By David Hobbs

The concept of producing a practical, winged, aircraft able to use aerodynamic lift for flight, yet capable of Vertical Take Off and Landing (VTOL) has fascinated designers since the dawn of powered flight. Whilst helicopters have achieved it, their fixed wing cousins have not, to anything like the same degree.
During World War II, the Germans produced a VTO (no 'L' because it did not land) 'target defence interceptor' called the Bachem BA 349 'Natter'. It was powered by a single Walter HWK 109 rocket motor augmented by four boosters and launched vertically up a railed structure 80 feet high. It had a rate of climb in excess of 35,000 feet per minute but a powered endurance of only two minutes and was, in effect, a 'manned missile' intended to intercept daylight bombing raids. It was armed with 33 Type R4M unguided rocket projectiles in the nose and, as soon as he had fired them, the pilot ejected himself and the rocket motor for parachute descents while the remaining wooden airframe structure crashed to the ground. Ten were deployed to Kircheim-on-Teck in April 1945 but the war ended before they could be used operationally.
The "Natter" was a weapon of desperation but, no doubt stimulated by it, the Admiralty wrote a more rational specification in 1945 for a "quick reaction" fighter capable of countering Kamikaze aircraft. The Fairey Aviation Company sketched a design for a small, turbojet powered, delta winged 'tail sitter' that achieved VTO by being boosted up rails fixed to a carrier's flight deck. It would have landed 'more or less' conventionally. The end of the war against Japan took the urgency out of the requirement but it continued as a post war research project with some interest from the RN and RAF. A number of scale models were launched vertically from a rail structure at WRE Woomera. There was some USN interest in turbo-prop powered 'tail sitters' in the USA at the same time but these, too, came to nothing and the concept proved to be a dead end.
High speed research studies carried out at the Royal Aircraft Establishment, Farnborough, in the late 1940s led scientists to predict that future supersonic aircraft would need wings so small that conventional take off and landing on flight decks would not be possible. Thus, they believed VTOL would be inevitable for future generations of fast jets because there was no other way of operating them. The concept had nothing to do with simplified deck operations or improving rough sea landing capability.
By 1954, the Admiralty's Construction Department had prepared plans for a light fleet carrier capable of operating the new Supermarine N113 (Scimitar) fighter in the short term but suitable for the operation of VTOL aircraft in the mid 1960s. The design was unfettered with conflicting requirements and, although not perfect, had greater aircraft operating potential than the Invincible class designed 15 years later. The same department produced sketch proposals for modifications to the Majestic class that would have enabled MELBOURNE and SYDNEY to operate the same types.
Ashore, NATO became interested in VTOL strike fighters. This followed a large and expensive programme of airfield construction in Europe intended to enable tactical aircraft to support NATO armies against any Soviet aggression. Despite the evidence from two world wars and Korea that airfields are extremely difficult to destroy, a belief grew that the new concrete runways and hard-standings were vulnerable to attack and that aircraft should be dispersed "into the field". The Treaty Organisation was trying to standardise a number of weapons and systems at the time, ranging from rifles and their ammunition to radars. In consequence two relevant NATO Basic Military Requirements (NBMR) were written. NBMR 3 called for a lightweight, single-role, VTOL strike aircraft capable of carrying a single nuclear weapon on a short-range tactical mission. It had to be able to take off and land vertically on unprepared fields near the Forward Edge of the Battle Area (FEBA). NBMR 4 asked

A RN F/A 2 Sea Harrier. The Sea Harrier of today is a different beast from its Falklands War days. The aircraft employs a very sophisticated air-search radar, the 'Blue-Vixen', and AMRAAMs (Advanced Medium Range Air-Air Missiles) for long range air superiority tasks and was until very recently, considered the best air superiority fighter in Europe. (RN)

for a VTOL tactical transport aircraft in the C 130 class able to support NBMR 3 in the field. Both completely under-estimated the logistic problems posed by dispersed operations and took no account of bad weather recovery, homing through hostile or friendly airspace, intelligence briefing, site defence and many other practical details.
