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

Halberstadt CL IV

   The Halberstadt CL IV was introduced with the vast expansion of the Schlachtstaffeln for the March 1918 offensive to supplement - and eventually supersede - the Halberstadt CL II.
   By this period the Schlastas had become highly organised formations and operated with devastating effect in close support of their own infantry or in breaking up Allied counter-attacks. The effective fighting strength of a Schlasta had not to be less than four aircraft; the actual establishment was six. This number was found to be the maximum for efficient command - or co-ordination - once airborne. They were intended for use only at decisive points of attack, and not squandered singly over the whole front of an attack. Less-important sectors had to dispense with their services. Utmost precision in the time of their attack was necessary. To arrive too soon would draw enemy attention prematurely to the point of the attack; if too late they became a danger to their own advancing troops. Consequently, highly detailed and precise orders were compiled by the German Staff. In attack the prior objective of the "Battle Flights" was to fly ahead of the infantry, straffing, and to keep down the fire of the enemy's infantry and their artillery batteries. Each flight was given a specific target, and there were orders not to abandon this for a more favourable one.
   In defence, as soon as the enemy's preparations indicated an imminent offensive, the Schlastas were ordered in to relentlessly attack and disorganize assembly points in an endeavour to delay or break up the attack. As the infantry battle swayed to and fro the "Battle Flights" were held in readiness until local reserves could be mustered to mount an organised counterattack, to which the air support could be added.
   During the final German onslaught of March 1918 no less than thirty eight Schlachtstaffeln had been formed and were largely equipped with Halberstadt CL II and CL IV aircraft, supplemented by Hannover CL IIIa units. Some twenty-seven of these units were opposed to the British forces.
   Although intended as a replacement for the CL II, the Halberstadt CL IV was not unlike its predecessor in concept, and did not offer much improvement in performance other than in manoeuvrability, which, for the duties required, was a prerequisite quality. The same 160 h.p. Mercedes D III power plant was retained, although the airscrew spinner was omitted, and modified bulbous panels encowled the nose, imparting a more aggressive appearance. As before, the wooden fuselage was ply-skinned and still incorporated the communal cockpit with an elevated gun ring for the observer.
   Horizontal tail surfaces were considerably redesigned, being of greater span and higher aspect ratio than in the CL II. The one-piece elevator was horn balanced, which, together with the shorter fuselage, afforded a much greater degree of fore-and-aft sensitivity and all-round improvement in manoeuvrability.
   The wings were of normal wooden construction as in the CL II, but due to the fuselage being some 3 ft. shorter, it was necessary for them to be repositioned to ensure location of the centre of gravity around the crew compartment. Particular attention was paid to the lower wing/fuselage junction to ensure a smoother airflow over the tail surfaces. No actual fairing was used, but the wing root was washed out, and to achieve this the rear spar had to be both bent and twisted. The upper wing was largely the same as on the earlier machine, with swept outer panels; radiator and gravity fuel tank were located in the starboard and port sides of the centre-section, respectively. The large balanced ailerons were retained at the upper wingtips, operated through torque tubes as before.
   Steel-tube vees of streamline section, with two spreader bars, were employed in the undercarriage chassis and the axle sprung with multiple steel springs. The ash tailskid was hinged to a small underfin, which was added to increase directional stability.
   Provision was made for the mounting of two fixed forward-firing machine-guns, but only one was usually fitted. Anti-personnel grenades in shallow boxes were carried on the fuselage sides, and rows of Very cartridges were often strapped across the rear fuselage decking.
   After the failure of the 1918 offensive when the Allies began to counterattack, the Schlastas came to be used more and more in defensive support of their own infantry instead of in their intended offensive role. Life was indeed very hectic and uncertain in these units and, not being armoured, they had only their manoeuvrability to avoid the small-arms fire to which they were increasingly exposed and to which they so often became victims.
   When not on close-support duties they were used as ordinary two-seat fighters on escort work, and were able to give an extremely good account of themselves when attacked by Allied aircraft. They also found employment towards the end of the war on bright moonlight nights when they attempted to intercept and destroy Allied bombing machines as they returned from their missions. Night sorties against Allied billets and aerodromes were also made. Although these lacked the decisiveness of the daylight attacks, they had a considerable nuisance value and caused many casualties.

