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The third-ever F-16C model ever built, departed on May 7, 2025 Edwards Air Force Base (AFB) for the last time enroute to the 309th Aerospace Maintenance and Generation Group at Davis-Monthan AFB, Arizona.
As the photos in this post show, James Sutton, 412th Maintenance Instrumentation Squadron flight test instrumentation technician, was a former dedicated crew chief for F-16C Block 25 tail number 83-1120 and re-enacted a walkthrough inspection, for the last time…
83-1120 had a great career.
According to F-16.net, this Viper had its air intake modified to a big inlet standard (MSID intake) and with GE engine prior to 1993. It was then modified with a large (MCID) inlet and a GE-110 engine.
83-1120 was then the first F-16 to be fitted with Conformal Fuel Tanks (CFTs) and fitted with internal FLIR to reduce the drag associated with LANTIRN pods after Lockheed Martin proposed the F-16 ES (Enhanced Strategic), a reach-extended version of the F-16 for the Israeli Strike Fighter competition in 1994. The F-16ES featured an unrefueled mission radius of 1,025 mi. increasing the range of the Viper by 40%: to reach such a fit 83-1120 had with a 320-gal. centerline tank and two 600-gal. underwing tanks besides CFTs. Its combat load was made of two 2,000-lb. bombs and four air-to-air missiles. After losing the Israeli contract to the F-15I, some ES technologies (like the CFTs) were used in new F-16 models like the Block 60. This Viper was then demodified as the F-16ES test bed.
As we have already explained, 83-1120 was even modified with a diverterless supersonic inlet, or DSI, developed for the Joint Strike Fighter (JSF) – now the F-35 Lightning II – program. According to Code One Magazine, 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).
Photo credit: Lockheed Martin and Giancarlo Casem / U.S. Air Force
