O.Thetford, P.Gray German Aircraft of the First World War (Putnam)

Albatros D I and D II

   The year 1916 saw the introduction of the Albatros D I in a successful endeavour to wrest from the Allies the supremacy their Nieuports and D.H. 2s had now gained from the Fokker monoplanes. They began operations with the newly-formed Jagdstaffeln (of which Oswald Boelcke's Jasta 2 undoubtedly became the most well known). These units were equipped from the autumn of 1916. The new aircraft gradually replaced the older Halberstadt D II and IIIs and Fokker D II and IIIs as they became available, and usually they went to pilots in order of seniority.
   Designed by Messrs. Thelen and Schubert, this sleek, streamlined, semi-monocoque aircraft was looked upon at the time as being somewhat unorthodox, as indeed it was. Although the wing structure adhered to former practice, the fuselage was certainly of a revolutionary nature, differing so radically from the fabric-covered, braced box-girder type fuselage structures then in almost universal use. In employing the 150 h.p. Benz Bz III or 160 h.p. Mercedes D III engine it was the most powerful single seat fighting scout yet brought into use in the German Air Force, and this additional power enabled it to carry the extra load of twin fixed Spandau machine-guns without loss of performance. Such armament had previously been tried on the Fokker and Halberstadt D types, but due to their lower power, performance deteriorated considerably with the added weight of the second gun, so they continued to operate with a single gun, sacrificing fire-power for performance.
   Although, due to its heavier wing loading, the Albatros D I had not the manoeuvrability of the majority of its single-seat adversaries, it possessed the speed to attack when to advantage and, more important, to break off combat when expedient. It also had the fire-power of its twin machine-guns, with which to destroy much more quickly.
   Albatros had, of course, pioneered wooden fuselage construction, but the D I was the first attempt to strike a compromise between the usual slab-side and the extremely expensive true monocoque structure. How successful this compromise was may be gauged from the subsequent lineage of Albatros D type machines. The fuselage structure consisted basically of 3/8 in. thick ply formers and six spruce longerons, to which was pinned and screwed the outer covering of three-ply. In section it varied from a circular nose entry to a horizontal knife edge aft, with the middle cross-sections being of flat-sided oval shape. The engine was cleanly installed in the nose, with quickly detachable metal panels adjacent to the cylinder block and immediately aft of the large bulbous spinner, to facilitate servicing. Exhaust manifolds varied in that they sometimes were of the funnel type ejecting vertically and sometimes of the horizontal type exhausting sideways to starboard.
   The clean contours of the fuselage were spoilt to a certain extent by the box-shaped Windhoff radiators mounted on the sides between the wings. Built into the rear fuselage were the pleasingly curved tail surfaces. The fixed surfaces were of wood and the upper and lower fin - which supported the ash tailskid - were covered in plywood skin. The tailplane was fabric-covered. The control surfaces were of welded steel-tube framework with fabric covering, and small triangular balance portions were incorporated in both the one-piece elevator and the rudder.
   The wings were a fabric-covered wooden structure, following the usual Albatros formula of two box-spars positioned well forward and with a wire trailing edge; they were rectangular in shape, with just the smallest suggestion of rake at the tips. Ribs were of three-ply fretted with lightening holes and narrowly flanged with spruce. Ailerons were of steel-tube framework with a slight inverse taper, and were actuated by a crank arm located at mid-span. The top wing was built in one piece and secured to the trestle-type centre-section cabane by eye bolts which could be located in five different positions enabling the stagger to be adjusted from 0 to 12 cm. (approx. 4 3/4 in.).
   A conventional streamlined steel-tube vee-type undercarriage chassis was fitted to sockets mounted on the fuselage; a single spreader bar behind the axle tied the vees together, and the wheels were sprung with rubber shock cord.
   Throughout the winter of 1916-17 the Albatros D I and D II operated in increasing numbers, and with their twin machine-gun armament reaped a grim harvest among the ill-armed Allied B.E.2c reconnaissance planes. Although they completely outclassed the British D.H. 2 single-seat fighting scout in speed and armament, they did not have it all their own way with this opponent, which, due to its superior manoeuvrability, was often agile enough to elude their guns.
   Although the D I was a satisfactory and pleasant aircraft to fly, its main shortcoming in combat was that the top wing rather obscured the pilot's forward and upward field of vision. It was decided, therefore, to reduce the gap and re-position the upper wing closer to the fuselage. The outcome of this was the Albatros D II. The large semicircular centre-section cut-out was retained and the pilot was enabled to see over the top wing more easily and with a much-improved field of vision. The method of reducing the gap was to dispense with the trestle-type centre-section cabane and substitute two sets of outsplayed "N" centre-section struts. This achieved the desired suit, and it was additionally found that with the struts splayed out the pilot's forward view under the wing was materially improved too. Slight alteration was also necessary to the length of the streamlined steel-tube interplane struts. Apart from these modifications, the rest of the machine was virtually the same as the D I.
   At a later date an attempt was made to clean up and improve the D II by disposing of the cumbersome radiator system and installing an aerofoil-shaped Teeves and Braun radiator in the starboard side of the upper wing centre-section. In this ultimate version the D II certainly presented a neat and clean appearance.
   Many famous German pilots flew the D I and D II Albatroses, and initially they operated in mixed flights, together with Halberstadt and Fokker D IIs and IIIs, until sufficient Albatroses were available for a Jasta to standardise on the type. The first patrol to include the new Albatros scouts was led by Oswald Boelcke, who commanded Jasta 2, when a sortie was made on 17th September 1916. A few weeks later, on 28th October, Boelcke, whose victory score then stood at forty, crashed to his death when his Albatros was struck by that of Erwin Bohme as both converged in a diving attack on two D.H. 2s of No. 24 Squadron, R.F.C. The death of this redoubtable and chivalrous airman was soon avenged by none other than Manfred von Richthofen, who later went on to double Boelcke's score before he was shot down in April 1918. He was not destined, however, to become noted for his chivalry. One of the D IIs flown by Richthofen in Jasta 2 was 491/16, and he scored his first victory in this type on 17th September 1916. Manfred von Richthofen eventually became leader of Jasta 2, and on 23rd November 1916 he shot down Major Lanoe G. Hawker, V.C., in a D.H. 2 after a long individual combat, his eleventh aerial victory. It was generally supposed that the superior performance of von Richthofen's Albatros D II was the greatest factor in enabling him to overcome such an experienced pilot as Hawker. No less a pilot than Major J. B. McCudden, V.C., was able to testify to the fire-power of the Albatros when, on return from a patrol on 9th November 1916, he discovered twenty-four hits on his D.H. 2 after his first encounter with the type. Never again were so many hits registered on a machine of his.
   Prinz Friedrich Karl of Prussia was another redoubtable exponent of the D I and D II. He was actually C.O. of a Fl. Abt. unit, but kept a personal Albatros D I ready for his use with the nearby Jasta 2, with which Staffel he used to hunt when he was able to get away from his reconnaissance duties. He was eventually shot down, however, in a skull-inscribed D I of Jasta 2 on 21st March 1917.
   Although it has not been possible to ascertain how many were built, records show that in November 1916 50 D Is and 28 D IIs were serving at the Front; January 1917 saw 39 D Is in use and as many as 214 D IIs. By November 1917 the figures were reduced to 9 D Is and 11 D IIs, by which time the D III and D V were very much in prominence.

