CONVAIR F-102 Delta Dagger
Single-Seat Supersonic Interceptor Aircraft
The CONVAIR F-102 Delta Dagger was an interim delta-wing interceptor design fielded by the USAF until the arrival of the more capable CONVAIR F-106 Delta Dart series.
Authored By: Dan Alex | Last Edited:
The CONVAIR F-102 "Delta Dagger" was a product of the ensuing Cold War years following the close of World War 2 in which jet technology and aerodynamics advanced to all new tiers. As such, development of evermore powerful and streamlined aircraft ensued giving rise to one of the more exciting periods of military aviation. One of the primary threats to both Western Europe and United States interests remained the long range, nuclear-capable bombers of the Soviet Union to which "interceptors" were developed in response. The interceptor was built on the concept of pure speed and engaged aerial targets with missiles at range using complex computer fire control systems (FCS). The F-102 served as a deterrent for such enemies during its early tenure while eventually evolving to a limited ground attack mount by the time of the Vietnam War. Used by less than a handful of nations worldwide, the F-102 served just over 20 years before being formally retired from service. While sharing a undeniable appearance to the upcoming F-106 "Delta Dart", the F-102 was more of an interim interceptor design until the original project goals were fulfilled in the F-106.
In August of 1945, the United States Army Air Force, just beginning to wind down war time operations of World War 2, was high on the idea of jet-propelled aircraft and put forth a requirement for an interceptor aircraft with supersonic capabilities. Jet propulsion was in its infancy during the war while many technological hurdles were eventually overcome - including the arrival of the first operational jet fighter - the German Messerschmitt Me 262. The USAF required a maximum speed of 700 miles per hour with a service ceiling of 50,000 feet - these two qualities would ensure a Soviet bomber counter. CONVAIR eventually turned to the works of German engineer Alexander Lippisch who championed the use of the "delta-wing" area design when concerning high-speed flight. Convair was born in 1943 from the merger of CONsolidated Aircraft and Vultee AIRcraft (hence the "CONVAIR" naming). CONVAIR was eventually acquired by General Dynamics and lost to aviation history.
CONVAIR put work into a delta-wing inspired development of their own known under the designation of "XF-92A" for the USAF. The concept incorporated extremely swept leading wing edges with straight trailing edges while eliminating the horizontal tailplanes found in traditional aircraft designs. First flight of the experimental airframe occurred on April 1st, 1948. Power was derived from a single Allison J33-A-29 series turbojet engine of 7,500lbs thrust, providing speeds of 718 miles per hour with a service ceiling of 50,750 feet. The fuselage was well-streamlined but rather stocky in shape, capped by a triangular vertical tail fin and accompanying triangular main wing assemblies aft of a framed cockpit enclosure. The engine was aspirated through the open nose enclosure. However, pilots did not revere the type due to its inherently violent flight tendencies and underperforming qualities. The USAF eventually completed the research project with a formal cancellation.
In October of 1948, the USAF delivered a new set of requirements for an interceptor built around the highly advanced MX-1179 electronic fire control system (FCS) to manage the proposed onboard radar and missile weaponry. The aircraft would have to feature Mach 2-capable speeds and be production-ready by 1954 with the hope of stocking the USAF inventory with a highly-capable interceptor and Soviet bomber deterrent. The project advanced along two fronts - Hughes was selected to produce the critical FCS while CONVAIR eventually won the rights to develop the airframe. Utilizing the knowledge gained during development of the XF-92, CONVAIR put forth their new XF-102 prototype which was of similar form.
The XF-102 was not unlike the XF-92 before it though featuring a much longer fuselage and larger area delta-wings. As in the preceding design, all wing surfaces were triangular in shape with pointed tips and swept leading edges. A single engine was buried in the tubular fuselage to provide the needed thrust while a cockpit was fitted well-ahead in the design. While intended to fit the upcoming Wright J67 (based on the British Bristol-Siddeley Olympus under license) series turbojet engine, delays forced the selection of the Westinghouse J40 series for the interim. When the J40 project proved a disaster, the Pratt & Whitney J57 series was selected instead. Development of the MX-1179 FCS was also still ongoing and this forced the installation of the less-complex MG-3 FCS system for the time being. The XF-102 would, therefore, serve as a technological stepping stone in working out project kinks while the major technological components were advanced on their own timeline. It was seen that the XF-102 would give rise to the basic F-102A production series interceptor while a later mark, the F-102B, would institute the required FCS and engine as planned. In this approach, the USAF would be given a capable interceptor until the program goals were fully met, resulting in a very streamlined end-product.
