Thursday, February 25, 2016

Aircraft walkaround vol.60: Grumman F9F Cougar

Subject: Grumman F9F Cougar
Location: Intrepid Air and Sea Museum, New York, USA, 2014
Comments:The Grumman F9F/F-9 Cougar was an aircraft carrier-based fighter aircraft for the United States Navy. Based on Grumman's earlier F9F Panther, the Cougar replaced the Panther's straight wing with a more modern swept wing. Thrust was also increased significantly. The Navy considered the Cougar an updated version of the Panther, despite having a different official name, and thus Cougars started off from F9F-6upward.Prototypes were quickly produced by modifying Panthers, and the first (XF9F-6) flew on 20 September 1951. The aircraft was still subsonic, but the critical Mach number was increased from 0.79 to 0.86 at sea level and to 0.895 at 35,000 ft (10,000 m), improving performance markedly over the Panther. The Cougar was too late for Korean War service, however, and thus combat effectiveness estimates of the Cougar against potential foes such as the (likewise subsonic, but not carrier-rated) Soviet Mikoyan-Gurevich MiG-15 necessarily remain in the sphere of conjecture. Initial production (646 airframes) was the F9F-6, delivered from mid-1952 through July 1954. Armament was four 20 mm (.79 in) M2 cannons in the nose and provision for two 1,000 lb (450 kg) bombs or 150 US gal (570 l) drop tanks under the wings. Most were fitted with a UHF homing antenna under the nose, and some were fitted with probes for inflight refuelling. Later redesignated F-9F in 1962. Sixty were built as F9F-6P reconnaissance aircraft with cameras instead of the nose cannonAfter withdrawal from active service, many F9F-6s were used as unmanned drones for combat training, designated F9F-6K, or as drone directors, designated F9F-6D. The F9F-6K and the F9F-6D were redesignated the QF-9F and DF-9F, respectively. F9F-7 referred to the next batch of Cougars that were given the Allison J33 engine instead of the Pratt & Whitney J48, a licensed-built Rolls-Royce Tay. A total of 168 were built, but the J33 proved both less powerful and less reliable than the J48. Almost all were converted to take J48s, and were thus indistinguishable from F9F-6s. These were redesignated F-9H in 1962. The F9F-8 was the definitive fighter version. It featured an 8 in (20 cm) stretch in the fuselage and modified wings with greater chord and wing area (from 300 to 337 square feet), to improve low-speed, high angle of attack flying and to give more room for fuel tanks. As a result of the wing changes, top speed was increased from 687 to 704 mph and minimum catapult speed was lowered to 127 knots (146 mph). It also was now capable of breaking the sound barrier in a steep dive. All four ammunition boxes were mounted above the guns, in contrast to the split location of most previous F9Fs including the Panther. Six hundred and one aircraft were delivered between April 1954 and March 1957; most were given inflight refuelling probes, and late production were given the ability to carry four AIM-9 Sidewinder air-to-air missiles under the wings. Most earlier aircraft were modified to this configuration. A number were given nuclear bombing equipment. These were redesignated F-9J in 1962. The F9F-8B aircraft were F9F-8s converted into single-seat attack-fighters, later redesignated AF-9JA total of 110 F9F-8Ps were produced with an extensively modified nose carrying cameras. They were withdrawn after 1960 to reserve squadrons. In 1962, surviving F9F-6P and F9F-8P aircraft were re-designated RF-9F and RF-9J respectivelyThe Navy acquired 377 two-seat F9F-8T trainers between 1956 and 1960. They were used for advanced training, weapons training and carrier training, and served until 1974. They were armed with twin 20 mm (.79 in) cannon and could carry a full bombs or missiles load. In the 1962 redesignation, these were called TF-9J. (ref: Wikipedia)