Britain, France, the USA and Germany all put effort into NBMR 3 but only Britain put design effort into NBMR 4. Aircraft such as the Hawker P1127, Dassault Mirage IIIV and VAK 191 were all flown for evaluation purposes with paper studies based on them put up for the glittering prize of standardised NATO production. The British Treasury hoped that production by an international consortium would radically reduce development costs for a new UK aircraft but NATO had no power to order anything itself and could only recommend a solution. Sensitive to the political issues at stake, it named the British and French entries as "joint technical winners" and left the various governments to make of that what they would.
In 1961, the British concept had evolved into a practical strike fighter design which was given the Hawker type number 1154. It was more capable than the NBMR had demanded and was to have a single Bristol Siddeley BS 100 engine, developed from the Pegasus, with rotating nozzles giving a far more elegant solution to the VTOL problem than the batteries of lift and thrust jets fitted in the rival designs. It could certainly land vertically and with a form of reheat' known as "plenum chamber burning"; it was capable of VTO with a small military load for a few minutes endurance. It did much better with a short take off run, however, and was better referred to as a Vertical/Short Take off and Landing (V/STOL) aircraft. It would have been expensive to develop and operate but it would have been supersonic at height and would have offered a useful performance increase over aircraft like the Hunter and Scimitar. With an engine optimised to give a thrust to weight (T/W) ratio of better than 1:1 on landing, however, it would have had a poor Specific Fuel Consumption (sfc) in cruising flight. This would have led to a payload/ radius of action capability inferior to that of other contemporary fighters, especially those designed in the USA. Export potential would not have been great, as it would have been expensive and very specialised. Sir Sydney Camm, Hawker's chief designer, is believed to have said that V/STOL fighters would not sell well until they approached the capability of the F-4 Phantom. Time has shown him to be right.
To complicate matters, in 1961 the UK Defence Secretary insisted that the P1154 form the basis of a joint project to replace the de Havilland Sea Vixen in RN service and the Hawker Hunter in RAF service. This despite the fact that the former wanted a two seat, twin-engine, high flying fighter with a very powerful radar forming the core of an integrated weapons system and the latter a single seat, single-engine, low flying ground attack aircraft without radar. Further, the naval version had to be stressed for catapulting, carry a large fuel load to give endurance on combat air patrol (CAP) and weapons for at least two interceptions. The RAF version could accept less fuel and lighter structure to give "quick dash" strike capability. Two years were wasted trying to produce a common airframe that met these two very different requirements before the RN managed to convince the British Government that the USN Phantom II was the only aircraft capable of delivering the operational capability that it required. Eighteen months later the simplified RAF version was, in turn, cancelled in favour of a buy of Phantoms. The NBMR 4 design, by then identified as the Armstrong Whitworth Type 681 was also cancelled.
Some operational analysis of V/STOL operations was carried out in 1965 using nine aircraft derived from the P1127 and given the name Kestrel. Three each were purchased by the Governments of the UK, USA and Germany to form a Tripartite Evaluation Squadron, which operated from RAF West Raynham. Pilots and ground crews were drawn from the RAF, USAF, Luftwaffe and US Navy. The RN was not represented. When the squadron disbanded, six of the eight surviving aircraft went to the USA for further evaluation while two continued with development work in the UK. The Luftwaffe and USAF both concluded that operations from hardened aircraft shelters on conventional airfields by conventional aircraft were both cheaper and more efficient than dispersed operations by VTOL aircraft. Had there been operational merit in the latter, it is difficult not to believe that the USAF would have hastened it into service in the Vietnam War.
After all the investment, some interest in V/STOL remained in the UK and a developed version of the Kestrel went into operational service with the RAF in 1969. This had little to do with cost-effective delivery of an interdiction/strike capability and more to do with the sitting Labour Government's wish to provide some work for the British aviation industry which had suffered a series of cancelled projects in the preceding months. The new version was given the name Harrier, originally intended for the P1154 had it gone into service. 84 were ordered in the first batch but, significantly, the RAF ordered 200 of the cheaper but more capable Jaguar strike aircraft to form the main component of its strike force.
