The PV-2 Harpoon: the mechanized harpooner from Burbank

In late 1942, the Vega Division of Lockheed proposed an evolutionary derivative of the PV-1 Ventura (itself the US Navy variant of the Model 18 Lodestar) with bigger wings and increased fuel capacity after it was obvious that the Ventura experienced takeoff problems when carrying a full load of fuel. Internally designated V-143 (or alternately Model 15-27-01), it had a wingspan of 75 feet (23 meters), a wing area of 686 square feet (63.7 m²), a gross weight of 33,668 lb (15,271 kg), and a range of 1,790 miles (2,880 kg). The twin vertical stabilizers of the design had greater area, and the V-146 would carry a greater internal weapons load than the Ventura, with provisions for 4,000 lb (1,814 kg) of bombs or depth charges, but also eight 5 inch (12.7 cm) HVAR rockets below the wings, and defensive armament comprised two 0.50-in machine guns in the upper nose, three 0.50-in machine guns in an undernose pack, and twin 0.50-inch machine guns in both dorsal and ventral turrets (the latter defensive armament set used on the PV-1). In June 1943, the US Navy ordered 500 V-143s (BuNos 37035/37534) under the designation PV-2, and the official name Harpoon was assigned to the aircraft.

Left: The Lockheed PV-2 Harpoon during flight testing in December 1943
Right: A PV-2 Harpoon (BuNo 37211) on display at the Palm Springs Air Museum in Palm Springs, California, photographed by me in March 2024.

The first flight of the PV-2 Harpoon occurred on December 3, 1943. However, early flight tests showed a tendency for the wings to wrinkle, so Lockheed opted for a wing redesign rather than a slight six foot wing reduction for making the wing uniformly flexible. The first 30 PV-2s delivered to the US Navy in 1944 which had the original defective wings were relegated to training duties with the outer wing tanks sealed off and designated PV-2C, and because of the redesign of the Harpoon's wing, only 69 PV-2s had been delivered by the end of 1944. When the wing problems were remedied, the PV-2 entered service in February 1945, and it began operational deployment from the Aleutian Islands the next month. Even before the PV-2 had entered service, the Navy placed additional orders for 908 more PV-2s (BuNos 37535/37634, 84057/84589, 102001/102275), which were equipped with eight 0.50-inch forward-firing machine guns and hence received the designation PV-2D. (In an interesting footnote, one PV-1 Ventura with the BuNo 34986 was modified with the PV-2 tail empennage and unofficially became known as the "PV-1 1/2", with the Lockheed Vega designation V-153 applied to this conversion.) In April-May 1945 the Harpoon made its combat debut when it launched rocket attacks on the Japanese-held Kuril Islands, and it also hunted Japanese submarines and shipping in the vicinity of island chains in the Western Pacific during the summer of 1945. The combat career of the Harpoon was rather brief, and by time Japan surrendered, only 35 PV-2Ds (BuNos 37535/37550, 37624/37634, and 84057/84064) had been delivered, after which the remaining PV-2Ds on order were canceled after V-J Day and by which time a total of 535 PV-2s had been built. A handful of PV-2s and PV-2Ds in service were also modified into crew trainers and redesignated PV-2T. The US Navy continued operating the Harpoon for a few more years (the Naval Reserve had eleven of its patrol squadrons equipped with the PV-2 at one time) until August 1948, when it retired the Harpoon fleet. Several PV-2s which were declared surplus to Navy requirements after World War II ended up on the commercial market, with some being modified as private transports with deluxe interiors and a few others converted to agricultural spraying aircraft.

A PV-2 of the Aeronavale (French Naval Aviation)

Shortly before World War II ended, the Brazilian Air Force became the first foreign user of the PV-2 when it acquired six aircraft, erroneously designating them B-34A, and these aircraft served with Brazil (some of them modified as transports) in service until the 1950s. In 1945, the Royal New Zealand Air Force (RNZAF) ordered 48 PV-2s to replace its PV-1s, and the first four were delivered in February 1945, but problems with these planes were encountered and further deliveries were cancelled, leading to the RNZAF returning these PV-2s to the US Navy in late April-mid May 1945. During the 1950s, a number of countries acquired numerous ex-US Navy Harpoons, including France, Italy, Japan, Peru, Netherlands, and Portugal (some PV-2s which served with Portugal were previously in French and Dutch service). The Aeronautica Militare Italiana withdrew its PV-2s from service in the late 1950s as it began acquiring the Grumman S2F Tracker, and the Royal Dutch Navy sold its PV-2s to Portugal in 1953 as it took deliveries of the P2V Neptune, while Peru operated the Harpoon until the 1960s. The Portuguese Air Force used some PV-2s for counter-insurgency missions against Angolan independence fighters in the 1960s during Angola's 1961-1974 war for independence from Portugal, and the Harpoon was retired from Portuguese service in the early 1970s by the time Angola became independent in 1975.

As a side note, in 1943 Lockheed Vega proposed a development of the Harpoon featuring modified armament, strengthened undercarriage, and "C Series" R-2800 Double Wasp engines, designated V-154 by the company and unofficially called "PV-4". However, the "PV-4" proceeded no further than the design phase.

References:

Buttler, T., and Griffith, A., 2015. American Secret Projects 1: Fighters, Bombers, and Attack Aircraft, 1937 to 1945. Manchester, UK: Crecy Publishing.

Marson, P.J., 2001. The Lockheed Twins. Tonbridge, UK: Air-Britain Historians Ltd.

