F-16 Fighting Falcon Production Block Designations

As the design of the F-16 evolved, improvements were incorporated during the production phase. These were designated as Type Versions (also known as miniblocks or sub-blocks) and Blocks, and given alpha-numeric designations. This document will attempt to describe those designations based on the research I have done. It is not meant as a definitive history of the F-16 - others have already done that. My purpose is to provide a resource, primarily for scale modelers, to identify just which airplane had which parts (engine, inlet, cockpit) when it was built.

The Prototypes

There were two YF-16 prototypes aircraft built to compete against Northrop's YF-17 in the Light Weight Fighter (LWF) competition in the mid-1970s. These two aircraft, serial numbers 72-01567 and 72-01568, preceded the award of a production contract so they are only identified by their serial numbers. Both airframes were powered by Pratt & Whitney F100-PW-100 engines.

The first prototype was later fitted with movable canards on the intake to conduct testing of unconventional methods of flight control. It was then known as the YF-16/CCV.

Full Scale Development

After General Dynamics won the LWF competition and was awarded the F-16 production contract, eight aircraft were built as Full Scale Development (FSD) aircraft - six single-seat F-16As (75-0745 through 75-0750) and two two-seat F-16Bs (75-0751 and 75-0752).

FSD airframe 75-0745 was later fitted with the General Electric F101 DFE for testing. This ultimately led to the F110-GE engine being offered as an option in later F-16C/D production aircraft.

F-16XL

Two of the FSD airframes were later converted to the unique F-16XL variant. Airframes 75-0749 and 75-0747 became F-16XL-1 and F-16XL-2, respectively. F-16XL-2 was a single-seat FSD airframe, and was rebuilt as a two-seat F-16XL and the F110-GE-100 engine replaced the F100-PW-200. F-16XL-1 retained it's F100-PW-200 engine. Both airframes were fitted with the extended rudder dorsals and drag chutes to accommodate the heavier weight of the modified aircraft when landing.

AFTI / F-16

In 1979 FSD airframe 75-0750 was later modified with a dorsal spine and canards were fitted to the intake, much like the earlier YF-16/CCV. The modified aircraft became known as the AFTI/F-16. AFTi is an acronym for Advanced Fighter Technology Integration. The aircraft flew as a test platform until 2001 when it was retired and flown to the U.S. Air Force Aviation Museum at Wright-Patterson Air Force Base in Dayton Ohio.

F-16 / 79

FSD airframe 75-0752 was later fitted with the General Electric J79-GE-119 engine for testing. The intake was also modified with an enlarged splitter plate, and the aft fuselage was extended to accommodate the longer J79 engine. A 2000 pound steel heat shield was also added to protect the airframe structure around the engine. With higher fuel consumption, lower thrust and greater weight, the modification was never put into production. The aircraft was later refitted with the standard F100-PW-200 engine, and returned to General Dynamics as a testbed airframe.

Block 01/05/10

The first production F-16A and F-16B aircraft were called Block 01 airframes. They were quickly followed by the Block 05 and Block 10 versions. All three blocks are virtually identical externally, all were powered by the F100-PW-200 engine, used the Westinghouse AN/APG-66 radar, and all had the smaller square-tipped horizontal stabilizers. Blocks 01 and 05 were characterized by black radomes early in their careers, later replaced with the now standard gray radomes. All Block 01 and Block 05 airframes were upgraded to Block 10 after they were in service.

Block 15

Block 15 was the first major change to the production F-16, also known as the MSIP (Multinational Staged Improvement Program) mod. Most noticeable were the larger horizontal stabilizers and the re-arrangement of some of the instruments in the cockpit. Less noticeable were internal changes that included inlet hardpoints for mounting sensor pods, stronger wing hardpoints, and a host of other internal changes. The Block 15 aircraft were all equipped with the same F100-PW-200 engine and AN/APG-66 radar.

Block 15 ADF

A later variant, called the Air Defense Fighter (ADF), was a modification to one F-16A Block 10 (80-0525) and 216 Block 15 aircraft in U.S. service. ADF mods included a different rudder dorsal housing, AIM-7 capability, IFF antennas (bird slicers) on the top of the nose and the bottom of the intake, a spotlight mounted in the left side of the nose, and a host of other internal changes. Twenty four two-seat F-16B Block 15s were converted to ADF configuration but they did not get the modified dorsal housing or the spotlight. It has been widely and incorrectly reported that the new bulges in the dorsal housing housed the antennas of the AN/ARC-200 radio that was part of the ADF upgrade. In fact the bulges cover parts of the hydraulic rudder actuator system, which was relocated to install the AN/ARC-200 in the original actuator location. The F-16B/ADF did not have the AN/ARC-200 installed, so the hydraulics remained in their original locations and there was no need for the modified dorsal housing. Of all the photographs of ADF birds I have seen, only about half seems to have the IFF antenna farms. I don't know if the systems had not been installed or if they had been removed at the time of the photograph.