TECHNICAL DATA
   Description: Single-seat fighting scout.
   Manufacturers:
   Albatros Werke G.m.b.H. (Alb.).
   Luft-Verkehrs Gesellschaft (Lvg). (1)
   Oesterreichische Flugzeugfabrik A.G. (Oeffag) (1) (built for Austro-Hungarian forces and powered with 185 h.p. Austro-Daimler).
   Power Plant: One 150 h.p. Benz Bz III or 160 h.p. Mercedes D III 6 cylinder inline water-cooled engine, D I: 160 h.p. Mercedes D III only D II.
   Dimensions: Span, 8.50 m. (27 ft. 10 3/4 in.). Length, 7.40 m. (24 ft. 3 1/8 in.). Height. 2.95 m. (9 ft. 6 3/8 in.), D I; 2.641 m. (8 ft. 6 3/8 in), D II. Wing area, 22.9 sq.m. (247 sq.ft.), D I; 24.5 sq.m. (264 sq.ft.), D II.
   Weights: Empty, 647 kg. (1,423 lb.), D I; 637 kg. (1,401 lb.), D II. Loaded, 898 kg. (1,976 lb.), D I; 888 kg. (1,954 lb.), D II.
   Performance: Maximum speed, 175 km.hr. (109.4 m.p.h.). Initial climb, 1,000 m. (3,280 ft.) in 6 min. (5 min. for D II). Ceiling, 17,000 ft. Duration, 1 1/2 hr.
   Armament: Two fixed Spandau machine-guns synchronised to fire through airscrew.
(1) D II only.

