Avro 621 Tutor, Avro 646 Sea Tutor и Avro 626 Prefect
В начале 1930-х годов выявилась необходимость в замене основного самолета первоначального обучения британских ВВС Avro 504N. Его логичным преемником стал Avro 621 Tutor, спроектированный в 1929 году Роем Чедвиком. Каркас фюзеляжа равнокрылого биплана сварен
из стальных труб и обтянут полотном. Самолет - двухместный, члены экипажа размещены тандемом в открытых кабинах. Прототип с гражданской регистрацией был оснащен звездообразным двигателем Armstrong Siddeley Mongoose IIIA. На сравнительные испытания самолет поступил в декабре 1929 года.
В 1930 году по результатам испытаний Avro 621 был выбран британскими ВВС, заказавшими установочную партию из 21 машины по спецификации 3/30 с открыто установленным 5-цилиндровым мотором Mongoose (как на прототипе), но почти все остальные серийные самолеты получили 7-цилиндровые двигатели Armstrong Siddeley Lynx IVC мощностью 240 л.с, закрытые узкими кольцами Тауненда. Некоторое количество самолетов построили и для гражданских заказчиков, а также на экспорт, в том числе для Ирландии, Канады и Китая.
Британские ВВС получили 394 из 795 построенных самолетов, серийный выпуск которых продолжался до мая 1936 года. Большинство самолетов строилось по спецификации 18/31, хотя в 1934-1936 годах некоторое количество двухпоплавковых гидропланов Avro 646 Sea Tutor собрали по спецификации 26/34, они прослужили до апреля 1938 года. Поставки серийных самолетов Tutor начались в 1933 году, и за короткий срок они стали основными учебными самолетами британских ВВС. Множество самолетов поступило в университетские эскадрильи и подразделения британских Вспомогательных ВВС. В конце 1930-х годов, с перевооружением частей первой линии британской авиации на самолеты-монопланы, потребовался также учебный самолет-моноплан. На смену Tutor пришли учебные монопланы Miles Magister. 57 самолетов Tutor собрали по лицензии в Южной Африке.
В 1930 году "Avro" изменила конструкцию планера машины, в большей степени приспособив ее под требования ВВС третьих стран. Новый вариант получил обозначение Avro 626 Prefect. Помимо первоначальной подготовки пилотов на этом самолете стало возможным обучать курсантов воздушной стрельбе, бомбометанию, навигации, ночным полетам, аэрофотографированию, радиосвязи и пр. Штатно экипаж самолета состоял из двух человек, но в задней кабине предусматривалась возможность размещения воздушного стрелка.
На Avro 626 поступило значительное количество заказов, и до прекращения серийного производства в 1939 году произвели 178 самолетов. Для британских ВВС самолеты поставлялись с января по июль 1935 года, а для Новой Зеландии - в июле. Самолеты Prefect заменили Avro 621 Tutor в навигационном училище, дислоцированном в Эндовере. Avro 626 выпускались либо с двигателями Armstrong Siddeley Lynx IVC мощностью 240 л. с, либо с моторами Armstrong Siddeley Cheetah V мощностью 260 л. с. Не менее трех самолетов с гражданской регистрацией пережили Вторую мировую войну.
Обозначение Avro 637 получили 8 самолетов, доработанных в патрульные по заказу Китая.
Avro 621 Tutor Mk II: один экземпляр с доработанными стойками бипланной коробки
PWS 18: обозначение 40 самолетов Tutor, построенных по лицензии польской фирмой PWS
Avro 621 Tutor
Тип: двухместный самолет первоначального обучения
Силовая установка: один звездообразный двигатель Armstrong Siddeley Lynx IVC мощностью 240 л. с. (179 кВт)
Характеристики: максимальная скорость на оптимальной высоте 196 км/ч; крейсерская скорость на высоте 305 м - 169 км/ч; скороподъемность на уровне моря 305 м/мин; практический потолок 4940 м; дальность полета 400 км
Масса: пустого 839 кг; максимальная взлетная 1115 кг
Размеры: размах крыла 10,36 м; длина 8,08 м; высота 2,92 м; площадь крыла 27,96 м2
Flight, April 1930
THE "AVRO TRAINER"
A New Machine with Many Interesting Features
SO long has the 504 been in existence as a type and so well has it done its work, that the thought that some day it must of necessity be replaced seldom occurs to one. Without thinking much about it, one has come to take the good old 504 for granted. It was first produced in 1913, underwent development during 1914 and onwards and during the war was used for a variety of purposes (for example, as a bomber of Zeppelin sheds!) finally to become standardised as the world's finest training machine. And although modern ideas of what constitutes a good bomber are a little different from what they were in 1914 and '15, the famous 504 is still the standard training machine of many air forces. It has been slightly modernised, it is true, but in all essentials it is the same machine as the prototype of 1913. A period of usefulness of 17 years is sufficient for any aircraft type, although there is no reason to doubt that the 504 will still be going strong when it attains, as a type, its twenty-first birthday.
