Praga. Самолеты

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   Более успешной деятельностью "Praga" стало производство гражданских самолетов. Особенно удачным был E.114 Air Baby, строившийся ограниченной серией даже после окончания Второй мировой войны. Это был высокоплан с размещение двух членов ДальшеMore>>> экипажа бок о бок, изначально оснащенный двухцилиндровым мотором Praga B мощностью 40 л.с., также строился вариант E.115 с мотором Praga D мощностью 65 л. с.
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ТАКТИКО-ТЕХНИЧЕСКИЕ ХАРАКТЕРИСТИКИ

   Praga E.114 Air Baby

   Тип: двухместный моноплан
   Силовая установка: один 2-цилиндровый мотор Praga B мощностью 40 л. с. (30 кВт)
   Летные характеристики: максимальная скорость 150 км/ч; практический потолок 3300 м; дальность 510 км
   Масса: пустого 265 кг; максимальная взлетная 465 кг
   Размеры: размах крыла 10,90 м; длина 6,58 м; высота 1,65 м; площадь крыла 15,20 мг

Самолеты Hillson

После демонстрации в Великобритании в августе 1935 года чехословацкого легкого самолета Praga E.114 деревообрабатывающая компания из Манчестера "F. Hills & Sons" приобрела лицензию на производство данной машины. Самолет представлял собой высокоплан со свободнонесущим крылом и двухместной кабиной. Чтобы попасть в кабину, необходимо было отклонить вверх часть передней кромки центроплана крыла. Максимальная взлетная масса самолета составляла 490 кг. Силовая установка включала один двухцилиндровый мотор Praga B мощностью 36 л. с. В 1936-1937 годах было построено около 30 самолетов Praga, часть из них получила 2-цилиндровые моторы Aeronca J.A.P. J-99 мощностью 40 л. с. На Praga E.114 летом 1936 года Х.Л. Брук установил новый рекорд перелета на маршруте из Лимпни в Кейптаун, затратив на перелет 16 суток.
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ТАКТИКО-ТЕХНИЧЕСКИЕ ХАРАКТЕРИСТИКИ

   Hillson Praga

   Тип: двухместный легкий самолет
   Силовая установка: один 2-цилиндровый ПД Praga B, 36 л. с. (27 кВт)
   Летные характеристики: макс. скорость 150 км/ч; крейсерская скорость 128 км/ч; дальность 450 км
   Масса: пустого 265 кг; максимальная взлетная масса 490 кг
   Размеры: размах крыла 10,97 м; длина 6,75 м; высота 1,68 м; площадь крыла 14,12 м2

Flight, January 1936

COMPACT COMFORT
Flying the Hillson Praga: A Small Machine with a Good Performance

   EXACTLY what a true light aeroplane should be depends entirely on the use to which it is put, but there is very little doubt that the modern owner expects cabin comfort for serious work - unless, of course, he can obtain, alternatively, a well-screened pusher.
   The Praga E.114 Air Baby - which is to be manufactured in this country by F. Hills and Sons, of Stockton-on-Tees, at their Trafford Park (Manchester) works and is to be known as the Hillson Praga - provides one example of what a really light aeroplane might be. At the time of its first visit to this country it was described and illustrated (Flight, August 22, 1935), and last week I had an opportunity of discovering something about its qualities, both from a pilot's and a passenger's point of view.
   First, however, it would be useful to run over some of the points in which the prospective private owner would be interested if he saw the machine, which is, of course, a cantilever high-wing monoplane, largely of wood and plywood construction, with side-by-side cabin seating and fitted with a 40 h.p. flat twin Praga B. engine. A Pobjoy Cataract engine can be fitted if required.
   In the first place, remembering its small size, there is ample room in the cabin. Pilot and passenger sit, of course, elbow to elbow, but they are not cramped, and is plenty of room for a tall passenger when the - comprising a part of the leading edge and screen - is clamped down. Behind each there is a space for a back type parachute, or, alternatively, a cushion, and the quickly detachable back rests are fitted with large canvas luggage containers. The controls and engine installation are accessible, and, in the Czech model at least, a fire extinguisher, permanently trained on the carburetter, is a standard fitting.
   The wings do not fold, but the span is little over 36ft. and the entire wing can, it is claimed, be removed by two people in five minutes. It is actually attached by four bolts.
   Low-pressure tyres are fitted, and though the undercarriage movement appears to be very small, the machine taxies comfortably enough over rough ground.
   Various features on the original model will be modified in the production machines. The central throttle, for instance, may be replaced by two separate controls, the control column shape may be altered for improved comfort, and some adjustable loading device may be incorporated. There should be no difficulty in making a watertight screen joint - at present the interior is distinctly damp while flying in heavy rain.
   The general conditions during the initial flight were far from ideal. Heavy rain, reduced visibility, and a cloud ceiling of less than 800 ft. do not encourage one to hurl a strange aeroplane about a sky out of which another machine may or may not suddenly appear, or to try the effects of various control movements at the stall. Furthermore, the Praga's one bad point from the pilot's angle - a nonexistent rearward view - was unduly noticeable in such circumstances. Nevertheless, the good forward view partially compensates for this defect, and it is possible, by judicious use of the rudder, to obtain a rearward glimpse through the side windows. When cruising, the nose is well below the horizon, and with a narrow cowling it is possible to see downwards and forwards from either seat.
   Naturally, with such a low-powered engine, the take-off is prolonged, but the actual distance travelled before "unsticking" is by no means as great as one might imagine. The maker's figure of 260 ft. is probably not overoptimistic, and the climb is better than expectation. The controls are particularly light, nicely synchronised and reasonably effective. In the prevailing bad weather there was a tendency, as in all comparatively slow machines, to wallow - in other words, the reply to corrective control movements was not quite immediate. Once again, however, it must be remembered that “aerobatic” control characteristics are neither essential nor even advisable on a machine of this kind. Most of us have spent far too much time in training aeroplanes which do what they are asked almost before the controls have been moved. Nevertheless, when the Praga was being demonstrated here in August the Chechoslovakian pilot showed that it had a very pretty aerobatic repertoire.
   Quite a lot of rudder is necessary to start turns, though these can be made, if necessary, on the ailerons alone - but the machine is perfectly stable and requires no particular rudder or opposite aileron once the turn has started. This machine was tail-heavy at cruising revolutions, so that it flew itself round nicely in turns of about 45 degrees.
   The normal steep sideslip is not possible, the nose slewing away after a few seconds, but an equally useful and very pleasant “crab” sideslip can be held indefinitely with almost full rudder and a little aileron. The machine is, in fact, quite stable and happy in this manoeuvre at 60 m.p.h. or so.
   Naturally, such a clean aeroplane has a flat glide, and with no wind would probably float after a too fast approach. But, with a stall that is so innocuous, there would be no excuse for gliding too fast. The actual landing is the simplest thing in the world, since the machine stalls in a leisurely manner, giving ample time for last-minute corrections, and the aileron control remains, weak but adequate, up to the moment of contact.
   “Indicator” makes some further comments on this interesting little machine in the Private Flying section.
H. A. T.

