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

Halberstadt D II and D III

   The first single-seat scout product of the Halberstadter Flugzeug-Werke was the 100 h.p. Mercedes-engined D I of late 1915. This was an orthodox slab-sided, two-bay aircraft typical of its period, with a flush-type radiator located in the starboard side of the centre-section panel and a claw brake mounted in the centre of the axle. The D I was subsequently modified by installing a 120 h.p. Argus As II engine which was completely cowled in behind a car-type radiator, with an ungainly exhaust manifold ejecting over the top wing.
   In 1916 the aircraft was again re-engined with the 120 h.p. Mercedes D II, and in this form it went into production as the D II to supplement the Fokker D type biplanes, which were then replacing the obsolescent Fokker monoplanes. The Halberstadt D II was a neat little aeroplane and its two-bay wing structure made it exceedingly strong. The fuselage was a normal wooden structure with hollow square-section longerons. The vertical and lateral spacers were kept in place rather ingeniously by small wood blocks tacked to the longerons and the tension of the bracing cables anchored to special angular wiring plates at each corner. At the extreme nose were curved metal panels housing the fore end of the 120 h.p. Mercedes D II. The panels adjacent to the cylinder block - which was left exposed - were also metal. Exhaust systems varied: at first a long exhaust pipe led down the starboard side of the fuselage as far aft as the cockpit; later a chimney-type manifold was fitted, exhausting over the top wing. The curved decking forward of the cockpit and the remainder of the nose was ply covered. Aft of the cockpit was a curved decking built up of formers and light stringers which terminated some distance in advance of the tail, an arrangement that could not have improved the airflow over the control surfaces. To the rear of this decking the fuselage tapered wedge-like to a horizontal knife-edge and, except for the extreme rear panel, which was ply-covered, the rear half of the fuselage was fabric-covered.
   There were no fin surfaces in the empennage, which was constructed throughout of light-gauge steel tube. The elevators were of trapezoidal shape, almost identical to those of the contemporary Fokker types. The rudder of approximately triangular profile, was braced by two steel struts, yet it appeared to be a singularly vulnerable structure. Underneath the tail was an inverted steel-tube tripod to which was hinged the wooden tailskid.
   The wings, of almost rectangular shape, had a slightly rounded rake to the tips. They were of conventional construction with two I-section spars and built-up ribs with webs and battens. Unusual in German aircraft was the trailing edge, which in this instance was a light wooden member. Ailerons were of steel-tube construction, of constant chord and unbalanced, actuated by a crank in similar fashion to the Albatros scouts. A flush radiator, conforming to the aerofoil section, was fitted in the starboard side of the centre-section. In the opposite side the gravity fuel tank was installed and a deep angular cut-out was made in the centre-section trailing edge. The upper wing was sited close to the fuselage, supported on an inverted pyramid of steel struts at the front spar and an inverted vee at the rear spar. All interplane struts were of steel tube.
   A normal vee-type undercarriage chassis with two spreader bars was welded from streamlined steel tube. Short horizontal tubes were welded at the apices of the vees, which also served as anchorages for the elastic-cord shock absorbers.
   The Halberstadt D III which followed did not differ radically from the D II. Powered by the Argus As II engine of 120 h.p., it was fitted with a less-cumbersome manifold exhausting sideways to starboard. Ailerons were of increased span, with a considerable area of horn balance at the tips. There was also an alteration to the method of attaching the upper wing, the centre-section struts being vertical instead of meeting on the centre-line. The centre-section cut-out was also revised to a cleaner and near semicircular shape. Apart from these modifications, the D II and D III were virtually identical.
   At a later date a 150 h.p. Benz Bz III engine was installed in the D III airframe and two machine-guns were fitted; in this guise the machine was designated D IV, but it cannot be confirmed that many of the type were built. Relatively few D IIs and IIIs were built, though some were constructed under licence by Hannoversche Waggonfabrik. The report of the Inter-Allied Commission after the Armistice recorded that 100 Halberstadt D II and D IIIs were at the Front in January 1917. They were supplied initially to the Kampfeinsitzerkommandos serving with the Fl. Abt. reconnaissance units for protection duties. However, with the formation of the first Jastas in the late summer of 1916 they joined the Fokker D IIIs and D IVs, and some of the first Albatros D Is, to form a motley, composite equipage for these units.
   By the end of 1916 the Halberstadt D II and D III had become obsolescent and were largely withdrawn from the Western Front or relegated to quieter sectors. However, while on operations they were able to give a good account of themselves and were certainly respected by their Allied adversaries.

