В.Кондратьев Самолеты первой мировой войны

Двухстоечный биплан смешанной конструкции с толкающим винтом, ферменной хвостовой частью фюзеляжа, деревянной гондолой и полотняной обшивкой крыльев и оперения. Экипаж - два человека: пилот и стрелок-наблюдатель, сидящий в передней кабине. Первый боевой аэроплан, созданный одним из основоположников британской авиации знаменитым авиаконструктором сэром Джеффри Де Хэвиллендом, главным инженером лондонской авиастроительной фирмы "Эйркрафт Мэньюфэкчуринг Компани Лимитед" (Aircraft Manufacturing Company Ltd. - сокращенно - Airco).
   Перейдя из компании RAF в "Эйркрафт Мэньюфэкчуринг", Джефри де Хэвилленд перепроектировал созданный им ранее самолет F.E.2B, который в то время производился на заводах RAF. У новой машины, получившей обозначение D.H. 1, уменьшился размах крыльев, была увеличена площадь оперения и добавлен киль. Самолет разработан и построен во второй половине 1914 года. Первый полет опытного экземпляра машины под управлением самого Джеффри Де Хэвилленда состоялся в январе 1915-го. Прототип, оснащенный 120-сильным рядным шестицилиндровым двигателем жидкостного охлаждения "Бердмор", показал неплохие летные данные. Руководство фирмы предложило аэроплан военному ведомству в качестве фронтового разведчика и самолета для воздушного боя. в связи с чем в носовой части гондолы предусматривалась установка подвижного пулемета на шкворневой установке.
   Руководство RFC заказало 100 экземпляров машины, однако, поскольку весь выпуск "Бердморов" шел на самолеты FE.2 и RE.5, производимые "Королевским авиационным заводом" (RAF), изделие Де Хэвилленда пришлось оснастить гораздо менее мощным 80-сильным французским двигателем "Рено" (двухрядный восьмицилиндровый мотор воздушного охлаждения). Это вызвало резкое ухудшение летных данных, прежде всего - скорости и скороподъемности.
   Серийные машины выпускались на заводе фирмы "Сэвидж" в Кингс-Линне. От прототипа они отличались наличием вооружения, формой гондолы и размещением органов управления в обеих кабинах.
   Наращивание выпуска "бердморов" позволило с весны 1915-го начать устанавливать эти моторы на DH.1. Модификация получила индекс DH. 1 а.
   В RFC поступило в общем счете 73 экземпляра DH.1 и DH.1a. Большинство из них служило в дивизионах ПВО, а затем - в учебных подразделениях. Они были списаны и отправлены на слом в начале 1918 года.
   Шесть DH.1а включили в состав 14-го дивизиона RFC, воевавшего в Палестине. Отсутствие сильного воздушного противника на этом второстепенном ТВД позволяло использовать их до весны 1918-го в качестве разведчиков, а также эскортных истребителей для сопровождения невооруженных машин.
  
  
  
МОДИФИКАЦИИ
  
   DH.1 - двигатель "Рено", 80 л.с.
   DH.1А - двигатель "Бердмор", 120 л.с.
  
  
ЛЕТНО-ТЕХНИЧЕСКИЕ ХАРАКТЕРИСТИКИ
   DH.1 (в скобках DH.1а)
  
Размах, м 12,5
Длина, м 8,82
Площадь крыла, кв.м 37,99
Сухой вес, кг 615 (758)
Взлетный вес, кг 927 (1088)
Скорость макс, км/ч 125 (143)
Время набора высоты
   1000 м, мин., сек. 11,0 (6,30)
Потолок практический, м 4115

A.Jackson De Havilland Aircraft since 1909 (Putnam)