Burbank's sentry stars for the US Air Force

In the late 1940s Lockheed investigated the idea of adapting the Constellation airliner for patrol and airborne early warning duties. The US Navy tacitly recognized the Constellation's potential as an AEW platform, and in late 1948 it ordered two L-749s with AEW radar (BuNos 124437/124438) designated PO-1W, and the first of the two PO-1Ws flew on June 9, 1949. The PO-1W carried large, long-range search radars in massive radomes above and below the fuselage, and the huge amount of side area possessed by the radomes meant that the PO-1W had bigger vertical stabilizers than those of the L-749. Impressed by flight tests of the PO-1W, in the summer of 1950 Lockheed put forward an AEW version of the L-1049 Super Constellation, the L-1049A, and in 1951 the Navy ordered six L-1049As with the designation PO-2W (BuNos 126512/126513, 128323/128326). When the Navy's Bureau of Aeronautics introduced the W-for-Airborne Early Warning aircraft mission category in 1951, the PO-1W and PO-2W were redesignated WV-1 and WV-2 respectively. Deliveries of the WV-2 to Navy electronic warfare units began in 1953, with 136 more WV-2s (BuNos 131387/131392, 135746/135761, 137887/137890, 141289/141333, 143184/143225, 143226/143230, and 145924/145941*) completed. Although airborne early warning versions of the Super Constellation weren't given an official name, Lockheed dubbed them the Warning Star.

*Twenty-two more WV-2s (BuNos 131393/131399 and 145942/145956) were on the US Navy's order books in addition to the first six WV-2s initially designated PO-2W and the other 136 completed WV-2s, but they were cancelled without being built.  

Left: The first RC-121C (serial number 51-3836) in flight, 1955
Right: An EC-121D (serial number 53-0128) in flight with two F-104s, 1958

Even before the first WV-2s began flying, the US Air Force was shopping for an airborne early warning aircraft of its own, and in 1951 it procured ten L-1049Bs originally ordered by the Navy, designating them RC-121C and assigning serial numbers 51-3836/3845 to these aircraft. The RC-121C first flew in 1952 and deliveries to the USAF began in January 1953. A Navy order for 72 WV-2s was also diverted to the Air Force and given the designation RC-121D. The first flight of the RC-121D took place in May 1954 and the deliveries started the following month, with operational deployment of the RC-121D commencing on December 21. Serial numbers 52-3411/3425, 53-533/556, 53-3398/3403, 54-2304/2308 and 55-118/139 were allocated to the RC-121Ds, and one C-121C (serial number 54-183) was converted to an RC-121D. The RC-121C and RC-121D were redesignated EC-121C and EC-121D respectively in 1955. Like the WV-2, the EC-121C and EC-121D were equipped with dorsal and ventral radomes to house the AN/APS-45 height finder and AN/APS-20 search radar respectively, and they could carry a crew of 18 (two pilots, two navigators, two weapons controllers, two flight engineers, one radio operator, two crew chiefs, five radar operators, and two radar technicians). However, in contrast to the EC-121C, the EC-121D had the wingtip tanks of the WV-2 and utilized select equipment changes. The EC-121C and EC-121D were tasked with providing complementary early warning radar coverage to the North Pacific and North Atlantic barriers by flying orbits 300 miles (480 km) offshore from the continental US in what were termed "contiguous barriers", and coverage orbits overlapped those of land-based early warning radars. Three R7V-1s (BuNos 128436, 128438/128439, 131638) acquired by the US Air Force in 1954 were designated TC-121G and reserialled 54-4050/4052 and 54-4058 after being modified to traincrews to fly the EC-121C and EC-121D (serial number 54-4051 would later be converted to a VIP transport and redesignated VC-121G). Two RC/EC-121Cs were lost in accidents, one ditching in San Pablo Bay near San Francisco on November 21, 1953, and another crashing during a flight in rainy weather in Marysville, California, on March 22, 1961, and after the latter accident the remaining EC-121Cs were converted to AEW crew training aircraft and redesignated TC-121C. In 1962, 42 EC-121D airframes and seven ex-USN WV-2s (the latter reserialled 55-5262/55-5268) were redesignated EC-121H after being modified with the SAGE (Semi-Automatic Ground Environment) electronic suite for the AEW role and upgraded new dorsal and ventral radomes housing the APS-103 and APS-95 search radars respectively. The designation EC-121J was assigned to two EC-121Ds (serial numbers 52-3416 and 55-137) modified with additional electronic equipment in the early 1960s, and the US Air Force also acquired three examples of the EC-121P anti-submarine variant of the EC-121K for avionics testing, referring to them as the JEC-121P.

Left: EC-121Ds (serial number 53-3400 in the foreground) at Khorat Royal Thai Air Force Base, Thailand, in 1968. (Courtesy of US Air Force)
Right: An EC-121R on a surveillance mission over Southeast Asia on January 15, 1969. (Courtesy of US Air Force)

