World War Aircraft Through Sound Barrier

While the bombers were carrying more over greater ranges, fighters were beginning to go significantly faster. Basically subsonic types like the Hunter and Saab’s Lansen were capable of exceeding the speed of sound in a shallow dive, but the first combat aircraft in the world to exceed Mach 1 in level flight was the North American F-iOO Super Sabre. Powered by an afterburning J57, the F-iOO was the first of the famous Century series of USAF fighters. With a 45°-swept wing of only 6 per cent thick- ness/chord ratio, the Super Sabre was unusual in having inboard ailerons, no flaps, and full-span leading-edge slats.

In 1954, shortly after its service debut, the F-100 had to be grounded when it was found to be prone to stability problems in the roll and yaw axes. But the solution to this new problem — which included the addition of wing span and fin height — did not hold up development for too long. The F-100 turned into a firm favourite with its operators (which included Denmark, France and Turkey), gaining a fine record both as fighter-bomber and top-cover fighter during the Vietnam war. Following up the success of the MiG-15, Mikoyan produced the better-behaved Mig-17 Fresco before jumping on to the supersonic band- wagon with the MiG-19 Farmer. This type had a highly swept wing and twin afterburning engines. Large Fowler flaps and deep wing fences (to stop spanwise flow of the air and therefore loss of lift) guaranteed satisfactory low-speed handling. An all-moving tailpiane later replaced the original fixed unit. Extreme manoeuvrability and the tre- mendous power of the 30 mm cannon made the Farmer a potent fighter, and it also entered large- scale production as the Shenyang F-6 in China. The first of an eventual total of 10,000 entered service in 1953, and the Farmer is still in use as a daytime fighter and limited all-weather intercepter armed with Alkali air-to-air missiles.

Contemporary with the MiG-19 was the Ameri- can project for a single-seat supersonic all-weather intercepter which led to Convair’s none too suc- cessful F-102 Delta Dagger. The company had flown the world’s first true delta wing back in 1948, but the prototype Delta Dagger’s drag proved very much higher than anticipated and the first F-102s never in fact exceeded Mach 1. The fuselage had to be redesigned to conform with the National Advisory Committee for Aeronautics’ recently formulated area rule before Mach 1.25 could be achieved. But the Delta Dagger showed the way as far as electronics were concerned, combining radar, computer and missiles in a semi-automatic system for the first time. It was not until the superficially similar but radically redesigned F- 106 Delta Dart ~T powered by the afterburning Pratt & Whitney J75 turbojet entered service in 1959 that USAF Air Defence Command got a true Mach 2-plus intercepter with an automatic weapon system

. Only now is a successor for the F-106 currently being sought in the long-running Improved Manned Intercepter programme. While Convair was perfecting the F-106, McDonnell had produced its first aircraft for the US Air Force. The formidable F-101 Voodoo, which entered service in 1957, was big, with a maximum gross weight of around 22,680 kg (50,000 lb), and heavily armed with Falcon air-to- air guided missiles and Genie unguided nuclear rockets for the intercepter role, and with mines and conventional or nuclear bombs for attack. It was also endowed with an internal-fuel range of 2,400 km (1,500 miles) and a maximum speed of Mach 1.8 or more. Powered by two afterburning J57s of up to 6,800 kg (15,000 lb) thrust each, the F-101 resulted from a Strategic Air Command require- ment for a long-range fighter-bomber escort. The type saw service with Tactical Air and Air Defence Commands in the USA, however, and the F-1O1F still serves as an all-weather intercepter with the Canadian Armed Forces. The second half of the 1950s saw the emergence of a spate of delta designs. In 1955 Saab found that the double delta was the best way of packaging fuel and equipment in its Draken. Dassault

