The Convair F-106 Delta Dart was the primary all-weather interceptor aircraft for the United States Air Force from the 1960s through the 1980s. Designed as the so-called "Ultimate Interceptor", it has proven to be the last dedicated interceptor in USAF service to date. It was gradually retired during the 1980s, with the QF-106 drone conversions of the aircraft being used until 1998.

Design and development

The F-106 emerged from the USAF's 1954 interceptor program as an advanced derivative of the F-102 Delta Dagger known as the F-102B, for which the United States Air Force placed an order for in November 1955. The aircraft featured so many modifications and design changes it became a new design in its own right, redesignated F-106 on 17 June 1956.

The F-102's delta wing had to be redesigned with an area ruled fuselage to exceed supersonic speed in level flight. To exceed Mach 2, the largely new F-106 featured a more powerful J-75-P-17 afterburning turbojet with enlarged intake diameter to compensate for the increased airflow requirements and a variable geometry inlet duct, which allowed the aircraft improved performance particularly at supersonic speeds, as well as permitting a shorter inlet duct. The fuselage was cleaned up and simplified in many ways featuring a modified, slightly enlarged wing area and a redesigned vertical tail surface. The aircraft's exhaust nozzle featured a device known as an idle thrust reducer, which allowed taxiing without the jet blast blowing unsecured objects around, without adversely affecting performance at high thrust levels, including afterburners. The fuselage was also slightly longer than the F-102 Delta Dagger's.

The first prototype F-106, an aerodynamic test bed, flew on 26 December 1956 from Edwards Air Force Base, with the second, fitted with a fuller set of equipment, following 26 February 1957. Initial flight tests at the end of 1956 and beginning of 1957 were disappointing, with performance less than anticipated, while the engine and avionics proved unreliable. These problems, and the delays associated with them nearly led to the abandoning of the program, but the Air Force decided to order 350 F-106s instead of the planned 1,000. After some minor redesign, the new aircraft, designated F-106A were delivered to 15 fighter interceptor squadrons along with the F-106B two-seat combat-capable trainer variant, starting in October 1959.

On 15 December 1959, Major Joseph W. Rogers set a world speed record of 1,525.96 mph (2,455.79 km/h) in a Delta Dart at 40,500 ft (12,300 m).

The F-106 was envisaged as specialized all-weather missile armed interceptor to shoot down bombers. It was complemented by other Century Series fighters for other roles such as daylight air superiority or fighter-bombing. To support its role, the F-106 was equipped with the Hughes MA-1 integrated fire-control system, which could be linked to the Semi-Automatic Ground Environment (SAGE) network for ground control interception (GCI) missions, allowing the aircraft to be steered by controllers. The MA-1 proved extremely troublesome and was eventually upgraded more than 60 times in service. Similar to the F-102, it was designed without a gun, or provision for carrying bombs, but it carried its missiles in an internal weapons bay for clean supersonic flight. It was armed with four Hughes AIM-4 Falcon air-to-air missiles, along with a single GAR-11/AIM-26A Falcon nuclear -tipped semi-active radar (SAR)-homing missile (which detected reflected radar signals), or a 1.5 kiloton -warhead AIR-2 (MB-2) Genie air-to-air rocket intended to be fired into enemy bomber formations. Like its predecessor the F-102 Delta Dagger, it could carry a drop tank under each wing. Later fighters such as the Phantom and F-15 Eagle carried missiles recessed in the fuselage or externally, but stealth fighter s would re-adopt the idea of carrying missiles or bombs internally for reduced radar signature.

Operational history

The F-106 served in the continental USA, Alaska, and Iceland, as well as brief periods in Germany and South Korea. In service, the F-106's official name, "Delta Dart," was rarely used, and the aircraft was universally known simply as the "Six."

Although contemplated for use in Vietnam the F-106 never saw combat nor was it exported to foreign users. Following the resolution of initial teething problems (in particular, an ejection seat that killed the first 12 pilots to eject from the aircraft) its exceptional performance made it very popular with its pilots.

