USA - 1952
The Douglas B-66 Destroyer was originally envisaged as a replacement for the World War 2-era piston-engined Douglas B-26 Invader in the tactical bombing role for both day and night operations. On June 14, 1951, the USAF issued a formal requirement for a tactical bombing aircraft to meet this need. The initial requirement specifically asked for a reconnaissance vehicle, but in August the requirement was amended to include tactical bombing as well.
Several companies responded with proposals to meet this requirement. North American proposed an improved version of its B-45 Tornado four-jet bomber. Boeing proposed an adaptation of its B-47 Stratojet six-jet medium bomber. Martin proposed a version of the B-51 3-engined low-level bomber. Most promising, however, was Douglas's proposal of a land-based version of the Navy's XA3D-1 Skywarrior twin-engined carrier-based strategic bomber that was then currently under development. However, the XA3D-1 was not scheduled to fly for yet another year and was somewhat of an unknown quantity.
On August 29, 1951, Douglas formally issued a proposal for an adaptation of its XA3D-1 to meet this requirement. On November 29, 1951, the USAF Aircraft and Weapons Board announced that the Douglas design had been approved. The designation B-66 was assigned on January 12, 1952.
The Air Force originally thought that the B-66 would be more or less an off-the-shelf copy of the A3D, so there would be no need for prototype XB-66. Instead, a small initial batch of pre-production aircraft designated RB-66A (Douglas Model 1326) would be acquired for test and evaluation purposes. There would be two separate production versions that would be acquired--a reconnaissance version designated RB-66B and a bomber version designated B-66B. The reconnaissance version would have the higher priority, and would be equipped with night photography capability and would carry electronic countermeasures and reconnaissance equipment.
The general operational requirements were issued on January 21, 1952. A fast, highly-maneuverable tactical reconnassance bomber was called for, with a 1000-nautical mile radius. It had to be capable of carrying at least a 10,000 pound load of atomic weapons, conventional bombs, or photographic flash bombs. The plane had to be capable of carrying large amounts of electronic equipment without adversely affecting its normal performance. In addition, defensive armament had to be carried and electronic countermeasures equipment was required to deal with enemy radars. Finally, the aircraft had to be simple and easy to maintain and had to be able to operate from makeshift or temporary runways.
Letter Contract AF 33(600)-9646 was issued on February 12, 1952, calling for the acquisition of a test quantity of 5 RB-66As. It was decided that it would not be worthwile to acquire any examples of the Navy A3D because by now it was anticipated that the Air Force version would be quite different. The definitive contract was signed on December 4, 1952. 127 production aircraft were ordered in Letter Contract AF 33(600)-16314, signed on April 24, 1952.
The design of the B-66 was assigned to a Douglas-Long Beach team under the direction of John C. Buckwalter. Work on the project began in early 1952. The B-66 shared the same basic configuration of the A3D, with a high-mounted sweptback wing with negative dihedral. The two engines were mounted in pods attached to underwing pylons. The crew of three were seated together in a cockpit in the forward part of the nose. The main landing gear members retracted into wells in the rear fuselage.
The first step in the design was the elimination of the features of the Navy A3D that were specific to its carrier-based role, such as folding wings, arrester gear, and catapult harnesses. This was fairly simple to do.
The next step was not so straightforward. An early problem was the fact that the A3D did not have ejector seats, the crew escaping the aircraft via a chute in the rear of the cockpit. Since the B-66 would be flying at low altitudes and at fairly high speeds (the A3D was envisaged as a high-altitude strategic bomber), upward-firing ejector seats for the three crew members had to be provided. The use of ejector seats in turn required that the cockpit canopy be extensively revised to accommodate the escape hatches needed for the ejecting crew. In addition, the cockpit itself had to be extensively revised, with the pilot sitting centrally forward and the navigator and gunner/reconnaissance system operator seated immediately aft.
Because of the low altitudes and high speeds that were anticipated, the airframe structure had to be strengthened. The wing had a revised planform with a reduced thickness/chord ratio at the root. New ailerons and flaps were fitted. In addition, the 30-inch radar antenna of the A3D had to be replaced by a 45-inch antenna for the APS-27 and K-5 bombing and navigation radar. Since the R/B-66 had to be capable of operating from semi-improved or temporary airfields, larger landing gear tires were required. New emergency air brakes, wing spoilers, improved lateral controls, and a two percent reduction in the wing angle of incidence were needed to minimize Dutch roll. The hydraulic system had to be revised and the fuel system had to be redesigned. The photo-navigator station had to be relocated, and the aircraft had to be fitted for inflight refuelling. For the reconnaissance mission, a battery of four cameras was to be mounted in the center fuselage bay. A new remotely-controlled General Electric tail turret with two 20-mm cannon was fitted as the defensive armament.
