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Aviation History
1969
1969 - 0818.PDF
724 V/STOL SURVEY RAF AND THE HARRIER . . . was adopted because of a Government decision to recognise the unique prestige value, commercial attractiveness and poten tial stimulus to more advanced programmes which the project offers; the Jaguar was undertaken because it provided another link with the continent, and in particular with a country whose friendship (a commodity not easy to come by) needed to be cultivated in the context of wider technical/political/commer cial European partnership; the Phantom was bought because it was on the shelf when needed. In other words, force of circumstances rather than abstract planning has brought about this juxtaposition, which is probably not a bad thing. Cer tainly it will enable two quite comparable types, one with VTOL, and the other with short-field performance, to be operated in a comparative manner, and may even allow HSA's claim to be verified that Harrier is superior to any other aero plane in the close-support role in being able to drop the greatest weapon-load per hour. Operational deployment Four squadrons will be formed from the 77 Harrier FGA.l single-seaters and 13 T.2 tandem two-seat operational trainers. One squadron will be retained in the United Kingdom, at Wittering, while the remaining three will be deployed in Germany, where they will be operating in conditions ideally suited to demonstrating the viability of V/STOL operation (and, incidentally, in a country with the greatest V/STOL interest outside America: VJ101, VAK 191B, Do31, VFW VC.400 and AVS). Operational flexibility from dispersed sites is the key factor of course. The Arab-Israel six-day war gave prominence to the vulnerability of undispersed targets to pre-emptive strikes. Equally ominous from this aspect was the over-night penetra tion of Czechoslovakia by Russian forces last year. A large number of design variables have to be carefully balanced to enable an acceptable end-product to be derived, and it is in structive to look at some actual figures to see what advantages and penalties accrue from V/STOL. The major penalty paid, of course, is the power (and thus size and weight of engine and fuel) required for vertical opera tions. Harrier has a gross weight of some 23,0001b in the normal or STOL take-off mode. Its empty weight is about 12,0001b, and maximum weight for in-service vertical opera tion would be about 16,0001b, giving an excess of 3,0001b available lift with the 19,0001b-thrust Pegasus 101 of the pro duction aircraft. This margin, is necessary to give reasonably rapid upward acceleration in all climates to avoid turbulence, istone ingestion, suck-down and .genteraflly to preserve an acceptable safety margin (some thrust, of course, is also needed for control purposes). So the balance of 4,0001b is available for fuel or weight. If this is split equally, the aeroplane could carry two 1,0001b bombs over a radius corresponding to 2,0001b or 250gal of fuel—say 70-100 miles, allowing two or three minutes over the target for identification and weapon delivery (these are necessarily "ball park" figures since the performance of the Harrier is classified). The aircraft could therefore be deployed from the traditional jungle clearing up to 35-50 miles from the target. Quoting radii of action of 50 miles or so may come as a surprise to those used to the more usual 250 miles or so. The answer is, of course, that Harrier is an immediate close support aircraft, and meant for operation from temporary bases very close to the battle-front; obviously a permanent airfield could not be permanently contained at this range. The popular con cept of true front-line operation, incidentally, is not considered to be realistic. Aircraft worth nearly £1 million each are not deployed in an area under direct enemy surveillance, or where the temporary misfortunes of war, saboteur activity, even stray artillery shells can put them at risk. For this reason a forward base will probably not be nearer to the enemy than about 10 miles. Under these conditions it is highly unlikely that the Harrier FLIGHT International, I May 1969 could not be operated from a stretch of ground larger than the minimum size necessary for purely vertical operation, so enabling the significant payload advantage of STOL opera tion to accrue. The high thrust-weight ratio enables very high accelerations along the ground to be used (much greater than normally available to conventional strike aircraft) thus reduc ing the ground roll necessary before thrust-vectoring can lift the aircraft clear of surrounding obstacles. Full use could be made of the present 6,0001b weapon load (at which the Harrier is rated) from very short strips. The RAF plans to operate the Harrier from three types of base: normal permanent airfields, located probably 100-200 miles behind the battle zone, dispersed supported forward sites and unsupported sites. The first would have the usual arming, fuelling and maintenance facilities and might operate a detachment or a squadron of aircraft. The second area would have limited fuelling and arming facilities to operate one or two aircraft for a day or so. In the third category come the dispersed, unsupported sites, much nearer the front line but far enough away to ensure that they would not be overrun without warning. A base airfield would probably have up to six supported dispersed sites associated with it, so that a full squadron could be dispersed. This is a compromise between the demands for maximum dispersion and the mounting logistic difficulties of organising and operating communications, vehicles, supplies and manpower as the number of sites increase. Operation from areas such as railways, sidings, roads, docks, rivers and canals would provide valuable and feasible ready- made commtmication and logistic facilities in more built-up areas. The Harrier is designed to be self-supporting, with a given probability of successfully accomplishing its mission, over a 24hr period. This allows the aircraft to be flown in, either vertically or STOL, to an unsupported sub-site, where opera tions could be conducted in direct touch with the local army commander. The great attribute of the Harrier is (as pre viously noted) flexibility of use, and the methods of operation described are susceptible of variations ad infinitum to take account (and advantage) of local conditions. The up-rated Pegasus Recently the Ministry of Technology announced that jt was financing an up-rated version of the Pegasus. This version will be known as the Pegasus 11 and will have a static thrust rating of about 21,5001b. The cost of the development pro gramme is believed to be about £3 million. No major changes to the basic engine are involved, the increased thrust being obtained primarily by raising the turbine temperature. This programme is of the greatest significance for the . Harrier, because it will confer a quite phenomenal performance increase out of proportion when compared with similar up- rating when applied to a conventional aircraft. For example the radius of action with a given payload would be doubled, or conversely the payload for a given radius could be in creased by some 80 per cent. Again, the same payload/range may be obtained with several hundred feet less ground roll, thus easing the site selection and maintenance problem. While the performance of the existing Harrier as a weapon system has grown out of recognition from that of its predecessors, the cry for greater performance is still relentless and the peculiar problems of V/STOL operation make the provision of truly adequate payloads always a matter of great difficulty. Another aspect of this engine improvement is that it will allow Harriers to be defensively dispersed into VTOL-only unsupported, sites at a substantially greater distance from the ground battle, at the same time carrying a sufficient warload and fuel so that a strike operation can be mounted without having to fly back to the main base for arming. The signifi cance lies in the increased flexibility which this offers, both by way of site selection and the decreasing risk of being overrun or destroyed by an air strike. It can therefore be seen that while the RAF has laid the groundwork for the efficient operation, of this aircraft, it is hardly possible for anyone yet to realise the full versatility of the Harrier: a versatility certainly as great as that conferred by the advent of the helicopter in the 1940s. M.w.
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