AUTHOR’S NOTE: Because the Delta Dart was the Ultimate Interceptor we couldn’t stop at just one piece about the Six. Part Deux- The Ultimate Interceptor Trivia beckons right here.
First flown on 26 December 1956 at Edwards Air Force Base (AFB), the Convair F-106 Delta Dart was the ultimate all-weather air defense interceptor. Not (usually) equipped with any type of gun armament, the Six carried air-to-air missiles, some of them nuclear-tipped, to take down enemy interlopers. A development of Convair’s F-102 Delta Dagger, the F-106 was similar in design philosophy yet vastly different in practical application. Delta Darts served the Air Force and Air Defense Command (ADC) and Air National Guard (ANG) units between 1959 and 1988- some very hot Cold War years.
Delta wing designs were developed during the 1950s for the Navy and for the Air Force. The Navy flew the manta-winged Douglas F4D-1/F-6A Skyray, but for only a few years until multi-mission aircraft truly became prevalent in Naval and Marine Corps service. Tailless delta wing aircraft designs of that era included the Avro Vulcan strategic bomber, the Convair B-58 Hustler strategic bomber, F-102 Delta Dagger, and F2Y Sea Dart, and the Dassault Mirage I and III among others.
The F-102, though operational, was somewhat of a letdown to both the Air Force and Convair. A chameleon during its development, the Deuce was improved to the F-102A standard. The F-106 would be an improvement of another order of magnitude over the F-102A. Initially referred to as the F-102B, the new aircraft would be powered by a much more powerful afterburning turbojet engine. The first engine considered was a license-built version of the Bristol Olympus engine used in the Avro Vulcan to be built by Wright and designated J67 in USAF service.
Wright fell behind in their development of the J67, so in 1955 Convair switched power plants to the Pratt & Whitney J75 twin-spool, axial-flow afterburning turbojet engine- a proven performer that also equipped the Republic F-105 Thunderchief and was flying the world’s airways as the JT4A. But the larger size and increased airflow requirements of the J75 required larger engine air intakes and internal intake duct modifications. The intakes were equipped with variable intake ramps and were moved back closer to the engines. Equipped with a slightly larger wing, a more elliptical fuselage cross section drawn using the area rule, and a clamshell-type airbrake fitted at the base of the swept vertical stabilizer, the newly designated F-106 prototype took to the skies. Initial flight testing revealed unrealized performance results along with engine and avionics problems that threatened to sink the F-106 program entirely.
Rather than pull the plug on the F-106, the Air Force decided to order substantially fewer of them than originally planned. Convair got busy working the problems, and though the ordered quantity of jets (350) was far fewer than planned (1,000), by the time the F-106A Delta Dart entered service during October of 1959, the jet was much closer to its designed capabilities than it had been during initial test. The single seat F-106A and the tandem twin seat F-106B combat-capable trainer became the country’s primary air defense weapons system and remained so for many years.
The design characteristics of the F-106 included the Hughes MA-1 integrated fire-control system, which when linked to the Semi-Automatic Ground Environment (SAGE) network for ground control interception (GCI) missions, allowed the aircraft to be steered by ground-based controllers. Or at least that was the plan. The MA-1 was plagued by bugs and was updated/upgraded dozens of times. The system also didn’t control engine power settings- that was up to the pilot. The Six wasn’t equipped to carry air-to-ground ordnance internally or externally but could carry a drop tank under each wing. Missile weapons were housed in a ventral weapons bay. Missiles carried by the F-106A usually consisted of four Hughes AIM-4F or AIM-4G Falcon air-to-air missiles. Optional missile armament included a single GAR-11/AIM-26A Super Falcon nuclear-tipped semi-active radar homing (SARH) missile guided by enemy radar emissions or a 1.5 kiloton-warhead Douglas AIR-2 (MB-2) Genie air-to-air rocket for use against formations of enemy bombers.
In order to operate the MA-1 system the Six was ultimately equipped with a center mounted control column equipped with two grip handles used to control both the aircraft and the radar system- somewhat similar to the arrangement in the F-102. The right-hand grip was used for control of the aircraft and the left-hand grip was used for operation of the radar. A center-mounted button gave the pilot control of the radar antenna. A button on the left-hand grip was used to steer the “pipper” onto the target following steering generated by the radar antenna and displayed on the radar scope. Missile selection was done via a switch mounted on the left-hand cockpit console and the missile launch button was on the right-hand grip. What could go wrong? Task-saturated Six pilots figured it all out while they rode herd on Soviet Bear Bombers transiting (innocently?) back and forth between the Soviet Union and Cuba.