In retrospect, this British fascination with the platform, rather than the operational effect it was intended to create is difficult to understand. It contrasts starkly with the German decision to focus on a strike capability that was best provided by conventional aircraft operating from conventional airfields. Even more difficult to understand is the NATO planners' assumption that concrete runways were the vulnerable part of the equation, not the aircraft or their logistic and technical support. On the ground, near the FEBA, aircraft and the hundreds of men and vehicles needed to make them work would have been vulnerable to small arms, mortar and artillery fire in addition to missile and air attack. In hardened shelters on an airfield in a rear area, they must have been less so, even though it took longer to reach an urgent target. The concept of dispersal away from airfields was quietly dropped in the 1970s.
The US Marine Corps was impressed by the Harrier's undoubted ability to deliver bombs in amphibious operations and to move ashore with the marines and their helicopters. I believe they were also impressed by the fact that it was so highly specialised in the short-range ground attack role that it was not likely to be miss-employed on naval missions as the F-8 Crusader and F-4 Phantom often were. The politics behind procurement can be surprisingly devious. Despite a licence agreement between Hawker Siddeley and McDonnell Douglas the AV-8A Harrier was built in such small batches that all were built in the UK.
After the cancellation of its CVA-01 carrier project, the RN found considerable political opposition to the idea of maintaining any sort of fighter aircraft in ships at sea. The Chief of Naval Staff, Admiral Sir Varyl Begg was an opponent of embarked aviation and acted quickly to run down the conventional carrier force. He focused attention on a future navy comprising cruisers armed with missiles and, to a limited extent, VTOL aircraft or helicopters. Design work started on a command cruiser which went through more than 50 iterations and which had an aviation facility which grew from a single spot for a helicopter aft to a runway running the length of the ship with an island structure to starboard. The latter proved so superior, even for the operation of a modest number of helicopters that it was adopted. The ability to embark Harriers was obvious and, from the outset, was a factor in the design of what became the Invincible class.
There is a myth that V/STOL fighters can use small, simple and, therefore cheap, ships, often called Harrier Carriers, which provide affordable capability. In researching background papers for this article, I found a Paper written in 1966, only six weeks after the cancellation of CVA-01, which puts the counter argument. It compares a baseline V/STOL aircraft, the Kestrel, with the maritime Jaguar, in development at the time for the French Navy and seeks to put numerical values on their relative cost effectiveness. Kestrels were more expensive to buy than Jaguars in the ratio 8:5. Because the latter was designed for cruise efficiency in flight and the former for its take off and landing performance, Jaguars have better SFC and carry more weapons further, faster. For a given task, fewer Jaguars than Kestrels would be needed.
The Paper compares two weapon effort planning scenarios, sinking a destroyer sized contact and destroying a bridge. Different parameters were used, some favouring the Kestrel, some the Jaguar. On average, it was evaluated that 12 Kestrels would be needed to do the same task as 8 Jaguars and there are tasks that the latter could do that the former could not. Thus cost factors of 96 against 40 were given making the Jaguar more than twice as cost effective as the Kestrel. The larger number of Kestrels need a large ship from which to operate but it would be a simple V/STOL carrier. There is, therefore, a cost penalty of building the V/STOL capability into every aircraft rather than the single ship from which they operate. Taking the CTOL (Controlled Take Off and Landing) comparison further, the Paper examines the cost of putting V/STOL capability back into the carrier. It uses prices equivalent to half the cost of a Jaguar for each catapult and the cost of a whole Jaguar for the arrester wire system. For a Hermes sized ship with two catapults and arrester wires, this modified the cost factors to 96 against 50. It is still nearly twice as expensive to procure the less capable V/STOL aircraft and the 'cheap ship' has been 'bought' by expenditure on an expensive but less capable aircraft. The numbers may vary, but these factors still hold good for today's Joint Strike Fighter where comparisons show that the USN's carrier version is cheaper but goes further with more weapons than the V/STOL version. It is arguable that the British decision to take V/STOL to sea was politically rather than capability based.
