During the Vietnam war, one aircraft suffered the least amount of damage, even though it had been on some 4000 combat sorties, only six of them were lost to enemy action.
That aircraft was the F-111 aardvark, a swing wing, medium range multi role combat aircraft which started in service in July 1967, and although it had a shaky start, the aircraft ordered by Secretary of defense Robert McNamara to cover both the needs of the USAF and the US Navy in one aircraft, became one of the USAF’s most trusted assets.
This is the story of “the pig” as it was known to the Australian Air Force and why it was such a groundbreaking aircraft.
In early 1960s, the USAF we’re looking to replace their Republic F-105 Thunderchief fighter bombers and around the same time the U.S. Navy we’re looking for a replacement for their F4 Phantom and F8 Crusader.
Both services wanted their own individual aircraft tailored to their needs but by now the costs of developing new aircraft for each of the services was spiralling out of control and the newly appointed secretary of defence Robert McNamara was determined to do what he had done at the Ford Motor Company and streamline the process by using one common aircraft for both services.
McNamara, an Air Force veteran who was brought in along with others to streamline manufacturing and management at the Ford Motor Company before becoming its president for a short while, was drafted in by the new John F Kennedy administration in 1961 to be the secretary of defence.
In 1961, McNamara shortly after taking office, gave the go ahead for the tactical fighter experiment or TFX to come up with one aircraft that could be used by both services despite their best efforts to keep their programs separate.
It was agreed that the design would be based on the air forces requirements and a modified version of that would be used for the Navy. Proposals went out to the leading aviation companies including Boeing, Lockheed, McDonald , North American, General Dynamics and Republic.
Boeing and General Dynamics were selected to submit enhanced designs. The Air Force preferred the Boeing option and the Navy disliked both but the selection board picked the Boeing 818 option to go forward.
However, in 1962 McNamara selected General Dynamics over Boeing because it had a much greater commonality of parts between the Air Force and Navy versions which would keep the costs down. General Dynamics signed a contract in December 1962 and the proposal became the F-111.
The most revolutionary feature of the F-111, the swing-wing was the result of years of NASA research to create a wing that would work well at both low speed and high transonic or supersonic speeds that could be reliably put into production. By 1958, NASA had come up with a way to optimise the swing wing design with pivot points father out from the aircraft centre line and you asf leaders we’re encouraged to look at using this.
Swing wing aircraft had been tried before such as the 1952 Grumman XF10F Jaguar for the US Navy but that prototype had so many other issues it was cancelled before it was put into production.
General Dynamics also shared the design with Grumman Who had greater experience with carrier based aircraft and they also brought their swing wing technology experience. In fact it was reported the swing wing was the only thing that worked well on the Grumman XF10F Jaguar.
The project was known as the the F-111 but it didn’t have a official name like the F4 Phantom or F8 Crusader. It was given the nick name “Aardvark” by Instructor Pilot Al Mateczun in 1969 because of its long drooping nose and terrain-following radar which was used to follow the ground for very low high-speed flight.
Aardvark is an Afrikans word for a South African mammal with a long nose that sniffs out its food on the ground and translates as “ground pig” in English. The Australian Air Force, the RAAF, when they received their F-111Cs, shortened that to the rather more undignified name “the pig”.
The advanced electronics, swing-wing configuration, and after-burning turbofan engines would give the F-111 unrivaled abilities that included attack, interdiction, strategic bombing, reconnaissance, and electronic warfare. But the F-111 project was also meant to save costs, and with such a lot of new technology being packed into a single aircraft, it soon became clear that the development was going to be more costly in both time and money than anticipated.
Advanced features like terrain following radar or TFR was integrated into the flight control systems and allowed hands-off flight at high speeds and low levels down to just 200 feet or 61 metres.
The unique feature of the swing-wing configuration would give the F-111 the ability to fly at low speed, take off from short runways, and cruise more economically with the wings forward. With the wings closed and pulled back it became almost a delta wing that could fly at Mach 1.2 at sea level and Mach 2.3 at altitude but it was not a nimble dogfighter.
Due to the use of every available clear space in the aircraft fuselage and wings, it had a range of 3690 miles or 5940 kilometers with external drop tanks minimizing its reliance on refueling tankers and had a service ceiling of 66,000 feet or 20,000 meters.
The twin Pratt and Whitley TF30 afterburning turbofan engines produced almost 18,000 lbs of thrust each dry and 21,100 lbs of thrust with the afterburner to give it a very high turn of speed, something which the unarmed electronic warfare version, the EF-111 Raven relied upon to outrun its adversaries.
One of the other unusual features was the two-man side by side crew capsule which could be ejected by rockets in one piece from maximum speed and altitude down to zero altitude and just 92 km/h.
This would keep the crew safe from the dangers of a high-speed ejection at up to Mach 2.3 and included a 10-minute supply of oxygen-independent of the aircraft. It also included stabilizers and a break parachute to stop it from spinning out of control before the main parachute opened. If it landed in open water it was self-righting and watertight with flotation devices and a radio location beacon for rescue purposes.
To make maximum use of the low-speed take-off and landing abilities of the swing wing, the aircraft undercarriage was designed to be able to take off from short unmade runways in the Air Force version and was reinforced for the Navy version to withstand heavy landings and assisted launches From an aircraft carrier.
The F-111A version would be for the USAF and the F-111B would be for the US Navy, the only difference between them would be the landing gear, a greater wing length and the nose cone which was over 2.5 meters shorter so it would fit into the existing carrier elevator decks. In the first production run, there would be 18 Air Force A versions and five Navy B versions.
However, the Navy was forced into making compromise after compromise, and tensions between them and the contractors were running high.