Block 10/15 MLU

The Mid Life Update (MLU) program refurbished older NATO (not USAF) Block 10/15 airframes with the same MMC, HUD, CMFDs, etc. and brings them up to essentially Block 20 avionics standards. The MLU-modified (referred to as F-16AM and F-16BM) aircraft however are not Block 20 airframes, but MLU-modified Blocks 10 and 15. Note the difference in the mounting of the IFF antennas (compared to the ADF variant).

Block 20

All Block 20 aircraft are new production aircraft with much more capable avionics and many structural upgrades, including the same wings and aft fuselage as the Block 50/52 airframes. In fact Block 20 production did not start until after Block 50/52 production. A new Modular Mission Computer (MMC) is the core of the avionics upgrade which includes an F-16C/D style cockpit with Color MFDs (CMFDs), a new HUD and the AN/APG-66(V2A) radar. The Block 20 can also carry sensor pods on the intake stations, and on two-seat models the rear seat has the same HUD repeater monitor as the Block 40/42. All Block 20s are powered by the F100-PW-220 engine with NSI (small mouth) intakes.

Block 25

Block 25 were the first F-16C and F-16D aircraft, most commonly called the 'second generation' of the F-16. Changes were numerous, but largely internal. Externally, Block 25 introduced the enlarged rudder dorsal and a slightly different vent pattern on the gun muzzle panel. The cockpit was completely redone, with 4"x4" monochrome (green) Multi-Function Displays (MFDs) replacing the older Stores Control Panel (SCP) LED display and many of the dial-type indicators ("steam gauges"). A larger HUD, a new AN/AGP-68 radar, and many other improvements found their way into the Block 25. All Block 25 aircraft were powered by the F100-PW-200 engine, and most have been upgraded to the -220E with increased thrust and Digital Electronic Engine Control (DEEC).

Block 30/32

Block 30 F110-GE on the left, Block 32 F100-PW on the right, AN/ALR-69 "beer can" antennas

Block 30 introduced the General Electric F110-GE-100 engine as a powerplant option. This was the first time any engine other that a Pratt & Whitney had been offered in a production F-16.

Block 32 airframes were powered by the F100-PW-220 engine. In spite of the so-called Common Engine Bay, the two powerplants are not interchangeable, thus the two different production Blocks (30 & 32).

Block 30/32 also added the capability to carry and fire the AIM-120A AMRAAM missile, additional chaff/flare dispensers, and RWR antennas ("beer cans") on the leading edge flaps for the AN/ALR-69 RWR.

Inlet Design

MCID big mouth inlet on the left, NSI small mouth inlet on the right

A matter of much debate, especially in the scale modeling community, is the issue of different intakes fitted to the Block 30 aircraft. The F110-GE engine has a higher air mass flow capability than the F-100-PW engine. This resulted in the design of the misleadingly-named Modular Common Inlet Duct (MCID), also known as the "big mouth" intake. The original intake, referred to as the Normal Shock Inlet (NSI), is now called the "small mouth" intake.

All Block 32 airframes have the NSI small mouth intake mated to their F100-PW engines. The MCID large mouth intake is fitted to many - but not all - F110-GE powered Block 30s. One cannot assume that just because a Block 30 airframe is powered by a F110-GE engine that it has the larger MCID intake. In fact some 174 Block 30 airframes had NSI small-mouth intakes installed - and this includes all of the Block 30 F-16N and TF-16N aircraft delivered to the U.S. Navy. One cannot go by production serial numbers either as there was no clean break when the switch occurred.

I have the NSI/MCID data in a spreadsheet for Block 25/30/32 aircraft and have converted the spreadsheet into an HTML document. This data covers from the first F-16 to have a GE engine installed to the last Block 30/32 built. If you want to confirm which intake is installed on a particular Block 30 airframe you can look up the USAF serial number here. Be forewarned - when I took the Excel file, copied it into a table in a Word document, then had Word write it out as a web page the resulting HTML file is over 26,000 lines long and over 1.4 MB in size !!! (Now you know why I use Notepad as my web page editor...)