TECHNICAL DATA
   Description: Single-seat fighting scout.
   Manufacturers: Halberstadter Flugzeug-Werke G.m.b.H. (Halb.).
   Sub-contractors: Automobil und Aviatik A.G. (Av.); Hannoversche Waggonfabrik A.G. (Han.).
   Power Plant:
   One 120 h.p. Mercedes D II 6 cylinder in-line water-cooled engine (D II).
   One 120 h.p. Argus As II 6 cylinder in-line water-cooled engine (D III).
   Dimensions: Span, 8.8 m. (28 ft. 10 1/2 in.). Length, 7.3 m. (23 ft. 11 1/2 in.). Height, 2.66 m. (8 ft. 9 1/8 in.).
   Weights: Empty, 561 kg. (1,234 lb.). Loaded, 771 kg. (1,696 lb.).
   Performance: Maximum speed, 145 km.hr. (90 m.p.h.). Initial climb, 1,000 m. (3,280 ft.) in 4 min., 3,000 m. (9,840 ft.) in 15 min. Ceiling, 19,600 ft.
   Armament: One fixed Spandau machine-gun forward mounted on port side of fuselage.

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

HALBERSTADT D II & D III German

   The production derivative of the D I, which entered service with the Fliegertruppe from June 1916 as the D II, differed from its progenitor in a number of respects apart from its 120 hp Mercedes D II six-cylinder water-cooled engine. The car-type radiator was discarded in favour of an exposed cylinder block and wing-mounted radiator, with an inordinately massive exhaust stack to starboard, and the pilot’s cockpit was raised and faired by means of a turtle deck. Early production D IIs retained the balanced ailerons of the D I, but later examples adopted wide-chord, unbalanced ailerons. The armament of one LMG 08/15 machine gun on the starboard side of the forward fuselage was retained, and the D II, which possessed an exceptionally robust structure, was licence-built by the Automobil und Aviatik AG and the Hannoversche Waggonfabrik AG. Each produced 30, which, somewhat confusingly, were initially designated Aviatik D I and Hannover D I respectively. After completing an initial batch of 12 D IIs, the parent company continued with a batch of 24 D IIs and D IIIs, there being no fundamental difference between the two models apart from engine, the latter having a 120 hp Argus As II. During manufacture of a follow-on batch of 30 D IIIs by the Halberstadter Flugzeugwerke production was switched to the improved D V and - apart from licence manufacture of the D II - total production of the D II and D III was 50 aircraft. The following data relate to the D II.

Max speed, 93 mph (150 km/h) at sea level.
Time to 3,280 ft (1 000 m), 3.5 min.
Range, 155 mis (250 km).
Empty weight 1,147 lb (520 kg).
Loaded weight, 1,610 lb (730 kg).
Span 28 ft 10 3/8 in (8,80 m).
Length, 23 ft 11 3/8 in (7,30 m).
Wing area, 254 sqft (23,60 m2).

J.Herris Halberstadt Aircraft of WWI. Volume 2: CL.IV-CLS.I & Fighters (A Centennial Perspective on Great War Airplanes 45)

Halberstadt D.II

  The first truly mass-production version of the Halberstadt fighter was the D.II that was powered by the 120 hp Mercedes D.II engine. The aircraft was armed with a single fixed machine gun mounted on the right side of the centerline. The upper wing had an angular cut-out at the rear of the center section to provide better field of view for the pilot.
  The planform of both wings was rectangular with a chord of 1520 mm. D.II and D.III production machines had unbalanced ailerons that did not extend beyond the wing tips but did protrude rearward beyond the trailing edge of the wing. The wing chord over the ailerons was 1670 mm, so the ailerons projected 150 mm beyond the wing trailing edge.
  Upon reaching the front, the Halberstadt D.II proved superior to the Fokker E.III in all respects and immediately became popular with their pilots. The Halberstadts were faster than the E.III, had better climb rate, were more maneuverable, and were much more stable, enabling the pilot to 'fly the mission, not the airplane.'
  The Fokker E.IV did have two guns to the Halberstadt's single gun and was as fast as the Halberstadt. However, the Halberstadt still climbed better and was much more maneuverable. Very importantly, the Halberstadt was much stronger and more robust than any of the Fokker Eindeckers.