De Havilland D.H.1

   Geoffrey de Havilland's first design after joining the Aircraft Manufacturing Co. Ltd. as Chief Designer in June 1914, was a two seat reconnaissance biplane armed with a forward firing machine gun. Following contemporary practice, it was a twin boom, two bay, wire braced biplane of fabric covered wooden construction and the mainplanes were of the normal two spar type, wire braced internally. A pusher layout was chosen to give the observer/gunner the maximum possible arc of fire from the front cockpit, and the design included three unusual features; coil springs in the undercarriage to absorb landing shocks, an elementary form of oleo leg to damp out the rebound, and the provision of air brakes. These were in the form of rotatable auxiliary aerofoils protruding some three feet on each side of the nacelle just behind the front centre section struts. The diversion of all available supplies of its intended engine, the 120 h.p. watercooled Beardmore, to F.E.2 and R.E.5 production resulted in the 70 h.p. aircooled Renault being fitted instead.
   The prototype, designated Airco D.H.1, was completed and flown at Hendon in January 1915 and the designer showed his confidence in it by taking off without any preliminary straight hops and at once commencing to circle. He also piloted it during tests which not only showed it to be inherently stable and capable of being flown 'hands off' but also that the air brakes were ineffective. They were consequently removed. A small number of production D.H.1s were then built but these had the more normal type of rubber cord shock absorbers in the undercarriage, forward facing exhaust pipes and the front cockpit coaming lowered to the top longerons to improve the pilot's view and to permit free rotation of the single Lewis gun on its pillar mounting. Five of these aircraft reached Royal Flying Corps training units during 1915.
   Production on a larger scale was delayed until the 120 h.p. Beardmore was available in quantity but was finally undertaken by Savages Ltd. At King's Lynn in order to leave Airco free to develop newer types. With the Beardmore engine the machine carried the designation D.H.1A and was identified by the upright six cylinder engine, the large radiator behind the pilot's head and the gravity fuel tank mounted under the port upper wing root. The prototype D.H.1A, which bore the R.F.C. serial 4606, was converted from an Airco-built D.H.1. Although 73 D.H.1s and D.H.1As were delivered to the Royal Flying Corps, they saw little war service and in 1916 six were shipped to the Middle East Brigade for operational use by No. 14 Squadron. Home Defence squadrons received 24 and a further 43 went to training units such as No. 35 Reserve Squadron, Northolt and No. 199 Training Squadron. The type remained operational until early in 1917 after which it was relegated to second line duties until finally withdrawn from service at the end of 1918.

SPECIFICATION AND DATA
   Manufacturers:
   The Aircraft Manufacturing Co. Ltd., Hendon, London, N.W.9
   Savages Ltd., King's Lynn, Norfolk
   Power Plants:
   (D.H.1) One 70 h.p. Renault
   (D.H.1A) One 120 h.p. Beardmore

   Dimensions, Weights and Performances:
   D.H.1 D.H.1A
Span 41 ft. 0 in. 41 ft. 0 in.
Length 28 ft. 11 5/8 in. 28 ft. 11 1/4 in.
Height 11 ft. 4 in. 11 ft. 2 in.
Wing area 426 1/4 sq. ft. 426 1/4 sq. ft.
Tare weight 1,356 lb. 1,610 1b.
All-up weight 2,044 lb. 2,340 lb.
Maximum speed 80 m.p.h. 90 m.p.h.
Initial climb 350 ft./min. 600 ft./min.
Service ceiling - 13,500 ft.

   Production: Prototype and 100 production aircraft with R.F.C. serial ranges 4600-4649 and A1611-A1660.

P.Lewis The British Fighter since 1912 (Putnam)

