A Brief History of the F-16

Introduction

In the early 1970s, the US Air Force initiated the Lightweight Fighter (LFX) program to develop an agile, inexpensive dogfighter to augment the newly acquired F-15 Eagle. A number of promising designs arose from the competition, but two designs were selected for the fly-off competition – the General Dynamics' single-engine YF-16 versus the Northrop YF-17. Ironically, the Northrop design was actually LAST on the Air Force’s evaluation list, but many allies looked at the LFX with concern as this aircraft would likely equip their air arms as well. They wanted the potential of twin-engine safety given the experience many had with the single-engined F-104. The YF-17 was the only twin-engine design submitted, so the competition was with the top and bottom contenders. Even though the YF-17 lost to the Air Force, the Navy also demanded twin-engine safety and selected the Northrop design. In even greater irony, the Navy took Northrop’s design and had McDonnell Douglas build it as the F/A-18 Hornet, but that is a whole other story.

Design Innovations

The YF-16 was designed around the Pratt & Whitney F100-PW-100 engine, the same one that powered the F-15 Eagle. So advanced was the F100 engine that there were serious concerns within the US government about exporting the engine outside the United States. As a result, General Dynamics offered a variant of the F-16 that was powered by the General Electric J79 (the same engine powering the F-4, F-104, Kfir, etc.) so that the aircraft could be sold on the export market. Fortunately, these concerns were overcome and the F-16/79 was never put into production. Too bad as the J79 had better instantaneous throttle response and the F-104 would routinely beat the F-16 (and others) in the Baltic drag races.

The YF-16 was a revolutionary design with absolutely no direct connection between the pilot and flight control systems. Pitch, roll, yaw, speed brakes, and lift augmentation were all controlled through computers – fly-by-wire. Its extreme (then) maneuverability was achieved by moving the center of gravity beyond the point of aircraft stability. Only the computers kept the aircraft under control. The aircraft could easily achieve and sustain 9 Gs (nine times the normal force of gravity). One of the innovations to improve the pilot’s tolerance to high-G was to tilt the ejection seat back 30 degrees. How effective this ultimately was will be determined in the history books, but it should be noted that the F/A-22 Raptor, a significantly more maneuverable fighter, does not have its ejection seat tilted aft.

The canopy of the F-16 was also innovative. It uses a very strong polycarbonate to protect the pilot, and does so without a canopy bow obstructing visibility. The flexibility of the polycarbonate allows the aircraft to sustain a serious bird strike without failure of the canopy (though the flex of the impact would sometimes destroy the Heads-Up Display (HUD). The down side of the polycarbonate is that the canopy must be jettisoned to eject – the canopy is strong enough to prevent the seat and pilot from safely passing through.

The F100 engine had some teething problems during its initial years of operations. A phenomenon called stagnation stall would usually cause the engine to shut down and not restart until maintenance could be performed. This was (sort of) okay in the twin-engined F-15, but it got very quiet after a stagnation stall in the F-16 and a number of aircraft were lost to this situation. Pratt & Whitney developed a variant of the F100 for the F-16, the F100-PW-200, to minimize the problem but problems continued with the engine.

Evaluation

When a new weapons system comes online like the F-16, it goes through a series of hands-on evaluations. First up are the Developmental Test and Evaluation folks (DT&E) who run the aircraft through its initial flight tests and start to 'open the flight envelope'. For the USAF, this testing is performed at Edwards AFB in the high desert of California. DT&E of the YF-16 was a new chapter in flight test as this was the first true fly-by-wire aircraft that relied solely on computers for stability. To make the aircraft highly maneuverable, the center of gravity was intentionally designed to be aft of the center of lift.

There was no point in a manual back-up flight control system as the aircraft would simply fly out of the controllability envelope. The only chance of survival in such an extreme case would be the quick rocket flight on the ACES II ejection seat. To avoid such a problem, General Dynamics provided redundant flight computers to keep the aircraft under control. This is where electric power is critical after an engine failure to maintain controlled flight while having time to restart the engine or direct the aircraft away from populated areas before taking the rocket ride.