W.Green, G.Swanborough The Complete Book of Fighters

ALBATROS D I Germany

   Designed by Herren Thelen, Schubert and Gnadig in a successful endeavour to wrest from the Allies the aerial superiority gained over the Fokker monoplanes by the Nieuport 11 Bebe and the Airco D.H.2, DI was the first fighter to be developed by the Albatros-Werke. Introduced in August 1916 were 12 pre-series aircraft ordered in the previous June after April Typen-Prufung by the Idflieg. Aerodynamically clean for its time, the D I had a semi-monocoque wooden fuselage which differed radically from the fabric-skinned, braced box-girder type fuselages then in almost universal use. The wings were conventional fabric-covered wooden structures, the power plant was either the 150 hp Benz Bz III or 160 hp Mercedes D III six-cylinder inline water-cooled engine, and armament consisted of paired 7,92-mm LMG 08/15 synchronised machine guns. Fifty series D Is were ordered in July 1916, and these were delivered to the Front (where 50 pre-series and series D Is were in service in November), but no further production of this fighter was undertaken as the DI had been overtaken by the D II which, in fact, arrived at the Front at the same time as the earlier type.

Max speed, 109mph (175km/h).
Time to 3,280 ft (1000m), 6.0 min.
Endurance, 1.5 hrs.
Empty weight, 1,422 lb (645 kg).
Loaded weight, 1,809 lb (898 kg).
Span, 27ft 10 2/3 in (8,50 m). Length, 24 ft 3 1/3 in (7,40 m).
Height, 9 ft 6 3/8 in (2,95 m).
Wing area, 246.50 sq ft (22,90 m2).


ALBATROS D II

   One of the most serious design faults of the DI was the poor forward and upward fields of vision provided for the pilot, and to rectify this deficiency the upper wing was lowered and the wing cellule was staggered, reducing overall height by 14 in (36 cm). With this and other more minor changes, the fighter was redesignated D II, and an initial production batch of 100 was ordered in August 1916, arrangements being made for the DII to be licence-built by LVG (Luft-Verkehrs-Gesellschaft). It was also to be built by Oeffag (Oesterreichische Flugzeugfabrik) for the Austro-Hungarian K.u.K. Luftfahrttruppen with a 185 hp Austro-Daimler engine. The standard D II had the 160 hp Daimler D III and armament remained a pair of LMG 08/15 guns. Twenty-eight D IIs were at the Front in November 1916, and the strength of this type peaked in January 1917, when 214 were recorded at the Front.

Max speed, 109 mph (175 km/h).
Time to 3,280 ft (1 000 m), 5.5 min.
Endurance, 1.5 hrs.
Empty weight, 1,404 lb (637 kg).
Loaded weight, 1,958 lb (888 kg).
Span, 27 ft 10 2/3 in (8,50 m).
Length, 24 ft 3 1/3 in (7,40 m).
Height, 8 ft 6 in (2,59 m).
Wing area, 263.72 sq ft (24,50 m2).