After the October 1962 missile crisis, four EC-121Ds of the 966th Airborne Early Warning and Control Squadron based at McRoy AFB near Orlando Florida, were fitted with upgraded electronics and given the designation EC-121Q, and they monitored activities in Cuban airspace and tracked U-2 overflights of Cuba as part of Operation Gold Digger. After the start of Operation Rolling Thunder in March 1965, EC-121s began providing radar early warning and limited airborne control of USAF fighter squadrons fighting North Vietnamese MiGs, and the Big Eye Task Force stationed at the Tan Son Nhut Air Base in Saigon, South Vietnam, was set by the USAF's 552nd Airborne Early Warning and Control Wing to provide support for EC-121Ds making orbits around the Gulf of Tonkin. The first time that the EC-121 successfully used airborne-control interception in the Vietnam War occurred on July 10, 1965, when it provided warning to a pair of F-4C Phantom II jet fighters, which led the F-4Cs to shoot down two North Vietnamese MiG-17s. The Big Eye Task Force relocated to Thailand in 1967 due to the threat of attacks on Tan Son Nhut AB by the Viet Cong and changed its name to the College Eye Task Force, and in April of that year all EC-121s operating with the College Eye Task Force were fitted with QRC-248 IFF transponder interrogators. Back in January 1967, as part of Project Quick Look, the NC-121D (originally designated GRC-121D), which had been built as a WV-2 with BuNo 143226 before being transferred to the US Air Force and given the new serial number 56-6956, was used as a testbed for the QRC-248 system. Beginning in July 1967, the Air Force EC-121s fitted with the QRC-248 system orbited airspace over Laos to provide airborne control of US military aircraft going after Viet Cong activities along the Ho Chi Minh trail. In August 1967, one WV-2 (EC-121K after 1962) originally operated by the Navy with BuNo 143184 and designated EC-121M (not to be confused with the EC-121M ELINT version of the EC-121K) after being acquired by the US Air Force began operational testing of the top-secret Rivet Gym electronics suite (consisting of voice communications intercept stations manned by Vietnamese-speaking intelligence specialists) under Project Rivet Top. After being moved to Korat Royal Thai Air Force Base along with the College Eye Task Force in October 1967, the Rivet Top prototype undertook AEW operations over the Gulf of Tonkin beginning in April 1968, and the EC-121s assigned to the College Eye Task Force were fitted with the Rivet Gym electronics suite the following month. The EC-121R (nicknamed "Batcat") was an EC-121 iteration with ground sensors to detect enemy activities along the Ho Chi Minh trail, and 28 EC-121K/P aircraft and two examples of the WC-121N (WV-3 before 1962) weather reconnaissance aircraft were modified to EC-121Rs after being acquired by the US Air Force in 1966-1967 and assigned serial numbers 67-21471/21500. Painted in the tree-color Southeast Asia camouflage scheme and lacking radomes, the EC-121Rs were deployed to Thailand as part of Operation Igloo White and undertook eavesdropping activities over the Ho Chi Minh trail from October 1967 to December 1971.

Left: An EC-121T (serial number 53-548) (built as an RC/EC-121D) on display at the Yanks Air Museum in Chino, California, photographed by me on July 27, 2022.

The Warning Star that I've seen at the Yanks Air Museum is an example of the last USAF variant of the EC-121, the EC-121T. In the summer of 1970, 22 EC-121D/H aircraft and one EC-121J were fitted with improved electronic systems, namely a digital data receiver, and they were redesignated EC-121T. Many of the EC-121Ts had the dorsal radome and radar removed, but others retained it. On November 12, EC-121Ts began arriving in Thailand from McClellan AFB in California to provide an integrated tactical data display with real-time inputs in support of Operation Kingpin, a mission to rescue US prisoners of war presumably held at the Son Tay prison in Hanoi. The EC-121T would provide radar early warning to jet fighters during the last years of the Vietnam War, especially during Operations Linebacker and Linebacker II, and EC-121Ts with callsign Disco provided radar support while orbiting Laotian airspace and the Gulf of Tonkin in 1971-1972. The last Disco EC-121T mission was flown on August 15, 1973, and the EC-121s stationed at Khorat RTAFB were withdrawn from Southeast Asia on June 1, 1974. The EC-121T was retired from service on March 28, 1975, while the TC-121G would follow suit in June.

In late 1975, the US Air Force began withdrawing the EC-121 from operational service as it prepared to take deliveries of the new jet-powered Boeing E-3 Sentry. All remaining EC-121s were transferred to the US Air Force Reserve's 79th AEWCS at Homestead AFB in Miami-Dade County, Florida, in early 1976, and they continued monitoring Soviet military activities in Cuba until October 1978, when they were retired, ending the quarter-century career of the USAF's Warning Stars.

References:  

Breffort, D., 2006. Lockheed Constellation: From Excalibur to Starliner, Civilian and Military Variants. Paris, France: Histoire and Collections.

Michel, M.L., 1997. Clashes: Air Combat Over North Vietnam 1965–1972. Annapolis, MD: Naval Institute Press.

Winchester, J., 2001. Lockheed Constellation. St. Paul, MN: MBI Publishing.

Transonic all-weather interceptor from Inglewood: the F-86D Sabre Dog

The F-86 Sabre was the most prolific US Air Force air superiority jet fighter built in the 1946-1951 time period, becoming America's chief air combat star of the Korean War by ambushing and fighting MiG-15s in the skies over North Korea. However, it should be noted that the F-86 family itself spawned a variant that would become the second all-weather jet fighter-interceptor to be built in southern California, and this aircraft was originally bestowed a distinct F-for-Fighter designation before being eventually reclassified as an F-86 variant.

The first YF-95/YF-86D prototype (serial number 50-577) on the tarmac at the North American Aviation field near Los Angeles International Airport,

On March 28, 1949, North American Aviation envisaged an all-weather interceptor variant of the F-86 Sabre under the company designation NA-164. The US Air Force showed interest in this proposal, and on April 7 North American itself felt confident enough to undertake engineering work on the production version, to which it applied the designation NA-165. The NA-164/165 differed from the F-86 in having a longer fuselage, a single 7,650 lb (34 kN) thrust General Electric J47-GE-17 turbojet, a clamshell cockpit canopy with a rear hinge, and a 30-inch nose radome on the upper lip of the air intake. The nose radome would carry an AN/APG-36 search radar for interception of enemy aircraft, and because the NA-164/165 was a single-seat aircraft in stark contrast to the F-89 Scorpion and F-94A/B being two-seaters, it required sophisticated electronic systems. Instead of the F-86's four 20-mm cannons, the NA-164/165 itself would be armed with twenty-four 2.75 inch Mighty Mouse unguided air-to-air rockets carried in a retractable tray in the aircraft's belly, although the cannon armament installation of the baseline Sabre was studied as a standby plan. On October 7, 1949, two NA-164 prototypes (serial numbers 50-577/578) and 122 examples of the NA-165 production version (serial numbers 50-455/576) were ordered and the NA-164 was given the designation YF-95 while the designation F-95A was given to the NA-165. The USSR's first successful nuclear weapons test in September 1949 prompted the USAF to order 31 more F-95As (serial numbers 50-704/734), and the YF-95 made its first flight on December 27, 1949. The YF-95 prototypes retained the cockpit canopy, flight controls, and V-shaped windscreen of the F-86A, and the rocket armament and fire-control system were not yet available when flight tests of the YF-95 began.

