Convair F-106 Delta Dart

The Convair F-106 Delta Dart was the primary all-weather interceptor aircraft of the United States Air Force from the 1960s through the 1980s. Designed as the so-called "Ultimate Interceptor", it proved to be the last dedicated interceptor in U.S. Air Force service to date. It was gradually retired during the 1980s, with the QF-106 drone conversions of the aircraft being used until 1998.^[2]

Design and development

The F-106 was the ultimate development of the USAF's 1954 interceptor program of the early 1950s. The initial winner of this competition had been the F-102 Delta Dagger, but early versions of this aircraft had demonstrated extremely poor performance, limited to subsonic speeds and relatively low altitudes. During the testing program the F-102 underwent numerous changes to improve its performance, notably the application of the area rule to the fuselage shaping and a change of engine, and the dropping of the advanced MX-1179 fire control system and its replacement with a slightly upgraded version of the MX-1 already in use on subsonic designs. The resulting aircraft became the F-102A, and in spite of being considered barely suitable for its mission, the Air Force sent out a production contract in March 1954, with the first deliveries expected the next year.^{[citation needed]}

By December 1951 the Air Force had already turned its attention to a further improved version, the F-102B. Initially the main planned change was the replacement of the A-model's Pratt & Whitney J57 (itself replacing the original J40) with the more powerful Bristol Olympus, produced under license as the Wright J67. By the time this would be available, the MX-1179 was expected to be available, and was selected as well. The result would be the "ultimate interceptor" the Air Force wanted originally. However, while initial work on the Olympus appeared to go well, by August 1953 Wright was already a full year behind schedule in development. Continued development did not improve issues, and in early 1955 the Air Force OK'ed the switch to the Pratt & Whitney J75.^{[citation needed][N 1]}

The J75 was somewhat larger than the J57 in the F-102A, and had greater mass flow. This demanded changes to the inlets to allow more airflow, and this led to the further refinement of using a variable-geometry inlet duct to allow the intakes to be tuned to best performance across a wide range of supersonic speeds. This change also led to the ducts being somewhat shorter. The fuselage grew slightly longer, and was cleaned up and simplified in many ways. The wing was slightly enlarged in area, and a redesigned vertical tail surface was used. The aircraft's exhaust nozzle featured a device known as an idle thrust reducer, which allowed taxiing without the jet blast affecting unsecured objects, without adversely affecting performance at high thrust levels, including afterburners.^{[citation needed]}

A mock-up with the expected layout of the MX-1179, now known as the MA-1, was inspected and approved in December 1955. With growing confidence that the aircraft was now improving, an extended production contract for 17 F-102Bs was sent out on 18 April 1956. On 17 June, the aircraft was officially redesigned as the F-106A.^{[citation needed]}

A QF-106 Delta Dart shows its area ruled fuselage

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.^[3] 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,^[3][4] 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.^[5]

F-106A Delta Darts from 5 FIS at CFB Moose Jaw in 1982

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).^[6][7][8]

The F-106 was envisaged as a 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.^[9] 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.^[10] Like its predecessor, the F-102 Delta Dagger, it could carry a drop tank under each wing.^[11] Later fighters such as the McDonnell Douglas F-4 Phantom II and McDonnell Douglas F-15 Eagle carried missiles recessed in the fuselage or externally, but stealth fighters would re-adopt the idea of carrying missiles or bombs internally for reduced radar signature.

Operational history

A Soviet Tu-95 is intercepted by a F-106A off Cape Cod in 1982

The F-106 served in the continental US, Alaska, and Iceland, as well as for brief periods in Germany and South Korea. The F-106 was the second highest sequentially numbered P/F- aircraft to enter service under the old number sequence (the F-111 was highest), before the system was reset under the 1962 United States Tri-Service aircraft designation system. In service, the F-106's official name, "Delta Dart," was rarely used, and the aircraft was universally known simply as the "Six."^{[citation needed]}

Although contemplated for use in the Vietnam War 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 ^[12] – its exceptional performance made it very popular with its pilots. After the cancellation of their own Avro Arrow, the Canadian government briefly considered purchasing the F-106C/D.

In an effort to standardize aircraft types, the USAF was directed to conduct Operation Highspeed, a flyoff 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 Republic F-105 Thunderchief fighter-bomber.^[13] 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.

An F-106A of the 87th FIS above Charleston AFB, SC in 1982.