In the meantime, modern demand will not be denied, and progress cannot be stopped by sentimental affection. The time has come when the old faithful machine must have a successor; and after 17 years of experience with the old machine, what could be more natural than that the Avro firm should produce that successor? In designing a new training machine the Avro engineers, headed by Mr. Roy Chadwick (who was with A. V. Roe in the early days, and who has remained with the firm ever since), would be expected to retain those features which made the 504 such a success. It is not altogether easy to assign relative values to the different characteristics of the 504, but to us it has always seemed that much of the secret of the phenomenal popularity of the 504 is to be found in the large-span, high aspect ratio, heavily-staggered wings and long fuselage, giving a good lever arm to the tail surfaces and getting them fairly well clear of the downwash. And if one examines the new "Avro Trainer" (as the successor to the 504 is called) it will be found that those features are retained. In fact, although the Trainer has scarcely a single dimension in common with the 504, the "family likeness" is quite striking. The two most marked changes are: the different shape of the rudder, and the different undercarriage.
It is on the practical rather than on the aerodynamic side that one would look for improvements in the Trainer, and one does not look in vain. Rarely have we seen a machine in which the user's point of view has so evidently been studied. The machine is primarily intended for training purposes, and the requirements of training have quite obviously been kept prominently in view throughout the design. Large, comfortable cockpits, good view, effective windscreens, an undercarriage of wide track, these are some of the features of the Trainer.
Layout of Cockpits
Very great care has been taken in planning the layout of the cockpits. Both are not only identical in size, but the controls, instrument arrangement, etc., are the same in both, so that a pupil changing from one cockpit to another will at once feel at home, and will not be in danger of having to fumble about, in an emergency, for any control or switch. Owing to the heavy stagger of the wings, both cockpits are well clear, and both occupants have a good chance of using their parachutes.
The cockpit floors are of Duralumin, and the controls, with the exception of the actual joy sticks and foot bars, are covered in by a tunnel-shaped raising of the floor, along the centre line. Behind the aft cockpit there is a slight drop from cockpit floor to the bottom fairing, so that any dirt which has collected can be swept along and dropped through a small trapdoor.
The inside of the fuselage structure is lined with leatherette and only a few controls, etc., project through this into the cockpits, so that the latter are entirely without that conglomeration of struts and other structure members which has been the rule in cockpits of aeroplanes hitherto. At the same time the detachable fuselage fairings enable the structure to be examined quite readily whenever it is desired to do so.
The controls are of normal type, but a very neat adjustment is provided for the foot bars to suit pilots of different heights. This adjustment, made by means of a small wheel operating a worm, can be made during flight quite easily. Of controls which are not quite standard yet, reference may be made to the locking arrangement of the Handley Page slots. A sliding bolt arrangement on the starboard side enables the instructor to lock the slots and to unlock them again during flight.
An exhaust heated cockpit is a boon for work in winter, or for flying at considerable altitudes, and in the Avro Trainer this takes the form of a duct along the side of the control tunnel on the floor, the hot air entering through openings near the feet of the occupants.
Altogether the Avro Trainer is an exceptionally interesting machine, and carefully thought out for the work it has to perform. Whether it is the successor to the 504 time alone will show. It starts with very good prospects of taking the place of its famous ancestor.