experimented with swept and delta wings, and British and French engines, to arrive at the Mirage, a design which has probably done more for company and country than all the other Dassault types combined. A Nato light strike fighter competition in 1953 saw Dassault proposing a swept-wing design which eventually became the French Navy’s Eten- dard. But the French Air Force also needed a small intercepter, and for this Dassault proposed a delta powered by two Rolls-Royce Vipers and a liquid- propellant rocket booster. Operationally this came to nothing, but Dassault persevered and in 1956 flew the prototype Mirage III, an altogether larger delta-winged aircraft powered by a French engine, the Atar 101. In 1958 the Mirage lilA prototype— incorporating bigger, thinner conical-camber wings and a new fuselage for the developed Atar 9 engine — hit the aviation headlines by becoming the first European aircraft to achieve Mach 2 in level flight. The French Air Force responded by ordering 100 of the Mirage IIIC intercepter version. Since then Dassault has never looked back, selling vigorously abroad and enjoying an effective monopoly at home. From the IIIC were developed the two-seat trainer IIIB; the multi-mission,

limited all-weather IIIE; the reconnaissance IIIR; and the Israeli-inspired Mirage 5, a day-only ground-attack version with simplified avionics and more fuel and weapon load. With an Atar 9 of about 6,125 kg (13,500 ib) thrust, the Mirage was regarded by the Israelis as underpowered. So, having a plentiful supply of General Electric J79 engines for their Phantoms, they decided in the late 1960s to re-engine the type with the 8,120 kg (17,900 ib) American powerplant. The technical difficulties were formidable, but the resulting Kfir and canard-equipped Kfir C2 will keep the Mirage shape prominent in the skies for many years to come. After Korea the US armed forces began to call for higher-performance fighters and fighter-bombers. Ed Heinemann of Douglas came up with the almost unbelievable A-4 Skyhawk, a design small enough to be stored in aircraft carriers without having to fold its ‘wet’ delta wings, and yet able to carry a heavier-than-specified bomb load over a distance greater than that required. Early versions, weighing a mere 6,804 kg (15,000 lb), were pow- ered by a single J65 but could still carry a 2,270 kg (5,000 ib) warload over a 740 km (400 nautical mile) radius of action. These days powered by a J52 of more than 4,990 kg (11,000 ib) thrust and weighing anything up to 12,300 kg (27,000 lb), the latest Skyhawks can carry a 4,082 kg (9,000 lb) weapon load and drop it with pinpoint accuracy

with the aid of advanced avionics which include a British head-up display. First delivered in 1956, the Skyhawk continues in production 20 years later, probably the longest run by any Western combat aircraft. Russia’s light fighter of the time, the MiG-21, is also a classic in its own right. The quest for greater performance resulted in an afterburning turbojet producing 4,990 kg (11,000 lb) of thrust to drive a thin-delta aircraft with swept tailplanes at speeds approaching Mach 2. The early models were day-only fighters, their endurance limited by a small fuel load and the comparative inefficiency of the single-shaft engine. But since then more fuel, better electronics and improved performance have been built in over a huge production run. The straightforward Fowler flaps of the first MiG-2 is have been replaced by blown surfaces to reduce landing speed, and the new avionics make the type a useful, if still short-ranged, multi-purpose aircraft. The MiG-21PF, with a completely redesigned and enlarged nose inlet housing interception radar inside the shock cone, first

appeared in public at the Tushino display in 1961. The last fifteen years have seen this basic shape developed over hundreds of export aircraft.

Contemporary with the MiG-19 was the Ameri- can project for a single-seat supersonic all-weather intercepter which led to Convair’s none too suc- cessful F-102 Delta Dagger. The company had flown the world’s first true delta wing back in 1948, but the prototype Delta Dagger’s drag proved very much higher than anticipated and the first F-102s never in fact exceeded Mach 1. The fuselage had to be redesigned to conform with the National Advisory Committee for Aeronautics’ recently formulated area rule before Mach 1.25 could be achieved. But the Delta Dagger showed the way as far as electronics were concerned, combining radar, computer and missiles in a semi-automatic system for the first time. It was not until the superficially  similar but radically redesigned F- 106 Delta Dart ~T powered by the afterburning Pratt & Whitney J75 turbojet entered service in 1959 that USAF Air Defence Command got a true Mach 2-plus