TECHNICAL DATA
   Description: Light two-seat C type, ground attack and escort.
   Manufacturers: Halberstadter Flugzeug-Werke G.m.b.H. (Halb.).
   Sub-contractor: Luftfahrzeug Gesellschaft m.b.H. (Rol.).
   Power Plant: One 160 h.p. Mercedes D III 6 cylinder in-line water-cooled engine.
   Dimensions: Span, 10.742 m. (35 ft. 2 7/8 in.). Length, 6.538 m. (21 ft. 5 1/2 in.). Height, 2.67 m. (8 ft. 9 1/8 in.). Area, 27 sq.m. (297 sq.ft.).
   Weights: Empty, 728 kg. (1,602 lb.). Loaded, 1,068 kg. (2,349.6 lb.).
   Performance: Maximum speed, 165 km.hr. (103.12 m.p.h.). Climb, 5,000 m. (16,400 ft.) in 32 min. Duration, 3-3 1/2 hr.
   Armament: One or two fixed Spandau machine-guns forward and one manually operated Parabellum machine-gun in rear cockpit. Anti-personnel grenades and four or five 10 kg. (22 lb.) bombs.

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

HALBERSTADT CL IV Germany

   Early in 1918, the Halberstadter Flugzeugwerke began work on a higher-performance and more manoeuvrable derivative of the CL II. By February the prototype of this CL IV had arrived at Adlershof for its official type test. Lighter than its predecessor as a result of some structural refinement, the CL IV possessed a similar armament and a 160 hp Mercedes D IIIa engine. It passed its type test during March-April 1918, the official report referring to its ‘‘very favourable climb rate and superlative handling qualities”. Commencing in May 1918, a total of 450 CL IVs was ordered from Halberstadt and a further 250 were ordered from the Luftfahrzeug Gesellschaft (Roland). The CL IV supplemented the CL II in the Schlachtstaffeln, and a total of 136 was recorded at the Front on 31 August 1918, deliveries still being under way when hostilities terminated.

Max speed, 104 mph (168 km/h) at 16,405 ft (5 000 m).
Time to 16,405 ft (5 000 m), 32 min.
Endurance, 325 hrs.
Empty weight, 1,605 lb (728 kg).
Loaded weight, 2,354 lb (1 068 kg).
Span, 35 ft 2 3/4 in (10,74 m).
Length, 21 ft 5 1/2 in (6,54 m).
Height, 8 ft 9 in (2,67m).
Wing area, 311.7 sqft (28,96 m2).

J.Herris Halberstadt Aircraft of WWI. Volume 1: A-types to C.III (A Centennial Perspective on Great War Airplanes 44)

Halberstadt CL-Type Specifications
Spec \ Type CL.II Prototype CL.II Production CL.IV
Engine 160 hp Mercedes D.III 160 hp Mercedes D.III 170 hp Mercedes D.IIIa
Span, upper 9.40 m 10.77 m 10.70 m
Span, lower 9.40 m 10.65 m 9.98 m
Chord, upper 1.6 m 1.60 m 1.60 m
Chord, lower 1.30 m 1.30 m 1.30 m
Wing Area 24.0 m2 27.5 m2 26.66 m2
Length 7.32 m 7.30 m 6.50 m (later 6.89 m)
Height - - 2.70 m
Weight empty 701 kg 773 kg 700 kg
Weight loaded 1,071 kg 1,133 kg 1,040 kg
Speed 165 km/h 165 km/h 165 km/h
Climb
1,000 minutes - 3.5 4.3
2,000 minutes - - 5.5
3,000 minutes - - 12.7
4,000 minutes - - 22.1
5,000 minutes - 38 30.8
CL.IV(Rol) Empty Wt. 720 kg, Loaded Wt. 1,060 kg.

