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British Aerospace Harrier

Originally published by Aviation History magazine. Published Online: June 12, 2006 
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'The airplane won't amount to a damn thing until they get a machine that will action like a hummingbird: go straight up, go forward, go backward, come straight down and alight like a hummingbird. It isn't easy; [but] somebody is going to do it, said Thomas Edison, the great American inventor. But it would be many years before somebody fulfilled his prophecy.

Meanwhile, conventional fixed-wing aircraft have proven themselves admirably, lifting tons of personnel and equipment from gravity's embrace, flying around the globe nonstop or traveling faster than the speed of sound.

Helicopters, on the other had, can do three things conventional airplanes cannot: take off vertically, land vertically and hover. However, the same machine cannot match the high forward speed or maximum altitudes capable of an airplane. Therefore, there has historically been a major gap between fixed-wing aircraft and helicopters in both the civilian and military aeronautical world. The need for an aircraft that could not only take off vertically from any point large enough to allow adequate space for the machine itself, but also achieve speeds fast enough to make it viable in the fixed-wing world became apparent to military planners shortly after World War II with the advent of the jet engine. The turbojet engine pushed known aeronautical knowledge to the limits. For the first time since the Wright brothers lifted off in the Wright Flyer at Kill Devil Hill, airplanes had reached the point where they required great lengths of hard smooth-surfaced runway to both take off and land. And for naval aviation, stream-driven catapults were required in addition to the carriers' forward speed to provide sufficient speed to launch aircraft. The gap between helicopters and airplanes widened significantly.

To fill this gap, engineers attacked the problem of combining the advantages of the helicopter with those of the airplane: vertical takeoff and landing capabilities plus speed. For this, a completely new aircraft was required – a machine that utilized wings instead of rotor blades, and was powered by both vertical and aft thrust.

With these requirements in mind, Rolls Royce in 1953 created a machine it referred to as the Thrust Measurement Rig to test the principles of vertical flight utilizing the thrust provided by turbojet engines. It was an odd contraption fitted with two Rolls Royce turbojets mounted horizontally, with their jets vectored vertically downward to provide the thrust required to lift the device. Resembling a box construction of welded steel tubing, the machine, although it had no wings and could not achieve the speeds of an airplane, did provide a great deal of information concerning the capabilities of the turbine engine. The experiment of vectored jet thrust was successful and the machine, nicknamed the Flying Bedstead, completed more than 500 hovering flights to prove the viability of flying by thrust alone.

Then, in 1957, the French SNECMA design team successfully flew an Attouste jet-engine-powered oddity that resembled a futuristic rocket ship. With the vertically mounted engine being the main section of fuselage, supported by four fin-shaped supports of tubing, this unusual machine – strangely resembling a 1950s rocket to Mars – rose vertically and hovered to dangerous heights successfully on several occasions.

In America, the Doke VZ 40A, a more conventional design that resembled an airplane with a shrouded propeller mounted at each wing tip, hovered effortlessly and managed forward flight with a semblance of controllability. Yet, because of lack of financing, it faded into obscurity as another noble effort that died in development.

Meanwhile, the Chrysler Corporation, with its great number of government contacts and massive capability to finance experimentation, developed the Flying Jeep. This futuristic machine consisted of two shrouded fans connected by a short airframe upon which the pilot/driver was accommodated. The thrust of the fans could be directed through a system of controllable vanes. It hovered and moved about remarkably well, but the U.S. Army, although impressed, failed to adopt the vehicle into its inventory.

Other machines followed. The German Dornier Do-31, another airplane look-alike that utilized both lift engines and vector-thrust, and the Ryan tail-sitting X-13 Vertijet taught engineers valuable lessons. During the same period, Bell Aircraft conducted test of its own with its Model 65. This innovative machine resembled a high-wing airplane with a turbine engine mounted on each side of the fuselage. To provide vertical thrust, both engines were swiveled downward. Then, in 1956, Bell constructed the X-14. This design resembled a conventional airplane but mounted two Armstrong Siddeley Viper engines side by side in the nose. It also differed in that the engines were fixed in place and the thrust was vectored downward by way of a cascade vane system under the aircraft's center of gravity. The X-14 was so successful that it flew in text programs from 1957 until 1981, when it was finally retired from service at the National Aeronautics and Space Administration (NASA), which had taken it over from Bell.

As these developments were taking place in the United States, the British were also busily pursuing experiments in vectored thrust on their side of the Atlantic. The Short Brothers and the Harland Company, teaming up with Rolls Royce, constructed the SC-1, a stubby bumblebee-shaped airplane powered by five Rolls Royce RB 108 turbine engines. Four were mounted vertically in a compartment at the fuselage center to provide lift, with the fifth in the tail to provide thrust. To control the aircraft's pitch and roll in hover configuration when there was inadequate airflow over the normal aerodynamic control surfaces, the lift engines could be partially swiveled while high pressure air was directed to reaction control valves that controlled the air ejector nozzles at the nose, tail and wing tips. In 1960 the SC-1 dramatically demonstrated the ability to hover, shift to forward flight and return to hover – all under the power of vectored thrust. The concept of extremity-placed ejector nozzles, or puffers, to control roll and pitch would become the standard for future British V/STOL (Vertical and Short Takeoff and Landing) developments.

