McDonnell Douglas A-4 Skyhawk

A-4 Skyhawk, McDonnell Douglas

This small and simple tailed delta jet, originally designed as carrier-based (nuclear) bomber, later enjoyed a long career as an extremely versatile attack aircraft. Later developments had a large dorsal spine to make room for electronics. The A-4 was kept in production for 22 years, and is still serving with some air forces. The OA-4 is a two-seat FAC version for the USMC, and the trainer version is known as TA-4. 2960 built.

Type: A-4F Skyhawk
Function: attack
Year: 1966
Crew: 1
Engines: 1 * 41.4 kN Pratt & Whitney J52-P8A turbojet
Wing Span: 8.38 m
Wing area: 24.15 m²
Wing loading: 344.4 kg/m²
Length: 12.22 m
Height: 4.57 m
Empty Weight: 4536 kg
Max.Weight: 11113 kg
Thrust/weight: 0.51
Speed: 1100 km/h
Rate of climb: 43 m/s
Ceiling: 13940 m
Range: 3220 km
Armament: 2*g20mm, 3720 kg payload

Type: A-4M Skyhawk
Function: attack
Crew: 1
Engines: 1 * 5080 kg P&W J52-P-408A
Wing Span: 8.38 m
Length: 12.29 m
Height: 4.57 m
Wing Area: 24.15 m2
Empty Weight: 4747 kg
Max.Weight: 11113 kg
Speed: 1078 km/h
Ceiling: 12880 m
Armament: 2*g20 mm 4153 kg

Mission

The mission of an A-4 attack squadron is to attack and to destroy surface targets in support of the landing force commander, escort helicopters, and conduct other operations as directed. Developed in the early 1950s, the A-4 Skyhawk was originally designated the A-4D as a lightweight, daylight only nuclear capable strike aircraft for use in large numbers from aircraft carriers. There are numerous models of the A-4 in use. The A-4M and the TA-4F are currently used by Marine Corps Reserve squadrons. All models have two internally mounted 20mm (.8 inch) cannons, and are capable of delivering conventional and nuclear weapons under day and night visual meteorological conditions. The A-4M uses a heads-up display and computer aided delivery of its bomb load with the angle rate bombing system. The Marine Reserve has two squadrons of A-4s with 12 aircraft each. Additionally, each squadron has two TA-4 aircraft.

History

The Skyhawk was designed by Douglas' Ed Heinemann in response to a U.S. Navy call for a jet-powered attack aircraft to replace the A-1 Skyraider. Heinemann opted for a design that would minimize size, weight, and complexity. The result was an aircraft that weighed only half of the Navy's specification and had a wing so compact that it did not need to be folded for carrier stowage. The diminutive Skyhawk soon received the nicknames "Scooter", "Bantam Bomber", "Tinker Toy Bomber" and on account of its nimble performance, "Heinemann's Hot-Rod."

The Navy issued a contract for the type on June 12 1952, and the first prototype first flew on June 22, 1954. Deliveries to Navy and U.S. Marine Corps squadrons commenced in late 1956. The Skyhawk remained in production until 1975, with a total of 2,960 aircraft built, including 555 two-seat trainers. The US Navy began removing the aircraft from its front-line squadrons in 1967, with the last retiring in 1975. The Marines would pass on the Navy's replacement, the A-7 Corsair II, instead keeping Skyhawks in service, and ordering the new A-4M. The last USMC Skyhawk was delivered in 1979, and were used until the mid-1990s until they were replaced by the similarly small, but V/STOL vertical landing AV-8 Harrier.

The Diamondbacks of VMA-131, Marine Aircraft Group 49 retired their last four OA-4Ms on June 22,1994. Trainer versions of the Skyhawk remained in Navy service, however, finding a new lease on life with the advent of adversary training, where the nimble A-4 was used as a stand-in for the MiG-17 in dissimilar air combat training (DACT) It served in that role until 1999, when the last were replaced with the T-45 Goshawk. Their nimble performance also made them suitable to replace the F-4 Phantom when the services downsized their aircraft for the Blue Angels demonstration team, popularized on a 80s rock video, until the availability of the F/A-18 Hornet in the 1980s. The last US Navy Skyhawks, TA-4J models belonging to composite squadron VC-8, remained in military use for target-towing and as adversary aircraft for combat training at Naval Air Station Roosevelt Roads. They were officially retired on May 3, 2003.