One of the more significant changes was the need for different engines. The XA3D-1 was to be powered by a pair of 7000 lb.s.t. XJ40-WE-3, with production A3D-1s using the 7500 lb.s.t. J40-WE-12. Unfortunately, the J40 turned out to be completely unsuitable and was the cause of the failure of several combat aircraft projects of the era. Alternatives had to be considered. Westinghouse offered a new version of the J40, but this was unsuitable because of its excessive fuel consumption and because it offered a thrust of only 7250 pounds. The General Electric J73 was better, but it was ruled to be unsuitable because of its higher cost and its longer development cycle. Douglas preferred the Pratt and Whitney J57 turbojet (which it had selected for the J40 replacement in the A3D), but this engine was already committed to other combat aircraft projects that had a higher priority than the R/B-66 and the Air Force didn't think that the manufacturer could produce enough engines to meet the demand. This left the Allison J71, which was built by a division of the General Motors Corporation. It offered a thrust of 9750 pounds. This engine was deemed to be an acceptable alternative, and a production order specifying the J71 engine was signed on August 5, 1952.
The mockup was inspected at Douglas in late June of 1952. The Air Force was fairly pleased with what they saw, but they recommended that the landing gear be redesigned to accept a heavier load of 83,000 pounds.
The first of five RB-66A pre-production aircraft (52-2828/2832) flew at Long Beach on June 28, 1954, with George R. Jansen in command. It was a short hop to Edwards AFB. The aircraft was powered by a pair of 9570 lb. s.t Allison YJ71-A-9 engines. In the first few test flights, the aircraft was found not to handle very well, the landing gear doors did not function properly, and the vision from the cockpit was poor. The first RB-66A was formally accepted by the USAF in June, but the plane remained with Douglas for correction of the defects.
The four remaining RB-66As were accepted between August and December of 1954. Because of the early performance and handling problems that were encountered, speed and load restrictions had to be imposed which in turn impeded the progress of flight testing. The aircraft flight control system proved to be unreliable, the aircraft's wings vibrated excessively, and the aircraft had the dangerous property of pitching up unexpectedly. Because of these difficulties as well as due to schedule slippages, the Air Force began to consider the possibility of cancelling the B-66 project and started looking around for a substitute.
The B-66 program was on the verge of cancellation at this point, but it was concluded that it would be far too expensive at this stage to cancel the program outright and try to find a substitute. In addition, many of the problems with the RB-66A had already been identified and progress was being made in correcting them. Consequently, the Air Force decided that it was better to retain the program, but the number of planes ordered was cut back by 48. In the meantime, it was found that a parachute brake would have to be provided, as well as the need for the addition of an anti-skid device. The cockpit enclosure had to be revised and the cockpit instruments had to be relocated. Gradually, the problems with the B-66 were identified and corrected, and the aircraft turned out to be a fairly reliable design. The control system was reconfigured, the tail turret was reconfigured, and better engine pylons were installed. The J71-A-9 engines were replaced by production J71-A-11 engines. The buffeting was reduced to an acceptable level, and the the aircraft's speed was increased to 550 knots. The Air Force was now sufficiently pleased with the progress on identifying and fixing the problems that the delivery of production RB-66Bs was expected by the end of 1955.
None of the five RB-66As were ever used operationally by the USAF. However, the first RB-66A was bailed to General Electric for testing of the 11,200 lb.s.t CJ805-3 turbojet. It was later used to test the 16,00 lb.s.t CJ805-23 aft-fan engine.
The Douglas Destroyer was initially manufactured in two separate versions--a reconnaissance version designated RB-66B (Douglas Model 1329) and a bomber version designated B-66B (Douglas Model 1327A). They were basically similar in overall configuration, differing primarily in the equipment carried. The RB-66B carried flash bombs in its bomb bay for night photography missions and was equipped with a battery of reconnaissance cameras. The RB-66B could be fitted with a removable inflight refuelling probe attached to the right side of the forward fuselage.