J.Herris Albatros Aircraft of WWI. Vol.4: Fighters (A Centennial Perspective on Great War Airplanes 27)

Albatros D.I

   When it arrived on the Western Front in late August 1916 the Albatros D.I was a significant advance over existing Allied fighters. Key features that made it so formidable included the first use of the powerful and reliable 160 hp Mercedes D.III engine in a fighter, fitting two synchronized machine guns, and the strong, streamlined semi-monocoque fuselage constructed of wood frames covered by a thin plywood skin. The result was a compact, robust, streamlined fighter of very good performance and firepower that was easy to fly.
   The speed, climb rate, diving speed, and firepower of the Albatros D.I were all superior to the performance of the DH.2 and Nieuport fighters that were the best and most numerous Allied adversaries and that gave the Albatros immediate technical superiority. Together with the Halberstadt and Fokker biplane fighters that had arrived slightly earlier, Albatros appeared at the front just in time to help supply the first specialized German fighter units with fighters. The first 16 Jastas, formed in September and October 1916, were primarily equipped with those types and some leftover Fokker Eindeckers. Eventually the Albatros demonstrated superior performance and combat effectiveness over these competitors and consequently was built in much greater numbers. The combination of specialized fighter units with aggressive unit tactics developed by ace Oswald Boelcke and the new Albatros fighters enabled the German air service to quickly establish air superiority. However, the Allies had so many more aircraft than Germany that they were able to perform their reconnaissance and artillery-spotting missions despite the increasing losses to the German fighters.
   The Albatros D.I design did have room for improvement. It used conventional wood and fabric wing construction typical of the time, the high-mounted wing and cabane strut design obscured the pilot's field of view, especially upward to the front, and the ear-type radiator installation was problematic. The ear radiators created significant drag and when leakage occurred from solder failures or combat damage, allowed water to drain from the engine's cylinder head, quickly resulting in overheating and engine seizure when it occurred. In fact, the widespread problems with ear and side radiators in different aircraft types resulted in Idflieg banning them from all German combat aircraft on 10 November 1916. However, Idflieg’s order did not affect aircraft already built or in advanced stages of construction, and some manufacturers continued to use them for some time.
   The Albatros also had a high wing-loading compared to the light, rotary-powered Allied fighters, giving a wider turning circle. The more agile Allied fighters used their maneuverability to defend themselves from attack, whereas the Albatros used its superior performance to attack when desired and to disengage when in an inferior tactical position. The slow, stable Allied reconnaissance planes found themselves at a severe disadvantage when attacked by Albatros fighters and their losses spiked.
   After 50 production D.I fighters were built, production shifted to the improved D.II. Meanwhile, the D.I was adapted with floats and larger wings and tail surfaces as the Navy's W.4 floatplane fighter.


Albatros D.II

   The Albatros D.II was a refinement of the D.I developed to address some of its shortcomings. In particular, the cabane structure was redesigned to improve the pilot's field of view forward and upward, the upper wing being lowered to just above the pilot's eye-level. Although early production D.II fighters retained the drag-producing ear radiators of the D.I, the ear radiators were later replaced in production by the Teves and Braun airfoil-shaped radiator that fit flush in the upper wing. In other respects the D.II was essentially identical to the D.I, and German production increased to 275 fighters, of which 75 were built under license by LVG. These were initially designated LVD D.Is but the designation was rationalized to Albatros D.II(LVG).
   The D.II arrived at the front very soon after the D.I and continued its success, the increased quantity available forming the backbone of the new German Jastas. The immediate success of the Albatros fighters in combat impressed Germany's Austro-Hungarian allies and license production of the Albatros D.II and later D.III was expedited for the Austro-Hungarian air service; details are given in that section.


Albatros Fighter Production Orders
Date Ordered Type Qty Serials(1)
July 1916 D.I 50 D.421-470/16
Aug. 1916 D.II 50 D.472-521/16
1916 D.II 50 D.890-939/16
Sept. 1916 D.II 100 D.1700-1799/16
Aug. 1916 D.II(LVG) 75 D.1024-1098/16
Notes:
   1. Serials D.384-391/16 assigned to prototype fighters.
   3. D.I total of 50, D.II total of 275, D.III total of 1,340 (500 by Albatros & 840 by OAW).
   4. D.V total 900, D.Va total 1662 (1,062 by Albatros Si 600 by OAW). Total of all Albatros fighters 4,227.