An F-86D Sabre Dog (serial number 52-3722) in flight 

On July 24, 1950, the F-95 was redesignated F-86D after congressional taxpayers told North American Aviation that funds could be saved if the F-95 were classified as merely an evolutionary development of the Sabre, and thus the YF-95 prototypes became YF-86D. Beginning in September and continuing for two years the Hughes E-3 fire control system was tested aboard the YF-86Ds, and in February 1951 the YF-86D began firing trials of the Mighty Mouse rockets. Deliveries of the F-86D to the US Air Force began in March 1951, and the pressure of the Korean War precipitated an order for 188 F-86D-20-NAs (serial numbers 51-2944/3131) on April 11, 1951, followed by an order for 638 F-86D-25/30/35-NAs (serial numbers 51-5857/6262 and 51-8274/8505) on July 18. Whereas the F-86D-20-NA block had the internal designation NA-177, the latter order (company designation NA-173) was originally designated F-86G when first envisaged in August 1950, differing in having 120-gallon drop tanks for combat missions but ended up being classified as F-86Ds when finalized. Unlike the YF-86D prototypes, the production F-86D had the clamshell canopy, enlarged vertical stabilizer, and a slightly lowered all-flying horizontal stabilizer. The F-86D set a new airspeed record of 698 mph (1,124 km/h) over the Salton Sea in southern California on November 18, 1952, and nine months later, that world airspeed record was shattered on July 16, 1953, when another F-86D flew over the same area at a speed of 716 mph (1,151.8 km/h). The US Air Force was so impressed by the F-86D's performance that yet another production contract for the F-86D was signed on March 6, 1952 for 901 F-86D-40/45/50-NAs (serial numbers 52-3598/4304 and 52-9983/10176), internally designated NA-190, and the final production order was placed on June 12, 1953 for 624 F-86D-55/60-NAs (serials 53-557/1071, 53-3675/3710, and 53-4018/4090), which bore the company designation NA-201. The first 238 F-86D-45-NAs were fitted with the J47-GE-17B turbojet, but the remaining F-86D-45s and all the F-86D-50/55/60-NAs used a more powerful 7,650 lb (34 kN) J47-GE-33 turbojet, which had better cooling and afterburner ignition. The last F-86D was delivered in September 1955, by which time a total of 2,506 F-86Ds (including the prototypes) had been built. The "D" suffix in the F-86D designation led USAF pilots nicknaming this aircraft the Sabre Dog.

In a typical intercept mission, the F-86D's AN/APG-37 radar searched the sky in a forward direction, sweeping back and forth and up and down in a 3.5-second cycle and locating target 30 miles (48 km) away. When the target showed up as a blip on the radar scope, the pilot locked the radar onto the target and the AN/APA-84 computer determined a lead collision course. He flew this course by keeping the steering dot on his scope inside a reference circle. When the automatic tracking system indicated that there were only 20 seconds to go, the pilot steered more precisely to keep the dot in a smaller circle. The pilot chose whether to fire 6, 12, or all 24 of the Mighty Mouse rockets, and pressed the trigger. However, the actual firing instant was determined by the computer, not by the pilot, and when the computer deemed the range to be right, the rocket pack was extended and the rockets were fired. The range at which the computer fired the rockets at the target was typically about 500 yards. It took a half-second for the pack to lower, and only a fifth of a second to fire all 24 rockets. After firing, the rockets fanned out in a predetermined pattern reminiscent of a shotgun blast. When the last rocket was away, the pack automatically retracted back into the fuselage belly, and an "8" appeared on the pilot's scope, warning him that the target was only 260 yards ahead and that he had better break away..

Although the F-86D was the backbone of the USAF's Air Defense Command (ADC) for much of the early-to-mid 1950s, differences among the multitude of operational F-86D production blocks meant that they required different sets of spare parts, different instruction manuals, and different maintenance procedures, leading to maintenance and repair headaches. Therefore, the US Air Force initiated Project Pull-Out in late 1953 to withdraw all F-86Ds built prior to deployment of the F-86D-45-NA production block from operational units and upgrade them to F-86D-45 standard. Upgrades to the early production block F-86Ds included fitting them with braking parachutes and upgraded computer electronics, and when Project Pull-Out was completed in September 1955, a total of 1,128 F-86D-10 to D-40 aircraft had been modified, receiving the designation blocks F-86D-11/16/21/26/31/36/41. Several F-86Ds were deployed overseas to Europe, the Far East, and North Africa beginning in 1954, and in spite of being designed to intercept enemy bombers, the F-86D would never fire a shot in anger against enemy aircraft in its capacity as an interceptor.   

An F-86L (serial number 50-560) on display at the March Field Air Museum, photographed by me in April 2019. This aircraft was one of the first 122 production F-86Ds to be built.