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 arrestor hook for landing emergencies.^[14]

Air-to-air combat testing suggested the "Six" was a reasonable match for the McDonnell Douglas F-4 Phantom II in a dogfight, with superior high-altitude turn performance and overall maneuverability (aided by the aircraft's lower wing loading). However, the Phantom had better radar – operated by an additional crewman – and could carry a load of up to four radar-guided Sparrow and four infrared Sidewinder missiles, while the Falcon missiles proved a disappointment for dogfighting over Vietnam.^[15] 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.

In 1972, some F-106As were upgraded in Project Six Shooter that involved fitting the F-106 with a new bubble canopy, a canopy without the metal bracing along the top.^[16] This greatly improved pilot visibility. Also added was an optical gunsight, and provision for a single M61 Vulcan 20 mm cannon. The M61 Vulcan had 650 rounds of ammunition in the center weapons bay and it replaced 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.^[2]

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.^[17] A handful of F-106s were retained by NASA for test purposes through 1998.

The Cornfield Bomber

The Cornfield Bomber, pictured here shortly after earning its nickname.

On 2 February 1970, an F-106 of the 71st Fighter-Interceptor Squadron, piloted by Capt Gary Foust, entered a flat spin over Montana. Foust followed procedures and ejected from the aircraft. The resulting change of balance caused the aircraft to stabilize and later land "wheels up" in a snow-covered field, suffering only minor damage. The aircraft, promptly nicknamed "The Cornfield Bomber", was then sent back to base by rail, repaired and returned to service, and is now on display at the National Museum of the United States Air Force.^[18]

Variants

An F-106A of the Montana ANG viewed from the rear

• F-102B : The original designation of the F-106A.

• F-106A : (Convair Model 8-24) Improved version of the F-102. 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. 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.

A two-seat F-106B trainer variant of the New Jersey ANG

• F-106B : (Convair Model 8-27) 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.^{[N 2]}

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.^[19]

The QF-106 Delta Dart target drone.

• F-106C : Unbuilt version. Aircraft was intended to have the AN/ASG-18 radar and fire control system fitted originally developed for the North American XF-108 Rapier. For its time, it was the largest radar to ever be fitted to a fighter, actually requiring hydraulic actuators to turn the antenna. To accommodate this larger radar system, the nose cone was longer and of greater diameter. The design featured an improved raised canopy design featuring better visibility, canards and lengthened rectangular inlet ducts. The aircraft was to be capable of carrying one GAR-9/AIM-47A in its center bay and one AIM-26A in each side bay. At one time, the US Air Force had considered acquiring 350 of these advanced interceptors, but the F-106C/D project was cancelled on 23 September 1958.^{[20] [N 3]}

• F-106D : Unbuilt two-seat version of the F-106C.
• F-106X : Unbuilt version (early 1968). It would have been outfitted with canards and powered by a JT4B-22 turbojet. It was envisioned as an alternative to the Lockheed YF-12, and was to have had a fire control system with "look-down, shoot-down" capability fed by a 40-inch radar dish.^[7]
• F-106E : Unbuilt version. On 3 September 1968, Convair issued a proposal for an "improved" interceptor that was to be designated F-106E/F. It was to be compatible with the upcoming airborne warning and control systems as well as with the "over-the-horizon" radar defense network. The F-106E/F would have had a longer nose and a new and improved radar with a look-down/shoot-down tracking and missile launch capability. It would also have had a two-way UHF voice and datalink radio. It would have been capable of launching both nuclear and non-nuclear missiles, including the AIM-26 Nuclear Falcon and the AIM-47.^[21]
• F-106F : Unbuilt two seat version of the F-106E.
• QF-106A : Converted into drones, were still capable of being flown both as manned and unmanned aircraft.

Operators

 United States

United States Air Force^[22]

NASA

One of the last two F-106s in active service, seen here in 1990 as a safety chase aircraft in the B-1B aircraft production acceptance flight test program.

