a Fulcrum on American soil, passes away

Russian test pilot Anatoly Kvochur passes away Russian test pilot Anatoly Kvochur passed away on… Read More

2 days ago