Flight, June 1931
SPECIAL TYPES AT THE DISPLAY
A VERY versatile machine is the Avro 626 Advanced Training type. It has been so designed that its equipment can be changed rapidly, if desired, so that the same machine can be used, in addition to ordinary flying training, for training in gunnery, wireless, photography, flying by instruments, etc. It is, however, rather intended that users should have one machine for each purpose, as this permits of simultaneous training in the various subjects. At the same time, the use of a standard type of machine has many advantages, as spares for engine and aircraft are the same for all models.
The Avro 626 is largely of metal construction, and has a welded steel tube fuselage. The engine fitted as standard is an Armstrong-Siddeley "Lynx IV" of 215 h.p., but, if desired, the machine can be supplied fitted with other engines of approximately the same power. The wings are staggered so as to give a good view.
The main data are :- Wing span, 34 ft. (10.4 m.); total flying weight, 2,750 lb. (1,250 kg.); endurance at full throttle, 1 hr. at ground level and 2 1/4 hr. at 10,000 ft.; landing speed, 45 m.p.h. (72 km./h.); maximum speed, 110 m.p.h. (177 km./h.).
Flight, November 1932
A. V. Roe & Co., Ltd.
Newton Heath, Manchester
THE name A. V. Roe goes back to the earliest days of aviation in Great Britain, and Sir Alliott V. Roe was a pioneer of British design and construction. It is worth recalling that at the beginning of flying, when almost all the rest of the world's experimenters were developing the "pusher" type of aircraft, Mr. A. V. Roe (as he then was) foresaw the advantages of the tractor type of aeroplane, the type which was destined later to become almost universal. Sir Alliott V. Roe is no longer associated with the firm which bears his name, the company having now been included in the group of firms presided over by Sir John D. Siddeley.
Almost from its earliest days the Avro firm has specialised in training types of aircraft. Considerable numbers of other types have been produced from time to time, but it is the training type which has brought the Avro firm world renown, and there was thus poetic justice as well as good common sense in the decision made by the British Air Ministry recently, when the question of replacing the good old Avro 504 arose, to award the order to A. V. Roe & Co., Ltd., and to standardise the Avro 621 as the training machine of the British Royal Air Force. The 621 is known also as the "Tutor".
The Avro 621
The 621 is an equal-span, single-bay biplane of all-metal construction, but with fabric covering. The fuselage is a welded steel tube structure, while the wings have strip-steel spars and pressed light metal ribs. Bristol-Frise ailerons are fitted. The power plant of the 621 is an Armstrong-Siddeley Lynx developing 215 b.h.p. at 1,900 r.p.m. By giving the wings a pronounced stagger, not only do both occupants obtain a good view, but both are able to use their parachutes in emergency.
Both cockpits are identical in size and arrangement and, of course, full dual controls are provided, so that the machine can be flown equally well from either cockpit.
A wide-track undercarriage is used, and the shock-absorbing qualities have been so proportioned that, although the machine can be landed heavily without damage to the structure, the springing is hard enough to make the pupil realise that he has made a bad landing.
In addition to its uses as a landplane training machine, the Avro 621 can be fitted with floats and used for seaplane training. The floats are fitted with water rudders and the airscrew is of metal, while hand-turning gear is provided for starting the engine.
The main dimensions, weights and performance figures are given in the following data :-
Length o.a. 26 ft. 4 1/2 in. (8 m.)
Wing span 34 ft. 0 in. (10,36 m.)
Wing area 300 sq. ft. (27,9 m!.)
Tare weight 1,800 lb. (818 kg.)
Normal load 649 lb. (295 kg.)
Normal gross weight 2,449 lb. (1 113 kg.)
Max. permissible gross weight (aerobatic) 2,500 lb. (1 135 kg.)
Maximum speed 115 m.p.h. (185km./h.)
Cruising speed 95 m.p.h. (153 m.p.h.)
Initial rate of climb 880 ft./min. (4,5 m./sec.)
Service ceiling 15,000 ft. (4 570 m.)
