F-102 Delta Dagger's Weapons Bays Combined Rockets And Missiles In A Feat Of Cold War Ingenuity

It was the Air Force's first supersonic interceptor. In order to obtain that title, it carried its weapons internally via some remarkable engineering.

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Today, internal weapons carriage is essentially a must-have feature for any next-generation stealth fighter. Designers of the latest low observable aircraft face the significant challenge of cramming often-bulky weapons inside a densely-packed airframe. Back in the early days of the Cold War, the team from the Convair company faced a similar predicament, albeit for other reasons, and managed to do an extremely elegant job with the weapons bays of its F-102 Delta Dagger interceptor.

In the days long before low observability, a whole generation of U.S. tactical jets also carried much — or even all — of their ordnance internally. The reasoning then was that any extraneous protrusions, missiles and rocket pods included, were to be done away with if possible, to minimize drag and ensure that the maximum speed and efficiency could be eked out of the airframe.

 

First flown in prototype form on October 24, 1953, the F-102 was designed as a destroyer of long-range Soviet bombers and was intended to replace a previous generation of subsonic interceptors primarily armed with guns and unguided rockets then in service with the U.S. Air Force’s Air Defense Command. Convair optimized the Delta Dagger for speed and decided to equip it with radar and with weapons offering longer reach, all with the aim of taking down nuclear-armed Soviet bombers before they could reach their targets.

Ensuring the F-102 achieved its intended straight-line performance was a struggle, hampered by the constraints of engine technology at the time, but above all by the limited understanding of aerodynamics in the supersonic realm. When drafted, the F-102 was planned to reach a top speed of Mach 1.88. But when flown in prototype YF-102 form, the fighter proved unwilling to push beyond Mach 0.98 in level flight. By 1954, the planned maximum speed had been revised to a more modest Mach 1.23 and, after a series of aerodynamic revisions, the delta-winged F-102 duly entered service as the U.S. Air Force’s first supersonic interceptor. A specially prepared YF-102A pre-production aircraft even recorded a speed of Mach 1.535 — the fastest of any Delta Dagger.

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An F-102A prepares to ripple-fire a salvo of three Falcon missiles.

The internal weapons carriage was necessary to ensure the F-102 slipped through the air in supersonic pursuit of its bomber targets. Carrying its full load of weapons in its belly, the smooth lines of the Delta Dagger were interrupted only by the optional external drop tanks, each carrying either 215 or 192 gallons of additional fuel. However, carrying drop tanks limited the maximum speed to Mach 0.95. 

From the start, the F-102 was intended to carry six air-to-air missiles (AAMs), all from the Hughes Falcon family, which eventually included variants of the AIM-4 and AIM-26. The F-102 carried its six missiles on trapeze launchers, two of which were installed in tandem in each of three weapons bays: left, center, and right. “You almost had to be a contortionist to load the center rails,” recalled Bill McAuley, a weapons technician with the 142nd Fighter Wing, Oregon Air National Guard.

When selected by the pilot, the appropriate launchers popped out of the bays and three missiles would be fired in a salvo. The timing of this was determined automatically by the radar fire-control system.

From the outset, the F-102’s bays had been designed around the Falcon series of missiles. This first-generation weapon was eventually developed into a wide range of variants, and Delta Dagger pilots were ultimately provided with multiple options when engaging threats with missiles.

An experimental version of the Falcon had been first tested in 1949 and the weapon initially entered service with the U.S. Air Force’s F-89H Scorpion interceptor. The weapon was available in semi-active radar-homing (SARH) and infrared-homing versions, a mix of missiles providing flexibility for engaging targets under different circumstances and when confronting various countermeasures. 

USAF/WIKIMEDIA COMMONS

A 431st Fighter Interceptor Squadron F-102A with a single Falcon visible in the right-hand bay.

The first of the radar-homing models were known as GAR-1s, while their infrared counterparts were GAR-2s. The effective range parameters for the initial SARH versions were between 5,000 and 25,000 feet. Equivalent data for the GAR-2 is not immediately available, but it seems the weapon’s performance was considered generally disappointing and production came to an end after just 1,600 examples had been completed.

The type designations were later changed to fit a new unified nomenclature system from 1962 onwards, with the base variants of the GAR-1 and 2 becoming the AIM-4 and AIM-4B, respectively.  