The first RB-66B flew in March of 1955, and deliveries began on February 1, 1956. 145 RB-66Bs were built, which made this version numerically the most important of the Destroyer variants. The RB-66B was basically similar to the RB-66A pre-production aircraft, differing in being powered by Allison J71-A-11 turbojets. Higher-thrust J71-A-13 turbojets were fitted at the factory to the last 17 RB-66Bs built, and earlier machines were retrofitted with these engines.
The first RB-66Bs were issued to the 9th Tactical Reconnaissance Squadron of the 363rd Tactical Reconnaissance Wing, based at Shaw AFB in South Carolina in January of 1956. They replaced the obsolescent RB-26 Invader. Two more squandrons within the 363rd TRW, the 41st and the 43rd, were equipped with RB-66Bs by the end of the year. The RB-66B very soon became the primary night photographic reconnaissance weapon system of the Tactical Air Command.
The 12th TRS baseed at Itami, Japan, received its first RB-66Bs by the end of 1956. Two RB-66B squadrons were activated within the USAF in Europe.
In the mid-1960s, 52 RB-66Bs were modified as EB-66E electronic countermeasures aircraft. All of the reconnaissance equipment was removed and replaced by electronic jamming equipment. The tail turret was removed, and automatic jamming equipment was fitted in its place. Numerous antennae protruded from the aircraft, and chaff dispensing pods were carried. They were used during the Vietnam War as electronic warfare aircraft, joining strike aircraft during their missions over North Vietnam to jam enemy radar installations.
Engines: Two Allison J71-A-11 or -13 turbojets, 10,200 lb.s.t. Performance: Maximum speed 631 mph at 6000 feet. Cruising speed 525 mph. Initial climb rate 5000 feet per minute. Service ceiling 38,900 feet. 925 miles combat radius. Maximum rang 2425 miles. Weights: 43,476 pounds empty, 59,550 pounds loaded, 83,000 pounds maximum Dimensions: Wingspan 72 feet 6 inches, length 75 feet 2 inches, height 23 feet 7 inches, wing area 780 square feet. Armament: 2 20-mm cannon in remotely-controlled tail turret.
The Douglas Destroyer was initially manufactured in two separate versions--a reconnaissance version designated RB-66B (Douglas Model 1329) and a bomber version designated B-66B (Dougla Model 1327A). They were basically similar in overall configuration, differing primarily in the equipment carried.
72 B-66Bs were built, all of them in the Long Beach plant. An additional 69 B-66Bs (55-0315/0383) were cancelled. The last example was delivered in October of 1957. The B-66B was powered by a pair of 10,200 lb.s.t. Allison J71-A-11 turbojets. J71-A-13 turbojets of a similar rating were later retrofitted to most machines. The aircraft's design gross weight was raised to 78,000 pounds, 8000 pounds greater than that of the RB-66B. In comparison with the RB-66B, the bomb bay was lengthened by 17.5 inches, the capacity ot the aft fuselage tanks was increased, and pylons were provided to support extra 500-gallon underwing drop tanks. A K-5 bombing system was provided, subcontracted by Western Electric and Bell Telephone Laboratories.
The first official B-66B flight took place on January 4, 1955. The B-66Bs began entering the Tactical Air Command in March of 1956, which was about a year later than originally expected. The first recepient was the 17th Light Bombardment Wing, based at Hurlburt Field in Florida. In September of 1956, TAC began to transfer its B-66Bs to the United States Air Forces in Europe.
During the early stages of the Southeast Asian War, thirteen B-66Bs were adapted to serve in the electronic countermeasures role as radar jamming aircraft. They were redesignated EB-66B. All of the bombing equipment was removed and replaced by electronic jamming equipment. The tail turret was removed, and automatic jamming equipment was fitted in its place. Numerous antennae protruded from the aircraft, and chaff dispensing pods were carried. They were used during the Vietnam War as electronic warfare aircraft, joining strike aircraft during their missions over North Vietnam to jam enemy radar installations. They were not "Wild Weasel" aircraft, since they did not have provisions to attack the radar installations directly.
Two B-66Bs (53-0488 and 54-0481) were modified for high-altitude parachute drops of Gemini and Apollo space capsules. The bomb bay doors were removed and the capsules were carried semi-externally underneath the fuselage.