Halberstadt D.III

  The Halberstadt D.III shared its airframe with the D.II; the difference between the types is that the D.III used the 120 hp Argus As.II engine instead of the preferred 120 hp Mercedes D.II. Performance was essentially the same; however, the Argus engine tended to lose power with altitude a little faster than the Mercedes, giving the D.III slightly less climb rate than the D.II at altitude. Given the shared airframe, the D.III inherited the delightful handling characteristics of the D.II and was similarly popular with its pilots.
  Some units, for example Jasta 4, mounted a second machine gun on the D.III to improve its firepower. Normally this added gun was fitted below the standard gun on the right side of the aircraft. The additional weight of the second gun somewhat reduced performance and agility, which could reduce the D.III's performance in a dog-fight with another fighter. However, the fire-power and reliability of the second gun was much compensation for that, especially when in combat against a two-seater.
  On December 22, 1916, a meeting was held with experienced fighter pilots at Cambrai to discuss the future of fighter development. Most of the pilots strongly preferred a Halberstadt D.V powered by the 120 hp Mercedes engine and armed with two machine guns. The reason given was that the Halberstadt was a 'delight to fly.'
  Only one of the participants advocated the 150 hp engine, a then little-known ace named Manfred von Richthofen. He preferred a more powerful fighter armed with two guns and having a faster dive than the Halberstadt. This design, embodied in the Albatros fighters, was more suited to aggressive squadron tactics that emphasized a powerful unit diving attack as the key offensive move.
  Although much more maneuverable and 'delightful to fly' than Albatros scouts and better in a dog-fight, the Halberstadt fighters were not as effective in a diving attack due to their slow dive. The performance of the Albatros fighters was better suited to the offensive tactics of the new Jastas.
  As more Albatros fighters reached the front, the Halberstadt fighters were gradually replaced and send to the training units where they were used for advanced fighter pilot training.


Halberstadt Fighter Type Description
Type Engine Ailerons Wings Remarks
Prototype (1) 100 hp Mercedes D.I Plain ailerons Exhaust cut into wing leading edge Single fixed gun on port
D.I 100 hp Mercedes D.I Horn-balanced ailerons or unbalanced ailerons with trailing edge flush with wing trailing edge. Two-piece upper wing joined at centerline. Angular cut-out. Single fixed gun on starboard. Long exhaust on starboard.
D.II (2)(3) 120 hp Mercedes D.II Unbalanced ailerons that extend beyond the wing trailing edge. Two-piece upper wing joined at centerline. Angular cut-out. Single fixed gun on starboard. Second gun sometimes added.
D.III 120 hp Argus As.II Unbalanced ailerons that extend beyond the wing trailing edge. Two-piece upper wing joined at centerline. Angular cut-out Single fixed gun on starboard. Second gun sometimes added. Short 'rino' vertical exhaust
D.IV 150 hp Benz Bz.III Inset triangular balanced ailerons. Aileron push-pull rod controls Prototypes only. Twin machine guns
D.V 120 hp Argus As.II (4) or, some aircraft 120 hp Mercedes D.II Inset balanced ailerons with trailing edge flush the wing trailing edge. Three-piece upper wing, cabane joined to the center section. Semi-circular cut-out. 31 (33?) to Turkey, both engine types used. Single fixed gun on port. Second gun sometimes added to starboard. Short, downward exhaust on starboard.
Notes:
(1) Prototypes had frontal radiator and aileron cables over &. under wings. All others had airfoil radiators and production aircraft had aileron cables inside their lower wings.
(2) D.II(Av) was originally designated Aviatik D.I. When aircraft designations were rationalized, it became the Halberstadt D.II(Av). Visual distinctions of the Aviatik-built D.II were the exhaust pipe exiting the engine cowling and extreme aft location of Militar Nummer on rear fuselage painted in black.
(3) D.II(Han) was Hannover D.I until aircraft designations were rationalized. Visual distinctions of the Hannover-built D.II were the Militar Nummer on rear fuselage painted in white. They usually wore two-tone green/red-brown camouflage from the factory.
(4)Mercedes engines used an overhead camshaft; Argus engines used pushrods.