Two months before the start of the War, the Royal Aircraft Factory parted with one of its most experienced and talented designers when Geoffrey de Havilland left in June, 1914, to work in the civilian industry by joining the design staff of the Aircraft Manufacturing Company at Hendon. Since being founded in 1912, Airco had been making aircraft which were not of its own design but its head, George Holt Thomas, was keen on setting up a design office so that the firm could establish itself as a company manufacturing its own designs.
   De Havilland’s first type for his new employers was to be a reconnaissance and fighting machine, perforce a biplane, and his success with the tractor B.E. series and the B.S.1 at Farnborough encouraged him to adhere to the same layout. The general form was evolving on the drawing board when it was realized by the War Office that there was still no practical means of firing a gun ahead through the propeller. Proposals for solving this problem had been submitted to the War Office by the Edwards brothers but had come to naught. The request was made that the tractor project should be abandoned and that a pusher layout be substituted.
   The revised machine was to be designed around the air-cooled 70 h.p. Renault V-8 engine and was to carry a front gunner in addition to the pilot. Although the new machine was by no means de Havilland’s first essay in design, it was designated D.H.1 and this and his succeeding types for the same company continued to be known by their designer’s initials, the name Airco being rarely applied as well.
   The D.H.1 exhibited a marked overall resemblance to the F.E.2 but was slightly smaller and heavier. One or two features of note were incorporated in an otherwise conventional two-bay pusher layout. These included a landing-gear embodying coil springs and oleo tubes for shock-absorbing, and a pair of aerofoil surfaces - some 3 ft. in span each - mounted on each side of the nacelle between the centre-section struts to act as airbrakes.
   On completion in January, 1915, de Havilland carried out the tests of the D.H.1 at Hendon. Its performance was reasonably good, although the Renault’s 70 h.p. was considerably lower than the 120 h.p. of the Beardmore which Airco had hoped would become available for it. Negligible effect was produced by turning the airbrakes through their 90° angle across the slipstream and drag was lessened when they were subsequently removed. The D.H.1 was forced to wait some time for its Beardmore engine as the few available went to the Royal Aircraft Factory. A number were built powered by the Renault and were fitted with cut-down sides to the gunner’s cockpit and undercarriages which reverted to rubber-cord springing. The production version built at King’s Lynn by Savages was designated D.H.1A, and benefited from the power of the Beardmore, the radiator of which was installed prominently immediately behind the pilot’s head. The gunner’s armament was a single Lewis gun on a pillar mounting in the nose, from which he had an excellent field of fire, and on some examples a Lewis gun was fitted for the pilot to fire over the gunner. In spite of its useful attributes, the D.H.1 never really got into its stride as a weapon of war as the F.E.2 was already well developed and the seventy-three D.H.1s and D.H.1As constructed were distributed mainly among Home Defence and training units, six of them finding their way out to the Middle East in 1916.

F.Mason The British Fighter since 1912 (Putnam)

Airco D.H.1

   In June 1914 Geoffrey de Havilland, one of Britain’s pioneer designer/pilots and originator of the Royal Aircraft Factory’s B.E. series at Farnborough, joined the Aircraft Manufacturing Company (Airco) at Hendon and at once embarked on a pusher biplane intended for air fighting and reconnaissance.
   Benefitting from his experience at Farnborough, de Havilland’s first Airco design, the D.H.1 almost inevitably featured the pusher engine configuration owing to the absence of any reliable gun interrupter gear. The two-man crew comprised a gunner/observer in the nose of the nacelle and the pilot situated amidships. Power was intended to be provided by a 120hp Beardmore at the outset, but no example was available and the D.H.1 was fitted with a 70hp Renault. With this engine the prototype was first flown by de Havilland himself at Hendon in January 1915 and, despite its limited power, returned a fairly good performance by current standards. The two-bay wings, of two-spar construction, were provided with generous gap but without stagger, and the tail unit, comprising tailplane, elevator, fin and rudder, was carried on two pairs of wooden booms which converged in plan to meet on the rudder hinge line - though there was no stern post as such. As originally completed the prototype, probably un-numbered, featured a pair of air brakes each consisting of a three-feet aerofoil hinged to the fuselage immediately aft of the front centre section struts; these were found to be unsatisfactory and were quickly discarded.
   The D.H.1 was ordered into limited production, but by the time the first examples began to appear the Beardmore engine was becoming available and was first fitted in aircraft No 4606, this version being designated the D.H.1A. By that time, however, Airco had become heavily involved with development of the more important D.H.2 single-seat fighter, and the majority of production D.H.1As came to be built by Savages Ltd of King’s Lynn, Norfolk. On all production aircraft the coaming of the front cockpit was cut down much lower so as to improve the arc of fire for the Lewis gun.
   A total of seventy-two production D.H.1s and 1As was produced; only six were sent overseas, these joining the Middle East Brigade and No 14 Squadron at Ismailia in 1916. At home, twenty-four aircraft served with Home Defence squadrons, and forty-three were delivered to training units (including No 35 Reserve Squadron and No 199 Training Squadron). The survivors were finally withdrawn from RAF charge at the time of the Armistice in 1918.
  