Aircraft on display

F-106A

• 56-0454 – Holloman AFB, New Mexico.^[23]
• 56-0459 – McChord Air Museum, McChord AFB, Washington.^[24]
• 56-0460 – Minot AFB, North Dakota.^[25]
• 56-0461 – former K. I. Sawyer Air Force Base, Michigan.^[26]
• 57-0230 – Jacksonville Air National Guard Base at Jacksonville International Airport, Florida.^[27]
• 58-0774 – Hill Aerospace Museum, Hill AFB, Utah.^[28]
• 58-0787 – National Museum of the United States Air Force, Wright-Patterson AFB, Dayton, Ohio. Nicknamed the "Cornfield Bomber," this F-106 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.^[29]
• 58-0793 – Castle Air Museum at the former Castle AFB, Atwater, California.^[30]
• 59-0003 – Pima Air & Space Museum, adjacent to Davis-Monthan AFB in Tucson, Arizona.^[31]
• 59-0010 – Aerospace Museum of California, McClellan Airfield (former McClellan AFB), Sacramento, California.^[32]
• 59-0023 – Air Mobility Command Museum, Dover AFB, Delaware.^[33]
• 59-0043 – AMARC, Davis-Monthan AFB, Arizona.^[34]
• 59-0069 – Great Falls Air National Guard Base, Great Falls Airport, Montana.^[35]
• 59-0086 – Pacific Coast Air Museum, Santa Rosa, California.^[36]
• 59-0105 – Camp Blanding Museum, Camp Blanding Florida National Guard Joint Training Center, Middleburg, Florida.^[37]
• 59-0123 – Museum of Aviation, Robins AFB, Warner Robins, Georgia.^[38]
• 59-0134 – Peterson Air and Space Museum, Peterson AFB, Colorado Springs, Colorado.^[39]
• 59-0137 – Evergreen Aviation & Space Museum, McMinnville, Oregon.^[40]
• 59-0145 – Tyndall Air Park, Tyndall AFB, Florida.^[41]

NF-106A

• 56-0451 – Selfridge Military Air Museum, Selfridge Air National Guard Base, Michigan.^[42]

F-106B

• 57-2513 – Yanks Air Museum, Chino, California.^[43]
• 57-2523 – Atlantic City Air National Guard Base, Atlantic City, New Jersey.^[44]
• 57-2533 – Kelly Field Heritage Museum, Lackland AFB/Kelly Field (former Kelly AFB), Texas.^[45]
• 59-0146 – Fresno Air National Guard Base at Fresno Yosemite International Airport, California.^[46]
• 59-0158 – Edwards AFB Century Circle, Edwards AFB, California.^[47]

NF-106B

• 57-2516 – Virginia Air and Space Center / Hampton History Center, Hampton, Virginia.^[48]

Specifications (F-106A)

F-106A Delta Dart from California ANG fires the AIR-2 Genie rocket.

Data from Quest for Performance^[49]

General characteristics

• Crew: 1
• Length: 70.7 ft (21.55 m)
• Wingspan: 38.25 ft (11.67 m)
• Height: 20.28 ft (6.18 m)
• Wing area: 661.5ft²/61.52m² (Original Wing) or 695 ft²/64.57m² (Conically-Cambered Wing) ()
• Airfoil: NACA 0004-65 mod root and tip
• Empty weight: 24,420 lb (11,077 kg)
• Loaded weight: 34,510 lb (15,670 kg)
• Powerplant: 1 × Pratt & Whitney J75-17 afterburning turbojet, 24,500 lbf (109 kN)
• * Zero-lift drag coefficient: 0.0083
• Drag area: 5.8 ft² (0.54 m²)
• Aspect ratio: 2.10

Performance

• Maximum speed: Mach 2.3 (1,525 mph, 2,455 km/h)
• Range: 1,800 mi (1,600 nm, 2,900 km)combat
• Ferry range: 2,700 mi(2,300 nm, 4,300 km)
• Service ceiling: 57,000 ft (17,000 m)
• Rate of climb: 29,000 ft/min (150 m/s)
• Wing loading: 52 lb/ft² (255 kg/m²)
• Thrust/weight: 0.71
  
• Lift-to-drag ratio: 12.1
• Time to altitude: 6.9 min to 52,700 ft (16,065 m)

• Guns: 1 20 mm caliber M61 Vulcan 6-barreled rotary cannon (After 1972 refit)
• Missiles:
  
  • 2 AIM-4F Falcon
  • 2 AIM-4G Falcon
  • 1 AIR-2A Genie nuclear rocket or AIM-26 Super Falcon missile (Prior to 1972 refit)

See also

The Mercury Seven stand in front of an F-106B

• Century Series
• Sky Scorcher

Related development

• Convair XF-92
• Convair F-102 Delta Dagger

Aircraft of comparable role, configuration and era

• Avro Canada CF-105 Arrow
• Dassault Mirage III
• English Electric Lightning
• Mikoyan-Gurevich MiG-21/Chengdu J-7
• Saab 35 Draken
• Sukhoi Su-9/Su-11
• Sukhoi Su-15

Related lists

• List of fighter aircraft
• List of military aircraft of the United States

References

Notes

Citations

Bibliography

External links

Wikimedia Commons has media related to F-106 Delta Dart.

• F-106 Delta Dart Ultimate Interceptor, by Pat's World
• Convair F-106A Delta Dart
• NMUSAF exhibit: Convair F-106A "Delta Dart
• AeroWeb list of surviving F-106 Delta Darts on display in the US including radio-controlled drones