Albatros Fighter Specifications
D.I D.II D.II(LVG) D.III
Engine 160 hp Mercedes D.III 160 hp Mercedes D.III 160 hp Mercedes D.III 160 hp Mercedes D.III
Span (Upper) 8.50 m 8.50 m 8.50 m 9.00 m
Span (Lower) 8.00 m 8.00 m 8.10 m 8.81 m
Chord (Upper) 1.6 m 1.6 m 1.6 m 1.5 m
Chord (Lower) 1.6 m 1.6 m 1.6 m 1.1 m
Wing Area 24.9 m2 24.9 m2 25.2 m2 20.9 m2
Length 7.40 m 7.40 m 7.40 m 7.33 m
Height 2.95 m 2.64 m - 2.90 m
Empty Weight 694 kg 673 kg 710 kg 673 kg
Useful Load 227.5 kg 225 kg 227.5 kg 235 kg
Loaded Weight 921.5 kg 898 kg 937.5 kg 908 kg
Wing Loading 39.7 kg/m2 - 37.3 kg/m2 44.2 kg/m2
Power Loading 5.76 kg/hp 5.61 kg/hp 5.86 kg/hp 5.68 kg/hp
Max. Speed 175 km/h 175 km/h 175 km/h 175 km/h
Climb, 1,000 m 4 minutes 4 min. 50 sec. - 2 min. 30 sec.
Climb, 2,000 m 9 min. 30 sec. 9 min. 10 sec. - 6 minutes
Climb, 3,000 m 15 minutes 12 min. 40 sec. - 11 minutes
Climb, 4,000 m 23 minutes 26 minutes - 17 minutes
Climb, 5,000 m 40 minutes 37 minutes - 24 min. 30 sec.
Type-Test Accept. April-June 1916 Mid-1916 November 1916 September 1916
Note: All were armed with two machine guns

Журнал Flight

Flight, January 4, 1917.

THE NEW ALBATROS SCOUTING BIPLANE.

   In our last issue we gave a few particulars of some of the more recent German aeroplanes, including the new Albatros scout, of which we are able, this week, to give an illustration. Until comparatively recently, the Germans have not paid any particular attention to the reduction of head resistance, the aim of their aeroplane designers having been more particularly directed along lines of stability, as witness the early Tauben and "Arrow" biplanes. While fighting adversaries who were, long before the outbreak of war, specialists, so to speak, in high-speed machines, the gentle. Hun has evidently at last realised the utility, on occasion, of a good pace, always coupled, of course, with other qualities such as climb and manoeuvring power, and at any rate, in the machine illustrated, "Speed" appears to be the keynote of the design. The large powerful engine, the stream-line body, the small wings, and the reduction of struts to a minimum, all point towards it. In the case of the body, it will be noticed that the method of stream-lining has even been carried to the extent of a hemispherical nosepiece over the propeller boss - a refinement which is not normally met with in German machines. The lines near the tail plane give indication that as far as construction is concerned, the body is not a true monocoque, but has four main rails in the usual fashion, and that the streamlining is effected by a superstructure. The nature of the latter is not quite clear, but it appears to be a metal cover, probably aluminium. A detail which was quite clear in the original photograph, but which has been obliterated in the reproduction, is the new fitting for the interplane struts.
   Instead of the old familiar steel cup in which rests a ring forming the anchorage for the bracing wires, a much smaller fitting is employed, consisting, apparently, of an eye-bolt, with forked ends passing through the spar, the eye-bolt in the end of the strut fitting into the forked end of that in the spar. The Mercedes engine is almost totally covered in, the radiator, mounted above the engine, only just clearing the fuselage covering. The tail planes, it will be observed, are neatly joined to the body, the appearance being, in fact, that the body covering is run upwards to form the covering of the fin as well. The rudder is partly balanced, wholly on top of the body and some little distance ahead of the elevator, as mentioned in our brief description last week.

  

Flight, June 28, 1917.

THE ALBATROS D.I "CHASER" BIPLANE.