Despite the completion of Project Pull-Out, the F-86Ds were still beset by engine failures and reliability issues with the E-4 fire control system with which they were equipped.  Thus, in the mid-1950s, the US Air Force decided to adapt numerous F-86Ds to use the Semi-Automatic Ground Environment (SAGE) datalink system, which involved use of a large, high-speed ground-based computer for handling and coordinating air surveillance data from various ground radar installations that was transmitted in real-time to a special data receiver aboard the interceptor, and then converted to an on-board system into heading, speed, altitude, target bearing, and range information to guide the pilot in his interception of an enemy aircraft. The first F-86D to have the SAGE system installed flew on December 27, 1955, and beginning in May 1956, under Project Follow-On, it and 575 more F-86Ds were fitted with not only the SAGE system but also extended wingtips and wing leading edges, and engine cooling ducts, resulting in the designation F-86L for these conversions. Thus, the SAGE-equipped F-86D-11 to F-86D-46 aircraft were redesignated F-86L-11 to F-86L-46, whereas the Block 50, 55, and 60 F-86Ds were given the designations F-86L-50 to F-86L-60. The F-86L entered service with the ADC in October, and by this time the ADC had begun withdrawing the F-86D from squadron service beginning in August of that year. Retirement of the F-86D from ADC units was complete by April 1958, and some of the F-86Ds were turned over to the Air National Guard, in which they served until 1961. The F-86L's operational career was rather brief because the deployment of the supersonic F-102 Delta Dagger and F-106 Delta Dart made the F-86L obsolete, leading to retirement of the F-86L from USAF service in 1960. The Air National Guard acquired the F-86L in late 1957 amid the ADC's deployment of the F-102 and F-106, operating F-86Ls until the summer of 1965. From 1958 to 1961, sufficient numbers of retired F-86Ds were exported to Denmark, Greece, Yugoslavia, Turkey, the Philippines, Japan, Taiwan, and South Korea. On the other hand, 17 retired F-86Ls were sold to Thailand in 1964, serving with the Royal Thai Air Force until 1976. In Yugoslav service, F-86Ds were designated L-13 (L stood for Lovac, which means "fighter" in Serbian), and a number of F-86Ds modified for reconnaissance were called IF-86D (with I standing for Izviđač, which is Serbian for "reconnaissance").

A line-up of Fiat-built F-86Ks for the Aeronautica Militare

As the USAF began taking deliveries of the F-86D, America's NATO allies in mainland Europe wanted an all-weather interceptor able to tackle the emerging threat of nuclear-armed Soviet strategic bombers. However, the sophistication of the E-4 fire control system of the F-86D along with its reliability issues meant that exporting the E-4 to US allies was not an option. In response to a USAF request in January 1953 to have Italy operate an interceptor similar in appearance to the F-86D but with cannons, on May 14, 1953, North American conceived an export version of the F-86D, the NA-205, which retained the nose radome radar of the F-86D but was armed with four 20 mm M24A1 cannons designed to operate with a new fire control system designed by North American, the MG-4, which was less technologically complex than the E-4. Two F-86Ds (serial numbers 52-3630 and 52-3804) were selected for the NA-205 project and designated YF-86K, and on May 16, North American signed an agreement with the Italian company Fiat to assemble 50 examples of the production version, the F-86K, which had USAF serials 53-8273/8322 assigned to them although they intended for export to Europe. A batch of 120 F-86Ks to be built for Norway and Netherlands (serial numbers 54-1231/1350; company designation NA-213) was ordered on December 18, and the YF-86K was first flown on July 15, 1954, while the first flight of the production F-86K took place on March 8, 1955, and the first F-86K built under license in Italy flew on May 23. The company designation NA-207 was given to the first batch of F-86Ks built by Fiat, and 171 more F-86Ks (serial numbers 55-4811/4936 and 56-4116/4160) were manufactured under license by Fiat, with North American giving the internal designations NA-221, NA-232, and NA-242 to the latter aircraft. The F-86Ks with the internal designation NA-242 differed from other Fiat-assembled F-86Ks in having slightly increased wingspan and greater wing area. Besides its cannon armament, the F-86K differed from the F-86D in havng a slightly longer nose to house the cannons and ammunition. The US-built F-86Ks (except one retained by the US Air Force were testing) were delivered to Norway and the Netherlands in 1955-1956, and of the 221 F-86Ks license-built by Fiat, 63 were delivered to the Aeronautica Militare, sixty-two went to the French Air Force, and 86 were delivered to West Germany's Luftwaffe, while the Netherlands received six and four were given to Norway. By the 1960s France, Italy, the Netherlands, Norway, and West Germany retired the F-86K from service as the F-104G and Dassault Mirage IIIC entered frontline service, and seventy-four ex-Luftwaffe F-86Ks were sold to Venezuela in 1966 (five of which were later given to the Honduran Air Force in 1969) while 40 F-86Ks previously in Italian service were sold to the Turkish Air Force, which operated them until 1969.

Acme S-1 Sierra: Torrance's native pusher airplane

As I've long recognized, the Western Museum of Flight in Torrance is ubiquitous for housing a variety of aircraft built in the Los Angeles basin, including those made by Northrop as well as Radioplane (renamed Northrop Ventura in 1962). However, unknown to most aviation enthusiasts, this museum happens to have a very exotic homebuilt airplane on display, built at the very airport in Torrance near which the Western Museum of Flight is located, the Acme S-1 Sierra. Therefore, I am dedicating this post to discussing this unusual homebuilt pusher-engine aircraft from Torrance.

The Acme S-1 Sierra (aka "Sierra Sue") on display at the Western Museum of Flight. Photographed by me on April 21, 2024.

In the late 1940s, two former employees for North American Aviation, Ron Beattie and Walt Fellers, who came to work for the Northrop company after the end of the World War II, proposed a single-seat high-performance aircraft to meet Goodyear Racing Plane specifications and investigate the advantages of an airplane utilizing a pusher propeller layout. This design featured a teardrop-shaped fuselage and a Y-shaped tail empennage with ruddervators on the upper fins, and it had straight wings midway up the fuselage, and large air scoops placed at the forward ends of the wing roots. It was 20 feet 2 in (6.14 meters) long with a wingspan of 18 feet (5.49 meters), an empty weight of 590 lb (268 kg), and a top speed of 200 mph (322 km/h), and power came from one 85 hp (62 kW) Continental O-85 4-cylinder horizontally opposed piston engine situated behind the cockpit and driving a tail-mounted two-bladed pusher propeller. The Acme Aircraft Company based in Torrance, California, was entrusted to build the aircraft, and when this plane was completed in late 1948 it was now called the Acme Sierra, bearing the civil registration N12K (although this aircraft was sometimes nicknamed "Sierra Sue"). The first flight of the Acme Sierra occurred on November 23, 1953, and when Acme Aircraft was renamed Sierradyne Incorporated that year, the Acme Sierra itself received the internal designation S-1.  