Halberstadt Fighter Specifications
Spec \ Type D.l D.II D.III D.IV D.V
Engine 100 hp Mercedes D.l 120 hp Mercedes D.II 120 hp Argus As.II 150 hp Benz Bz.III 120 hp Argus As.II
Span, upper - 8.8 m 8.8 m 8.4 m 8.8 m
Span, lower - 7.92 m - - 7.8 m
Chord, upper - 1.52 m 1.52 m 1.5 m 1.5 m
Chord, lower - 1.52 m 1.52 m - 1.5 m
Wing Area 24.0 m2 23.6 m2 23.6 m2 24.0 m2 23.6 m2
Length - 7.3 m 7.3 m - 7.3 m
Weight empty 551 kg 520 kg 525 kg - 600 kg
Weight loaded 739 kg 730 kg - 815 kg 812 kg
Speed - - - - 160 km/h
Climb
1,000 minutes 4.5 3.5 4 - 4
2,000 minutes 10 8.5 9 - 9
3,000 minutes 18.5 14.5 15 - 15
4,000 minutes 35 22.5 - - 24
5,000 minutes - 38.5 - - -
D.II(Av) Empty Wt. 575 kg, Loaded Wt. 728 kg.
D.II(Han) Empty Wt. 561 kg, Loaded Wt. 744 kg


Halberstadt Fighter Production
Order Date Quantity Type Engine Serial Numbers & Notes
March 8, 1916 12 D.l D.II 100 hp Mercedes D.l
120 hp Mercedes D.II D.100-111/16
March 8, 1916 3 D.IV 150 hp Benz Bz.III (*) Unknown
May 1916 24 D.II 120 hp Mercedes D.II D.115-138/16
July 1916 30 D.III 120 hp Argus As.II D.392-421/16
July 1916 30 D.II(Av) 120 hp Mercedes D.II D.582-611/16 (was Aviatik D.l). From D.401/16 onwards these may have been D.V fighters.
July 1916 30 D.II(Han) 120 hp Mercedes D.II D.800-829/16 (was Hannover D.l)
August 1916 20 D.III 120 hp Argus As.II D.1099-1118/16. According to Reinhard Zankl these were D.Vs.
October 1916 20 D.V 120 hp Argus As.II D.2310-2329/16
January 1917 12 D.V 120 hp Argus As.II D.200-211/17 (not confirmed). No documentation was found on this series before and after it went to Turkey.
June 1917 25 D.V 120 hp Argus As.II D.3500-3524/17
(*)Other sources give the engine as a 160 hp Mercedes D.III.

J.Herris Aviatik Aircraft of WWI (A Centennial Perspective on Great War Airplanes 10)

Aviatik D.I

   Aviatik built the Halberstadt D.II under license as the Aviatik D.I. When Idflieg rationalized aircraft designations, it was logically re-designated the Halberstadt D.II(Av).

C.Owers, J.Herris Hannover Aircraft of WWI (A Centennial Perspective on Great War Airplanes 46)

Hannover Aircraft Orders & Production, 1915-1919
Known Serials Quantity Comments
Halberstadt D.II(Han)
800-829/16 30 800/16 type test October 1916

Журнал Flight

Flight, April 5, 1917.

THE 1916 HALBERSTADT BIPLANE.

