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К Estel
Дата 07.03.2020 17:34:45 Найти в дереве
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Ладно. Понял, что говорю с чистым авиатором, ну или авиалюбителем, которому

самолет - Бог, а все остальное - ерунда.

Ок, про ерунду. Короткие варианты ответов: разница между 7 и 12 градусов - это разница в ракетном вооружении кораблей: у "инвинсиблов" справа от трамплина стоял ЗРК "Си Дарт" и трамплин выше 7 градусов ограничивал его сектор обстрела. Существенная деталь конструкции палубных машин - включая СВВП - это не палец зацепления за трек катапульты носовой стойки (cat toe, официально Catapult Towing Bar), впервые примененный вместо веревок-бриделей осенью 1962 на, как это ни странно, самолете ДРЛО, "Хокае" - у СВВП ничего похожего нет. И не тормозной крюк/гак, он есть не только у палубных машин, но у СВВП его тоже нет. А трамплинные взлёты начинались именно с СВВП. Это - собственно шасси самолета и динамические перегрузки, которые они испытывают при взлете с трамплинов - и не только уже СВВП - двигаясь по дуге, ведь в этом случае несущий элемент нагрузки при нарастании угла атаки - именно шасси. Так стоит ли удивляться тому, что "кузнецовские" Су-25УТГ ломали стойки на посадке, если они так передавлены на взлете с трамплинов. А ведь в отличие от СВВП там еще и ударные горизонтальные нагрузки на основные стойки в момент сброса внешних тормозных решеток, которые зачем-то называют "задержниками": это все убивает шасси самолета и элементы набора фюзеляжа, которые делят с ними нагрузку.
Вот поэтому когда говорят, что STOVL и STOBAR, снимая нагрузку и требования с оборудования полётной палубы (не надо катапульт), передают её на самолеты, тут надо отчетливо понимать, что это не только про моторесурс двигателя/ей, вынужденных проводить на форсаже куда больше времени, это и динамические перегрузки такого характерного взлета шасси и всего набора планера, а главное - что самолет нежнее корабля и убивается он быстрее, и эти две бескатапультные схемы уже хотя бы потому дороже по факту, что самолеты быстрее расходуют не столько вмененный, сколько фактический ресурс. И если мерять всё в конце концов баблом, то отказ от формально более дорогих катапульт всегда по факту дороже их;-)

Вот Вам обещанный Хоббс с более развернутым ответом про историю трамплина в Британии, текст 2008 года:

The most significant change to the original ‘through-deck’ design, however, was the ‘ski-jump’. Like the steam catapult, angled deck and mirror landing aid before it, the ‘ski-jump’ was the ‘brainchild’ of a serving naval officer, in this case Lieutenant Commander D R Taylor RN who had been carrying out a period of aeronautical engineering study at Southampton University for the award of an M Phil. The original Invincible design had envisaged launching fighters from a rolling, short take-off up to 450ft long and the runway was angled one degree to port of the ship’s centreline so that aircraft would clear the protective ‘zareba’ around the Sea Dart launcher. By the forward edge of the flight deck a Sea Harrier would, typically, have accelerated to about 90 knots and with a wind over the deck (WOD) of 20 knots this gave an end speed of 110 knots relative to the free stream air passing over the ship. This was still below the wing’s stalling speed and so when he reached the bow the pilot would select the nozzles down to about 50 degrees relative to the fuselage and raise the nose slightly to give optimal wing incidence. Most of the aircraft weight would thus be borne by engine thrust but a proportion of that thrust was still directed aft and would continue to accelerate the aircraft. Once the wing’s stalling speed was exceeded the pilot rotated the nozzles fully aft and the aircraft was flown like a normal fighter. This technique was practised in Hermes from 1977 onwards using Harrier development aircraft and prototype Sea Harriers flown by test pilots. There was insufficient engine thrust to allow the aircraft to take off vertically with full fuel and weapons but a rolling short take-off allowed the aircraft to launch from a flat deck 30 per cent heavier than the maximum weight at which vertical take-off would have been possible. The P 1127/ Kestrel/ Harrier/ Sea Harrier series of aircraft were particularly well suited to this form of short take-off from a carrier deck since, being designed to hover before landing, they were fitted with a system of flying controls that worked when the wing was not giving lift and there were minimal forces acting on the tailplane and rudder. When the aircraft were in wing-borne flight they used conventional elevators, ailerons and rudder. When the engine exhaust nozzles were rotated below 10 degrees these surfaces continued to move but, additionally a series of ‘puffer jets’, fed by pipes which took high-pressure air bled from the engine were activated. These gave the pilot control authority using his conventional controls. Large control deflections took more bleed air and reduced the amount of hover thrust available causing the aircraft to descend if thrust was only marginally greater than weight. Sea Harriers were fitted with a small tank of demineralised water which could be injected into the engine to give a few seconds of optimum performance during a hover landing onto a carrier so that the aircraft could land on at a reasonable weight but, even then, fuel had to be jettisoned down to a few minutes’ supply in hot conditions, leaving only a small safety margin if the landing had to be aborted for some reason. A flat deck launch, however, left the aircraft low and slow close to the surface of the sea for up to 15 seconds after launch and at night or in bad weather this was clearly not ideal. Any sort of malfunction would leave the pilot very little time to eject. Another drawback was that Sea Harriers would not always be able to achieve their full load-carrying potential from the small deck run available in Invincible and her sisters. In his first paper Taylor examined several ways of launching V/ STOL aircraft more efficiently. These included the use of catapults and ballistas but the most elegant proposal was for a curved ramp or ‘ski-jump’ at the forward end of the flight deck which allowed the aircraft to leave the deck after nozzle rotation at the apex of the curve at a speed which could be significantly less than that needed for a flat-deck take-off. This effect could be translated into a much shorter deck run or a higher launch weight. A 20-degree ski-jump offered a launch speed reduction of 30 knots at a given aircraft weight compared with a flat deck. At the highest aircraft weights associated with strike missions this represented a 30 per cent reduction in launch end-speed which, because the take-off deck run depends on speed squared, reduces the required deck run by about 50 per cent. At the lower short take-off weights associated with fighter missions the decreased end-speed requirement represented a 40 per cent reduction in velocity and required a deck run of only about one third of that needed for a flat deck launch. Alternatively, from a longer deck run end-speed remained comparable with that achieved with a flat deck launch; only about 4 knots being lost ‘climbing the hill’. The aircraft was, thus, effectively launched with 30 knots excess end-speed and could carry 30 knots x 66lb per knot or roughly 2000lbs more payload than it could from a flat deck. Of interest, the US Marine Corps elected to retain flat decks on its amphibious carriers to allow more space for helicopter operations. Their AV-8 Harriers do, however have the advantage of a deck run nearly twice as long as that in Invincible but still have to accept the low, slow climb away from the deck. A ‘ski-jump’ was erected at RAE Bedford made from Fairey girder bridge components and trials were carried with development Harriers and Sea Harriers. Theoretically launch performance increased with ‘ski-jump’ angle but in practical terms, there was an optimum end-speed corresponding with maximum launch weight. For a desired maximum launch weight there was a minimum angle, the size of which was derived from the radius which would avoid undercarriage stress becoming a limiting factor at that weight. This effectively sized the ‘ski-jump’ since excess load factor was proportional to end-speed squared divided by the radius of the curve. In practice, practical curve radii for the Sea Harrier was found to lie in the range 600 to 800ft. The application of Euclid’s law then determined how long and how high the actual ‘ski-jump’ structure would be for a given exit angle. The size of the structure was found to grow markedly above 12 degrees and this was a disincentive to considering bigger angles. The advantages of the ‘ski-jump’ were immediately apparent and work was put in hand by the ship department to evaluate its installation on Invincible, despite the ‘frozen’ design. The result was positive but cautious. The merits of installation were agreed to justify the extra cost of drawings and modification during build. From our point of view in the Ships and Bases Section of DGA( N) the advantages of the 12-degree structure were obvious but the ability to operate Sea Harriers had only been listed as number 6 in a list of six requirements for the design in NSR 7097 and DG Ships was concerned that a ‘ski-jump’would significantly limit the adjacent Sea Dart mounting’s arcs of fire. It was eventually agreed that a small 7-degree ‘ski-jump’ would be fitted, a compromise between improved Sea Harrier performance and surface-to-air guided weapon capability. The design section at Bath responsible for Hermes, with whom I also worked, were not constrained by a Sea Dart installation and saw the improved operation of aircraft as their priority. They went for a larger 12-degree structure which was installed during the ship’s 1980 conversion in Portsmouth. This was to prove far more effective and was copied on the third ship of the Invincible class, Ark Royal. The first two ships were subsequently modified with 12-degree ‘ski-jumps’ during refits. It was thought at the time that research into improved ‘ski-jumps’ would continue and to assist with this a ‘ski-jump’ installed on the dummy flight deck at RNAS Yeovilton was designed to be infinitely variable at considerable cost. In the event the Hermes structure was found to be ideal and even the ‘ski-jump’ fitted in the Queen Elizabeth class thirty years later is similar.