The Acme S-1 Sierra at an airfield in Hawthorne in 1967 after being acquired by Northrop for testing the configuration of the N-308 attack aircraft project and rebranded as Northrop Turbo-Pusher (courtesy of Aerofiles).

Although it was not entered in any air races, the S-1 Sierra obtained extensive aerodynamic data during flight testing suggesting some aerodynamic benefits of a pusher-engine aircraft. During the 1960s, it was used by Sierradyne for tests of the aerodynamic benefits of the boundary layer control concept advocated by Swiss-born American aerodynamicist Werner Pfenninger and supported by Northrop. When the US Air Force in the late 1960s began contemplating plans for a purpose-built ground attack aircraft (which led to the A-X requirement), Walt Fellers in 1967 conceived a pusher-engine proposal for Northrop for the A-X program, the N-308, and that same year Northrop acquired the S-1 Sierra for use as a technology demonstrator to test the pusher-engine layout of the N-308, re-labeling it as the Northrop Turbo-Pusher. The S-1 Sierra's final flight ended in mishap on November 24, 1967, when its pilot created so much overload failure by improper operation of the flight controls and/or airbrakes that he crashed-landed the aircraft after a demonstration flight at Langley AFB in Virginia.

By 1970, Northrop dropped the N-308 in favor of the twin-turbofan N-312 and N-320 proposals for the A-X program after the US Air Force judged a turbofan-powered ground attack aircraft to be much faster than its inventory of A-1E Skyraiders compared to a turboprop-powered design, and the N-320 was designated YA-9 after being selected by the Air Force along with the rival Fairchild Republic A-10 for prototyping (the YA-9 itself ended up losing the A-X competition to the A-10 in 1973, but that's another story). Meanwhile, the S-1 Sierra which had ended its flying career as a technology demonstrator for the N-308 was eventually spared from scrapping and found a home at the Western Museum of Flight, which was initially based in Hawthorne before relocating to its present location in Torrance, the very city where the S-1 Sierra was built. 

References:

Chong, T., 2016. Flying Wings & Radical Things: Northrop's Secret Aerospace Projects & Concepts 1939-1994. Forest Lake, MN: Specialty Press.

Underwood, J.W., and Caler, J., 1958. Experimental Light Aircraft and Midget Racers. Fallbrook, CA: Aero Publishers.

Burbank's flying classroom for Canada: The Silver Star

During the near end of my visit to the Planes of Fame Museum in Chino last month, I happened to notice a jet aircraft inside the USS Enterprise Hangar, and the appearance of this airplane was so familiar to me that I wondered if it was a P-80/F-80 Shooting Star jet fighter or the T-33 jet trainer derivative. Oddly, this machine has the vertical stabilizer marked with a civil registration rather than a serial number, so I was curious about its manufacturing and operational history, and after doing online research, it occurred to me that the aircraft with civil registration N133AT was indeed a T-33, albeit a Canadian-built version known by the Canadian military designation CT-133. Given the superfluous operational history of the aircraft which is currently marked N133AT and emblazoned with in US Air Force markings, but also the fact that the T-33 was built under license in Canada, I'm dedicating this post to encapsulating the full history of the T-33 in Canadian service.

A Lockheed T-33A Silver Star Mk. 1 (serial number 14679) at RCAF Chatham in New Brunswick, initially built for the US Air Force with serial number 50-1275.

In the late 1940s the Royal Canadian Air Force was shopping for a jet aircraft able to provide advanced training for its fighter pilots due to the lack of a two-seat trainer version of the F-86 Sabre jet fighter that would be built under license by Canadair and enter service with RCAF fighter squadrons in 1950. After much consideration, the RCAF selected the T-33 to fulfill advanced training needs, and from May 1951 to March 1952, twenty T-33As were obtained second-hand from the US Air Force by the RCAF and assigned the serial numbers 14675/14694, followed by delivery of ten more T-33As were in late 1952 with the serials 516713/516717 and 516743/516747, and these T-33As were dubbed the Silver Star Mk. 1 by the Royal Canadian Air Force. Some of Silver Star Mk. 1 aircraft were later returned to the US Air Force in 1953-1955, but many remained in service with the RCAF until early 1955, when they were retired from service and later transferred to the air forces of Greece and Turkey.

A CT-133 Silver Star Mk. 3 (serial number 21326) in flight 

While the Royal Canadian Air Force began taking deliveries of its first T-33s, in 1951 the homegrown Canadian aircraft company Canadair received a contract to build the T-33 under license, and it assigned the company designation CL-30 to the Canadian version of the T-33, which differed in being powered by a Rolls-Royce Nene 10 turbojet rather than the Allison J33 that powered the T-33. One T-33A (serial number 51-4198) was modified by Lockheed to serve as the prototype for the CL-30, and upon delivery to the Royal Canadian Air Force on November 27, 1951, it was christened the Silver Star Mk. 2 and given the RCAF serial 146595. Lockheed referred to the Silver Star Mk. 2 as the T-33AN-X, and the CL-30 version was known as the T-33AN. On December 22, 1952, the first Canadian-built T-33 made its first flight at Cartierville, Quebec, with test pilot William S. Longhurst at the controls, and deliveries of CL-30/T-33AN to the Royal Canadian Air Force began in 1953 and lasted until 1959, by which time a total of 656 T-33s had been built under license by Canadair. The T-33AN, which became known as the Silver Star Mk. 3, was designated CT-133 by the RCAF, which allocated serial numbers 21001/21656 to the CT-133s. 