Sea Harriers began to enter front line service with the RN in 1980. Although not as capable as conventional carrier aircraft, it was immediately apparent that they were more effective in their mobile base than the discredited dispersed operations had been ashore. The new aircraft's Release to Service was limited at first by the novelty of its deck operations and weapons systems. It was still being expanded five years later. In addition to INVINCIBLE, the former CVA HERMES was modified to operate Sea Harriers from 1981 onwards.
Fighters embarked in these two ships were fundamental to the British plans to liberate the Falkland Islands after their seizure by Argentinean forces in 1982. 28 out of RN's total, at the time, of 32 Sea Harriers were deployed in four Naval Air Squadrons, one of which was formed at short notice. They flew 2,000 operational sorties and achieved 32 confirmed kills of enemy aircraft in air to air engagements. They also carried out successful strikes against enemy shipping and shore targets. None were lost in air combat but two were lost to ground fire and others in operational accidents. An overall serviceability rate in excess of 90% was achieved.
This performance surprised many outside the RN and was sufficient to prevent Argentine air forces from defeating the amphibious landings. However, by comparison with the air defence system the Service had wanted but lost with the cancellation of the CVA-01 replacement carrier project, the performance fell short of the optimum. Enemy aircraft and missiles were able to penetrate the defences and inflict heavy casualties in ships and lives. This was predictable due to the lack of embarked Airborne Early Warning (AEW) aircraft and shortcomings in Sea Harrier performance and armament. With only a basic pulse radar, no Beyond Visual Range (BVR) weapon, no high speed dash to gain position and no embarked tanker aircraft to sustain them on CAP (Combat Air Patrol) or give flexibility in recovery, the Sea Harrier was markedly inferior to the aircraft it replaced.
It did well because of the highly skilled pilots available from previous conventional carrier operations, many of which were instructors with thousands of flying hours. It also had a very good weapon in the newly supplied American AIM-9L Sidewinder and an excellent landing capability in high sea states that caused excessive ship motion. Although rated as a Fighter/Reconnaissance/Strike aircraft, the FRS-1 Sea Harrier could hardly be compared with USN carrier aircraft in the last two roles and relied on above average pilot skill in the first to command success. In 1982 that level of skill was available.
Given this very public success, hopes for export sales rose and several navies bought Sea Harrier or AV-8 derivatives but only in small numbers. They include India (23 plus 4 trainers); Spain (32 plus 3 trainers); Italy (16 plus 2 trainers) and Thailand (7 plus 2 trainers purchased from Spain second hand). Total P1127/Harrier/Sea Harrier/AV 8 production has amounted to 15 prototypes, 237 first generation single seaters, 98 Sea Harriers, 395 AV 8B second generation single seaters and 86 trainers of all versions.
By the 1990s, the Sea Harrier FRS-1's capability as a fighter was becoming marginal and replacement with the F/A-2 was timely. This has the Blue Vixen pulse doppler radar, track-while-scan capability and up to four AMRAAM missiles constituting one of the West's best fire control systems, albeit fitted in a 40 year old airframe design. Even with this upgrade, it faces tough opposition in many areas of potential conflict. The 'A' indicates a limited attack capability giving this improved version a limited swing performance.
Given this background, we have to answer several key questions before deciding whether V/STOL was a good idea for the RN;
Q: Was V/STOL inevitable?
A: Advances in wing design made it possible to produce very successful fast jets that could land on carriers conventionally. The RAE scientists were wrong; it was not, therefore, inevitable.
Q: Was V/STOL ever viable for the USN?
A: The USN considered and rejected it. It did not accept the reduction in operational capability that V/STOL brought with it. Even today, the USN will not accept the V/STOL version of the Joint Strike Fighter, which is being considered for the USMC.
Q: Why did the USMC opt for it?
A: It wanted a specific aircraft to support amphibious landings, moving ashore with the marines. Almost as important, it wanted one that could not be used for general fighter duties by the USN in a carrier battle group.
Q: Was it the best fighter that the RN could buy?