The Skyhawk proved to be one of the most popular US naval aircraft exports of the postwar era. Due to its small size, it could be operated from the older, smaller WWII-era aircraft carriers still used by many smaller navies during the 1960s. These older ships were often unable to accommodate newer USN fighters such as the F-4 Phantom II and F-8 Crusader, which were faster and more capable than the A-4, but significantly larger and heavier than older naval fighters.

Design

The aircraft is of conventional post-WW2 design, with a low-mounted delta-like wing, tricycle undercarriage, and a single turbojet engine in the rear fuselage, with intakes on the fuselage sides. The tail is of cruciform design, with the horizontal stabilizer mounted above the fuselage. Armament consisted of two 20 mm Colt Mk 12 cannon, one in each wing root, with 200 rounds per gun, plus a large variety of bombs, rockets, and missiles carried on a hardpoint under the fuselage centreline and hardpoints under each wing (originally one per wing, later two).

The design of the A-4 is a good example of the virtues of simplicity. The choice of a delta wing, for example, combined speed and maneuverability with a large fuel capacity and small overall size, thus not requiring folding wings, albeit at the expense of cruising efficiency. The leading edge slats are remarkably designed to drop automatically at the appropriate speed by gravity and air pressure, thereby not even needing motors or even a pilot switch. Similarly the main undercarriage did not penetrate the main wing spar, being mounted so that when retracted only the wheel itself was inside the wing and the undercarriage struts were housed in a fairing below the lower wing surface. This meant that the wing structure itself could be lighter for the same overall strength and combined with the lack of a (heavy) wing fold mechanism even more weight was saved. This is the exact reverse of what often happens in aircraft design where a small weight increase in one area leads to a compounding increase in weight in other areas to compensate, leading to the need for more powerful, heavier engines and so on in a tight vicious cycle.

The A-4 pioneered the concept of "buddy" self air-to-air refueling. This allowed the aircraft to be used as a tanker for others of the same type, removing the need for entirely different tanker aircraft - a particular advantage for small air arms or when operating in remote locations. This worked by designating a tanker aircraft and fitting it with a centre-mounted "buddy store" that was a large external fuel tank with a hose reel in the aft section and an extensible drogue type refueling bucket. This aircraft was fuelled up without armament and launched prior to the attack aircraft. The attack aircraft were then armed up to the maximum and given only just enough fuel to bring them up to the maximum take-off weight. Once airborne, they would then proceed to top up their fuel tanks from the tanker using the A-4's inbuilt re-fuelling probe on the starboard side of the aircraft nose. They could then proceed to the target with both full armament and fuel loads. While rarely used in service since the KA-3 Skywarrior tanker was available, every Boeing, formerly McDonell Douglas F-4 Phantom when the services downsized their aircraft for the Blue Angels demonstration team, popularized on a 80s rock video, until the availability of the F/A-18E/F Super Hornet is now built with this capability with the retirement of dedicated tankers imminent in the 2000s.

The A-4 was also designed to be able to make an emergency landing, in the event of a hydraulic failure, on the two drop tanks nearly always carried by these planes. Such landings resulted in only minor damage to the nose of the aircraft which could be repaired in less than an hour. The wings had automatic leading edge slats, operated by aerodynamic pressure alone, again a simple but effective and weight saving feature. Ed Heinemann is credited with having a large "K.I.S.S." sign put up on the wall of the drawing office when the aircraft was being designed. Whether this is true, the A-4 certainly is a shining example of the application of that principle to aircraft design.