As in other USAF programs, the XF-102 prototype was advanced to become the evaluation "YF-102" model form. First flight was recorded on October 24th, 1953 though this prototype was lost less than two weeks later. A second flyable prototype was made ready by January of the following year and went airborne, proving performance lacking - she could not break the sound barrier, achieving only subsonic flight. CONVAIR engineers then worked to correct the problems inherent in their YF-102 design by applying the German wartime-inspired "Whitcomb Area Rule" design approach which enabled fixed-wing airframes to reduce drag when reaching and exceeding Mach 1 speeds. The YF-102 airframe was then largely revised with a longer fuselage (4 feet was added) that was pinched at its midway point. Additionally, a newer, more powerful version of the J57 turbojet engine (PW J57-P-23 of 16,000lbs thrust) was installed and aspirated by revised air intakes that were themselves larger. Wings were further refined and, in this modified form, the YF-102 graduated to become the "YF-102A".
The YF-102A was first flown on December 20th, 1954 and was able to reach the required supersonic speeds and service ceiling thusly proving the redesign effort successful. With the new aircraft refined to acceptable levels, the USAF ordered the type for serial production as the "F-102 Delta Dagger". The initial production mark would become the "F-102A" and 889 would ultimately be manufactured by CONVAIR. The arrival of the F-102 marked the first production delta-wing supersonic aircraft in operational service anywhere in the world. Production spanned until September of 1958.
Outwardly, the F-102 exuded speed thanks to its sharp clean lines and single-minded purpose. The fuselage was long and slim with a cockpit set aft of a nose cone assembly. Intakes aspirated the single engine were to either side of the cockpit walls to which the fuselage ran the full distance to the rear, capped by the engine exhaust ring. The delta-wing configuration was set to either side of the rounded fuselage, highly swept along the leading edges and straight along the trailing edges, the two edges meeting together at outboard points. The fuselage spine was capped by a single large vertical tail fin that was essentially a third triangle surface ending in a clipped tip. The cockpit was a two-piece installation with framing, offering up adequate views to the sides, forward and above. The rear view was primarily blocked by the raised fuselage spine while the side intake bulges defeated any side "look-down" qualities. However, the F-102 was designed as an interceptor at heart and not a true "fighter" so vision out of the cockpit was not a pure requirement of the project. The undercarriage was of the conventional "tricycle" arrangement made up of two main landing gear legs set under the wings and a single nose wheel leg under the cockpit floor - all were fully-retractable. The initial production mark was given the Hughes MG-3 series FCS while later models featured the more advanced Hughes MG-10 series.
Power was supplied by a single Pratt & Whitney J57P-23 series turbojet engine of 11,700lb thrust. 17,200lb thrust output could be achieved with afterburner which was essentially raw fuel pumped directly into the engine for temporary bursts of speed at the cost of reduced operational ranges. This supplied the aircraft with a top listed speed of 825 miles per hour with a service ceiling nearing 54,000 feet - all well-above the original USAF interceptor requirements though not the Mach 2-capable aircraft originally envisioned. Range was out to 1,350 miles while rate-of-climb was in the vicinity of 17,400 feet-per-minute. As an interceptor, the F-102 would be required to climb to altitude within a given window of time, fly to the interception point at speed and deliver ordnance at range with accuracy.
Interestingly for the time, weaponry was held across three internal bays hidden under the main fuselage section. This helped to reduce exterior airflow under the aircraft and squeeze as much speed out of the design as possible. To some extent, this also lessened the aircraft's inherent radar signature. As an interceptor, the F-102 was fitted with air-to-air ordnance intended to take down the sizeable marauding Soviet bombers. A total of six missiles could be carried aboard and these were largely a mix of semi-active radar homing (the AIM-4A Falcon) and infrared homing (the AIM-4C Falcon) guidance types to cover the two most likely interception-target scenarios. Provisions were made for the carrying of 24 x Folding-Fin Aerial Rockets (FFARs) along the door panels of the two forward-most weapons bays and these could be used at short-ranges against a large target with acceptable results. The pilot or fire control system could manage the weapons through an additional control column in the cockpit. The FCS could direct the aircraft to the target automatically. Later in its operational service, the F-102 was cleared for fielding the AIM-26A Nuclear Falcon nuclear missile which broadened her deterrent-type nature with the Soviets. As this was the period of military aviation saw a definite shift away from onboard cannons towards missile technology, no internal gun was ever fitted to the series. Drop tanks - one under each wing - became commonplace to help increase the F-102s operational range.
