General Dynamics F-111

The General Dynamics F-111 "Aardvark" islong range strategic bomber, reconnaissancetactical strike aircraft.

The F-111 began inearly 1960s asTFX, an ambitious projectcombineUSAF requirement forfighter-bomber withUnited States Navy's need forlong-range air defence fighterreplaceF-4 Phantom II andF-8 Crusader. The prevailing fighter design philosophy ofday wasconcentrate on very high speed, raw power,air-to-air guided missiles. (This would change withinfew years as experiencethen-modern fighter types likePhantom showed that close-in dogfighting remainedimportant partair combat, leading toreintroductionguns as well as missiles andnew emphasis on manoeuvrability, but not until well afterbasic F-111 design was completed.)

ForUS Navy,trendever bigger, more powerful fighters posedproblem:current generationnaval fighters were already barely capablelanding on an aircraft carrier deck; andstill largerfaster fighter would be more difficult again. An airframe optimisedhigh speed (most obviously withhigh-angle wing sweep)inefficient at cruising speeds, which reduces range, payloadendurance,leadsvery high landing speeds. Onother hand, an airframe withstraight or modestly swept wing, while easierhandleablecarry heavy loadslong way onminimumfuel, has lower ultimate performancecombat. It was these considerations that led tofamous F-111 variable geometry,'swing-wing'.

The birth ofTFX was marked by controversy, withAir Force,Navy andUS Government all pullingprojectdifferent directions. At one stage,was even planneduseforUnited States Army andUnited States Marine Corps asclose support aircraft! Several manufacturers submitted bids;final two shortlisted were General DynamicsBoeing. The USAF andUSN,one offew matterswere ableagree on, both wantedBoeing design, but United States SecretaryDefense Robert McNamara overruled themchoseGeneral Dynamics aircraft instead, citing cost issues—an extraordinary irony consideringeventual priceF-111s!

The design eventually emerged as20 tonne aircraft (empty) withmaximum takeoff weightalmost 50 tonnes, powered by two afterburning Pratt & Whitney TF-30 turbofans in80 kN class,side-by-side accommodation forcrewtwo. The high mounted wings were attached topairgiant swivels, allowing ittake off, land,loiter withmodest 16 degree sweep (for maximum liftminimum landing speed), cruise at high sub-sonic speeds with35 degree sweep, or rotatewings right aft to72.5 degree sweep forvery fast maximum speedMach 2.4—particularly so forbomber, whichF-111 had become by this time, its "F" (for "fighter") designation notwithstanding.

Production versions ofF-111 did not have ejection seats. The pressurized crew compartment ejected asself-contained survival moduledescended under70 foot parachute.

First flight wasDecember 1964entry into service withUSAF began1967. It wasfirst variable geometry aircraft. Despite its clear advantages, variable geometry remainsrelatively unusual featuremilitary aircraft, duehigher cost, andextra weight imposed byswing-wing mechanism. Nevertheless, several other types have followed, includingSoviet Sukhoi Su-17 (1966), MiG-23 (1967)Tupolev Tu-160 bomber (1981),US F-14 Tomcat naval fighter (1970)B-1 bomber (1974), andEuropean Panavia Tornado (1974).

As2003,F-111 remainsserviceAustralia's RAAF.