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

Halberstadt CL.IV

  Developed from the highly successful Halberstadt CL.II, the CL.IV had a shorter fuselage and lighter weight due to careful attention to detail design and the reduced fuselage size. Powered by the same 170 hp Mercedes D.IIIa inline engine as used in later production CL.II aircraft, the empty aircraft weighed 161 pounds (73 kg) less than the CL.II. Aerodynamics were improved with better streamlining and a new wing section. The Mercedes D.IIIa was generally referred to as an 160 hp engine like the D.III, but had slightly more power due to its refinements and actually produced 165-170 hp.
  The CL.IV first flew in February 1918. It immediately demonstrated excellent climb and maneuverability. The type test was performed between 5-27 March. The load tests took three weeks because the designer, Karl Theis, had submitted three different sets of wings each with a slightly different structure. The strongest wings were chosen for production.
  In April-May Idflieg assigned the first production order for 150 of the Halberstadt CL.IV. An engine shortage delayed production. In May and June, Idflieg reported that comparative flight trials had demonstrated that the CL.IV was the best aircraft in the CL-category. The CL.IV arrived at the front in June 1918 and was reported as "unsurpassed by any CL-aircraft at the front."
  Pilots did report slight pitch instability due to the shorter fuselage. This made the aircraft tiring to fly and less suitable as a gun platform. Halberstadt engineers solved the problem by adding a frame to the tail section, increasing the fuselage length by about 0.4 m (15.7 inches). This longer fuselage was required for the Roland-built aircraft. However, Idflieg delayed making the change in Halberstadt-built aircraft pending evaluation of front-line reports. It is not known if later Halberstadt-built CL.IV aircraft had the extended fuselage.
  An early-production Roland-built CL.IV was static load tested between July 22 and August 14, 1918. Unfortunately, Roland engineers had 'improved' the wing structure and weakened it. The wings had to be built essentially on the original Halberstadt design. Conditional approval was granted for operational service pending a second load test. These were performed between 11-25 September. Minor structural problems were discovered requiring more strengthening. All Roland-built aircraft were delivered with the longer fuselages. All these changes made the Roland-built aircraft 20 kg heavier than Halberstadt-built aircraft.


Halberstadt CL.IV Production Orders
Date Quantity Serials Notes
May 1918 150 4600-4749/18
June 1918 200 5770-5969/18
July 1918 150 8050-8199/18 Roland
August 1918 200 6439-6589/18 Only aircraft in the 6500-6599/18 range have been seen
August 1918 200 9400-9599/18
November 1918 300 Not known Roland, cancelled
November 1918 100 Not known cancelled
3 prototypes normally ordered, one for flight tests, one for static tests, and one spare.