The French Dassault engineers, following the idea of separate engines for lift and forward flight, constructed a single-test machine known as the Balzac. Resembling a delta-wing fighter, the airplane seemed to hold promise for the French when, in 1965, it did manage to hover and attain forward flight. However, the Balzac design was involved in two crashes and no more were built.

The Soviet Yakovlev design bureau watched the American and West European developers carefully. Noting the successful efforts that combined both lift and forward-thrust engines, the Soviet engineers retained this line of thinking in their development of the Yak-38 Forger. This machine, powered by no less than three engines – two to provide hover thrust and one for forward flight – proved successful and entered operational service with the Soviet Navy. First seen by the West in 1976 on the flight deck of the Kiev when she entered the Mediterranean, the Yak-38 holds the distinction of being one of only two V/STOL fighter aircraft to enter military operational service following three decades of intense development. The other is the British Aerospace Harrier.

Breaking away from the idea of separate engines to operate in two environments – hover and forward flight – the technical director of Bristol Engine Company, Sir Stanley Hooker, took a new tack. He reasoned that if a single engine was powerful enough, and if the thrust provided by that engine could be directed or ducted where needed, then one power plant would not only be sufficient but also much easier to design an aircraft around.

His design, a large turbofan engine that could duct cool fan air to two swiveling nozzles at the front of an aircraft and hot exhaust air to like nozzles at the rear, became the Bristol Siddeley Pegasus. The accompanying airframe, designed by Hawker Siddeley, consisted of a negative dihedral, swept wing mounted high on the fuselage to keep clear of the side-mounted nozzles, two oversized fan inlets, and a ductwork of tubes that distributed high-pressure air to the puffers at the wing tips, nose and tail. Because the central section of fuselage contained the engine and thrust nozzles, two main landing gear were placed in a fore-and-aft tandem configuration along the fuselage center-line in front of, and behind, the engine. The wings were supported by two small wing-tip-mounted outrigger wheels. This combination of power plant and airframe was designated the XP-831.

On October 21, 1960, Hawker's chief test pilot, Bill Bedford, climbed into the cockpit of the prototype and started the engine. With cameras grinding away, the odd-looking aircraft – loosely tethered to the ground by cables – rose slightly, bounced slightly a few times and then hovered momentarily with its nose moving right and left as Bedford tested the controls. No one had ever flown such a machine before and the control inputs would be different than any other aircraft. Bedford had to learn in the cockpit. A few seconds later, the machine bounced to the ground, its first flight completed.

With an even more powerful engine, the second prototype – designated XP-836 – entered the test program and managed to switch from hover to forward flight and back to hover. The airplane now had proven the viability of the single engine with vectored thrust, and it was time to explore the flight envelope.

In 1962, the aircraft was christened Kestrel after the European falcon that can hover as it hunts. Testing continued and each flight proved that this was a machine that could indeed fill the gap between helicopters and jet fighters. But the Royal Air Force (RAF) and the Royal Navy were less than enthusiastic. They were more interested in supersonic aircraft and were not as impressed by the Kestrel as were other North Atlantic Treaty Organization (NATO) forces that early on could see the advantages of V/STOL.

With funding provided by a NATO group called the Neutral Weapons Development Program – primarily funded by U.S. dollars – a tripartite evaluation squadron consisting of officers from the United States, West Germany and the United Kingdom was formed to test the operational feasibility of the new aircraft. Nine Kestrels and 10 pilots were assigned to the squadron based at RAF West Rainham in Norfolk, England. The first official day of operations was April 1, 1965. The program got off to a bad start when on that day a U.S. Army pilot crashed the newest of the Kestrels, a plane only one month off the assembly line. But over the next nine months more than 900 sorties were flown, and the program was considered a resounding success.

Despite the early accomplishments of the Kestrel, the RAF and the Royal Navy still showed little enthusiasm for it and persisted in their efforts to acquire a supersonic aircraft. Hawker began working on the P-1154, a supersonic derivation of Kestrel to be known as the Harrier (after a large hovering falcon). Built in October 1964, the Harrier, along with two other aircraft projects, fell victim to budget cutting by the government and was cancelled.