The Avro 626
Similar in general appearance to the "Tutor" 621, the Avro 626 has been designed for complete instruction of military flying personnel, from flying instruction (ab initio to advanced aerobatics) through night flying to instruction in gunnery, bombing, photography, radio, etc, How wide is its scope may be gathered from the fact that the Avro 626 can be equipped for no less than 11 alternative training duties, and in all 11 cases the machine carries instructor as well as pupil. All the armament and equipment used for specialised instruction is of standard service pattern as used in military aircraft. It will doubtless be of interest to enumerate in a little more detail the training purposes for which this versatile aircraft can be used. (Obviously the equipment for any one or, at most two duties only is carried at the same time.) Dual-control flying instruction; blind flying and night flying; offensive gunnery, using Vickers gun; offensive gunnery using camera gun; defensive gunnery using Vickers or Lewis gun; defensive gunnery using camera gun; bombing for observer (prone position); bombing for pilot; wireless telegraphy and telephony; photography and navigation.
Although it is not intended that the one individual aircraft should be used for all these duties, but rather assumed that the user will have a series of machines, each equipped for a particular duty, it is nevertheless possible to change one complete set of equipment for another in a very short time - something like 2-3 hours.
To facilitate inspection and interchange of equipment, the sides of the fuselage, from the engine to a point aft of the gun turret, are covered with a series of quickly removable panels, so that in a moment the whole internal structure, equipment, controls, etc., can be exposed and made readily accessible.
Structurally the 626 is similar to the 621, and the engine is also the same, i.e., the Armstrong-Siddeley Lynx. The dimensions of the 626 are almost identical with those of the 621.
The tare and gross weights of the 626 vary, of course, in accordance with the particular duties for which the machine happens to be equipped. The tare weight varies from about 1,930 lb. (877 kg.) to about 2,000 lb. (910 kg.). The gross weight also varies according to the particular duties, but in no instance does it reach the permissible figure of 2,750 lb. (1 227 kg.) for aerobatics category or 3,000 lb. (1 363 kg.) for normal category.
The performance figures for the Avro 626 are substantially the same as for the "Tutor" 621.
Flight, November 1933
An Economical Military Machine with Low Power but High Performance
INTENDED primarily for duties like frontier patrol and police work, the Avro 637, although a fully-armed military aeroplane, is an extremely economical one. For countries where high cost and running expenses cannot be entertained, but which require aeroplanes with a wide variation of equipment, the 637 is excellent. In many countries suppression of bandits, frontier warfare, and smuggling is the regular job of their Air Force, and for this the Avro 637 can be used more economically than high-powered, more expensive machines, and with equal efficiency.
Usually, economy means that the best equipment cannot be obtained; the production of the Avro 637 has, however, changed that aspect, and makes available aircraft suitable in every respect for the work they have to do.
The 637 is called an "Economy, Bombing and Fighting Aeroplane," and is the third of the series of all-metal machines built by A. V. Roe, Ltd., at Manchester during the last few years. The first of the type was the Avro 621 or "Tutor," a machine suitable for all forms of flying training. Next came the 626, a somewhat enlarged and three-seater version of the former, arranged for every form of military training. The 637 possesses all advantages of the form of construction perfected in these types, and has incorporated in it many features facilitating maintenance and repair. It is a two-seater biplane powered with the Armstrong Siddeley "Cheetah" engine developing 260 h.p., at 2,000 r.p.m., at 2,500 ft. Its construction follows the same general lines as the Avro "Tutor," which we have recently described. The fuselage is a single unit of welded steel tubes. The undercarriage, of the divided axle type, is mounted in two separate units, the shock absorbing member utilising steel springs in conjunction with oleo gear to absorb the rebound.
In common with the previous machines, large removable panels on the sides of the fuselage facilitate inspection and maintenance of the controls, while grease gun lubrication is used wherever possible. One Vickers gun is fitted centrally in front of the pilot, who uses the front cockpit. This gun fires through a channel in the top decking and top engine cowling. The rear cockpit has a Lewis gun on an Avro mounting. Fuel tankage of liberal capacity is provided, thus giving the machine a long range. The normal bomb load is eight 20-lb. bombs.
The detail work of the equipment follows the usual Avro lines in its completeness. The pilot's seat is readily adjustable for height, while the observer is provided with a folding seat, which can be put back out of the way when he is using the gun or acting as photographer. Both seats, of course, accommodate a standard parachute. The controls are quite normal, with an adjustable rudder bar and the Avro screw-type tail plane incidence adjustment. The wheel brakes are operated by a hand lever differentially applied by the use of the rudder bar. The main planes are of all-metal construction, with steel spars and aluminium ribs.