142nd FW

Two Oregon Air Guardsmen load an AIM-4 Falcon into the weapons bay of an F-102 at Portland Air Base, Oregon, circa 1968.

The Falcon was improved throughout its service life, yielding the radar-guided GAR-1D, later known as the AIM-4A, with improved maneuverability and an increase in ceiling up to 60,000 feet, and the equivalent heat-seeking GAR-2A, or AIM-4C, which had a more sensitive infrared seeker. The AIM-4C was subsequently superseded by the improved AIM-4D, issued from 1963, and which could now be launched from a minimum range of 1,000 feet. This became the definitive infrared-guided Falcon for the F-102, and also featured a further improved seeker head that could lock onto targets at greater ranges.

The AIM-4A through D variants of the Falcons were all armed with a nearly 8-pound warhead that included just 2.7 pounds of explosive since a missile traveling at a speed of Mach 2-3 was judged to be adequate to bring down a bomber-size target. However, these early Falcons did require a direct hit, since they were not equipped with a proximity fuze.

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An F-102 driver poses with his jet and a full load of Falcon missiles.

As well as unguided rockets and conventionally armed AAMs, the United States developed harder-hitting bomber-killer weapons during the Cold War too. Such weapons were intended to take out larger or high-priority targets, namely entire formations of bombers. Best known of these is the nuclear-armed AIR-2 Genie unguided air-to-air rocket. While the Genie was never issued to the F-102 force, the Delta Dagger did still receive an AAM with an atomic warhead. This was the GAR-11, later redesignated the AIM-26A, or “Nuclear Falcon,” introduced in late 1961. 

Equipped with radar guidance, the new weapon had a top speed of Mach 2 and carried a W54 warhead with a yield of 0.5 kilotons. It also featured a proximity fuze to increase the probability of a kill. This was the only guided nuclear-armed AAM ever deployed by the U.S. Air Force and remained in the inventory until 1972.

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The nuclear-armed AIM-26A missile.

As well as the nuclear-tipped AIM-26A, a conventionally armed AIM-26B was also available to F-102 units. Again boasting a proximity fuze, this missile had a much larger (48.5-pound) warhead than the original non-nuclear Falcons and around half the Delta Dagger fleet was converted to carry this potent weapon.

The new AIM-26 series weapons were longer and considerably bulkier than the previous Falcons and required modifications to the trapeze launchers in the center bay, which was the only bay adapted to carry them. In this way, the F-102 could carry two of these missiles in the center, a pair of earlier Falcons in each of the two outboard bays, plus a reduced load of 12 unguided rockets.

Since early AAMs were less than reliable and had a fairly large minimum engagement envelope, the Delta Dagger’s complement of guided missiles was bolstered by a load of folding-fin aerial rockets, or FFARs, cleverly installed in tubes integrated within the weapons bay doors. The rockets were a useful backup in case the main missiles malfunctioned or were spoofed by countermeasures. They also increased the magazine depth of the F-102, allowing it to take out as many bombers as possible if World War III were to have come. 

RYAN FROST/WIKIMEDIA COMMONS

A preserved F-102 with the weapons bays doors open and the Falcon missiles extended on their trapezes. Note also the blue-tipped rockets visible in the weapons bay door.

The rockets could also be used at lower altitudes where the early AAMs were least effective. For example, it required around 16 seconds between locking on to a target and launching a radar-guided Falcon. That might be acceptable for downing a lumbering bomber at high altitude, but was unlikely to yield success in a lower-level dynamic engagement. The infrared-guided Falcon, meanwhile, performed best when engaging a target flying above the F-102, which reduced the chances of its seeker being confused by ground clutter.  

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Technicians working in the left weapons bay of an F-102. Six sets of blast tubes were installed in the doors to vent the flame and gasses from the rocket motors.

At first, the rocket armament comprised 36 T-214-2 2-inch FFARs, but these gave way to 24 2.75-inch Mighty Mouse FFARs by mid-1956, being introduced on the 190th production aircraft and then being retrofitted on earlier jets. Weighing 18.5 pounds, each Mighty Mouse carried a 6-pound high-explosive warhead. In this revised form, the F-102’s rocket tubes were arranged as three in each of the four innermost weapons bay doors, each tube carrying a pair of four-foot-long FFARs. The effective range of the Mighty Mouse was around 2 miles.