NF-16D VISTA

Of course there is one exception to the rule - a single aircraft 86-0048 designated NF-16D was built as a Variable Stability in-flight Simulator Test Aircraft (VISTA) was built with an F100-PW-229 engine and MCID large mouth intake. It was later changed to an F110-GE-100 engine with a special Asymmetric Vectoring Exhaust Nozzle (AVEN) and flown as the VISTA/MATV - Multi-Axis Thrust Vectoring - program. Afterwards the AVEN was replaced with a standard F110-GE nozzle. The engine has now been changed to the F100-PW-229 engine with a special thrust-vectoring nozzle and is used to support F-22 and JSF flight handling quality research at Edwards AFB.

Block 40/42

Block 40/42 F-16s introduces features that enhance the air-to-ground role without sacrificing the air-to-air role. This includes a Wide Angle Raster (WAR) HUD capable of displaying sensor imagery, LANTIRN (AN/AAQ-13 navigation pod and AN/AAQ-14 targeting pod) capability, an upgraded AN/APG-68(V) radar, GPS navigation, automatic terrain following, and many other features. Block 40/42 F-16D models have an extra HUD repeater display mounted on top of the glareshield in the rear cockpit. This allows the back-seater to see the same sensor imagery and symbology as the front seater sees through the WAR HUD.

Externally, Block 40/42 airframes have larger main gear wheels and tires, and the main gear doors have been bulged outward to accommodate them. The landing light has been moved from the starboard main gear door to the front of the nose gear door to avoid having the LANTIRN pods cast huge shadows during landing/takeoff. Block 40/42 F-16s are often called "Night Falcons" because of their increased ability to fight at night.

All Block 40s have the F110-GE-120 engine with MCID large mouth inlets, and all Block 42s have the F100-PW-200 engine with NSI small mouth inlets. In the photos above, the MCID inlet is on the left and the NSI inlet is on the right.

Block 50/52

Block 50/52 F-16s combine the structural improvements of the Block 40/42 with avionics upgrades. The radar is further upgraded to an AN/APG-68(V5), and the RWR is now an AN/ALR-56M. While Block 50/52s can physically carry LANTIRN pods, they have the same WAC HUD as Block 30/32s so they cannot display sensor imagery on the WAC HUD. More commonly seen on Block 50/52s is the AN/ASQ-213 HARM Targeting System (HTS pod) used in conjunction with the AGM-88 HARM missile in the SEAD (Suppression of Enemy Air Defenses) role.

All Block 50s have the F110-GE-129 engine with MCID large mouth inlets, and all Block 52s have the F100-PW-229 engine with NSI small mouth inlets.

The newest Block 50/52s delivered feature the same MMC and CMFDs as the Block 20 and MLU aircraft. USAF has an ongoing program to retrofit all Block 40/42/50/52 aircraft to this standard over the next several years.

Block 50/52 "Plus"

Block 50/52 "Plus" airframes are Block 50/52s with the latest avionics (MMC, CMFDs) and provisions to carry the Conformal Fuel Tanks (CFT). All two-seat "Plus" airframes include the enlarged Avionics Dorsal Spine (described below). They are being offered to export customers.

Block 60

The proposed Block 60 airframes build on the Block 50/52 "Plus" configuration with internal FLIR and other enhancements. They are being offered to export customers.

Avionics Dorsal Spine

LOAN Exhaust Nozzle

Lockheed ground tested the Low Observable Axisymmetric Nozzle (LOAN) on a Pratt & Whitney F100-PW-200 engine in an effort to significantly reduce RCS and IR signature emissions from the engine. While the original intent was to develop technologies for the upcoming JSF program, the technology could be used to retrofit F-16s worldwide. The nozzle improves stealth through a combination of technologies, including geometrical shaping, cooling systems and special internal and external coatings. A side benefit is reduced maintenance costs as the advanced cooling system is expected to more than double the life of the divergent flaps in the nozzle.

JSF Diverterless Supersonic Inlet

In 1996 Lockheed tested an experimental Diverterless Supersonic Inlet on F-16C 83-1120. It was primarily a trade study conducted as part of the JAST/JSF program. Rather than writing a long description of this unique mod I direct your attention to the excellent article appearing on the Code One website.