Emerging from this cancellation was a new aircraft that used knowledge gained from the Kestrel tests and the P-1154 design. Retaining the name Harrier, this design emerged from the drawing board with a more powerful engine of 19,000 pounds thrust, larger intakes and improved wing and tail. It also contained a unique inertial navigation system that could put a pilot precisely cover a target at both high altitude and treetop level. This new Harrier became the GR-1, for Ground attack and Reconnaissance.

When the first Harriers became operational with the Royal Navy, it quickly became apparent that the Harrier required much less flight deck than that found on the full-size aircraft carriers that currently launched the Sea Vixen, the Buccaneer and the F-4 Phantom. Those heavy turbojet aircraft depended upon steam catapults to achieve sufficient speed to become airborne, and upon arresting cables to stop them in a short distance on landing. The Harrier needed neither. The GR-1 could simply make an approach, slow to a hover, and then gently land on any spot large enough to contain it. That did impress the Royal Navy.

And the timing of Harrier's arrival for duty with the fleet was fortuitous. Britain was facing great economic problems at home and expenditures for both new items of military hardware and for expenses in maintenance and operations of equipment already in inventory were being cut drastically. The large aircraft carriers, being the most expensive ships to operate and maintain, were among the first to go. With them went the Royal Navy's heavy fixed-wing aircraft. The Harrier quickly became the mainstay fighter and attack aircraft of the fleet; it drew international attention with its capabilities. Even the U.S. Marines and Spanish navy adopted the Harrier (the Spanish renaming theirs Matador).

In 1975, the Royal Navy ordered a new version of Harrier that would be better meet the needs of the fleet. This new aircraft, the FRS-1 (for Fighter, Reconnaissance and Strike), was constructed with materials and coatings that resisted corrosion. Dubbed Sea Harrier, it contained no magnesium parts, had a raised cockpit for better all-around visibility, and incorporated more panel space for avionics. Unlike the previous GR-1s, which still served with the RAF in their ground attack and fighter role, the Sea Harrier was to fill the role of air defense interceptor to protect the fleet.

But the same budget cutbacks that benefited Harrier's acceptance by the navy interfered with its deployment. As desperately as the navy fought to keep its aircraft carriers, the liberal factions of Parliament fought to ax them. Although a Harrier does not require the massive deck space of a conventional aircraft carrier, it does require, when weighted down the fuel and ordnance, a sufficient area to perform a running takeoff because it consumes too much fuel in the act of vertical takeoff to perform a normal mission.

By 1971, the navy had lost the battle – and the carriers. Only the old HMS Hermes, now predestinated as a Landing Platform-Helicopter, remained. In the opinion of the Admiralty, this one ship would not suffice. Plans for minicarriers, Harrier carriers, and though-deck cruisers, came and went over the next two years, but only one, the HMS Invincible (a minicarrier), was constructed. And because of its size, only a handful of Harriers could operate from its deck. Things were looking very bleak for British naval aviation when a bit of salvation came in the form of a paper, written by Lieutenant Commander Doug Taylor, that came to the attention of the Admiralty. In it, Taylor described the advantages of launching Harriers with the aid of an inclined ramp or ski jump. With this system, it would be possible to carry more aircraft aboard ship because less flight deck would be needed for launching purposes.

The idea was tested at the Royal Aircraft Establishment at Bedford by building such a ramp on a runway and successful launching a Sea Harrier. It was found during these tests that a Harrier carrying a 10,000-pound load could take off at half the speed and use less than one-third the distance needed when operating from a flat deck. Both the Hermes and Invincible were fitted with ski jump

The Royal Air Force, having a different mission, remained satisfied with the GR-1, the follow-up GR-1A and eventually the GR-3, each version's performance improved by a larger engine than its predecessor. Its ability to operate off short stretches of roadway and open fields gives Harrier the unique capability of being stationed near the FEBA (the Forward Edge of the Battle Area). This allows for a rapid response in answer to calls for air support and makes the Harrier a critical element in an air-land battle. Easily camouflaged and hidden or dispersed in wooded tree lines, Harriers can deploy where no other turbine-engine fighter or ground-attack jet can operate.

The Harrier has two natural enemies, however: debris and birds. Debris – rocks, sticks and small objects stirred up by the downward jet blast – creates FOD, or Foreign Object Damage, on any aircraft with the power to stir it up. The Harrier, with its overly large intakes and vectored thrust nozzles, falls easy victim to debris ingested into the engine if care is not taken when taking off or landing. Further, for an aircraft that often is required to fly just above treetop level, encountering a bird can be as fatal as receiving a cannon hit.

During the South Atlantic (Falkland Islands) campaign in 1982, a GR-3 of Number 1 Squadron (RAF) received a bird strike below the windscreen just in front of the instrument panel. The bird penetrated the skin and entered the electronics by where it destroyed the inertial navigation system and other electronic devices. The pilots managed to return to base, and the aircraft was field repaired by simply deactivating the systems and taping a section of aluminum sheet over the hole.

