“We learned from the F-111B Without the F-111B we wouldn’t have been this smart,” said Mike Ciminera, F-14 Tomcat project designer. His is one example of a paradox of military aviation history: some of the greatest aircraft of all time never reached fully operational service.
The F-111B was designed in the 1960s as a component of Secretary of Defense Robert S. McNamara’s Tactical Fighter Experimental (TFX) program, an ambitious plan to build one plane for the U.S. Air Force and Navy alike. The Navy model was designed by General Dynamics with the aid of Grumman, employing the latest technology available at the time variable-geometry wings, afterburning turbofan engines, and advanced long-range radar and missile systems. The program guaranteed a carrier-based interceptor for intercepting Soviet bombers at long range, and meeting the Air Force low-level dash and nuclear delivery needs.
The engineering highlight was the swing-wing system, which enabled the aircraft to maximize lift and drag across a broad spectrum of speeds. Wings could be swept from 16° takeoff and landing to more than 70° for high-speed intercepts. This flexibility permitted the conflicting mission requirements: long loiter at range for fleet defense and supersonic dash as quickly as possible for interception. But in attempting to satisfy both services, compromises had been made at a cost. The Navy requirement for side-by-side accommodation for its radar intercept officer contributed fuselage cross-section, worsening transonic drag and limiting low-altitude dash capabilities. Wind tunnel flights at NASA anticipated the F-111B to manage no more than 39 nautical miles at Mach 1.2 from sea level a far cry from the requirement of 200 nmi.
Weight was also a fatal defect. Built to accommodate an Air Force gross weight of 75,000 pounds and within the Navy’s 50,000-pound carrier weight limit, the completed F-111B weighed close to 55,000 pounds overweight. This made carrier operations dangerous and compromised agility. In an era when dogfighting remained the key to air supremacy, the F-111B’s inability to roll and accelerate were liabilities. Testing revealed it could not keep up with the turn performance of then-current fighters such as the F-4 Phantom II, let alone the lighter, faster replacement that would eventually take its place.
That replacement the F-14 Tomcat was in large part a direct result of the F-111B’s deficiency. The VFX program by Grumman, started as soon as the Navy became aware of the F-111B’s deficiency, retained the swing-wing concept but improved it in combat maneuverability. Tomcat’s variable-sweep wings automatically swept for performance throughout its complete flight envelope, with the pilots unencumbered to concentrate on combat. Double vertical stabilizers improved yaw stability, and a more refined intake improved engine performance at multiple speeds. The F-14 was 230 mph faster, had a 40 percent longer combat radius, and landed just about 30 mph slower decisive for carrier safety.
weapons integration also improved. The AN/AWG-9 radar on the F-14, a development of long-range tracking ideas tested on the F-111B, was able to direct AIM-54 Phoenix missiles to six targets from more than 90 miles. Airborne early warning combined with the E-2 Hawkeye provided a layering fleet defense against Soviet missile and bomber attack. The Tomcat had the ability to load AIM-7 Sparrow and AIM-9 Sidewinder missiles in addition to an internal M61A1 Vulcan gun its solution to the Phantom gun problem.
Technologically, the F-111B legacy is the demonstration of concept of using variable-geometry wings in carrier fighter aircraft and the F-111’s development of improved radar-missile integration for long-range intercepts. Cancellation proved the risks of joint-service over-reaching, where conflicting operational requirements lead to compromise pleasing no one. The Navy’s transition to the F-14 proved that experience out of a failed program can lead to a platform custom-made for special mission requirements, superior in both fleet air defense and air-to-air combat.
Although the F-111B never entered the fleet, its legacy lasted for decades. The three-decade life of the Tomcat, from Cold War intercept to precision strike and reconnaissance, was made possible through the lessons learned from the engineering trials of its ill-fated predecessor. In the annals of military aviation, the F-111B serves as a reminder that even failure can contribute to the development of fighter design.