The requirements made by the Navy included using a large 48-inch or 120 cm radar dish mated to the AWG-9 radar with AIM-54 Phoenix missiles along with a longer loiter time and combined side-by-side crew capsule kept the weight higher than the Navy required even after an extensive weight loss program had been initiated.
When asked by Senator John C Stennis in a congressional hearing on the aircraft if a more powerful engine would cure the aircraft’s problems, Vice Admiral Thomas Conley then deputy chief of naval operations for air warfare responded by saying “There isn’t enough power in all of Christendom to make that aircraft what we want”.
The Navy finally lost patience with the F-111B and canceled the program in 1968. Prior to that point, Grumman had already got wind of the Navy’s discontent and started the development of a new naval aircraft that would do everything the F-111B did but at a lower weight and satisfied the Navy’s demands.
This would use the same swing wing, engine’s and radar and added an M61 Vulcan cannon and provisions for sidewinder, and Sparrow air to air missiles and bombs. This replacement would eventually become the Navys F-14 tomcat.
While the Navy’s F-111B floundered, the Air Force was keen to test the F-111A in combat and prove itself and it’s advanced technologies in the Vietnam War.
The operation was codenamed “Combat Lancer” and involved sending six F-111A’s from Nellis Air Force Base over 7000 miles via a trans-Pacific flight to the Ta Khli Royal Thai Air Base, 85 miles north of Bangkok, Thailand.
Their first mission was to target a bomb dump on Tiger Island on the Coast of South Vietnam. They Flew in at night over the sea in a high-speed low-level pass on the 25th of March 1968 and although there was heavy cloud, the mission and others flown at night were considered a success. More missions were flown over the next few night until 28th March 1968 when F-111A 66-0022 disappeared. Although an intense search and a generous reward were offered neither the crew nor the aircraft wreckage were ever recovered.
Then just two days later a second F111A whilst descending from 10,000 feet lost control and ended up in an uncontrolled role. The crew ejected safely and were picked up less than a mile from the crash point by an army helicopter rescue team. The wreckage was located and after initial inspection was sent back to the General Dynamics factory where with the help of the crew and a simulator were able to duplicate exactly what happened. It was determined that a catastrophic structural failure in the tailplane system was caused by a fatigue fracture.
If this wasn’t bad enough a 3rd accident occurred on the 22nd of April 1968 and another at Nellis Air Force Base on the 8th May ’68. By this time the combat Lancer programme had been first suspended and then terminated.
In December 1969, again at the Nellis Air Force Base during a training mission, an F-111A with just over 100 hours flight time on the clock was pulling up from a rocket firing pass when the left wing of the aircraft detached from the main body causing it to crash.
In the following investigation, again fatigue cracks were found, this time in the wing pivot which was present in the D6ac steel when manufactured. The process of ultrasound testing was found to be inadequate and also the hardening process of the D6ac steel was found to have too much variation depending upon the quench rate which could lead to cracks that although they were very small couldn’t be picked up by the test equipment but could still lead to failure once in service.
By 1969 new manufacturing techniques were implemented and the problem was eventually solved although 11 more failures were induced on the ground as opposed to in flight.
By this time the press and Congress we’re both condemning the aircraft as unreliable and unsafe but to the Air Force, the operations in Vietnam proved that one aircraft could have twice the range with twice the payload, 20% more speed and significantly higher navigational and bombing accuracy and required no tanker support, electronic countermeasure support and no fighter escort, all of which provided substantial cost savings.
During the rest of the Vietnam War, the F-111 flew more than 4000 combat missions with the loss of only six to enemy fire, the lowest of any aircraft during the conflict.
The F-111 would be used again in April 1986 to conduct airstrikes against Libya in Operation El Dorado Canyon along side B-52s, F/A 18’s, A-6 intruders and A-7 corsairs. Here, 24 F-111 strike aircraft and 5 EF-111A Ravens, the electronic countermeasures version, flew a round trip between RAF Lakenheath and RAF Upper Hayford in the United Kingdom to Libya, a journey of 6400 miles or 10,300 kilometres spanning 13 hours. Just one F-111 aircraft was lost over Libya after being shot down and crasing into the Mediterranean see.
Then in 1991, the F-111 saw active service during operation Desert Storm, completing 3.2 successful strike missions for every unsuccessful one , a Sorte rate better than any other US strike aircraft used during the operation. During desert storm 66 F-111F’s dropped almost 80% of the laser-guided bombs including the bunker Buster GBU-28’s and were credited with destroying more than 1500 Iraqi tanks and armoured vehicles using precision-guided munitions.
Although the F-111 ones were an outstanding aircraft during Desert Storm they made up just 9% of TAC’s fleet but took up 25% of the maintenance budget.
Eventually, the writing was on the wall for the F-111’s and after nearly 30 years in service it was retired. It was only at the ceremony marking the F-111’s retirement on the 27th of July 1996 that it was officially named Aardvark, its longstanding unofficial name which had been used since 1969.
In 1972 Grumman was contacted to convert 42 airframes at a total cost of $1.5 billion into the EF-111A Raven, the electronic warfare version which could be distinguished by the large pod on the top of the tailfin. These were unofficially called the Spark-Vark, a play on the Aardvark name.
The Ravens would be used as a penetrating electronic jamming aircraft with supersonic speed and although they had no armaments, their speed and acceleration were its main form of self-defence.
The Raven also saw service in Libya in 1986 and the Gulf War during Operation Desert Storm in 1991. The Ravens stayed in service until 1998 when they were also retired from service.
The F111 had a shaky start but eventually became one of the US most trusted military assets. It was the first production variable geometry wing aircraft and its success led to many other swing wing designs both in the US and in the Soviet Union where the design heavily influenced the MiG-23 and other Soviet swing-wing aircraft of the era.
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