In an effort to standardize aircraft types, the USAF was directed to conduct Operation Highspeed, a fly-off competition between the USAF F-106A and the U.S. Navy F4H-1 (F-4B) Phantom, which was not only as capable as the F-106 as a missile-armed interceptor, but could also carry as large a bomb load as the F-105 fighter bomber. The Phantom was the winner, but would first be tasked to escort and later replace the F-105 fighter-bomber in the late 1960s before replacing older interceptors in Air Defense Command in the 1970s.

The F-106 was progressively updated in service, with improved avionics, a modified wing featuring a noticeable conical camber, an infrared search and track system, streamlined supersonic wing tanks which provided virtually no degradation to overall aircraft performance, better instrumentation, and features like an inflight refuelling receptacle and an arresting hook for landing emergencies.

Air-to-air combat testing suggested the "Six" was a reasonable match for the F-4 Phantom II in a dogfight, with superior high-altitude turn performance and overall maneuverability (aided by the aircraft's lower wing loading ). But the Phantom had better radar, an additional crewman to operate the radar, and could carry a load of up to four radar-guided Sparrow and four infrared Sidewinder missiles, while Falcon missiles proved a disappointment for dogfighting over Vietnam. The F-4 had a higher thrust/weight ratio, superior climb performance, and better high speed/low-altitude maneuverability, and could be used as a fighter bomber. Air combat experience over Vietnam showed the need for increased pilot visibility and the utility of a built-in gun, which had been added to the "E" variant of USAF Phantoms. Some F-106As were upgraded in Project Six Shooter in 1972, fitted with a new bubble canopy without the metal bracing along the top (which greatly improved pilot visibility), an optical gunsight, and provision for a single M61 Vulcan 20 mm cannon with 650 rounds of ammunition in the center weapons bay, replacing the AIM-26 Super Falcon or Genie.

The F-15A started replacing the F-106 in 1981, with the "Sixes" typically passed on to Air National Guard units. The F-106 remained in service in various USAF and ANG units until 1988.

Starting in 1986, many of the surviving aircraft were converted into drones, designated QF-106A, and used for target practice. The last was destroyed in January 1998. The drones were still capable of being flown as manned aircraft, such as for ferrying to a test; during the test they were flown unmanned. A handful of F-106s were retained by NASA for test purposes through 1998.

Variants

*F-102B : The original designation of the F-106A. Fitted with the MA-1 Integrated Fire Control System with SAGE datalink, J-75 afterburning turbojet, enlarged intake, variable geometry inlet ramps and shortened intake ducts, refined fuselage shape, modified wings and redesigned tailfin; tailpipe fitted with a device to reduce the tendency of the jet exhaust to blow unsecured objects around while taxiing, yet allowing virtually maximum performance at high thrust settings including afterburner. Performance was deemed unsatisfactory and modifications were made.Weapons configurations (projected):2 x AIM-4 Falcon, 2 x AIM-4 Falcon, and 2 x AIM-4 Falcon or:2 x AIM-4 Falcon, 2 x AIM-26 Super-Falcon, and 2 x AIM-4 Falcon or:2 x AIM-4 Falcon, 1 x AIM-26 Super-Falcon, 1 x AIM-4, and 2 x AIM-4 Falcon or:2 x AIM-4 Falcon, 1 x AIR-2A Genie, 2 x AIM-4 Falcon

*F-106A : Modified F-106 with improved performance. Maximum speed at least Mach 2.5, with some estimates as high as Mach 2.85 in level flight. The aircraft was capable of low supersonic speeds without afterburner (but with a significant range penalty) and had a maximum altitude at least 57,000 ft. Many were fitted with a conically-cambered wing for improved takeoff, supersonic and high-altitude flight. To improve the aircraft's range the aircraft was fitted with two streamlined external supersonic tanks that still kept the aircraft capable of sustained roll rates of 100 degrees per second. Since these tanks produced virtually no significant performance degradation they were rarely jettisoned and were routinely carried around. After 1972, many F-106s were refitted with a new canopy featuring improved visibility, improved optic sights and provision for a gunpack in the center weapons bay.:Weapons configurations:2 x AIM-4 Falcon, 2 x AIM-4 Falcon, and 2x AIM-4 Falcon or:2 x AIM-4 Falcon, 2 x AIM-26 Super-Falcon, and 2 x AIM-4 Falcon or:2 x AIM-4 Falcon, 1 x AIM-26 Super-Falcon, 1 x AIM-4 Falcon, and 2 x AIM-4 Falcon or:2 x AIM-4 Falcon, 1 x AIR-2A or AIR-2B Genie, and 2 x AIM-4 Falcon:2 x AIM-4 Falcon, 1 x M61 gunpack with 650 rounds, and 2 x AIM-4 Falcon

*F-106B : Two-seat, combat-capable training version. Pilot and instructor are seated in tandem. Due to the extra seat, the fuselage is actually better area ruled; combined with a likely reduction in weight.