Combat

Skyhawks were the Navy's primary light bomber over both North Vietnam during the early years of the Vietnam War while the USAF was flying the supersonic F-105 Thunderchief. They would be supplanted by the A-7 Corsair II in the Navy light bomber role. Skyhawks carried out some of the first air strikes by the US during the conflict and a Marine Skyhawk is believed to have dropped the last US bombs on the country. On one occasion, an A-4C Skyhawk, piloted by LCDR Ted Swartz from attack squadron VA-76, shot down a MiG-17 with an unguided rocket (In May 1970, an Israeli Skyhawk piloted also shot down a MiG-17 with unguided rockets, over south Lebanon).

Lt. Cmdr John McCain flew A-4s, once having to clamber out over the refueling probe of a Skyhawk stationed on the carrier USS Forrestal in order to escape a devastating flight deck fire caused by a rogue Zuni rocket, which eventually cost the lives of 134 sailors. John McCain escaped from his jet by climbing out of the cockpit, walking down to the nose of the plane, and jumping off the refueling probe. Video tape shot aboard the Forrestal shows McCain narrowly escaping the explosion. He would ultimately be shot down over Vietnam while flying another Skyhawk.

Shortly afterwards, Israeli Air Force Skyhawks would be the primary ground attack aircraft in the War of Attrition and the Yom Kippur War. They cost only 1/4 what a Phantom cost and carried more bombs and had longer range than the air superiority fighters they replaced. The Skyhawks bore the brunt of losses to sophisticated SA-6 missile batteries. They have been replaced by F-16s.

During the Falklands Conflict, in spite of being armed with just iron bombs and lacking any electronic or missile self defense, Argentine Air Force Skyhawks sunk HMS Coventry (D118), HMS Antelope (F170) and RFA Sir Galahad (1966) besides producing heavy damage to several others like HMS Glasgow (D88), HMS Argonaut, HMS Broadsword and RFA Sir Tristram. Argentine Navy A-4Q's also played a role in the bombing attacks against British ships, destroying HMS Ardent (F184).

In all, 22 Skyhawks were lost or shot down during the war to a mixture of surface to air missiles such as the Sea Dart and the Sea Harriers guns and missiles.

More recently, Kuwaiti Air Force Skyhawks fought in the first Gulf War. Of the 36 that were delivered to Kuwait in 1970s, 23 survived the war and the Iraqi invasion, with only one being destroyed in combat.

Skyhawks were well loved by their crews for being tough and agile. These attributes, along with its low purchase and operating cost and easy maintenance, have contributed to the popularity of the A-4 both with American armed forces and internationally.