Engines: Two Allison J71-A-11 or -13 turbojets, 10,200 lb.s.t. Performance: Maximum speed 631 mph at 6000 feet. Cruising speed 528 mph. Initial climb rate 5000 feet per minute. Service ceiling 39,400 feet. 900 miles combat radius. Maximum rang 2470 miles. Weights: 42,540 pounds empty, 57,800 pounds loaded, 83,000 pounds maximum Dimensions: Wingspan 72 feet 6 inches, length 75 feet 2 inches, height 23 feet 7 inches, wing area 780 square feet. Armament
The RB-66C was a seven-seat specialized electronic reconnaissance and electronic countermeasures aircraft built at the Douglas plant in Tulsa, Oklahoma. The Tulsa plant was government-owned and had been leased to Douglas for production during the Korean War. 36 RB-66Cs were built.
The crew consisted of seven--pilot, navigator, gunner, plus four additional crewmembers who sat inside a pressurized compartment that replaced the camera/bomb bay of the B/RB-66B. The basic three cremembers in the front used upward-firing ejector seats, whereas the four additional ECM operators used downward-firing ejector seats. An extensive suite of specialized equipment was fitted to locate and identify enemy radar emissions. Additional ECM equipment was carried in wingtip pods. Chaff dispensing pods could be carried underneath the wing outboard of the engine nacelles. Later examples had the tail turret removed and replaced by additional ECM equipment installed in an extended tailcone. After the tail guns were removed, the gunner's position was usually left empty unless occupied by an instructor pilot or instructor navigator. Most of the RB-66Cs were equipped initially with J71-A-11 engines, but were retrofitted with J71-A-13s at a later time.
The first flight of the RB-66C took place on October 29, 1955. The last example was delivered in June of 1957. The RB-66C entered service with the 9th Tactical Reconnaissance Squadron at Shaw AFB in February of 1956. The RB-66Cs which had been delivered were momentarily grounded in June of 1956 because of a problem with the aircraft's center of gravity being affected by the fuel level. There were problems caused by buffeting with the wingtip pods, which required that a special vane be fitted to the wingtip pods. 12 aircraft went to the 42nd TRS based at Spangdahlem AB in Germany. 12 RB-66Cs were delivered to the 67th TRS based at Yokota AB in Japan.
TAC RB-66Cs carried out missions over Cuba during the Missile Crisis of 1962. They were first deployed to Southeast Asia in April of 1965. Soon, virtually all available RB-66Cs were on duty in Southeast Asia, where they carried most of the early electronic warfare operations during the early years of the US involvement in the war. They saw active service with the 41st and 42nd TEWS of the 355th Tactical Fighter Wing based at Takhli in Thailand. They were used to locate and identify North Vietnamese radar sites that directed missiles and AAA fire, so that strike aircraft could avoid them. The RB-66C had no offensive capability, so it could not attack the radar sites directly.
The RB-66C was redesignated EB-66C in 1966, when all B/RB-66 aircraft involved in electronic warfare were assigned the E prefix.
The WB-66D was the final production version of the Destroyer. It was a dedicated 5-seat weather reconnaissance aircraft, carrying a crew of five. 36 examples were built in the Tulsa, Oklahoma plant.
The WB-66D was essentially identical to the RB-66C--it retained the flight-refuelling probe and the tail gun of the earlier versions along with the forward cockpit carrying the pilot, navigator and gunner. However, it had no provision for bombs or cameras. The electronic reconnaissance compartment carried in the bomb bay of the RB-66C was replaced by a specialized pressurized weather equipment compartment. The compartment housed a pair of equipment operators who operated a battery of specialized equipment for weather analysis and reconnaissance. All WB-66Ds were equipped from the start with Allison J71-A-13 engines.
36 WB-66Ds were ordered under Letter Contract AF 33(600)-28368, which was amended accordingly on December 12, 1956. The first flight of the WB-66D took place on June 26, 1957. The last example was delivered in January of 1958.
The first WB-66Ds were delivered to the 9th TRS based at Shaw AFB, beginning in June of 1957. They replaced WB-26s and T-33s which had been previously carrying out the weather reconnaissance mission. WB-66Ds were also assigned to the 67th TRW (PACAF) and to the 66 TRW (USAFE) for overseas deployments.
The WB-66D began to be phased out in 1960, when the USAFE and the PACAF retired all of their weather