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A Brief History of the F-16

Introduction

In the early 1970s, the US Air Force initiated the Lightweight Fighter (LFX) program to developan agile, inexpensive dogfighter to augment the newly acquired F-15 Eagle. A number of promisingdesigns 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 designwas 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 potentialof twin-engine safety given the experience many had with the single-engined F-104.

The YF-17was 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 andselected the Northrop design. In even greater irony, the Navy took Northrop’s designand 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 thatpowered the F-15 Eagle. So advanced was the F100 engine that there were serious concerns withinthe US government about exporting the engine outside the United States. As a result, GeneralDynamics offered a variant of the F-16 that was powered by the General Electric J79 (the sameengine powering the F-4, F-104, Kfir, etc.) so that the aircraft could be sold on the exportmarket. 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 routinelybeat the F-16 (and others) in the Baltic drag races.

The YF-16 was a revolutionary design with absolutely no direct connection between the pilotand flight control systems. Pitch, roll, yaw, speed brakes, and lift augmentation were allcontrolled through computers – fly-by-wire. Its extreme (then) maneuverability was achievedby moving the center of gravity beyond the point of aircraft stability. Only the computerskept the aircraft under control. The aircraft could easily achieve and sustain 9 Gs (nine timesthe normal force of gravity). One of the innovations to improve the pilot’s toleranceto high-G was to tilt the ejection seat back 30 degrees. How effective this ultimately waswill be determined in the history books, but it should be noted that the F/A-22 Raptor, a significantlymore 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 protectthe pilot, and does so without a canopy bow obstructing visibility. The flexibility of thepolycarbonate 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 downside of the polycarbonate is that the canopy must be jettisoned to eject – the canopyis 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 phenomenoncalled stagnation stall would usually cause the engine to shut down and not restart until maintenancecould be performed. This was (sort of) okay in the twin-engined F-15, but it got very quietafter 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 minimizethe 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-onevaluations. First up are the Developmental Test and Evaluation folks (DT&E) who run theaircraft through its initial flight tests and start to 'open the flight envelope'. For theUSAF, this testing is performed at Edwards AFB in the high desert of California. DT&E ofthe YF-16 was a new chapter in flight test as this was the first true fly-by-wire aircraftthat relied solely on computers for stability. To make the aircraft highly maneuverable, thecenter 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 simplyfly out of the controllability envelope. The only chance of survival in such an extreme casewould be the quick rocket flight on the ACES II ejection seat. To avoid such a problem, GeneralDynamics provided redundant flight computers to keep the aircraft under control. This is whereelectric power is critical after an engine failure to maintain controlled flight while havingtime to restart the engine or direct the aircraft away from populated areas before taking therocket ride.

DT&E wasn't without its share of colorful events in an aircraft as revolutionary as theF-16. During air-to-ground gunnery evaluations at Edwards, the test pilot rolled in on thetarget, fired the M61 Vulcan 20mm cannon, and experienced a sudden uncommanded left roll. Thepilot was able to instantly regain control of the aircraft and after a quick controllabilitycheck, 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 wastraced to electrical interference between the gun and a control wire from the flight controlcomputers. When the computers 'heard' the gun motor over the line, it mis-interpreted the interferenceas a left roll command from the flight control stick and immediately complied. Shielding thewiring solved that problem.

Once the DT&E phase is completed, the hammer is tossed to the Air Force Operational Testand Evaluation Command (AFOTEC) folks. AFOFTEC is charged with assessing the operational effectivenessand maintainability of new systems before they are issued to the warfighters. The OT&Ealso ran into problems, so much so that the F-16 failed to the extent that the aircraft couldnot be easily 'fixed' before full-rate production. When AFOTEC fails a system, the programis usually cancelled, and this was the recommendation sent forth to HQ USAF. The decision fromHQ was to accept the aircraft over AFOTEC's objections and the aircraft started a rough earlyoperational history.

