Staff Writer (Updated: 6/26/2016):
While the type was been considerably improved through further developments, the Harrier line is entering her twilight years as more modern and capable systems make their way to the forefront (such as the joint venture Lockheed F-35 Lightning II). At any rate, the Harrier family line of aircraft has gone down as further proof of the ingenuity and innovation of British aircraft engineers.
Due to the unique nature of the Harrier's flight control system and it requiring a good amount of training and mettle on the part of the pilot, the Harrier has been regarded as one of the most dangerous aircraft to fly, and this statement backed by the many of the non-combat related accidents reported by US and Indian Harrier groups.
Breakdown of the Harrier Family Tree
The Harrier family line consists of four major versions composed of the Hawker Siddeley Harrier, the British Aerospace (BAe) Sea Harrier, the Boeing/BAe AV-8B Harrier II and the BAe Systems/Boeing Harrier II. Confusing at first, each model does differentiate from the other in some distinct way. The initial production model and beginning of the Harrier lineage was the Hawker Siddeley Harrier. The Sea Harrier (as the name implies) became the dedicated navalized version of the base Harrier and utilized for air-defense as a primary role and ground strike as secondary. The Sea Harrier also made use of the powerful Blue Fox radar and was a direct development of the land-based RAF Harrier GR.3. The Boeing/BAe AV-8B Harrier II became a "second generation" Harrier and is a highly-modified version of the original Harrier for use by the USMC while the BAe Harrier II is a British-modified strike version of the USMC Harrier II.
Hawker Aircraft Limited was absorbed by Hawker Siddeley Group in the late 1950s and became British Aerospace (BAe) in 1977.
This article covers the original first generation Hawker Siddeley Harrier. Other models are reviewed elsewhere on this site under their respective manufacturers.
Short Take-Off and Landings (also "STOL") were proving a pivotal part of the modern battlefield that changed substantially with the close of World War 2. The helicopter was debuted in the Korean War and solidified its role in the Vietnam conflict, in the latter becoming a dedicated weapons platform like never before. The ability for aircraft to go airborne in the shortest amount of time, using the shortest amount of runway distance, became an inherent advantage in responding to your enemy's initial round of attacks - particularly in the Cold War. The idea of an aircraft that could attain horizontal flight and translate this power to full-vertical performance was enticing to say the least and offered up warplanners options that were considered science fiction only decades before.
French engineer Michel Henry Marie Joseph Wibault developed a concept for V/STOL flight with his revision of the Brisol BE.25 Orion turboprop engine. The engine made use centrifugal compressors to drive thrust through two nozzles along the side of an aircraft's fuselage. Further revisions ultimately led him to propose the use of four such vectoring nozzles to achieve balance when in the vertical. Though a complex initiative, it proved a promising answer for sustained V/STOL flight so coveted by the military at the time. Wibault named his creation the "Ground Attack Gyroptere".
Wibault attached his engine design into a simplistic airframe featuring a single-seat cockpit, single vertical tail fin, swept back wings and a stout fuselage. Armament was envisioned as a pair of internal cannons backed by a retractable belly pod fitting 18 x unguided rockets. He proposed the idea to the French and American governments only to find rejection. In 1956, he approached NATO and the concept caught the imagination of American Colonel John Driscoll, who put Wibault in contact with people at Bristol Aero Engines Company.
Bristol engineers were concerned about the engines inherent complexity by driven by their curiosity in the concept. After some of their own revisions, they came away with the idea that a single reduction-geared axial-flow fan could take the place of the four compressors. Bristol had already been working on such a fan in their Olympus 21 series engine. The idea as to fit the Olympus with an Orion engine and the resulting solution would achieve the required action. The new Wibault design emerged under the Bristol company designation of BE.48. The Orion engine was then dropped in favor of a low-pressured Orpheus type. The Orpheus itself was high on fuel usage but proved a lighter and more promising arrangement in the long run. The Ground Attack Gryoptere of Wibualt's airframe design was reworked for the new engine. Despite some issues solved, the Wibualt design lacked a balancing solution through its two vectoring nozzles.
In 1957, the engine had evolved into the Bristol BE.53 and could produce up to 11,300lbf. With the powerplant in place, now all Bristol needed was an airframe to attach it to. Hunting eventually led Stanley Hooker of Bristol into contact with Sidney Camm of Hawker. Camm was intrigued in the prospect of the BE.53. The Hawker and Bristol teams now joined forces in a tentative development effort of the P.1127 "High Speed Helicopter". Hawker suggested an additional two nozzles be used in attempting to solve the aircraft balance conundrum. NATO, powered by the US Department of Defense, lent its financial backing to endorse 75% of engine production efforts while Bristol handled the remainder as a private venture. A new revised form of the engine emerged once again as the 11,300lb thrust powerplant dubbed the "Pegasus" in September of 1959. It was about this time that Hawker Aircraft Group became part of Hawker Siddeley Aviation while Bristol Aero Engines became Bristol Siddeley Engines (the former eventually becoming British Aerospace (BAe) and the latter ultimately becoming part of Rolls-Royce Aircraft Engines).
In 1960, the British Ministry of Aviation ordered two prototypes for evaluation as well as four developmental aircraft based on the P.1127 concept. A supersonic version was also beginning development by Hawker Siddeley under the designation of P.1154 for both the RAF and Royal Navy. An initial controlled flight was performed under the guidance of a tether line on October 20th, 1960 and included simple hovering exercises to test out the validity of the engine/airframe mating. Flight trials then came along beginning on March 13th, 1961 and put into action untethered hovering. Forward flight tests began on September 12, 1961 and ultimately culminated in a joint order by the Britain, the United States and Germany for nine evaluation P.1127s (now known as the "Kestrel") under the designation of Kestrel F(GA).Mk 1. The first Kestrel went airborne on March 7th, 1964.