Ejection seats used in the F-106A evolved from the initial Weber catapult seat, which was inadequate for ejections above supersonic speeds or below 120 knots at less than 2,000 feet. The next up was the Convair /ICESC (Industry Crew Escape System Committee) Supersonic Rotational B-seat. Capable of use at supersonic speeds, the ejection sequence was complicated enough that pilots lost their lives using it. The final solution was another Weber seat which was adequate under zero-zero conditions. The end result was that the first twelve pilots to attempt ejection from the F-106A were killed in the attempt, but the final Weber ejection seat solution was adequate.
Development of the F-106A continued after the jet went into service. Modifications made to F-106As during their service life included continuous electronic improvements to avionics, tape-style aircraft systems instrumentation, the Case 29 wing modification yielding a revised airfoil with visible conical camber, an infrared search and track (IRST) system, a revised supersonic drop tank design that was more streamlined and did not degrade the jet’s performance, a fuselage spine-mounted inflight refueling receptacle, and the first arresting hook on an Air Force jet designed for use at Air Force facilities equipped with emergency runway arrestor cables. A new TACAN system using microelectronic circuits resulting in a two-thirds size and weight reduction was installed in 1965.
Convair built a total of 277 F-106As and 63 F-106Bs. The F-106A went into service in May of 1959. The F-106B entered service in July of 1960. There were no dedicated F-106B squadrons. Rather, the Bravos were assigned to each F-106A-equipped squadron. The first F-106As were delivered to the Air Defense Command’s 539th Fighter Interceptor Squadron (FIS) Iron Hand at McGuire AFB in New Jersey, replacing the squadron’s North American F-86 Sabre interceptors on 30 May 1959. The first F-106A-equipped squadron to gain operational status was the 498th FIS Geiger Tigers at Geiger AFB in Washington State. However, the first operational units reported fuel-flow problems (especially in cold weather), generator defects, and starter problems. After a canopy was accidentally jettisoned in flight, December 1959 saw all F-106As temporarily grounded until the issues with the new interceptor were worked out. The F-106 had to be grounded again during late September 1961 after two crashes were caused by lingering fuel starvation issues. The Dart Board modification program finally resolved the fuel problems.
The F-106A, somewhat surprisingly, had excellent maneuverability thanks to low wing loading and was thought to be a potentially good dogfighter. The Air Force considered using the F-106A to provide top cover for bombing missions in Vietnam. In 1972, Project Six Shooter added a frameless canopy for improved visibility, an optical gunsight, and the ability to mount a single M61 Vulcan 20 mm cannon with 650 rounds of ammunition carried in place of the single Super Falcon or Genie missile. Though of course the Six never saw service in Vietnam (unlike the F-102 Delta Dagger) the addition of the frameless canopy, with its much improved visibility, was definitely worthwhile. The gun would have been used as a close-in alternative to the missiles. F-106As equipped with the gun sported a bulged fairing under the weapons bay.
The first ANG unit to operate the Delta Dart was the 186th FIS Vigilantes of the 120th Fighter Wing (FW) Montana Air National Guard (ANG) based at Great Falls Air National Guard Base (ANGB). Their jets began arriving on 3 April 1972. A total of six ANG units flew the F-106A and F-106B as part of the ADC network. F-106As began arriving at the 308th Aerospace Maintenance and Regeneration Group (AMARG) boneyard in January of 1982 as they were replaced by F-4 Phantom IIs. The 119th FIS Red Devils of the 177th FW New Jersey ANG based at Atlantic City ANGB was the final F-106A operator. The Red Devils pulled their last ADC F-106A alert duty on 7 July 1988. Shortly thereafter, the Red Devils retired their last Sixes in August of 1988. During its 29 years in service the F-106A had the lowest single-engine aircraft accident rate in Air Force history- even though 95 F-106As and 18 F-106Bs were lost to all causes.
Many of the remaining Delta Darts were expended as QF-106 targets during the 1990s. Honeywell and other companies modified the first ten of a total of 194 mothballed F-106 airframes beginning during the late 1980s. The program, designated Pacer Six, produced supersonic drone aircraft that could be used to test the advanced air-to-air missiles now inhabiting weapons bays and wingtip rails. QF-106s carried enhanced IR radiators or burners used to attract IR weapons in the hope that each QF-106 would live to be meat on the table another day. Despite the ersatz conservation attempt, these aircraft were shot down by the score at Eglin AFB, Tyndall AFB, and Holloman AFB until the last QF-106 was shot down at Holloman AFB on 20 February 1997. Since then the Air Force has destroyed hundreds of QF-4 Phantom II drones and is working through the inventory of retired F-16s. But the old saying still goes: When you’re out of Sixes, you’re out of interceptors.