Douglas A-4 Skyhawk
The Douglas A-4 Skyhawk is a single-seat subsonic carrier-capable light attack aircraft designed and produced by the American aerospace manufacturer Douglas Aircraft Company, later built by McDonnell Douglas. It was originally designated A4D under the United States Navy's pre-1962 designation system.
The Skyhawk was developed during the early 1950s on behalf of the Navy and United States Marine Corps as a replacement for the propeller-driven Douglas A-1 Skyraider. The A-4 is a compact, straightforward, and lightweight aircraft for the era; its maximum takeoff weight of was roughly half of the Navy's weight specification. The Skyhawk has a short-span delta wing configuration, a tricycle undercarriage, and is powered by a single turbojet engine. The U.S. Navy issued a contract for the aircraft on 12 June 1952. On 22 June 1954, the XA4D-1 prototype performed its maiden flight; it went on to set a world speed record of 695.163 mph on 15 October 1955. On 1 October 1956, the Skyhawk was introduced to operational service.
The Skyhawk's five hardpoints can carry a variety of missiles, bombs, and other munitions. It can carry a bomb load equivalent to that of the World War II-era Boeing B-17 bomber, and can deliver nuclear weapons using a low-altitude bombing system and a "loft" delivery technique. It pioneered the concept of "buddy" air-to-air refueling, which reduces the need for dedicated aerial tankers. The Skyhawk was originally powered by the Wright J65 turbojet engine; from the A-4E onwards, the Pratt & Whitney J52 engine was used instead. By the time production ended in February 1979, a total of 2,960 had been built for a variety of operators, including 555 as two-seat trainers.
The Skyhawk saw combat in several conflicts. The Navy operated the type as its principal light attack aircraft during the Vietnam War, carrying out some of the first U.S. air strikes of the conflict. The Skyhawk was the Israeli Air Force's main ground attack aircraft during the War of Attrition and the Yom Kippur War. In the Falklands War, Argentinean Skyhawks bombed Royal Navy vessels, sinking the Type 42 destroyer and the Type 21 frigate. Indonesian Air Force Skyhawks were used for counterinsurgency strikes in East Timor. Kuwaiti Air Force Skyhawks saw action during Operation Desert Storm. In 2022, nearly seven decades after the aircraft's first flight in 1954, a number of Skyhawks remained in service with the Argentine Air Force and the Brazilian Naval Aviation.
Design and development
The Skyhawk was designed by Douglas Aircraft's Ed Heinemann in response to a United States Navy call for a jet-powered attack aircraft to replace the piston-powered Douglas AD Skyraider. Heinemann opted for a design that would minimize its size, weight, and complexity. The result was an aircraft that weighed only half of the Navy's weight specification. It had a wing so compact that it did not need to be folded for carrier stowage. The first 500 production examples cost an average of each, less than the Navy's $1 million maximum. The diminutive Skyhawk soon received the nicknames "Scooter", "Kiddiecar", "Bantam Bomber", "Tinker Toy Bomber", and, on account of its speed and nimble performance, "Heinemann's Hot-Rod". The XA4D-1 prototype set a world speed record of 695.163 mph on 15 October 1955.The aircraft is of conventional post-World War II design, with a low-mounted delta wing, tricycle undercarriage, and a single turbojet engine in the rear fuselage, with two air 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 Mark 12 cannons, one in each wing root, with 100 rounds per gun, plus a large variety of bombs, rockets, and missiles carried on a hardpoint under the fuselage centerline and hardpoints under each wing.
The short-span delta wing did not require the complexity of wingtip folding, saving an estimated. Its spars were machined from a single forging that spanned across both wingtips. The leading edge slats were designed to drop automatically at the appropriate speed by gravity and air pressure, saving weight and space by omitting actuation motors and switches. Similarly, the main undercarriage did not penetrate the main wing spar, designed so that when retracted only the wheel itself was inside the wing and the undercarriage struts were housed in a fairing below the wing. Thus, the wing structure was lighter with the same overall strength. The rudder was constructed of a single panel reinforced with external ribs.