   THE 1916 Halberstadt fighting biplane - one of Hunland's crack machines, of which much was heard during the latter part of last year - has general details which are interesting from the constructional point of view. Unfortunately, the condition of the one we have been able to inspect, as may be seen from the accompanying photographs, was such that lack of detail in certain parts did not allow of scale drawings being prepared. Sketches of many details, together with the drawing of the complete machine - reconstructed from the "wreckage" and from particulars of a similar model captured more or less intact - will for the time being suffice to give a general impression of this machine.
   Prior to the war the Halberstadter Flugzeugwerke was known as the Deutsche Bristol Works, when taubes and Bristol Prier-type monoplanes were manufactured. During 1915 the new firm built a speedy biplane scout, having a Morane-Saulnier-type body and Oberursel motor - being, in fact, very similar to the Fokker biplane of that date. In 1916 the firm produced the improved type under review, which differed from the previous type in several respects, mainly in the arrangement of the planes and the installation of a stationary engine. Variations of this type have, we understand, been turned out, but it may be assumed that they differ only in minor details. The principal dimensions of this particular model are as follows :- The span of the upper and lower planes is 28 ft. 6 1/2 ins. and 25 ft. 9 ins. respectively; chord 5 ft. 1 1/2 ins.; gap 4 ft. 4 ins.; top plane staggered forward about 18 ins.
   The fuselage is somewhat similar to that of the Morane-Saulnier, and is of wood construction, the longerons being square in section, hollow and bound with fabric. From one of the accompanying sketches it will be seen that the construction the fuselage is one of the simplest, the struts being k<...>t in position by blocks of wood tacked to the longetons each side of the strut, and by ply angle-pieces tacked to the struts. The wiring plate - for the outside bracing - consists of a single sheet steel plate bent to a right angle and placed in position over the longeron and struts as shown. A bolt at each end of the plate passes through the strut, one of these bolts having an eye formed at its inner end to form the attachment for the cross wire bracing. Aft of the cockpit the fuselage is covered with fabric except for the last bay, which has a three-ply covering. At this part the elevator and rudder control cables pass through long slots, reinforced with metal edgings, in the three-ply. This material is also used for covering the fuselage forward of the cockpit. The top of the latter is in the form oа a turtle deck, which tapers at the rear until flush with the fuselage at a point midway between the tail and he cockpit. This sloping portion of the turtle deck is built up of stringers over which fabric is stretched. In order to keep the fabric separated a short distance from the sides of the fuselage - to avoid contact with nuts, wires, &c. - a beading is tacked along the outer corners of the longerons. The step in the side of the fuselage is fitted with a spring-closed aluminium trap door - as in some of our own machines - the action of which is clearly shown in one of the accompanying illustrations.
   The main planes are almost rectangular in planform, being only slightly raked. The top plane is situated very close to the fuselage, and is staggered forward, so that the range of vision appears to be very good. As on most German machines, the camber is fairly pronounced, especially so for a speed machine. In construction they present little out of the ordinary, the spars being of the orthodox I-section with built-up ribs of webs and battens. There are two pairs of interplane struts, of streamline steel tube, on each side of the body. The attachment of these struts to the spars is effected by means of a metal fitting, secured to the spar by two bolts, on which is formed a fork receiving the end of the strut, a bolt passing through both. The struts can thus hinge sideways so that top and bottom planes can, when the bracing wires are slackened, lie one on top of the other for transporting. A smaller fork formed on the side of the fitting serves as an anchorage for the bracing cable, while the incidence bracing cable is attached to a metal clip which passes over a ring contained within the strut fitting. The internal bracing cables are fastened to a long, narrow, wiring plate bolted to the side of the spar. A wood or fibre packing piece is inserted between the spar and the strut fitting to give the latter the correct angle necessitated by the staggering of the planes. A quick-release device, similar to that employed on the L.V-G. machines, is provided for the bracing cables, enabling the latter to be withdrawn without upsetting the adjustment.
   One of the accompanying sketches shows the method of attachment of the lower plane to the fuselage, and is, we think, self-explanatory. Suffice it to say that the lugs on the ends of the tubular cross members passing through the fuselage, in continuation of the wing spars, receive the forked ends of the latter, the locking being effected by means of the pin shown. A tongue formed on each of the aforesaid lugs serves as an anchorage for the lift wires.
   The top planes are attached to a cabane, with which is incorporated a service petrol tank having the same section as that of the wings. A portion of the latter is, of course cut away to receive this tank.
   The ailerons, which are mounted on the top plane only, are operated by a crank lever working in a slot formed in the wing, as in the Albatros machines. The pulleys carrying the aileron control cables are inside the wing, but an aluminium trap door allows for their inspection and adjustment. As is common practice with most German machines, the trailing edge of the aileron is given a slight up-turn.
   It will be seen that the tail surfaces follow Morane-Saulnier practice very closely, the elevators being exactly similar in plan-form. The rudder, however, is larger and of a peculiar pointed shape. They are constructed entirely of steel tubing, as shown in one of our sketches. The ribs are built up of lengths of tubing, the ends of which are brazed to the tubular spar - or rudder post, as the case may be - and the tubular trailing and leading edges. Short tubular distance pieces are arranged zig-zag fashion between the upper and lower members of the elevator ribs. The rudder post is supported by two substantial tie-rods of streamline steel tubing, anchored to the fuselage. The wood tail skid is supported by a tubular steel tripod, and is allowed a certain amount of swivel movement. The forward end is held by elastic shock absorbers, whilst the rear end, which comes in contact with the ground, is fitted with a metal shoe.
   A control of the Fokker type is fitted, consisting of a vertical column with hand grip, mounted on rocking shaft lying fore and aft and supported between two tubular cross members. The vertical column pivoted so as to rock backwards and forwards (elevator control) over a quadrant, the purpose of the latter being, apparently, to lock the column in position order that the pilot may have his hands free for firing the gun. The control cables from the elevators are in duplicate, and one pair is attached to the column just above the rocking shaft, and the other below to an extension of the column passing through a hole in the floor of the fuselage. The aileron control cables are attached to a double X-shaped quadrant mounted on the rocking shaft, the lower arms passing through the floor of the fuselage and carrying the cables from the aileron crank levers; the top arms carrying the cables which are attached to the ailerons near the trailing edge. A pivoted tubular rudder bar is mounted in the cross member carrying the front end of the rocking shaft. This bar is provided with end plates to prevent the pilot's feet from slipping off; whilst the distance from the seat to the rudder bar can be varied by means of the adjustable link, connecting the bar and the front-spar cross member, shown in our sketch.
   The chassis is of the orthodox V-type, each V consisting of two streamline steel struts welded to a short tubular skid, which serves as an anchorage for the rubber shock absorber. The rear strut is attached to the fuselage under the rear wing-spar attachment, a lug being formed on this fitting for the purpose.
   A pair of 28-in. wire wheels (disc) are mounted on a tubular steel axle, 1 7/8 in. diameter. The V's of the chassis are connected by two cross members, consisting of streamline steel tubes attached to the lower ends of each strut.
   As regards the engines fitted to the 1916 Halberstadts, these are, we understand, either 120 h.p. Argus (Benz type) or the new Mercedes-V. Unfortunately, we have not at present particulars as to the method of mounting the engine, &c, but hope to furnish details later.