USAF/Ken LaRock

Preserved at the National Museum of the United States Air Force in Dayton, Ohio, this F-102A retains the original 24-rocket installation.

The procedure for launching the FFARs was even more visually impressive than the one for employing missiles. In an era of stealth, it’s a prerequisite that an aircraft’s weapons bay doors are open for the shortest possible period, enabling stores release before detection by enemy radar. That wasn’t a consideration for the Delta Dagger, but the doors were still able to open, unleash all 24 rockets, and then snap closed again within around two seconds. The weapons bay doors themselves were electrically actuated and operated by a complex system of compressed air maintained at a pressure of 1,500 pounds per square inch. Depending on the target, the pilot could choose to fire the rockets in salvos of six, 12, or 24. If rockets were selected, the missile trapezes would not be lowered into the slipstream. 

For all the ingenuity of the F-102’s combined missile-and-rocket-toting weapons bay, FFARs as anti-aircraft weapons were, by the late 1950s, clearly from another era. Beginning in 1957, the rocket tubes were removed from the inner doors of the left and right bays, and from the two doors of the center bay, reducing the load to just 12 of the Mighty Mouse projectiles. This remained the standard ‘fit’ until the Delta Dagger was finally retired in 1976, making it the last USAF air defense fighter to carry FFARs in the air-to-air role.

USAF

An F-102A from the 509th Fighter Interceptor Squadron armed with AIM-4A and AIM-4D Falcon missiles at Da Nang Air Base, Vietnam, in 1968.

In the end, while the design of the F-102’s weapons installation was admirable, the fighter was only as good as its weapons. According to Peter E Davies’ masterful account of the aircraft, F-102 Delta Dagger Units, pilots were broadly skeptical about the effectiveness of the FFARs, which were prone to fanning out or sometimes colliding. On the other hand, the Falcons were first-generation AAMs with all the limitations that entailed. In particular, they lacked agility and required considerable time to prepare for action. Even the “fire and forget” infrared-guided AIM-4D needed two minutes to cool the seeker before launch. Once committed to combat in Vietnam, the Falcon proved less effective than the AIM-7 Sparrow and AIM-9 Sidewinder, although in that war it was called upon primarily to tackle low-flying, agile targets, which were quite different from the bombers that it had been designed to shoot down.

While the Delta Dagger’s weapons bays were a notably compact solution to providing a Cold War interceptor with a range of weapons options while retaining a low-drag profile, this complex arrangement was not immune to failure, which was sometimes quite dramatic.

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The third production F-102A unleashes a full salvo of 24 unguided rockets.

Davies recounts one such incident in a hangar at Thule Air Base, Greenland, in which an electrical fault in an F-102’s weapons bay resulted in an unplanned Falcon launch while the pilot was checking his jet’s fuel pumps. Despite the remaining load of Falcons and FFARs cooking off, there were no injuries to personnel, although both the F-102 and the hangar were wrecked. 

Sometimes human error played a part too. Davies recounts the accidental shootdown of a T-33 training jet during a missile evaluation test involving what was supposed to be an inert Falcon in 1958. On this occasion, the F-102 ripple-fired three live Falcons, taking off a portion of the trainer’s tail. The T-33’s two crew ejected safely at 43,000 feet.  

Ultimately, the demise of the “Century Series” aircraft spelled the end of internal weapons bays on U.S. fighter jets, at least for a time. The last of the F-106 Delta Darts — a much-improved development of the F-102 — bowed out of frontline service in 1988.  

Internal weapons bays were destined to come back into vogue before long, with the emergence of a new generation of stealthy fighters, starting with the F-22 Raptor, which would take to the air in prototype form just two years after the F-106's retirement. The F-22’s bays also use trapeze launchers — modern-day versions of those used in the F-102. 

While we are unlikely to see a Delta Dagger-style combined rocket/missile weapons bay on a jet anytime soon — well, there is the possibility of such an arrangement with laser-guided rockets — work continues to expand stealthy fighters’ internal air-to-air payload options. These include the development of smaller hit-to-kill missiles, Lockheed Martin’s Sidekick to boost the F-35’s missile load, and the AIM-260 Joint Air Tactical Missile (JATM). The latter will be the U.S. Air Force’s first known air-to-air missile to be tailored from the outset for internal carriage since the Cold War. 

Contact the author: thomas@thedrive.com