The aircraft's turbojet engine was accessed for service or replacement by removing the aft section of the fuselage and sliding out the engine. This obviated the need for access doors with their hinges and latches further reducing weight and complexity. This is the opposite of what can often happen in aircraft design where a small weight increase in one area leads to a compounding increase in weight in other areas to compensate, creating a demand for more powerful, heavier engines, larger wing and empennage area, and so on in a vicious circle.
The A-4 pioneered the concept of "buddy" air-to-air refueling. This allows the aircraft to supply others of the same type, reducing the need for dedicated tanker aircraft—a particular advantage for small air arms or when operating in remote locations. This allows for greatly improved operational flexibility and reassurance against the loss or malfunction of tanker aircraft, though this procedure reduces the effective combat force on board the carrier.
A designated supply A-4 would mount a center-mounted "buddy store", a large external fuel tank with a hose reel in the aft section and an extensible drogue refueling bucket. This aircraft was fueled up without armament and launched first. Attack aircraft were armed to the maximum and were given as much fuel as was allowable by maximum takeoff weight limits, which was far less than a full tank. It was SOP to launch one Skyhawk as a tanker per launch-recovery cycle. In combat, 2-3 Skyhawk tankers were launched, especially if several groups of aircraft were attacking a heavily defended target.
Once airborne, they topped off their fuel tanks from the tanker using the A-4's fixed refueling probe on the starboard side of the aircraft nose. They could then sortie with both full armament and fuel loads. The A-4 was rarely used for refueling in U.S. service after the KA-3 Skywarrior tanker became available aboard the larger carriers.
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 aircraft. Such landings resulted in only minor damage to the nose of the aircraft which could be repaired in less than an hour.
The Navy issued a contract for the type on 12 June 1952, and the first prototype first flew from Edwards Air Force Base, California on 22 June 1954. Deliveries to Navy and Marine Corps squadrons commenced in late 1956.
The Skyhawk remained in production until 1979, with 2,960 aircraft built, including 555 two-seat trainers. The last production A-4, an A-4M of Marine squadron VMA-331 had the flags of all nations that operated the A-4 painted on its fuselage sides.
Operational history
United States
The Skyhawk proved to be a relatively common United States Navy aircraft export. Due to its small size, it could be operated from older, smaller World War II-era aircraft carriers still used by smaller navies during the 1960s. These older ships were often unable to accommodate newer Navy 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.The Navy operated the A-4 in both Regular Navy and Naval Reserve light attack squadrons. Although the A-4's use as a training and adversary aircraft would continue well into the 1990s, the Navy began removing the aircraft from its frontline attack squadrons in 1967, with the last ones being retired in 1976.
The Marine Corps would not take the U.S. Navy's replacement, the LTV A-7 Corsair II, instead keeping Skyhawks in service with both Regular Marine Corps and Marine Corps Reserve attack squadrons, and ordering the new A-4M model. The last USMC Skyhawk was delivered in 1979, and they were used until the mid-1980s before they were replaced by the equally small, but more versatile STOVL AV-8 Harrier II.
VMA-131, Marine Aircraft Group 49 retired its last four OA-4Ms on 22 June 1994. VMA-124, Marine Air Group 42 also retired the last of their A-4s in mid 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 Mikoyan-Gurevich MiG-17 in dissimilar air combat training. It served in that role at TOPGUN until 1999.
The A-4's nimble performance also made it suitable to replace the McDonnell Douglas F-4 Phantom II when the Navy downsized its aircraft for the Blue Angels demonstration team, until McDonnell Douglas F/A-18 Hornets were available in the 1980s. The last U.S. Navy Skyhawks, TA-4J models belonging to the composite squadron VC-8, remained in military use for target towing, and as adversary aircraft, for combat training at Naval Station Roosevelt Roads. These aircraft were officially retired on 3 May 2003.
Skyhawks were well loved by their crews for being tough and agile. These attributes, along with their low purchase and operating cost as well as easy maintenance, have contributed to the popularity of the A-4 with American and international armed forces. Besides the U.S., at least four other nations have used Skyhawks in combat.