Saturday, February 20, 2016

Engine walkaround vol.19.: Napier Sabre IIA fighter engine

Subject: Napier Sabre IIA fighter engine
Location: Air and Space Museum, Le Bourget, France 2015 
Comments:The Napier Sabre was a British H-24-cylinder, liquid-cooled, sleeve valve, piston aero engine, designed by Major Frank Halford and built by Napier & Son during World War II. The engine evolved to become one of the most powerful inline piston aircraft engines in the world, developing from 2,200 horsepower (1,640 kW) in its earlier versions to 3,500 hp (2,600 kW) in late-model prototypes. The first operational aircraft to be powered by the Sabre were the Hawker Typhoon and Hawker Tempest; the first aircraft powered by the Sabre was the Napier-Heston Racer, which was designed to capture the world speed record. Other aircraft using the Sabre were early prototype and production variants of the Blackburn Firebrand, the Martin-Baker MB 3 prototype and a Hawker Fury prototype. The rapid introduction of jet engines after the war led to the quick demise of the Sabre, as there was less need for high power military piston aero engines and because Napier turned its attention to developing turboprop engines such as the Naiad and ElandPrior to the Sabre, Napier had been working on large aero engines for some time. Their most famous was the Lion, which had been a very successful engine between the World Wars and in modified form had powered several of the Supermarine Schneider Trophy competitors in 1923 and 1927, as well as several land speed record cars. By the late 1920s, the Lion was no longer competitive and work started on replacements. Napier followed the Lion with two new H-block designs: the H-16 (Rapier) and the H-24 (Dagger). The H-block has a compact layout, consisting of two horizontally opposed engines, lying one atop or beside another. Since the cylinders are opposed, the motion in one is balanced by the motion on the opposing side, leading to no first order vibration or second order vibration. In these new designs, Napier chose air cooling but in service, the rear cylinders proved to be impossible to cool properly, which made the engines unreliable.Halford started work with Napier, using the Dagger as the basis. The layout of the H-block, with its inherent balance and the Sabre's relatively short stroke, allowed it to run at a higher rate of rotation, to deliver more power from a smaller displacement, provided that good volumetric efficiency could be maintained (with better breathing), which sleeve valves could do. Another important effect of increasing the number of cylinders was that the piston area increases (for a given capacity and bore/stroke ratio) and this brings higher power. Problems arose as soon as mass production began. Prototype engines had been hand-assembled by Napier craftsmen and it proved to be difficult to adapt it to assembly-line production techniques. The sleeves often failed, leading to seized cylinders, which caused the loss of the sole prototype Martin-Baker MB 3. After testing some 18 different materials and manufacturing techniques, a process of nitriding and lapping the sleeves helped resolve the problem. Quality control proved to be inadequate, engines were often delivered with improperly cleaned castings, broken piston rings and machine cuttings left inside the engine. Mechanics were overworked trying to keep the Sabres running and during cold weather they had to run them every two hours during the night so that the engine oil would not congeal and prevent the engine from starting the next day. These problems took too long to remedy and the engine gained a bad reputation. By 1944, the Sabre V was delivering 2,400 horsepower (1,800 kW) consistently and the reputation of the engine started to improve. This was the last version to enter service, being used in the Hawker Typhoon and its derivative, the Hawker Tempest. Without the advanced supercharger, the engine's performance over 20,000 ft (6,100 m) fell off rapidly and pilots flying Sabre-powered aircraft, were generally instructed to enter dogfights only below this altitude. At low altitude, both planes were formidable, with the Typhoon readily outperforming its German counterpart, the FW 190. After the destruction of the Luftwaffe during early 1944, Typhoons were increasingly used as fighter-bombers, notably by the RAF Second Tactical Air Force. The Tempest became the principal destroyer of the V-1 flying bomb (Fieseler Fi 103), since it was the fastest of all the Allied fighters at low levels. Later on, the Tempest was responsible for the destruction of about 20 Messerschmitt Me 262 jet aircraft. Development continued and the later Sabre VII delivered 3,500 hp (2,600 kW) with a new supercharger. The final test engines delivered 5,500 hp (4,100 kW) at 45 lb/in2 boost. By the end of World War II, there were several engines in the same power class. ThePratt & Whitney R-4360 Wasp Major four-row, 28-cylinder radial produced 3,000 hp (2,280 kW) at first and later types produced 3,800 hp (2,834 kW), but these required almost twice the displacement in order to do so, 4,360 cubic inches (71 litres). (ref: Wikipedia)

Sunday, February 14, 2016

Aircraft walkaround vol.59: Grumman E-1 Tracer

Subject: Grumman E-1 Tracer
Location: Intrepid Air and Sea Museum, New York, USA 2014.
Comments: The E-1 Tracer was the first purpose built airborne early warning aircraft used by the United States Navy. It was a derivative of the Grumman C-1 Trader and first entered service in 1958. It was replaced by the more modern E-2 Hawkeye in the early 1970s. The E-1 was designated WF under the old US Navy system; the designation earned it the nickname "Willy Fudd". Since the S-2 Tracker was known as S2F under the old system, that aircraft was nicknamed "Stoof"; the WF/E-1 with its distinctive radome gained the nickname "Stoof with a Roof." The E-1 featured folding wings for compact storage aboard aircraft carriers. Unlike the S-2 and C-1 in which the wings folded upwards, the radome atop the fuselage necessitated the E-1 to fold its wings along the sides of the fuselage. As one of the first carrier based early warning aircraft, the E-1 Tracer served from 1958 to 1977, although considered only an interim type, being replaced by the Grumman E-2 Hawkeye in the mid-1960s. During the early years of the Vietnam War, E-1s saw extensive service, providing combat air patrol (CAP) fighters with target vectors, and controlling Alpha strikes over North Vietnam. With a radius of 250–300 miles, the E-1B served as an early warning to strike aircraft, of enemy MiG's activity.By May 1973, most E-1Bs were retired, with only four RVAW-110 Tracers based at NAS North Island, California, still in service. These aircraft were soon retired during mid-summer 1977 following a final cruise on board the USS Franklin D. Roosevelt (CV-42) and were ferried to the Davis-Monthan storage facility. The E-1B Tracer was struck from the inventory by 1977.