DT&E wasn't without its share of colorful events in an aircraft as revolutionary as the F-16. During air-to-ground gunnery evaluations at Edwards, the test pilot rolled in on the target, fired the M61 Vulcan 20mm cannon, and experienced a sudden uncommanded left roll. The pilot was able to instantly regain control of the aircraft and after a quick controllability check, resumed the gun test. On the very next pass, as soon as the pilot pulled the trigger, the aircraft rolled sharply left again. Back to base! In post-test analysis, the problem was traced to electrical interference between the gun and a control wire from the flight control computers. When the computers 'heard' the gun motor over the line, it mis-interpreted the interference as a left roll command from the flight control stick and immediately complied. Shielding the wiring solved that problem.

Once the DT&E phase is completed, the hammer is tossed to the Air Force Operational Test and Evaluation Command (AFOTEC) folks. AFOFTEC is charged with assessing the operational effectiveness and maintainability of new systems before they are issued to the warfighters. The OT&E also ran into problems, so much so that the F-16 failed to the extent that the aircraft could not be easily 'fixed' before full-rate production. When AFOTEC fails a system, the program is usually cancelled, and this was the recommendation sent forth to HQ USAF. The decision from HQ was to accept the aircraft over AFOTEC's objections and the aircraft started a rough early operational history.

Production

As with any production aircraft, the F-16 was produced in blocks. These were pre-planned configurations for which parts were ordered and the airframes were assembled according to the parts lists. As improvements to the aircraft were developed in flight test, operations, or even on the production line, these changes were scheduled into the planning for the next production block. It would just so happen that the production blocks for the F-16 would in themselves do more to describe the aircraft than any other aircraft produced to date.

The F-16 was launched in a rapid succession of Block 1, Block 5 and Block 10 aircraft. These versions had minor differences on the production line but they all shared the same teething problems identified by AFOTEC. The first USAF unit to receive the F-16 was the 388th TFW at Hill AFB in 1979. At the time, the Air Force was conducting a 'name the aircraft' contest and while the clear favorite was 'Viper' in honor of the futuristic rocket fighters of Battlestar Galactica fame, the brass selected 'Fighting Falcon' instead. Unfortunately, some of those problems started surfacing at Hill AFB as F-16s started falling out of the sky and earning the early Viper the nickname 'lawn dart'. Despite these early problems, Air Force engineers and General Dynamics took the time to get the problems identified in DT&E and OT&E fixed. These were rolled out during Block 15 production

In Block 15, the horizontal stabilator authority was improved by increasing its area by 30%. The initial blocks had a rigid side-stick controller for pitch and roll control. Block 15 added some movement to the stick to give the pilot some tactile feedback of control inputs. As mentioned earlier, the F100-PW-100 of the initial delivered aircraft were changed out in favor of the F100-PW-200. Additional improvements to the radar, communications, and even additional pylons brought the F-16 to its first 'effective' (and safer) configuration.

When you want an aircraft tested for reliability or safety, you sent it to Edwards AFB. When you want to ensure that a combat aircraft is really able to perform the mission, you send it to Israel. Early combat experience with the Israeli F-16s led to some ingenious modifications by the Israeli Air Force to an increase in weapons loads. General Dynamics incorporated these modified wheels, landing gear and structures into the F-16C Block 40/42 (and later) designs.

During the latter phase of Block 15 production, the Operational Capability Upgrade (OCU) was phased onto the production line. Why they didn't just call this Block 20... Anyway, the OCU upgraded the engine to the F100-PW-220, added the capability to carry and launch the AIM-120 AMRAAM and AGM-65 Maverick, and to employ the ALQ-131 ECM pod.

Remember that each enhancement requires a software update to the aircraft, not only to employ new weapons or pods, but also to compensate for the altered aerodynamics from simply adding antennas or carrying new external stores. A friend of mine was the test manager for the F-16A ADF, and there was concern that the altered airflow from just the 'bird cutter' IFF antennas would cause the F-16 to become unstable/uncontrollable.

The F-16A/B Block 15 OCU was a huge success and what many folks don't realize is that production of this aircraft continued alongside of the Block 50/52 F-16CJ/DJ. When NATO launched the Mid-Life Update (MLU) program, these aircraft were updated with many of the features that are only now being installed in the USAF F-16 Common Configuration Implementation Program (CCIP) aircraft. In many ways, the NATO MLU Block 15s are more advanced than USAF non-CCIP aircraft. When others wanted production MLU aircraft, these were build to Block 15 OCU and MLU specifications and these were designated F-16A/B Block 20.