   PERHAPS one of the most formidable of the various types of Hun machines our pilots have been "up against" has been the Albatros "Bu" chaser scout. Although, being comparatively heavy, it cannot claim the high speed and other performance qualities possessed by the "star" machines of the Allies, it has, nevertheless, proved itself a good fighter, and one that is decidedly handy on the control.
   Through the courtesy of our authorities we have been able to make a thorough examination of one of these scouts - D. 1/391, 1916, No. 2944, brought down some six months ago on the British front - which has enabled us to add from personal inspection yet another detailed description of an enemy machine to those that have already appeared in "FLIGHT."
   Having examined the Albatros "D. 1," it must be admitted that one could not but help admiring its general design and construction. Simplicity and strength formed the keynote throughout, complicated fittings and highly-finished parts being conspicuous by their absence. The "D. 1" bears signs of previous Albatros practice in several instances, mostly in a modified form, but there are also some radical innovations. Perhaps the most noticeable features consist of the monocoque fuselage - which is built up entirely of wood without any wire bracing - and the arrangement of the planes.
   The latter, contrary to Hun practice, have neither sweep-back nor dihedral - the top plane, in fact, being one complete unit. The wing curve is similar to the Albatros "C. III," but having a flatter camber, whilst the angle of incidence varies from 5° 3' at the centre to 4° and 2° at the left and right hand wing-tips respectively. A somewhat novel feature consists of the method of adjusting the stagger of the top plane from 0 to 12 cm., by moving it along the top of the cabane. This is effected in the following manner: In each end of the top horizontal tube of the cabane is formed a slot, which receives an eyebolt passing through the main spar of the plane. At each slot are five holes passing horizontally through the tube, one of which - according to the adjustment required - receives the bolt that locks the eyebolt in the cabane. The arrangement is shown in one of the accompanying sketches.
   In order that the correct gap should be maintained in each adjustment for stagger, the lower end of the interplane struts and the cabane struts can be adjusted accordingly at their attachments to the planes and fuselage respectively. As may be seen in two of the accompanying sketches, this is done by means of the screw adjustment on the ends of the struts as shown. Only one pair of struts on each side of the fuselage separate top and bottom planes, these struts being of streamline steel tube. The attachment fittings are shown in the sketches, from which it will be seen that the top fittings are slightly different from the lower ones, which, as previously stated, are adjustable. As in other Albatros machines the main spars are located well forward, the front one being some 4 ins. from the leading edge, and spaced 2 ft. 7 1/2 ins. from the rear one. They are of the usual Albatros rectangular section, fabric bound, and are bevelled off on the top at the extremities. The ribs, which are spaced 16 1/4 ins. apart in the top plane and 13 3/4 ins. in the bottom plane - except where the interplane struts are attached where the rib is displaced by a tubular compression member - are built up of slotted-out webs and somewhat narrow flanges. Between the leading edge and the front spar the upper surface of the plane is stiffened by a false rib between each of the ribs proper.
   The lower plane is attached to an abutment built out from, and flush with the side of the fuselage. The mounting, which is shown in one of our sketches, consists of a form of bayonet socket-joint, access to which is obtained by means of doors on the under sides of the plane. As on other Albatros machines, the ailerons are given a wash out at the tips and have operating cranks working in slots in the plane. They are hinged on auxiliary spars on the top plane only. The span of the top plane is 28 ft. 4 ins. and that of the lower 26 ft. 9 ins., the chord of both being 5 ft. 9 in., and the gap 5 ft. 3 ins. The total supporting surface is 269 sq.ft.
   The stabilising plane, semi-elliptical in plan form, is divided into two parts, and is exceptionally thick (5 3/4 ins.). It is non-lifting, and is mounted, in the line of flight, without any external bracing. The framework is of wood and the covering fabric. Hinged to the trailing edge of the stabilising plane is a single elevator balanced by small triangular extensions forward of the outer extremities. A rounded vertical fin, like the stabilising plane very thick, is mounted on the top of the fuselage some distance forward of the extremity of the latter. It has 'a wood framework and a covering of three-ply. To its trailing edge is hinged the rudder, which is balanced by a triangular portion extending forward, and at the top of, the rudder post. The rear edge of the rudder does not extend further than the extremity of the fuselage. A small triangular fin, also of three-ply, is formed under the fuselage by the supports for the tail skid. The framework of the elevator and rudder is of steel tubing, covered with fabric. The rudder control cables are inside the fuselage; two small doors on the top of the latter allow for inspection and adjustment. The elevator cables also pass inside the fuselage. The junctions of the fins and stabilising planes with the fuselage are rounded off with three-ply.