The Falklands campaign demonstrated the difference in the mission requirements between the RAF GR-3 and the Sea Harrier. While the GR-3s performed in a ground-attack role in support of the landing force, the FRS-1s defended the fleet against Argentine air attack. In this, they were greatly outmatched in both speed and firepower. The Argentine forces flew the French 748-mph Super Etendard, and 863-mph Mirage III, plus 646-mph American A-4 Skyhawk. With the exception of the A-4, the Argentine pilots held the speed advantage over the slower 720-mph Harriers.

In air-to-air combat, the Harrier pilots only had one trick up their sleeves – a maneuver that could only be performed with vectored thrust. Borrowing a technique developed by the U.S. Marines in the Av-8B (the American version of the Harrier), the British Harrier pilots relied on a maneuver known as viffing, or vectoring in forward flight. Because of its high wing-loading, the Harrier is not as agile at high speed as are conventional fighters. But it does have one distinct advantage – its controllable-thrust nozzles. When enemy aircraft approaches from the rear in a dog-fight, the Harrier pilot at the most appropriate moment slams his thrust lever to the forward (vertical thrust) position and turns tightly away. The Harrier, with the nozzles now pointed down and away from the aircraft, almost stops in midair. It then falls away as the pursuer blasts by, and then pulls up and becomes the hunter.

A more decisive factor favoring the Harriers in air-to-air combat over the Falkands was the damage done to Stanley Airport by an Avro Vulcan bomber on May 1, 1982. It prevented the Argentine jets from operating from the islands. Flying at maximum range from the Argentine mainland, they did not have enough fuel to engage in dogfights with the Harriers for any appreciable length of time.

In the ground-attack role, the GR-3s of Number One Squadron, the only RAF Harrier squadron to participate in the war, demonstrated outstanding capabilities. Carrying armament that ranged from 30mm pod-mounted Aden cannons and Matra 68mm rockets to iron bombs, Number One Squadron flew sortie after sortie against ground defenses.

The best tribute to the Harrier's capability lies in the fact that during the entire Falklands campaign only nine Harriers were lost, five shot down by ground fire and four due to accidents. None were shot down in air-to-air combat. Argentina, on the other hand, lost 31 aircraft to the Harrier in air combat with a further 30 destroyed on the ground by GR-3s.

Prior to May 1, many Argentines had dismissed the Harrier as a toy airplane. But their opinion changed after a number of encounters throughout the day. After several indecisive combats, first blood was drawn when Flt. Lt. Peter C. Barton of 801 Squadron from HMS Invincible sent a Sidewinder into a Mirage of Grupo 8 whose pilot, Primer Teniente Carlos Perona, managed to eject and despite his being injured in both ankles, struggled safely ashore north of Pebble Island.

From that day on, the Argentines referred to dark gray Sea Harriers as La Muerta Negra (black death) and concentrated their efforts solely on avoiding or speeding through the deadly screen of Harriers in their effort to take out the British ships. The Sea Harriers played a significant role in their ultimate failure.

The Harriers had finally proven themselves. But for all their remarkable attributes, the machines that fought in the South Atlantic had been almost obsolete in design when the war broke out. Vast improvements in aerospace materials and design techniques had taken place since the first GR-1 took to the skies. Composite materials and airframe bonding methods were replacing milled aluminum and rivets. In America, the McDonnell Douglas Aircraft Company had flown a new prototype Harrier, designated YAV-8B in 1978, that was vastly superior to the venerable British Aerospace design. But political and economic factors have a direct bearing on military expenditures for replacement items and Great Britain was in an economic decline. As late as 1988, the RAF and Royal Navy still flew the same aircraft that fought in the Falklands. Metal fatigue was setting in and replacement parts were running out. But late in the same year, a new machine began making a limited appearance in the RAF and Royal Navy hangars. The British Aerospace-assembled AV-8B Harrier II, now designated GR-5 by the British, began to arrive to replace aircraft assigned to bases in Germany. In all 60 aircraft were ordered, with options for more.

The Harrier II incorporated many improvements over its predecessors. It has a completely new supercritical-section wing with the main box spar produced entirely of carbon fiber composite, a Pegasus engine with improved front nozzles, a raised cockpit to improve the pilot's view, outrigger landing gears that have been moved further inboard to facilitate operations from narrow roads, and a totally new avionics package that includes both electronics countermeasures equipments and the Hughes Angle/Rate bombing system. The four wing pylons of the GR-3 have been replaced by eight for the RAF and six for the U.S. Marines. In all, the Harrier II is designed as a versatile aircraft that will continue to fill the gap for many years to come.

In all the variants since the GR-1, the Harrier has proven itself a tribute to man's ingenuity. Maybe it should have been named Hummingbird.

This article was written by Craig Roberts and originally published in the November 1990 issue of Aviation History.

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