   Type: Single-engine, two-seat reconnaissance and fighting scout with pusher engine.
   Manufacturers: The Aircraft Manufacturing Co Ltd, Hendon, London (prototypes and early production aircraft); Savages Ltd., King’s Lynn, Norfolk (production D.H.1As)
   Powerplant: (D.H.1) One 70hp Renault liquid-cooled in-line engine. (D.H.1A) One 120hp Beardmore liquid-cooled in-line engine. Two-blade propellers.
   Structure: Fabric-covered wooden construction with two-bay, two-spar wings with upper and lower ailerons. Wooden tail booms.
   Dimensions: Span, 41ft 0in; length (D.H.1), 28ft 11 5/8 in; (D.H.1A) 28ft 11 1/4 in; height (D.H.1), 11ft 4in; (D.H.1A) 11ft 2in; wing area, 426.25 sq ft.
   Weights: (D.H.1) tare, 1,356lb; all-up, 2,044lb. (D.H.1A), tare, 1,610lb; all-up, 2,340lb.
   Performance: (D.H.1) max speed, 80 mph at sea level; climb to 3,500ft, 11 min 15 sec. (D.H.2) max speed, 90 mph at sea level; climb to 5,000ft, 10 min 25 sec; service ceiling, 13,500ft.
   Armament: One 0.303in Lewis gun on pillar mounting in front cockpit.
   Prototypes: One D.H.1 (probably un-numbered, flown by Geoffrey de Havilland at Hendon in January 1915), and one D.H.1A (No 4606, converted from D.H.1)
   Production: Total of 72 production D.H.1s and 1As between Nos 4600-4648 and A1611-A1660.
   Summary of Service: 24 aircraft to Home Defence squadrons, 43 to Home Training Units and 6 to the Middle East (see text).

J.Bruce British Aeroplanes 1914-1918 (Putnam)

de Havilland 1 and 1A

  THE Aircraft Manufacturing Company was established by G. Holt Thomas early in 1912. The company held the British rights for the manufacture of Farman aeroplanes, and was content to build them for a time; but Holt Thomas wanted to establish a design department in the firm, and in June, 1914, he secured the services of Geoffrey de Havilland.
  Mr de Havilland (now Sir Geoffrey) came to the Aircraft Manufacturing Co. with a wealth of experience of aircraft design and construction. Not only had he designed and flown the Royal Aircraft Factory’s most successful types during his period of service there, but he had also seen many examples of the products of other manufacturers which had gone to Farnborough to be tested. For the Aircraft Manufacturing Co. he designed a series of remarkably good aeroplanes, several of which made substantial contributions towards the attainment of supremacy in the air for the Allies. These aircraft earned for their designer the unique compliment of being known by his name rather than by that of the manufacturer: the numerical D.H. designations were seldom prefaced by “Airco”.
  The D.H. 1 was not Geoffrey de Havilland’s first design by any means, but it was the first aeroplane designed by him for the Aircraft Manufacturing Co. It was intended for reconnaissance and fighting duties, and the lack of a machine-gun interrupter gear inevitably made it a two-seat pusher biplane. It was powered by a 70 h.p. Renault engine, and appeared in January, 1915. The forward cockpit was occupied by the observer-gunner, who had a good field of fire in all forward directions. The wings were of two-bay construction, and the tail unit was supported on the customary tail-booms. The undercarriage of the prototype incorporated coil springs and concealed oleo-struts, and when it first appeared the D.H.1 was fitted with air-brakes. These consisted of two small aerofoils, each of about 3 feet span, disposed one on either side of the nacelle and pivoted on an axis which crossed the fuselage just behind the forward centre-section struts; they could be rotated through 90° to present a flat surface to the airstream. The air-brakes were not successful, however, and were soon abandoned.
  The test flights were made by Geoffrey de Havilland himself, and the D.H.1 had quite a good performance, despite the fact that it had been designed for a more powerful engine. The intention was to fit the 120 h.p. Beardmore as the standard power unit, but the Royal Aircraft Factory had laid claim to the few Beardmores which were available in 1914, and production of the D.H. design was delayed. Some were built with the Renault engine: these differed from the prototype in having exhaust manifolds which led the gases well forward, presumably to avoid damage to the airscrew. In the production machines the forward cockpit was cut much lower than on the prototype in order to facilitate the use of a gun, and the undercarriage relied on the more usual rubber cord for shock-absorption.
  When powered by the Beardmore engine the aircraft was re-designated D.H.1A, and was identical in appearance to the production D.H.1s apart from the bulkier upright engine with its radiator behind the pilot’s cockpit.
  By the time production could be undertaken, the Aircraft Manufacturing Co. were too busy with later designs, and the D.H.1A was built by Savages of King’s Lynn under sub-contract. The type never achieved any prominence; comparatively few were built, and only six went overseas. These went to the relative obscurity of the Middle East, and the others were distributed to Home Defence and training units. However, the D.H.1 design is of historic interest, not only as the first of the long line of distinguished D.H. types which was continued after the demise of the Aircraft Manufacturing Co., but also as the immediate predecessor of the more famous D.H.2.