   In the fuselage are to be found many points of interest. It is a modification of the standard Albatros system of fuselage construction, but differs in that it approaches nearer the true monocoque. It is, in fact, a compromise between the two, and suggests itself as an excellent solution to the problem of the "commercial" monocoque - simple in construction, low in cost, and of great strength. In section it varies from circular at the nose, to a horizontal knife-edge at the rear - being flat-sided, with rounded top and bottom in the centre. It is built up of six longerons, three a side, the central ones being of small rectangular section spruce (3/4 x 5/16 in. aft of cockpit, forward of which they are 3/4 x 3/4 in. L-section). The top and middle longerons are placed one above the other, but the bottom ones are closer together. Top and bottom members are, except at certain points, of L-section, and up to the cockpit are of spruce, forward of which ash, 1 3/16 x 1 9/16 in. is employed.
   The longerons are supported in simple transverse "formers" or ribs, reinforced at the junctions with the longerons, spaced at intervals of, roughly, 2 ft. These formers are 3/8 in. thick and 3/4 in. deep. At the tail there are two thicket formers of the shape shown in one of the sketches. Forward of the cockpit there are four transverse formers, or supports, of three-ply, carrying the engine bearers, similar to those employed on other Albatros machines. Over the whole of this framework is laid a covering of three-ply, which is tacked and screwed to the longerons and formers. There is no wire bracing, nor are there any struts, except for two forming continuations of the front cabane struts extending to the chassis strut attachment. The pilot's seat is supported by two transverse tubes adjustably mounted on two auxiliary longerons on the side of the fuselage.
   The engine, a 170 h.p. Mercedes, No. 27911, does not call for any special reference, being mounted in a similar fashion to those on previous models. The radiators, however, differ from those usually employed. They are of the honeycomb type, and are mounted one on each side of the fuselage. Above, and to the left of the camshaft, is a flat water tank, one end connected to the engine jacket, and the other end to the tops of the radiators. The lower orifices of the radiators are connected to the water pump at the rear of the engine. On each side of the engine is mounted a machine gun, synchronized for firing through the propeller. They are centred about 1 ft., and are operated by two triggers mounted on the grip of the control lever. One of our sketches shows the ammunition-feed arrangement for the two guns.
   The control lever is of the Fokker type, operating the ailerons and the elevator. It consists of a 1 3/16-in. tube mounted on a 1 9/16-in. transverse tube supported on a wooden base. A locking device is fitted whereby the lever may be locked against a fore-and-aft movement enabling the pilot to remove his hands, but operate the ailerons with his knees. This locking device, which consists of an arrangement of rods forming an articulated parallelogram, is shown in our sketch, from which other details of the control may be seen.
   The landing chassis is of the conventional V-type with rubber sprung axle carrying a pair of 760 x 100 disc wheels. Behind the axle is a transverse tubular tie rod, and the two rear struts are cable braced. The chassis is easily dismantled by withdrawing the struts from the sockets mounted on the fuselage.


Flight, July 12, 1917.

SOME 1917 TYPE GERMAN AEROPLANES.

The Albatros D. I and D. II.

   These machines are built by the Albatros works at Johannisthal, Berlin, and its various branches, and under licence by the Bavarian Aircraft Works at Munich. As a detailed description of the D. I type was given in the June 28th issue of "FLIGHT," there is no need to deal with it here. The D. II resembles it very closely, except for minor alterations. For instance, the gap between the planes has been decreased, bringing the top plane much closer to the body, to which it is attached by two sets of struts in "N" formation, sloping outward slightly after the fashion of the Sopwith one and a-half strutter. In this type no provision is made for varying the stagger. In all other respects the D. II resembles closely the D.I, small alterations in dimensions being scarcely noticeable, except under the tape measure.