:Weapons configurations same as F-106A.

*NF-106B : This designation was given to two F-106Bs used as test aircraft with NASA and associated research facilities from 1966 to 1991.

Operators

USA

*United States Air Force

*Air National Guard

*NASA

Incidents

An F-106 of the 71st Fighter-Interceptor Squadron, piloted by Gary Faust, entered a flat spin over Montana on February 2, 1970. Faust followed procedures and ejected from the aircraft. The resulting change of balance caused the aircraft to stabilize, and it landed wheels up in a snow-covered field, suffering almost no damage. The aircraft was then sent back to base by rail, repaired and returned to service.

Aircraft on display

A partial list of statically displayed F-106 Delta Darts, by model, museum or base, location, and serial number:

F-106A

* Aerospace Museum of California, McClellan Airfield (former [[McClellan AFB ), Sacramento, California, AF Ser. No. 59-0010

* Air Mobility Command Museum, Dover AFB, Delaware, AF Ser. No. 59-0023

* California ANG - 144th Fighter Wing, Fresno ANGB, California AF Ser. No. 59-0146

* Evergreen Aviation & Space Museum McMinnville, Oregon, AF Ser. No. 59-0137

* Florida ANG - 125th Fighter Wing, Jacksonville ANGB, Jacksonville International Airport, FL

* Florida ANG - 125th FW, Homestead ARB, Homestead, Florida, AF Ser. No. 57-0230

* Florida ANG - 125th FW, Camp Blanding Museum, Middleburg, Florida, AF Ser. No. 59-0105

* Heritage Park, Holloman AFB, New Mexico

* Hill AFB Museum, Hill AFB, Utah, AF Ser. No. 58-0774

* McChord Air Museum, McChord AFB, Washington, AF Ser. No. 56-0459

* Minot AFB, North Dakota, AF Ser. No. 56-0460

* Montana ANG - 120th Fighter Wing, Great Falls ANGB, Great Falls, Montana, AF Ser. No. 56-0069

* Museum of Aviation Robins AFB, Georgia, AF Ser. No. 59-0123

*National Museum of the United States Air Force, Wright-Patterson AFB, Dayton, Ohio, AF Ser. No. 58-0787 (F-106 that landed itself with relatively minor damage in a farmer's field after its pilot lost control and ejected) It last served with the 49th Fighter Squadron before being brought to the museum in August 1986.

* Peterson Air and Space Museum, Peterson AFB, Colorado Springs, Colorado, AF Ser. No. 59-0134

* Pima Air & Space Museum, adjacent to Davis-Monthan AFB in Tucson, Arizona, AF Ser. No. 59-0003

* Tyndall Air Park, Tyndall AFB, Florida, AF Ser. No 59-0145

NF-106A

* Selfridge Military Air Museum, Selfridge ANGB, Michigan, AF Ser. No. 56-0451

F-106B

* Edwards AFB Century Circle, Edwards AFB, California, AF Ser. No. 59-0158

* Kelly Field Heritage Museum, Lackland AFB /Kelly Field (former Kelly AFB ), Texas, AF Ser. No. 57-2533

* New Jersey ANG - 177th Fighter Wing, Atlantic City ANGB, Atlantic City, New Jersey, AF Ser. No. 57-2523

NF-106B

* Virginia Air and Space Center / Hampton History Center, Hampton, Virginia, AF Ser. No 57-2516 and NASA /FAA Registration N816NA

Resources and Links

F-106 Delta Dart The Ultimate Interceptor

The original source for this article was the Wikipedia F-106 Delta Dart article.