Since the delta-wing fighter was a relatively new addition to the ranks of the USAF, it resulted in CONVAIR developing a viable two-seat trainer derivative of the fighter form to be designated as the "TF-102A". This form retained its combat capabilities but was decidedly handicapped in its performance thanks to a revised, bulged front fuselage section required of the side-by-side seating for student and instructor. A total of 111 TF-102 marks were produced and used extensively in training for all F-102 operators.
The F-102 was finally delivered to awaiting USAF units in April of 1956, two years after the intended proposal date to produce a viable operational interceptor product. Training of new pilots ensued through use of the available two-seat TF-102A conversion models. F-102s also served with the USAF Air Defense Command branch up until 1960, intent on defending the continental United States from Soviet air attack. F-102s in USAF service were not used in anger until American involvement in the Vietnam War broadened to which every capable aircraft was seemingly utilized to prevent the loss of South Vietnam to communist rule. F-102s arrived in the theater in 1962 and were initially used for their speed as interceptors and now painted over in the standard Southeast Asia camouflage pattern. Later in their tenure, F-102s were pressed into service as fighter escorts for the large, plodding and susceptible Boeing B-52 Stratofortress bombers. As the war evolved, the need for more "strike-oriented" aircraft increased and F-102s and TF-102 trainers were used in the ground attack role fitted with high-explosive rocket ordnance. The F-102 maintained a presence in the theater up until 1968 to which only one was lost to enemy air-to-air combat. In all of the war, a total of 15 F-102s were eventually lost.
Once the Pratt & Whitney J75 turbojet engine series became available, the F-102 airframe was heavily revised and modified to accept it. Other changes implemented into its design produced an essentially new interceptor which bypassed the intended F-102B production mark, instead being succeeded by the Mach 2-capable "F-106 Delta Dart" lineage detailed elsewhere on this site. The Delta Dart first flew on December 26th, 1956 to which the series was formally introduced in June of 1959. 342 of this type were produced and well-liked by its pilots.
As its peak usage years slowly passed behind it, the large stable of F-102 airframes were converted to piloted and pilotless target drones for weapons training. Initial conversions took place in 1973 and eventually totaled 217 conversions under the designations of "QF-102A" and, later, "PQM-102A/B" with the final F-102 drone being destroyed in 1986. These served to sharpen the skills of USAF "top gun" pilots in an active and "live" classroom setting.
There was a lesser known proposed "strike variant" of the F-102 as well and this would have been known under the designation of F-102C if produced. The type was to field the J57-P-47 series engine as well as an internal gun for close-in work. A pair of hardpoints under the wings were to be added for support of conventional drop ordnance. An internal refueling probe would have broadened the operational range of the aircraft as would have the proposed larger internal fuel stores. Two "YF-102C" developmental models were ultimately devised but never implemented.
The F-102 saw only limited use overseas and delivered to US allies in Turkey and Greece. Turkey received their 50 F-102A and trainers from 1968 onwards and these were used USAF models. Turkish use of the F-102 ended in 1979. Greece took delivery of their 24 F-102A and trainer mounts in 1969 and utilized them until 1978.The United States formally abandoned use of the F-102 interceptor in 1976. It served with Air Defense Command, Alaskan Air Command, the United States Air Forces in Europe, the Pacific Air Forces and the Air National Guard. In all, the F-102 stocked the inventories of some 70+ interceptor squadrons with 26 squadrons available during its peak usage (all with Air Defense Command). The advent of more capable "multi-role" aircraft and improved ground-launched intercepting missiles ultimately led to the end of the "interceptor" as an accepted part of the modern battlefield. The comparable F-106 soldiered on until 1988 with the Air National Guard.