THE HILLSON PRAGA TWO-SEATER
   With Praga B. With Pobjoy Cataract.
   Span 36 ft. 36 ft.
   Length 21.5 ft. 21.5 ft.
   Height 5.5 ft. 5.5 ft.
   Weight empty 584 lb. 617 lb.
   Disposable load 445 lb. 507 lb.
   Wing loading 6.27 lb./sq. ft. 6.85 lb./sq. ft.
   Power loading 25.7 lb./sq. ft. 14.8 lb./sq. ft.
   Top speed 93.3 m.p.h. 115 m.p.h.
   Cruising speed 79.6 m.p.h. 98.3 m.p.h.
   Landing speed 37.3 m.p.h. 38.6 m.p.h.
   Climb (in 3 min.) 1,310 ft. 2,460 ft.
   Duration 3.5 hr. -

Flight, April 1936

MODERN LIGHT AIRCRAFT REVIEWED

HILLSON PRAGA

   WITHIN the next month or so we should see the first of the Manchester-produced versions of the Praga Baby, a machine in the ultra-light class which has interested amateur pilots since it was first shown in this country by the Czechoslovakian manufacturers last summer. A high-wing cantilever two-seater cabin monoplane, the Praga is of extremely clean design and cruises a t something like 80 m.p.h. on a flat-twin engine of about 40 h.p.
   It is easy to fly and has a completely harmless stall - so much so that it really appears to be impossible to make it do anything out of the ordinary by misuse of the controls. Incorrect rigging caused the original demonstrator to be somewhat heavy on the ailerons, but these were effective enough to make the fact only incidentally noticeable. At his first attempt the pilot would probably find himself overshooting slightly on his approach, as the glide path is extremely flat, and this is likely to be the only trouble that he would experience. Full sideslips are not possible, but a most effective crab sideslip can be held indefinitely, and the machine, in any case, can be sat over or near the aerodrome boundary at the stall and sinking rapidly until such a moment as more speed is deemed to be desirable for the final hold-off and landing.
   The side-by-side accommodation is ample for persons of normal stature, and there is a luggage space at the rear of the cabin. The forward view over the engine is excellent, though there is a lack of rearward view which might, at first, worry the pilot who has been brought up on open machines. Simply and sturdily built, the Praga should require very little maintenance.
   The wing, fuselage, fin and rudder are entirely of wood and have plywood covering: the engine mounting, undercarriage, tailplane and elevator are of welded steel tubing, the horizontal surfaces being fabric-covered.
   A Praga flat-twin air-cooled engine giving 36 h.p. at 2,400 r.p.m. is fitted as standard. This is of 113.5 cu. in. capacity and is claimed to be extremely economical in the matter of fuel consumption. The main petrol tank is in the wing behind the cabin, the feed being by gravity.
   The specification of the Hillson Praga is as follows: Weight empty, 584 lb., disposable load, 445 lb.; span, 36ft.; length, 21.5ft.; maximum speed, 93.3 m.p.h.; cruising speed, 79.6 m.p.h.; landing speed, 37.3 m.p.h.; climb in three minutes, 1,310 ft.; duration, 3.5 hr.; price ?385. Makers: F. Hills and Sons, Ltd., Trafford Park, Manchester.