Flight, July 12, 1917.

SOME 1917 TYPE GERMAN AEROPLANES.

The Halberstadt Chaser.

   Details of this machine are already familiar to readers of "FLIGHT" through an illustrated description which appeared in our issue of April 5th, 1917. We are now able to supplement the information then given by approximate scale drawings and other data from L'Aerophile. The Halberstadt chaser is a single-seater of short span - 28 ft. 6 ins. and 25 ft. 9 ins. - and has, as distinct from the majority of other biplanes of the chaser type, two pairs of inter-plane struts on each side. The wings are staggered, and have a dihedral angle, but are not swept back. Ailerons are fitted to the top plane only, and are warped, their angle of incidence decreasing progressively towards the tips. They are hinged, as in nearly all German machines, not to the rear main spar, but to a false spar placed between the rear spar and the trailing edge. The chord of the wings is just under 5 ft. and the gap 4 ft. 3 ins. The result of this small gap is that the top plane is very low over the body, a tendency in German design that is very noticeable of late.
   The engine usually fitted in the Halberstadt chasers is a 120 h.p. Argus 6-cyl. water-cooled. It has overhead valves, which are not, however, operated by an overhead camshaft as in the Mercedes, but by tappet rods and rockers, as in the Benz. The petrol tank, which also serves as a seat, has a capacity of 76 litres (about 17 gallons). The pressure in the tank is maintained by a pressure pump driven off the engine a hand-operated pump being provided for cases of emergency. The petrol service tank, which has a capacity of 18 litres (about 4 gallons), is built into the centre section of the top plane, where are also mounted the radiator and small water tank.


Flight, August 23, 1917.

THE 1916 TYPE HALBERSTADT BIPLANE.