Afterword: Halberstadts Postwar by Colin Owers

<...>
  Some 13 CL.II and nine CL.IV fighters, together with 18 C.V reconnaissance biplanes were taken into US custody and inspected in Europe, but very few made it back to the USA. An inventory of Enemy Material in the USA of 27 August 1919, lists five Halberstadt C types, five Halberstadt C.V and one Halberstadt (spares). One of these was a CL.II as 6312(/17) that was offered for sale without engine for $250 in the 1920s at an Army sale of unwanted aircraft. This particular CL.II had been found in a Zeppelin hangar at Treves in France in an unserviceable condition.
<...>
  The Estonian Aviation Regiment obtained a number of Halberstadts of different varieties as illustrated. C.V 6905/18 was captured at Narva in 1919 and given the Serial No. 9. This was the C.V that was turned into a floatplane. In 1921 four C.V biplanes, four CL.IV (Rol) were purchased from the German stores at Vamdrup in Denmark.
  Amongst the approximate one hundred German aircraft that Lithuania captured or purchased were the following Halberstadt biplanes as tabulated at right.
  Polish Aviation used more than 20 Halberstadt CL.II, CL.IV, and C.V aircraft, which were found at Lawica/Poznan airfield after the end of WWI. The biggest part were remnants from the German Fliegerersatz-Abteilung 4 Posen and smallest come from Mokotow / Warszawa, ex German Fliegerbeobachterschule Warschau and Albatros-Militar-Wekstatten (REFLA) Warschau. Thirteen Halberstadt CL.IIs and CL.IIAs were refurbished at Poznan (most received new Polish numbers) and two were refurbished at Warsaw/Mokotow. All went to Squadrons at the front or to flying schools. Four Polish Halberstadt CL.IIs were lost during the Polish-Russian war. All Polish Halberstadt CL.IVs came from Lawica (two had Mercedes D.III engines and one (C.5894/18) had a Benz Bz.IV engine) and were used by 2 EW and 14 EW squadrons. One of them was captured and used by Russia, one was lost in Germany after the war (pilot got lost and crashed during a storm). All twelve Polish Halberstadt C.Vs were refurbished at Lawica. Most of them were from BFW production. Most were used during the Polish-Russian war in 2. Eskadra Wielkopolska. One aircraft, C.V C.8843/18, mounted a carrier for four 12.5 kg P.u.W. bombs. At least three Halb. C.Vs were lost during the Polish-Russian war and one fell into Russian hands.
  Soviet Russia used a number of Halberstadt types either captured during the Civil War and following conflicts, or purchased in the 1920s. Halberstadt CL.IV and C.V biplanes are known to have carried the Red star of the Soviets.
  Switzerland purchased Halberstadt C.V (DFW) 4146/18 via the IAACC in January 1920, and entered service with the Swiss air force as Serial 704. This machine was used mainly for high altitude training flights, however the lack of spares caused the Halberstadt to be withdrawn in June 1921 after only about 20 flying hours. It was then scrapped. Three Halberstadts also came onto the Swiss civil register. CH68 was registered as a CL.II but was a modified CL.IV with two-bay wings; two C.V biplanes were CH72 and CH85.
  As mentioned above, none of the Halberstadts that were taken to the USA after the war survived. However, now the National Museum of the USAF and the NASM Smithsonian Museum each display a Halberstadt CL.IV. How this came about is a remarkable story that has to go back to the end of the war when Paul Strahle was demobilized from the German Army Air Service. Credited with 14 victories, Strahle was a competent airman and purchased a number of surplus Halberstadt CL.IV airframes and spares from Hellmuth Hirth, the famous pre-war flyer. The actual number is unknown but included at least four. Luftverkehr Strahle was formed in 1919 and included civil conversion of the CL.IV that had a cabin over the rear cockpit for two passengers while the pilot's cockpit was unaltered. D.71, D.111 and D.144 were registered to the airline. From 1921 to 1923 he flew from Stuttgart to Constance, thence to Nuremberg. With the Depression Strahle performed aerial photography, this business lasting until 1938. D.71 was preserved along with the remaining stock of fuselages, wings, etc., in a barn. D.71 was placed on display in the Daimler-Benz Museum in 1960 until 1995 when it was restored by the staff of the Deutsches Technik Museum (MVT), Berlin. At this time, it was restored to its original colours, having previously been displayed in an inaccurate blue and white colour scheme. After negotiations, in 2004 D.71 was moved to a new museum in Schorndorf dedicated to three local technical pioneers, Strahle being the aviation pioneer.
  In the 1980s Strahle looked to have the aircraft restored. Not being able to raise any interest in Germany the airframes, etc., were purchased by Ken Hyde and Stan Parris and brought to the USA for restoration. They were traded to the USAF Museum for six surplus North American T-28 trainers. The USAF Museum did not have any genuine WWI German aircraft in its collection at this time. An arrangement was reached between the USAF Museum, the NASM and the MVT to restore three airframes. They were shipped to Berlin in 1989. Enough parts of D-IBAOD (formerly D.144), including the fuselage in two parts, enabled the machine to be restored as Strahle's aircraft as used for his photographic flights. This machine is now displayed in the MVT in Berlin. The USAF Museum's example was completed as an aircraft of Schlachtstaffel 21, a unit that had operated against US forces during the Chateau Thierry offensive in France. The Smithsonian's CL.IV was built by Roland under license and the original colors could be determined, including the fact that the serials were painted in light blue and not white as always thought. This machine required more work than the other two but enough material was available to enable a splendid restoration to be carried out.
<...>

M.Dusing German Aviation Industry in WWI. Volume 1 (A Centennial Perspective on Great War Airplanes 84)

Halberstadter Flugzeugwerke GmbH, Halberstadt (Halb)