VARIANTS
A-4A (formerly A4D-1)	Initial version with Wright J65-W-4 Turbojet engine 3,493 kg (7,700 lb st). First A-4A flew 14 August 1954, and this version entered service with the US Atlantic and Pacific Fleets 26 October 1956. 166 built. Uprated engines (3,855 kg; 8,500 lb st) fitted progressively to all aircraft.
B (formerly A4D-2)	Similar to A-4A but with improved bomb delivery system, provision for carrying Bullpup missiles, automatic dead reckoning navigation computer, flight refuelling capability (both tanker and receiver), dual hydraulic system, stiffer single surface rudder and powered tail, and Wright J65-W-16A turbojet (3,493 kg; 7,700 lb st). First flight 26 March 1956. 542 built. 50 reconditioned for Argentine Air Force. Uprated engines 3,855 kg (8,500 lb st) fitted progressively to all aircraft.
C (formerly A4D-2N)	Similar to B but with longer nose to accommodate additional equipment to improve all-weather capability. New items included advanced autopilot, low-altitude bombing/all-attitude indicating gyro system, terrain-clearance radar and angle of attack indicator. First flight 21 August 1958. Deliveries began in 1959. Production completed in December 1962. 638 built. Uprated engines 3,855 kg (8,500 lb st) fitted to all aircraft progressively.
E (formerly A4D-5)	Increased payload and 27% greater range. Powered by a Pratt & Whitney J52-P-6A turbojet (8,500 lb; 3,855 kg st). Douglas Escapec zero-height 90 knot rocket ejection seat. Four underwing and one under-fuselage bomb racks able to carry as many as 20 different items weighing up to 8,200 lb (3,720 kg) total. First flight 12 July 1961. Deliveries to US Navy began in November 1962. 499 built. 43 reported to have been supplied to Israel. Production completed.
TE	Original designation of prototypes of TA-4F.
F	Attack bomber with J52-P-8A turbojet rated at 41.4 kN (9,300 lb st), new lift-spoilers on wings to shorten landing run by up to 305 m (1,000 ft), nosewheel steering, low-pressure tyres, zero/zero ejection seat, additional bullet- and flak-resistant materials to protect pilot, updated electronics contained in fairing `hump' aft of cockpit. Prototype flew for the first time 31 August 1966. Deliveries to US Navy began 20 June 1967 and were completed in 1968 with 146 built.
TF	Tandem two-seat dual-control trainer version of F for US Navy. Fuselage extended 0.71 m (2 ft 4 in), fuselage fuel tankage reduced to 379 litres (100 US gallons; 83.3 Imp gallons), Pratt & Whitney J52-P-6 or -8A engines optional, Douglas Escapac rocket ejection seats. Provision to carry full range of weapons available for F. Reduced electronics. First prototype flew 30 June 1965. Deliveries to the US Navy began in 1966.
G	Similar to F for Royal Australian Navy. Equipped to carry Sidewinder air-to-air missiles. First of eight delivered 26 July 1967.
TG	Similar to TF for Royal Australian Navy. First of two delivered 26 July 1967.
H	Designation of version supplied to Israel. Delivery of an initial batch of 48 in 1967-68, followed by 60 more by early 1972. Retrofitted with Rafael MAHAT lightweight analog weapons delivery system.
TH	Tandem two-seat trainer version of the H for Israel, 10 delivered.
TJ	Tandem two-seat trainer, basically a simplified version of the TA-4F. Ordered for the US Naval Air Advanced Training Command, under $26,834,000 contract, followed by further contract in mid-1971. Deletion of the following equipment, although provisions retained: radar, dead reckoning navigation system, low-altitude bombing system, air-to-ground missile systems, weapons delivery computer and automatic release, intervalometer, gun pod, standard stores pylons, in-flight refueling system and spray tank provisions. Addition and relocation of certain instruments. J-52-P-6 engine standard. Provision for J-52-P-8A engine and combat electronics. Prototype flew in May 1969 and the first four were delivered to the US Navy 6 June 1969.
A-4K	Similar to the F, for the Royal New Zealand Air Force. Different radio, and braking parachute. First of 10 delivered to the RNZAF 16 January 1970.
KU	Designation of 30 aircraft similar to the M for Kuwait Air Force. Deliveries began in Spring 1977.
TA-A-4K	Similar to TA-4A-4 Skyhawk, for Royal New Zealand Air Force. The first of four was handed over 16 January 1970.
TA-4KU	Designation of six aircraft, similar to TA-4F, for Kuwait Air Force.
L	Modification of A-4C with uprated engine, bombing computing system and electronics relocated in fairing `hump' aft of cockpit as on A-4F. Delivery to US Navy Reserve carrier air wing in December 1969.
A-4M II	Similar to A-4F but with J52-P-408 turbojet rated at 50 kN and braking parachute standard, making possible combat operation from 1,220 m (4,000 ft) fields and claimed to increase combat effectiveness by 30 per cent. Larger windscreen and canopy; windscreen bullet-resistant. Increased ammunition capacity for 20 mm cannon. More powerful generator, provision of wind-driven back-up generator and self-contained engine starter. First of two prototypes flew for the first time 10 April 1970. About 50 initially ordered for US Marine Corps, the first of which was delivered 3 November 1970. Further order was placed subsequently, and the FY76 budget included $70 million for the procurement of a final 24 aircraft. Funds also allocated for the installation of improved electronic warfare equipment in service aircraft, and for the continued development of an Angle Rate Bombing System (ARBS) for future installation in A-4Ms (see A-4Y).