SPECIFICATION
  Manufacturers: The Aircraft Manufacturing Co., Ltd., Hendon, London, N.W.
  Other Contractors: Savages, Ltd., King’s Lynn, Norfolk.
  Power: D.H.1: 70 h.p. Renault. D.H.1A: 120 h.p. Beardmore.
  Dimensions: Span: 41 ft. Length: D.H.1, 28 ft 11 5/8 in.; D.H.1A, 28 ft 11 1/4 in. Height: D.H.1, 11 ft 4 m.; D.H.1A, 11 ft 2 in. Chord: 5 ft 6 in. Gap: 5 ft 7 in. Stagger: nil. Dihedral: 3°. Incidence: D.H.1, 4° 30'; D.H.1A, 5° 15'. Span of tail: D.H.1, 12 ft 5 1/2 in.; D.H.1A, 12 ft 3 in. Wheel track: 5 ft 9 3/4 in. Airscrew diameter: D.H.1, 9 ft 0-4 in.; D.H.1A, 8 ft 10-3 in.
  Areas: Wings: upper 187 sq ft, lower 175-25 sq ft, total 362-25 sq ft. Ailerons: each 16 sq ft, total 64 sq ft. Tailplane: 37-5 sq ft. Elevators: 23 sq ft. Fin: 3-7 sq ft. Rudder: 15-4 sq ft.

Weights (in lb):
Empty Military load Crew Fuel and Oil Loaded
D.H.1: 1.356 60 360 268 2,044
D.H.1A: 1,610 40 360 330 2,340
 Performance: D.H.1: maximum speed at 3,500 ft: 80 m.p.h. Climb to 3,500 ft: 11 min 15 sec. D.H.1A: maximum speed at ground level: 90 m.p.h.; at 2,000 ft: 89 m.p.h.; at 4,000 ft: 88 m.p.h.; at 6,000 ft: 90 m.p.h.; at 8,000 ft: 90 m.p.h.; at 10,000 ft: 86 m.p.h.; at 12,000 ft: 84 m.p.h. Climb to 1,000 ft: 1 min. 40 sec; to 2,000 ft: 3 min 35 sec; to 3,000 ft: 5 min 55 sec; to 3,500 ft: 6 min 27 sec; to 4,000 ft: 8 min 15 sec; to 5,000 ft: 10 min 25 sec; to 6,000 ft: 13 min 10 sec; to 7,000 ft: 16 min 20 sec; to 8,000 ft: 19 min 30 sec; to 9,000 ft: 23 min; to 10,000 ft: 27 min 30 sec; to 11,000 ft: 32 min 25 sec; to 12,000 ft: 38 min 25 sec. Service ceiling 13,500 ft.
  Tankage: D.H.1: petrol 30 gallons. D.H.1A: petrol, main pressure tank, 35-3 gallons; service gravity tank, 5-5 gallons; total 40-8 gallons. Oil: 2-3 gallons. Water: 5 gallons.
  Armament: One Lewis machine-gun on pillar mounting in front cockpit.
  Service Use: No unit was completely equipped with D.H.1s or 1As. The type was issued to some Home Defence and training units, including No. 35 Reserve Squadron, Northolt. Six went to the Middle East Brigade in 1916, where some were used operationally by No. 14 Squadron, R.F.C.
  Production and Allocation: The total number of D.H.is and iAs delivered to the R.F.C. was seventy-three. Of that total, forty-three went to training units, twenty-four to Home Defence units, and six to the Middle East Brigade.
  Serial Numbers: 4606, 4607, 4615. A.1611-A.1660.
  Costs:
   Airframe, without engine, instruments and gun £1,100 0s.
   70 h.p. Renault engine £522 10s.
   120 h.p. Beardmore engine £825 0s.

H.King Armament of British Aircraft (Putnam)

de Havilland

   D.H.1. Built in 1915, the D.H.I reconnaissance lighter pusher a projection of the Farnborough-designed F.E.2 - had a pillar-mounted Lewis gun in the nose of the nacelle, the forward coaming of which was lowered on production aircraft to increase the gunner's freedom. Whether the mounting was of the type designed by Capt Geoffrey de Havilland and mentioned in connection with the D.H.2 is not known.