Production

As with any production aircraft, the F-16 was produced in blocks. These were pre-planned configurationsfor 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 productionline, these changes were scheduled into the planning for the next production block. It wouldjust so happen that the production blocks for the F-16 would in themselves do more to describethe 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. Theseversions had minor differences on the production line but they all shared the same teethingproblems identified by AFOTEC. The first USAF unit to receive the F-16 was the 388th TFW atHill AFB in 1979. At the time, the Air Force was conducting a 'name the aircraft' contest andwhile the clear favorite was 'Viper' in honor of the futuristic rocket fighters of BattlestarGalactica fame, the brass selected 'Fighting Falcon' instead. Unfortunately, some of thoseproblems started surfacing at Hill AFB as F-16s started falling out of the sky and earningthe early Viper the nickname 'lawn dart'. Despite these early problems, Air Force engineersand General Dynamics took the time to get the problems identified in DT&E and OT&Efixed. 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 addedsome movement to the stick to give the pilot some tactile feedback of control inputs. As mentionedearlier, the F100-PW-100 of the initial delivered aircraft were changed out in favor of theF100-PW-200. Additional improvements to the radar, communications, and even additional pylonsbrought 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. Whenyou want to ensure that a combat aircraft is really able to perform the mission, you send itto Israel. Early combat experience with the Israeli F-16s led to some ingenious modificationsby the Israeli Air Force to an increase in weapons loads. General Dynamics incorporated thesemodified 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) wasphased onto the production line. Why they didn't just call this Block 20... Anyway, the OCUupgraded the engine to the F100-PW-220, added the capability to carry and launch the AIM-120AMRAAM 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 employnew weapons or pods, but also to compensate for the altered aerodynamics from simply addingantennas or carrying new external stores. A friend of mine was the test manager for the F-16AADF, and there was concern that the altered airflow from just the 'bird cutter' IFF antennaswould 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 productionof this aircraft continued alongside of the Block 50/52 F-16CJ/DJ. When NATO launched the Mid-LifeUpdate (MLU) program, these aircraft were updated with many of the features that are only nowbeing 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 otherswanted production MLU aircraft, these were build to Block 15 OCU and MLU specifications andthese were designated F-16A/B Block 20.

The F-16C (Block 25) differed from the F-16A in that it featured an updated cockpit, moreadvanced radar system, and a number of incremental updates over Block 15. These first F-16Cswere still exclusively Pratt-powered. The idea of the common engine between the F-15 and F-16went out the window when Pratt was forced to produce a specific F100 variant for the F-16 toreduce 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 groundingor 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 powerthe B-1B. They embarked on a program to create the F101DFE (Derivative Fighter Engine) thatwould later become the F110. GE's F110 turned out to be a very robust engine that turned outto be relatively insensitive to rapid throttle movements at altitudes and flight conditionsthat would compressor stall most other engines. The F110 was adopted for the F-14B and F-14Dprograms, studied as an alternate powerplant for the F-15E Strike Eagle, and integrated asan 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 installedin a common engine bay. For example, if a turbine problem threatened to ground all of the Pratt-poweredaircraft, the affected airframes could have their F100s removed and replaced with F110s untilthe problem was resolved. For the first time, a major engine problem would not ground the entirefleet of F-16s.

The next iteration of Vipers would be the GE F110 powered F-16C Block 30 and the F100-poweredF-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 Block30 and 32 were identical in capability. In mid-production of Block 30/32 Vipers, antennas thatsomewhat resemble beer cans were added to the leading edge flaps, just above stations 2 and8. 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 upto carry a greater weapons load, and the upgraded landing gear required bulges added to themain gear doors to get them to close over the larger wheels. Block 40/42 also integrated theLANTIRN night attack system to give aircrews eyes into the night. This capability was alreadyintegrated into the F-15E Strike Eagle. The F-16C could now deliver precision (laser) guidedweapons on any target, night or day. LANTIRN-equipped F-16s freed up the F-15E to perform longer-rangestrikes. The F-16C Block 40/42 aircraft were re-designated as F-16CG while the F-16D Block40/42 became the F-16DG.

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

The key distinguishing feature of the F-16CJ (aside from HARM missiles) is the HARM TargetingSystem (HTS) pod mounted to the right side of the engine intake. While many skeptics didn'tbelieve that a single-place Viper could effectively replace the specialized avionics and theextra set of eyes that all of the previous Weasels possessed, the F-16CJ has proven itselfin combat operations.

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

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/Baircraft in service with a growing number of air forces around the world. The F-16C/D Block25 and newer Vipers continue to serve the USAF, Air National Guard and Air Force Reserve. You'llalso see F-16C/D Block 50/52 and F-16E/F Block 60 aircraft also carrying the colors of manyinternational air forces as well.

To be continued...

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