Vietnam War era
Skyhawks were the U.S. Navy's primary light attack aircraft used over North Vietnam during the early years of the Vietnam War, later supplanted by the A-7 Corsair II in the U.S. Navy light attack role. Skyhawks carried out some of the first air strikes by the U.S. during the conflict, and a Marine Skyhawk is believed to have dropped the last American bombs on the country. Notable naval aviators who flew the Skyhawk included Lieutenant Commanders Everett Alvarez, Jr. and John McCain, and Commander James Stockdale. On 1 May 1967, an A-4C Skyhawk piloted by Lieutenant Commander Theodore R. Swartz of VA-76 aboard the carrier, shot down a North Vietnamese Air Force MiG-17 with an unguided Zuni rocket, serving as the Skyhawk's only air-to-air victory of the Vietnam War.From 1956 onwards, Navy Skyhawks were the first aircraft to be deployed outside of the U.S. armed with the AIM-9 Sidewinder. On strike missions, the Skyhawk's normal role, air-to-air armaments were used for self-defense. In the early to mid-1960s, standard U.S. Navy A-4B Skyhawk squadrons were assigned to provide fighter protection for anti-submarine warfare aircraft operating from some Essex-class anti-submarine warfare carriers; these aircraft retained their ground- and sea-attack capabilities. The A-4B lacked an air-to-air radar, and it required visual identification of targets and guidance from either ships or an airborne Grumman E-1 Tracer AEW aircraft.
Lightweight and safer to land on smaller decks, Skyhawks would later also play a similar role flying from Australian, Argentinean, and Brazilian upgraded World War II surplus light ASW carriers, which were unable to operate most large modern fighters. Primary air-to-air armament consisted of the internal 20 mm Colt cannons and ability to carry an AIM-9 Sidewinder missile on both underwing hardpoints, later additions of two more underwing hardpoints on some aircraft made for a total capacity of four AAMs.
The first combat loss of an A-4 occurred on 5 August 1964, when Lieutenant junior grade Everett Alvarez, of VA-144 aboard, was shot down while attacking enemy torpedo boats in North Vietnam. Alvarez safely ejected after being hit by anti-aircraft artillery fire, and became the first U.S. Naval POW of the war. He was released as a POW on 12 February 1973. The last A-4 loss in the Vietnam War occurred on 26 September 1972, when USMC pilot Captain James P. Walsh, USMC of VMA-211, flying close air support from Bien Hoa Air Base, South Vietnam, was hit by ground fire during the Battle of An Lộc. Captain Walsh ejected safely and was the last U.S. Marine to be taken prisoner during the war. He was released as a POW on 12 February 1973.
Although the first A-4Es were flown in Vietnam in early 1965, the A-4Cs continued to be used until late 1970. On 1 June 1965, the Chu Lai Short Airfield for Tactical Support was officially opened with the arrival of eight Skyhawks from Cubi Point, Philippine Islands. The group landed with the aid of arresting cables, refueled and took off with the aid of JATO, with fuel and bombs to support Marine combat units. The Skyhawks were from Marine Attack Squadron VMA-225 and VMA-311.
Lieutenant commander Michael J. Estocin of Attack Squadron 192 was posthumously awarded the Medal of Honor for his actions while flying surface-to-air missile suppression during coordinated strikes against targets in Haiphong, North Vietnam, on 20 April and 26 April 1967.
On 29 July 1967, the aircraft carrier was conducting combat operations in the Gulf of Tonkin during the Vietnam War. A Zuni rocket misfired, striking an external tank on an A-4. Fuel from the leaking tank caught fire, creating a massive conflagration that burned for hours, killing 134 sailors, and injuring 161.
During the conflict, 362 A-4/TA-4F Skyhawks were lost due to all causes. The U.S. Navy lost 271 A-4s, the U.S. Marine Corps lost 81 A-4s and 10 TA-4Fs. A total of 32 A-4s were lost to surface-to-air missiles, and one A-4 was lost in aerial combat to a MiG-17 on 25 April 1967.