Jane's All The World Aircraft 1919

AIRCO DE H.1
  
   The first of the series, produced just before the declaration of war, was a two-seater Renault-engined "pusher" machine.
  
  
Specification.
Type of machine Biplane ("Pusher")
Name or type No. of machine De H.1.
Span 41 ft.
Gap, maximum and minimum 5 ft. 7 In.
Overall length 28 ft 11 in.
Maximum height 11 ft. 4 in.
Chord 5 ft. 6 in.
Total surface of wings, including
   centre plane and ailerons 409.3 sq. ft.
Span of tail 12 ft. 5 1/2 in.
Total area of tail (empennage) 80.45 sq. ft.
Area of elevators 11.0 sq. ft. each.
Area of rudder 16.15 sq. ft.
Area of fin 4.05 sq. ft.
Area of each aileron 18.0 sq. ft.
Engine type and h.p. 80 h.p. Renault.
Airscrew, diam., pitch and revs. 9.03 dia.; 9.2 pitch; 870 revs.
Weight of machine empty 1,356 lbs.
Weight of machine full load 2,044 lbs.
Load per sq. ft. 4.99 lbs.
Weight per h.p. full load 25.5 lbs.
Tank capacity in gallons 30 gallons.
Performance.
   Speed low down 78 m.p.h.
   Landing speed 41 m.p.h.
   Climb.
   To 3,500 feet 11 1/4 minutes.
Disposable load apart from fuel 420 lbs.
Total weight of machine loaded 2,044 lbs.
  
  
  
   AIRCO DE H.1A
  
   This was a modified De H.1 fitted with a 120 Beardmore engine in place of the original Renault.
  
  
  
Specification.
Type of machine Biplane ("Pusher")
Name or type No. of machine De H.1a.
Span 41 ft.
Gap, maximum and minimum 5 ft. 7 in.
Overall length 28 ft. 11 1/4 in.
Maximum height 11 ft. 2 in.
Chord 5 ft. 6 in.
Total surface of wings, including
   centre plane and ailerons 409.3 sq. ft.
Span of tail 12 ft. 3 in.
Total area of tail (empennage) 79.9 sq. ft.
Area of elevators 11.0 sq. ft. each.
Area of rudder 15.6 sq. ft.
Area of fin 4.05 sq. ft.
Area of each aileron 18.0 sq. ft.
Engine type and h.p. 130 h.p. Beardmore.
Airscrew, diam., pitch and revs. 9.03 diam., 9.2 pitch, 1,350 revs.
Weight of machine empty 1.672 lbs.
Weight of machine full load 2,400 lbs.
Load per sq. ft. 5.87 lbs.
Weight per h.p. full load 18.45 lbs.
Tank capacity in gallons 33 gallons.
Performance.
   Speed low down 89 m.p.h.
   Landing speed 49 m.p.h.
   Climb.
   To 3,500 ft. 6.45 mins
Disposable load apart from fuel 420 lbs.
Total weight of machine loaded 2,400 lbs.

Журнал Flight

Flight, February 5, 1915.


THE AIRCRAFT MANUFACTURING CO.'S NEW GUN-CARRYING BIPLANE.