A: No, but it was the only aircraft that the British Government of the day, which cared little for cost effectiveness or capability issues, would allow it to buy. In practical terms, it was the only fighter that could be operated at sea once the mistake had been made of ordering ships of such limited capability as the Invincible class. In naval terms it was not the best fighter, nor was it the best that could be operated from a ship of the size the RN had planned to procure.
Q: Did it perform as expected?
A: It performed better than expected in the Falklands War but desperately needed the capability upgrades in the F/A-2 version.
Q: Could anything else have done better?
A: An embarked AEW capability would have made the most significant difference in the Falklands War. A USN fighter operated from a larger ship would have been a better platform.
Q: Is another V/STOL fighter a viable replacement for the Sea Harrier?
A: Look at the JSF. V/STOL versions lack the radius of action and weapon carrying options of the CTOL versions and cannot guarantee to land on vertically with unexpended ordnance in the hot summer temperatures found in the Gulf. They are more expensive to buy and maintain and offer less operational capability. Even today, 41 years after NBMR 3, CTOL remains the more cost-effective option.
We must conclude from these answers that V/STOL was seen as a good idea politically and provided something for the work force to build after the spate of cancellations in the mid 1960s. In the negative climate of opinion that surrounded naval aviation in the 1970s, it was the only fighter option available to the RN and no Government wanted to listen to well reasoned arguments about cost, capability or effectiveness. In naval terms, it was not the best fighter available, nor did it represent the most affordable weapons system. The Service was fortunate to have the skill base to make it work and to 'fight above its weight' in the Falklands War. The ability of Sea Harriers to recover in rough weather was fortuitous since it had not been called for in the Staff Requirement. Comparisons with ARK ROYAL were inappropriate, since she was at the end of a very long capability stretch since her original completion and had, in any case, been scrapped. The new generation of carriers the RN had tried to procure, the CVA-01 class, were specifically designed to be good at operating CTOL aircraft in rough weather with an eye to possible strike operations in the Barents Sea. The true comparison should be made with them.
With the introduction of simple carriers and their limited V/STOL air groups, the RN not only lost the ability to operate affordable AEW aircraft but also the capability to cross deck strike aircraft with its biggest and most important ally, the United States Navy. Worse, the change of direction made it impossible to purchase or make use of USN carrier aircraft types, forcing the RN down the lonely and expensive route of having to develop its own unusual and expensive fighter with few prospects of export sales. The USN had itself evaluated the idea of a Sea Control Ship with a mix of V/STOL fighters and helicopters embarked but had rejected it as being too expensive for the minimal capability provided! They cannot have been impressed by the loss of allied capability as the RN chose to follow this expensive option. The adoption of the CV version of the Joint Strike Fighter by the RN would reverse this situation and bring the Service back into line with its principal partner.
In historical terms, V/STOL was made to work and produced better results than the UK Government had a right to expect. Other aircraft and air defence systems would have performed better at a more competitive procurement cost had a more enlightened outlook prevailed in Whitehall. In terms of cost effective capability, V/STOL was not a good idea. A combination of F-4 Phantoms and Gannets was so nearly achievable and would have been better. A replacement combination of F-14 Tomcats and E-2C Hawkeyes could have gone into service in the 1980s and would still be very hard to beat even today.
Postscript May 02:
Those who opposed the procurement of a V/STOL fighter for the Royal Navy in the 1960s and 70s feared that weight growth, common to all previous carrier fighters in service, would eventually prevent the aircraft from flying. Their time-scale was out but they were right. The principal reason for the Sea Harrier's early withdrawal from service in 2006 its lack of power from its early Pegasus engine. Fitting the Pegasus 107 engine into an airframe designed over 40 years ago would be technically complex and the cost of modifying 30 airframes was unofficially believed to exceed AUS$500 million. There is a lesson here that no matter how good the weapon system, a fighter that relies on vertical landing performance will always need engine development if it is to continue to fly as weight grows during its service career. Let us hope that the lesson is learned before the decision on which type of JSF to order is taken.

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