The CT-133 had an extremely long service life with the Royal Canadian Air Force. In addition to being the RCAF's premier jet trainer throughout the 1950s and 1960s, it also served with the RCAF's Red Knight aerobatic display team, and CT-133s used by the Red Knight aerobatic team were painted red. The baseline unarmed CT-133 variant was called Silver Star Mk. 3PT, and one variant of the CT-133 was built for gunnery and bombing training, the Silver Star Mk. 3AT, whose armament comprised two .50 caliber Browning machine guns in the nose and underwing pylons for 1,000 lb (454 kg) bombs and HVAR rockets. More than 100 CT-133s were built as Silver Star Mk. 3ATs, and several Mk. 3PTs were converted to Mk. 3AT as well. The Silver Star Mk. 3PR was a photo-reconnaissance variant equipped with photographic reconnaissance equipment in the nose, and one CT-133 (serial number 21257) was built as a Mk. 3PR in 1954, while four existing CT-133s were converted to Mk. 3PR standard in 1963-1964. Other non-training uses of the CT-133 included target towing, threat simulation, and ejection seat testing; the designations ET-133 and TE-133 were allocated to CT-133s optimized for simulating aerial and anti-ship threat simulation respectively, while CT-133s modified as ejection seat testbeds bore the designation CX-133. 

When the newer Canadair CT-114 Tutor jet trainer entered service with the Royal Canadian Air Force in 1963, the RCAF began the phaseout of the CT-133 from training squadrons, and the retirement of the CT-133 from active training duties was completed by 1976. The Red Knight aerobatic team, for its part, replaced its CT-133s with the CT-114 in July 1968 (by which time the RCAF's training units had become the Training Command), although the aerobatic team itself disbanded in 1969 as a result of budget cuts and personnel reductions. Beginning in 1958 and continuing until the 1980s, more than 200 CT-133s were sold to Bolivia, France, Greece, Portugal, and Turkey after being retired from service with the RCAF in the 1950s and 1960s. There were still over 50 CT-133s serving the Canadian Forces well into the 1990s, and nine CT-133s were redesignated CE-133 in 1994 after being modified for electronic warfare training. They were fitted with new avionics as part of the AUP (Avionics Upgrade Program) modernization process from 1996 to 1999, but the majority were eventually phased out in 2002. The Canadian Forces finally retired the CT-133 Silver Star Mk. 3 from service on April 26, 2005, when four remaining examples were phased out by the Aerospace Engineering Test Establishment at CFB Cold Lake, Alberta.

Then and now: CT-133 serial number 21157 on the tarmac at a Royal Canadian Air Force base in Cold Lake, Alberta, 1958 (left); CT-133 serial number 21157 on display at the Planes of Fame Museum with civil registration N133AT, photographed by me on January 21, 2024 (right). 

The CT-133 which I saw at the Planes of Fame Museum last month was given the serial number 21157 when it was delivered to the Royal Canadian Air Force on November 20, 1953, and it also served as a target tug beginning in July 1958. In March 1965, this aircraft was retired from service and eventually sold to numerous civilian owners with the civil registration N155X, which was later changed to the current civil registration N133AT, and it would occasionally be used as a camera ship for several movies. The CT-133 now registered as N133AT was listed for sale on the Internet in April 2006 but it ended up being acquired by aviation enthusiasts for restoration to static display at the Plames of Fame Museum in Chino, California, where it resides to this day.

F-104 Starfighters for Belgium

Much has been written about the operational use of the Lockheed F-104 Starfighter jet fighter with West Germany, Italy, and Japan, bearing in mind the fact that the F-104s operated by the Luftwaffe (the air force of West Germany and ultimately the reunified German nation) were given nicknames like "Flying Coffin" and "Widowmaker" because they suffered a high accident rate. However, almost lost in talk regarding the F-104's operational career with Western and Central European air forces is the service career of the F-104 with the Belgian Air Force.

A Belgian Air Force F-104G Starfighter (serial number FX-82) on outdoor static display at the Planes of Fame Museum, photographed by me on January 21, 2024.

In the late 1950s, the Belgian Air Force was shopping for a new combat jet to replace the subsonic CF-100 Canuck interceptors and F-84F Thunderstreak fighter-bombers in its inventory, especially given that both the Canuck and Thunderstreak were becoming technologically obsolete. With the Luftwaffe as well as the post-World War II Italian air force (Aeronautica Militare) and Royal Netherlands Air Force purchasing the F-104, the Belgian Air Force decided to order the F-104G, and contracts were signed for the purchase of 112 F-104Gs, with twelve TF-104Gs ordered from Lockheed and 100 F-104Gs to be built under license by the homegrown Belgian aircraft manufacturer SABCA. The TF-104Gs were given the serial numbers FC-01/FC-12 while the SABCA-built F-104Gs for bore the serial numbers FX-1 to FX-100; twenty-eight of the F-104Gs ordered by Belgium (three TF-104Gs, 25 F-104Gs) were funded under the Mutual Assistance Program (MAP). Deliveries of the F-104G to the Belgian Air Force began in February 1963, with the F-104Gs and TF-104Gs replacing the F-84F and CF-100 in service with the 23 and 31 squadrons (both of 10 Wing) at Kleine Brogel and the 349 and 350 squadrons (both of 1 Wing) at Beauvechain (Bevekom) respectively. One F-104G ordered by the Belgian Air Force (serial number FX-27) crashed during a training flight at Sart-Dames-Avelines on November 21, 1963 prior to delivery due to a flameout of the turbojet engine, and a new F-104G (c/n 9082) also bearing the serial number FX-27 was built and delivered to replace the crashed aircraft, so a total of 111 F-104Gs and 12 TF-104Gs were built for the Belgian Air Force.