The F-16C (Block 25) differed from the F-16A in that it featured an updated cockpit, more advanced radar system, and a number of incremental updates over Block 15. These first F-16Cs were still exclusively Pratt-powered. The idea of the common engine between the F-15 and F-16 went out the window when Pratt was forced to produce a specific F100 variant for the F-16 to reduce the likelihood of an engine failure (not good on a single-engined aircraft). Unfortunately, whenever an F100 engine problem was identified after an accident, it usually resulted in grounding or restricting operations for the entire F-15 and/or F-16 fleets.

Meanwhile, General Electric had produced a very promising engine in the F101 that was to power the B-1B. They embarked on a program to create the F101DFE (Derivative Fighter Engine) that would later become the F110. GE's F110 turned out to be a very robust engine that turned out to be relatively insensitive to rapid throttle movements at altitudes and flight conditions that would compressor stall most other engines. The F110 was adopted for the F-14B and F-14D programs, studied as an alternate powerplant for the F-15E Strike Eagle, and integrated as an alternate powerplant for the F-16C/D.

The vision was to allow the F-16C airframe to fly with either the Pratt or GE engine installed in a common engine bay. For example, if a turbine problem threatened to ground all of the Pratt-powered aircraft, the affected airframes could have their F100s removed and replaced with F110s until the problem was resolved. For the first time, a major engine problem would not ground the entire fleet of F-16s.

The next iteration of Vipers would be the GE F110 powered F-16C Block 30 and the F100-powered F-16C Block 32. The GE engine required more airflow through the inlet which created the distinctive 'wide mouth' inlet that is unique to the GE-powered Vipers. Other than the engines, the Block 30 and 32 were identical in capability. In mid-production of Block 30/32 Vipers, antennas that somewhat resemble beer cans were added to the leading edge flaps, just above stations 2 and 8. In less polite circles, these were called 'donkey dildos', but we aren't that crude here.

Block 40/42 was a direct result of combat experience in Israel. The airframe was beefed up to carry a greater weapons load, and the upgraded landing gear required bulges added to the main gear doors to get them to close over the larger wheels. Block 40/42 also integrated the LANTIRN night attack system to give aircrews eyes into the night. This capability was already integrated into the F-15E Strike Eagle. The F-16C could now deliver precision (laser) guided weapons on any target, night or day. LANTIRN-equipped F-16s freed up the F-15E to perform longer-range strikes. The F-16C Block 40/42 aircraft were re-designated as F-16CG while the F-16D Block 40/42 became the F-16DG.

When it became evident that a replacement for the F-4G Wild Weasel was overdue, the F-16 was selected as the follow-on Weasel platform. The F-16C Block 30/32 had already been performing the companion Weasel mission, flying on the wing of an F-4G and serving as a "manned launch rail". These F-16s were very limited in their Weaseling capabilities without the sensors of the F-4G nearby. As a result, the HARM Targeting System (HTS) pod was developed to provide the new generation of F-16C/D Block 50/52 aircraft with the needed targeting information. These aircraft were re-designated as F-16CJ and F-16DJ.

The key distinguishing feature of the F-16CJ (aside from HARM missiles) is the HARM Targeting System (HTS) pod mounted to the right side of the engine intake. While many skeptics didn't believe that a single-place Viper could effectively replace the specialized avionics and the extra set of eyes that all of the previous Weasels possessed, the F-16CJ has proven itself in combat operations.

Sometime in the midst of F-16C/D production, General Dynamics sold its Fort Worth fighter division to Lockheed Aircraft Corporation who later became Lockheed-Martin. F-16s are still being produced in Fort Worth, though more of its resources are being turned towards the F-35 program.

The F-16E and F-16F are the designations applied to the Block 60 Vipers.

The F-16A/B has been almost completely retired out of the USAF fleet, though you'll see F-16A/B aircraft in service with a growing number of air forces around the world. The F-16C/D Block 25 and newer Vipers continue to serve the USAF, Air National Guard and Air Force Reserve. You'll also see F-16C/D Block 50/52 and F-16E/F Block 60 aircraft also carrying the colors of many international air forces as well.

To be continued...