   PROBABLY no other type of aeroplane presents greater difficulties and more complex problems to be solved than does the propeller or "pusher" type, and when a new machine of this class is produced one may be perfectly certain that the reason for its appearance is not that the design of a pusher offers a short cut to success, but that there is a demand existing for a machine of this type for special purposes. The reasons which make the design of a propeller biplane a matter of great difficulty may not be immediately apparent, but they are very real, and some may be briefly referred to. In the first place, there is a question of side areas which must be carefully proportioned if spiral instability is to be avoided. A very deep nacelle, while possessing the advantage of protecting the occupants against the rush of air, and at the same time giving a better stream-line, necessitates larger vertical surface in the tail-fin and rudder. Large vertical surfaces for a given weight again necessitate very careful arrangement of these surfaces in relation to the centre of gravity, which latter must of course also be in its proper position relatively to the main planes. Again, the shape of the nacelle enters very considerably into the question, as a nacelle having curved sides would obviously not have the same effect in a relative side-wind as one with perfectly flat sides of the same projected side area.
   By making the nacelle low the side area may be reduced, but then the difficulty enters of providing the necessary clearance between the ground and the propeller, if the latter is to be kept of the desired diameter. This difficulty can, of course, be overcome by lengthening the struts of the under-carriage, but practical considerations put a limit to the length it is advisable to make these members if extra head resistance and a "stilty" chassis are to be avoided. The arrangement of the engine in the rear of the nacelle is another problem which has to be dealt with. In order to make the nacelle of good stream-line form it should taper towards the rear, but where an air-cooled engine is used provision must at the same time be made for at least a portion of the cylinders to receive the necessary amount of draught to keep them from overheating, and this arrangement will partly spoil the stream-line form of the nacelle. Owing to the proximity of the tail planes to the propeller in an engine-behind machine, the effect of the slip stream on the former is a factor that cannot be neglected, and for which allowances must be made in the design and position of the tail planes.
   In our photographs is seen the new biplane designed by Mr. G. de Havilland, and built by the Aircraft Manufacturing Co., Ltd., which is an attempt to produce an aeroplane capable of being used as a fighting machine carrying a gun, and at the same time being reasonably stable and sufficiently fast to meet the requirements of the military authorities. Whether Mr. de Havilland has completely achieved his object the trials will show, but there can be no doubt that as an experiment the new machine gives promise of great possibilities. During its preliminary trials Mr. de Havilland flew it repeatedly with his hands off the controls, and when he did a turn, the machine automatically banked to the right degree for the speed and the radius of the curve. Thus there seems little doubt that the stability of the new biplane is all that can be desired in a machine that does not lay claim to being absolutely inherently stable.
   As regards speed, this has not been definitely determined yet, as the propeller fitted during the preliminary trials was not quite suitable, allowing the 70 h.p. Renault engine to run at much higher revolutions than those for which it is designed. Even under those unfavourable conditions the machine showed a speed of over 70 m.p.h. as registered on the speed indicator, so that there is every reason to believe that when a suitable propeller has been fitted this figure will be considerably exceeded. This is distinctly good, especially as the machine was originally designed for an engine of 80 h.p. When landing the speed appeared to us to be quite low for so substantial a machine, although the designer did not at any time attempt to land it at its absolute minimum speed.
   In its general appearance the new gun-carrier is of very pleasing lines, and, as one expects from a firm of so high standing as the Aircraft Manufacturing Co., Ltd., the workmanship is excellent. In later machines of this type several of the constructional details will be altered, as the experience obtained with the present one suggests various improvements, but the general arrangement will be retained.
   From the accompanying photographs it will be seen that the main planes have a very pronounced dihedral angle, which does not, however, extend throughout their whole length, but is confined to the outer ends of the planes from the second pair of inter-plane struts. The centre sections of the wings are straight. The end sections of the planes are attached to the centre sections by steel clips, and as upper and lower end sections are identical, one spare wing may be used to replace either a lower or an upper extension in case of damage by simply changing the fittings. The nacelle, which is of rectangular section with slightly curved sides formed by longitudinal stringers, projects forward from the main planes a considerable distance, and in the nose the top covering slopes down to allow of pointing the gun with which it is intended to fit the machine at a fairly steep downward angle. Pilot's and passenger's seats are arranged tandem fashion, the pilot sitting at the rear in order to allow the gunner a free range. In the rear of the nacelle is mounted a 70 h.p. Renault engine in such a manner that the tops of the cylinders project sufficiently far above the nacelle covering to ensure good cooling. The bottom of the rear portion of the nacelle is covered with an aluminium shield in order to preserve as far as possible the stream-line form, and as the two halves of the lower plane are attached to the sides of the nacelle and do not run right across it the air has here a comparatively unrestricted flow.
   The tail planes are carried on an outrigger of four steel tubes, and the fixed horizontal tail plane is hinged to the two upper of these tubes, while at the rear it attached to the vertical rudder post by a pin joint such a manner that the angle of incidence may be easily altered to compensate for any alteration of the weight carried in the nose of the nacelle. To the trailing edge of the fixed tail plane is hinged a divided elevator, whilst horizontally the machine is directed by a partly balanced rudder pivoting round the vertical tubular rudder post. The fixed vertical surface of the tail consists of a small fin placed on top of the fixed plane. A pivoted tail skid mounted on a downward extension of the rudder post protects the tail planes against contact with the ground, and as there is a considerable weight on the tail when rolling the skid acts at the same time as a very effective brake. In order to further reduce the speed on landing an air brake is fitted behind the pilot's seat, consisting of two small planes mounted on a tube resting on the upper longitudinals of the nacelle. This air brake is operated from the pilot's seat by means of a small hand lever, and works by being turned broadside on, thus offering a certain amount of extra head resistance. Control is by means of a single lever and a foot bar. Both upper and lower planes are fitted with ailerons.
   The undercarriage is of the simplest possible type, and appears to be very suitable. It consists of two pairs of struts forming two "V's," the apices of which are connected by two transverse members placed a short distance apart, and between which are accommodated the stub axles. Springing is provided by coil springs, and the rebound is taken by a piston working in a cylinder filled with oil. This type of under-carriage has proved very efficient, and has, among other advantages, that of preventing almost entirely the bouncing to which machines fitted with the ordinary rubber shock absorbers, are liable. By undoing two bolts one of the wheels and its shock absorbing arrangement may be removed for inspection or repair. A stream-line casing encloses the the whole shock absorber, and the under-carriage therefore offers a minimum of head resistance. As the wheel track is comparatively narrow, small skids are fitted near the tips of the lower plane in order to protect this in case the machine rolls slightly over to one side.
   Although the new machine has not, up to the time of writing, had an opportunity of being exhaustively tested, the preliminary trials were very encouraging, and Mr. de Havilland is to be congratulated upon his attempt to solve a difficult problem, and the Aircraft Company for the way in which they have carried out the construction.