Three Belgian Air Force F-104Gs (serial numbers FX-12, FX-30, FX-82) in flight, 1971. 

Operational use of the F-104G by the Belgian Air Force in its role as an interceptor began in August 1964. Although the 10 Wing and 1 Wing were exclusively tailored to the air defense and tactical nuclear strike roles respectively, the F-104Gs were swapped between the two operational wings to balance airframe fatigue between medium/high-altitude fighter missions and nuclear-armed fighter-bomber missions. In its role as a fighter-bomber for the Belgian Air Force, the F-104G was armed with B61 tactical nuclear free-fall bombs stored at facilities owned by the 52nd Special Ammunition Group at Meeuwen. By 1968, the F-104Gs of the 10 Wing switched to dual air defense/fighter-bomber missions and began training with conventional weapons such as the 20-mm Vulcan rotary cannon, three napalm bombs or two Snakeye bombs or two LAU rocket launcher pods each armed with nineteen 2.75-inch FFAR rockets. Beginning in late 1979, the Belgian Air Force began replacing the F-104G with F-16 Fighting Falcons (the TF-104Gs were phased out in 1980), and the last Belgian Air Force F-104Gs were retired from service on September 26, 1983. Besides the F-104G with serial number FX-27 that crashed in November 1963, a total of 38 F-104Gs and three TF-104Gs were lost in accidents during operational service. In the meantime, 18 Belgian Air Force F-104Gs were transferred to the Turkish Air Force and 23 were given to Taiwan. 

Nuclear-armed stinger from Hawthorne: the Northrop F-89J

In 1955, the Douglas Aircraft Company began full-scale development of a short-range unguided air-to-air rocket to carry a 1.5 kiloton W25 nuclear warhead, the MB-1 Genie, after it became clear that traditional World War II-era US fighter armament would be inadequate to repel a bombing attack by squadrons of the Soviet Union's new gas turbine powered strategic bombers, the Myasishchev M-4, Tupolev Tu-16, and Tupolev Tu-95. The MB-1 Genie obviated the need for precise accuracy when targeting enemy bombers because it was designed with a large nuclear blast radius. Beginning in March 1956, Northrop modified numerous F-89D Scorpion all-weather interceptors from the F-89D-35 to -75 production blocks to carry the MB-1 Genie under Project Bellboy, and the company designation N-160 was allocated to this scheme. The resulting Genie-armed Scorpion, designated F-89J, carried two MB-1 Genies below launching rails that were mounted on the underwing pylons and had the standard wingtip missile pod/tanks replaced with 600 gallon (2,271 liter) fuel tanks, although a few F-89Js retained the wingtip tanks of the F-89D. Later, the F-89J received an extra modification by adding two more underwing pylons inboard of the launching rails for the Genie to carry four Falcon air-to-air missiles tipped with non-nuclear warheads. The F-89J was equipped with the Hughes MG-12 fire-control system (a upgraded and more advanced development of the E-5 fire control system installed on the F-89D), which could allow it to attack enemy bombers at much higher altitudes by making it easier for the crew to launch the Genie rockets while in a nose-up, climbing altitude. During interception of an enemy bomber formation, the MG-12 fire-control radar tracked a target and assigned a Genie to its target, after which the pilot armed the nuclear warhead and fired the Genie at the bomber pack before pulling the interceptor into a tight turn to escape the nuclear detonation and then proceeding to use remote control to allow the Genie's nuclear warhead to explode and destroy enemy bombers.

Left: Two F-89Js (serial numbers 52-1848 and 52-1862) in flight, 1958
Right: An F-89J (serial number 52-1949) at the March Field Air Museum, photographed by me on December 17, 2022.

In November 1956, the US Air Force began taking deliveries of the F-89J, the 84th Fighter Interceptor Squadron based at Hamilton AFB in Novato, California being the first unit to receive the F-89J, and standing active alerts of the F-89J with the Genie started on January 1, 1957. A total of 350 F-89Ds were converted to F-89J standard, with modifications completed by February 1958, and the US Air Force assigned the system code WS-205G (Weapons System 205G) to the F-89J. On July 19, 1957, as part of Operation Plumbbob, the F-89J carried out the first and only live firing of a Genie (codenamed John) when an F-89J with serial number 53-2547 fired an MB-1 Genie over the Yucca Flats Nuclear Test Site in southern Nevada, with the rocket's warhead detonating at an altitude of 15,000 feet (4,500 meters). To prove that the Genie was safe for use over populated areas in the event that Soviet bombers would penetrate US airspace, a group of five Air Force officers volunteered to stand uncovered in their light summer uniforms underneath the blast, and they were apparently spared from the effects of the blast after the live-firing test of the Genie over the Yucca Flats.

Despite proving to the US Air Force that a live-firing of a nuclear-armed unguided air-to-air rocket was feasible, the F-89J was destined to have a brief operational career with the Air Defense Command, and beginning in July 1959 it was replaced in ADC units by the supersonic F-101B Voodoo and F-106 Delta Dart, which also carried the Genie air-to-air rocket. The F-89Js were then transferred to the Air National Guard, operating with ANG until late 1968, when they were retired. In an interesting footnote, in 1963 ten F-89Js were stripped of their nose radars, fitted with additional underwing fuel tanks, and eventually used for testing Nike missile defenses in Japan, being redesignated DF-89J.  

References:

Balzer, G., and Dario, M., 1993. Northrop F-89 Scorpion. Leicester, UK: Aerofax.

Chong, T., 2016. Flying Wings & Radical Things: Northrop's Secret Aerospace Projects & Concepts 1939-1994. Forest Lake, MN: Specialty Press.

Davis, L., and Menard, D., 1990. F-89 Scorpion in Action (Aircraft Number 104). Carrollton, TX: Squadron/Signal Publications.