   IN our issue of April 5th, 1917, we gave a description and a number of detail sketches of the construction of the German Halberstadt biplane. These, as well as the drawing showing the machine in flight, were prepared from a very incomplete set of parts, most of which were in a hopeless condition, while the whole nose of the machine and large portions of the wings were missing altogether. Nevertheless, by comparing these sketches with an actual complete machine since captured, it was found that all the particulars then given were absolutely correct. That this is so may be easily verified by referring back to our April 5th issue and comparing the drawing of the machine in the air with the photographs of a captured machine which, thanks to the courtesy of the military authorities, our representative was able to inspect at a home aerodrome a few days ago. The machine has, it may be noticed, been painted with the British identification marks for purposes of testing it over English soil and thus find out if there is anything particularly valuable in its performance which might be of any use to our constructors. Let it be said at once that there does not appear to be any phase of performance or evolution in which this once-upon-a-time much-talked-of machine can hold its own compared with a good British or French machine of the same size and power.
   So far as it is possible to gather, the Halberstadt has almost, if not quite, disappeared from the Western Front, which fact indicates that it is no longer a match for our or our Allies' modern fighters. The machine which has, more than any other, superseded the Halberstadt is the Albatros single-seater with the Nieuport-type wing bracing, illustrated and described in "FLIGHT" of July 12th. It might be objected that the machine of which we publish photographs this week is of a type that is nearly a year old. This we grant, but to the best of our knowledge there is not in existence - or at any rate not in use - a modern Halberstadt. Whether the reason for this is to be sought in so vastly superior a performance by the other makes of German fighters as to cause the German' authorities to concentrate on the production of these, or whether it is due to the Halberstadt in its present form being difficult to alter and improve to such an extent as to bring its performance up to that of the others, is a matter for conjecture. We have heard it said that while the Halberstadts were in use on the Western Front a surprisingly large percentage of those brought down were observed to come to earth in what appeared be our pilots to be a spinning nose-dive.
   If this be so - and we have heard the same remark made by so many independent observers that there can scarcely be any doubt about the correctness of the statement - it rather looks as if the Halberstadt was inclined towards spiral instability. An examination of the photographs tends to confirm this impression. In the first place, the total absence of any fixed vertical surface in front of the rudder, coupled with the fact that the body terminates in a horizontal knife-edge at the rear, at once makes one suspicious as to the adequacy of vertical surface to the rear of the centre of gravity. To make matters worse the body is very deep in front, the vertical surface here being also slightly augmented by a portion of the large water-cooled engine, although in the present machine this is, as a matter of fact, almost totally covered in.
   As to the possible reasons why the performance should be inferior to that of other machines of similar horse-power: The body does not impress one as being of particularly good form for low resistance. This is probably chiefly due to the peculiar way in which the turtle back deck is finished off abruptly at a point approximately half-way between the pilot and the tail. The break in the curve of the top covering is very pronounced at this point, and where high speeds are concerned little things like this soon begin to add up and increase the resistance.
   In regard to the wings, the first impression one receives is that the strutting and wiring is somewhat clumsy, two pairs of interplane struts on each side being scarcely deemed necessary - at any rate, by British and French designers - in a machine of only some 28 ft. span. Again, the wing section gave our representative, from a superficial inspection it is true, the impression of being very deeply cambered for a fast machine, although, without knowing the exact shape of the section and being able to compare it with known sections, it is not possible to pass judgment on this point. It does not, as well-known wing sections have shown, follow that a deeply cambered section may not have a very excellent L/D ratio as well as a good lift coefficient.
   As the Halberstadt has already been described and illustrated with regard to its constructional details, there does not appear to be any reason for elaborating these here. Since, however, the front part of the machine previously described was missing, a few words concerning this part may be of interest. The engine, a 120 h.p. Argus, is, as will be seen from the illustrations, almost totally hidden inside the body, only the top of the cylinders with their valve stems and springs projecting. The exhaust pipes are of a curious formation, looking somewhat like the weirdly shaped freak carrots sometimes deemed worthy of an illustration in the Press. As to the purpose of this writhing mass of tubes, this is not instantly apparent to the uninitiated, one pipe from each cylinder joining one from another, the resultant pipe joining further along its course up with similar ones, the whole to finish in a single outlet to the air.
   The only other feature of the Halberstadt biplane that is of any particular interest is the radiator, which is, as will be seen, mounted in the centre section of the top plane, to the curvature of which it conforms. Certainly this arrangement should make for reduced head resistance, and it may be taken for granted that it has been found in practice to give adequate cooling. That its position is such that, should it be pierced by a bullet, the hot water can hardly fail to give the pilot a liberal sprinkling, may be disconcerting to the pilot, but it is interesting from an aerodynamical point of view.