Flight, March 16, 1939

THE 1939 PRAGA LIGHTWEIGHTS
Improvements for the Smallest of the Praga Range : A Pusher Twin : The New Flat-Four Engine

   DURING the past year various minor but important changes have been made to the Praga E.114, or Baby, which was originally demonstrated in this country in 1936 and for which the manufacturing licence was obtained by F. Hills and Sons, Manchester. This lightweight was intended to offer as much as possible with the least initial expenditure by the club or the private owner, and the designer’s aim has been to keep the layout as simple as possible. For those who require a rather higher performance and slightly greater comfort there is now the E.117, which, with one of the new flat-four Praga D. engines, cruises at 118 m.p.h. The increased performance has been largely obtained by a reduction of wing area, though the landing speed is still only 43 m.p.h., and by the application of such items as spats for the undercarriage. The cabin is slightly roomier and there is a door on each side.
   In the 114, it will be remembered, the pilot and passenger, who are seated side by side, enter through the roof, which is in one piece with the leading edge and is hinged backwards at a point about one foot aft this edge, the joint being at the top of the windscreen. In the newer machine the arrangement is very similar, but the whole of the windscreen hinges back with the roof. This not only makes access rather easier, but it also permits a larger screen area and permits the fitting to be made adequately rainproof. One or two slight changes have been made to the tail design, and the fin and rudder area has been slightly increased.
   Last week the company sent over a 114 with one of the flat-four engines for demonstration in this country. The additional power - 40/45 to 60/80 h.p. - improves the performance, of course, but the main advantage of the extra 20 h.p is in the take-off and initial climb. With two up the take-off requires a much shorter run and the rate of climb is equal to that of any normal light aeroplane. The landing speed is very slightly higher than before, but is still well below 40 m.p.h.
   From the pilot’s point of view probably the most important change has been in the ailerons. These are now of the Frise type, with back-set hinges and a leading edge balancing effect. With the original machine the aileron control, though effective right down to low speeds, was distinctly heavy at cruising speeds. The new ailerons are light throughout the speed range, though they are not, perhaps, quite as effective in the ordinary course of events. The most noticeable improvement which they offer is in the control at or near the stall. Little or no drag is apparent at 40 m.p.h., and control remains even when the stick is held right back and the machine is sinking in customary Praga manner at some unindicated speed below this figure.
   From the stalling-characteristic point of view, the Praga Baby must be one of the safest small aeroplanes ever to be made. Without a violent pull-up the nose does not even drop and the machine simply remains on a level keel, while some aileron and rudder control remain.
   Once one has become accustomed to the somewhat claustrophobic effect of the cabin - which, nevertheless, is quite roomy enough for two people of normal size - the only criticism which can justly be levelled at the machine is that its approach angle is flat in the extreme. Low price has been the primary aim of the makers, and the addition of any form of air brake or flap would increase this price. With its larger-sized rudder, however, the new 114 can be side-slipped quite effectively provided that the manoeuvre is not attempted at too steep a lateral angle, and the machine will hold this slip without change of attitude at a speed of less than 60 m.p.h. Remembering the stalling characteristics, another justifiable means of losing height would be to hold the stick fairly well back and to let the machine sink more or less steadily towards the aerodrome boundary.
   The new flat-four Praga D. is of a most interesting design. The Elektron crankcase has been aerodynamically shaped to fair into the forward part of the fuselage of the machine, while the cylinder heads and induction pipes have also been designed to reduce drag as far as possible. General cleanliness has been obtained by the installation inside the crankcase of the pressure oil-piping.
   A single cylinder-head casting is used for each pair of cylinders, while the rocker chambers are cast in one piece with the head There are two separate camshafts, one at the rear and one at the front of the engine, each operating two pairs of push-rods, the valves being axially disposed in the head. The four-throw crankshaft is a one-piece drop forging. The normal cruising power of the Praga D. engine is 60 h.p. with a maximum output ot 79 h.p.
   Very shortly we may see in this country one of the Praga E.210 twin-engined cabin machines. This interesting pusher design was originally shown at the Paris Exhibition two years ago. and in the meantime has been thoroughly tested and is now in production. The engines are Walter Minors of 85-95 h.p., which give the machine a maximum speed of 143 m.p.h. and a cruising speed of 130 m.p.h., with a useful load of 920 lb. As in the case of all Praga civil machines, it is a cantilever high-wing monoplane.
   The Praga 114 is being sold in this country through Mr. W. Hauck, of 15-17. King Street, London, S.W.1, for approximately £450.