Flight, January 9, 1919.

"MILESTONES"

THE DE HAVILLAND, OR "AIRCO," MACHINES

The D.H. 1

   A FEW months before the outbreak of War the Aircraft Manufacturing Co., Ltd., or, as the firm is now styled, the Airco., were fortunate enough to secure the services of Mr. (now Capt., R.A.F.) Geoffrey de Havilland, who had up till then been engaged as designer at the Royal Aircraft Factory (now Royal Aircraft Establishment) at Farnborough. At the time, "FLIGHT" mentioned the fact, and ventured to predict a more than usually good performance of the machines designed by Mr. de Havilland for the A.M. Co. To how great an extent our prophecy was correct has long been realised by those who have had an opportunity to follow closely the developments of the D.H. machines, and will, we hope, be generally appreciated by all readers of "FLIGHT" after perusing the following article. The first machine designed by Mr. de Havilland for the Airco. made its appearance early in 1915, and was described in "FLIGHT" for February 5th, 1915. It was a two-seater of the pusher type, and during the preliminary trials, piloted by its distinguished designer, the machine gave promise of very good qualities, judged by the standard of those days. Although originally designed for a more powerful engine, the D.H. 1, as it was called, had a very good turn of speed for its power - the engine fitted was a 70 h.p. Renault - and was inherently stable to a very great extent, de Havilland flying it repeatedly "hands off." The D.H. 1 had its seats so arranged in tandem that the gunner was in the front seat, from where he had an excellent view, and a free field for his machine gun. The pilot sat behind the gunner, and as his seat was placed somewhat higher, he also had a fairly good view.

The D.H. 1A

   The D.H. 1 was followed by the D.H. 1A, which was practically identical, except that it was fitted with a 120 h.p. Beardmore engine. On the D.H. 1 the shock-absorbing arrangement consisted of coil springs taking the load, while the rebound was taken by a piston working in a cylinder filled with oil. This arrangement was discarded in the D.H. 1A for the ordinary rubber shock absorbers. Another experiment which was tried on the D.H. 1 was discarded in D.H. 1A, namely the air brakes. These consisted, in D.H. 1, of two small monoplane wings, each of some 3 ft. span, mounted on the top longerons of the nacelle. In normal flight these wings were set a t no angle of incidence, but for landing they could be rotated so as to present an area normal to the direction of flight. They were not a great success, however, and were not incorporated in D.H. 1A. As will be seen from the accompanying illustrations, D.H. 1A was as neat in appearance as it is well possible to make a pusher. This was accomplished by careful streamlining wherever possible, as, for instance, around the engine, which, being water cooled, could be more enclosed than could the aircooled Renault. To preserve the clean appearance of the nacelle, the radiator was not mounted on the sides, but was built into the front portion of the engine housing, just behind the back of the pilot. In addition to providing the cooling, this placing of the radiator may possibly have assisted materially in keeping the pilot warm. The performance of D.H. 1A was very good for its power, the speed being 89 m.p.h., and the climb to 6,000 ft. taking 12 mins. 10 secs.