Aircraft Development:

<...>
  As a further development, the Halb CL.IV type was created. This aircraft was even more maneuverable than the CL.II and reached 5,000 m in 31 minutes during competitive flights at Adlershof. The speed in straight flight was stated at 175 km/h at the time.
<...>

M.Kabatek, Fr.R.Kulczynski German Aircraft in Polish Service. Volume 1

Chapter 3: The Halberstadt CI.IV

  The first front-line successes of the Halberstadt Cl.II aircraft prompted the designers of Halberstadter Flugzeugwerke GmbH to start working on an improved model with better flying characteristics and maneuverability. The new type was designated Halberstadt CI.IV. The prototype was first flown in February 1918. In the same month, type tests (Typenprufung) began. Static testing of the airframe was completed between 5 and 27 March 1918.
  By shortening the fuselage of the Halberstadt CI.IV by 76 cm compared to the Cl.II, it was possible to reduce the empty weight of the airframe by 73 kg, which translated into a significant improvement in the rate of climb and maneuverability. An order for a pre-production batch of 150 Halberstadt CI.IV biplanes was placed by Idflieg at the turn of April 1918. The first machines were delivered to front line units in June, quickly acclaimed as the best in the Cl-class.
  The main shortcoming of this aircraft was its insufficient longitudinal stability (a side effect of the shortening of the fuselage), which made the aircraft more demanding to fly. Attempts were made to remedy this by adding a frame to the tail section thereby extending the fuselage by 40 cm. This modification was to be introduced on the aircraft built under license by the Luftfahrzeug Gesellschaft mbH, while the parent factory was to await initial feedback from combat crews before implementing it.
  As of 31 August 1918, a total of 136 Halberstadt CI.IV aircraft were in use with combat units. Although they were used extensively for close ground support, losses suffered by the units were surprisingly low. By the end of hostilities, Idflieg had placed seven production orders for a total of 1,300 machines. Ultimately, at least 837 were built, including 348 at the Luftfahrzeug Gesellschaft mbH factory.
  Only three Halberstadt CI.IV biplanes were used in the Polish air service. At various times they were used by the Stacja Lotnicza Lawica, 2. EW, 14. EW, 3. Pulk Lotniczy (3. PL - 3rd Air Regiment, formed on 29 August 1921 at Lawica), and WSP in Grudziadz. The last one was operated until the second half of March 1923.


Halberstadt CI.IV 5894/18

  The aircraft was probably captured on 2 January 1919, at the airship hangar in Poznan. It appears for the first time in surviving documentation on 21 January 1920 (at the time it was at the workshops of the Stacy a Lotnicza Lawica).
  On 7 April 1920, it was sent to the 2. EW based at Rivne. It reached the unit on 16 April. Unfortunately, it was lost during its first sortie:
  - 20 April 1920 - duty/combat sortie. Crew: sierz.pil. Stefan Niewitecki and ppor. obs. Jan Zardecki. Summary: crosscountry flight to Zviahel (the aircraft landed at 12:00), and subsequently a cross-country flight to Berdychiv. During the flight, the machine was hit by ground fire and made a forced landing. The crew was captured by the Soviets, but managed to escape from captivity.
  In May 1920, the aircraft was found by Polish troops and sent to the Stacy a Lotnicza Lawica. It was included in the listing of aircraft assembled at Lawica in June 1920.
  5894/18 was transferred from the 3. PL to the WSP in Grudziadz on 3 August 1922. The aircraft was lost in an air crash on 24 March 1923. The accident was caused by an engine failure and pilot error (after the engine stopped, the pilot allowed the aircraft to suddenly lose speed and enter a spin). Por.pil. Stanislaw Chlopecki, an instructor of the WSP in Grudziadz, was killed, and szer. Leon Michalski, who was a passenger, was seriously injured.


Halberstadt Cl.IV (525/18)

  This aircraft was probably purchased in Germany in the summer of 1920. Initially, it went to the Stacja Lotnicza Lawica. It appears for the first time in surviving documentation on 22 May 1921 - at the time it was in the inventory of the 14. EW based at Grudziadz.
  The aircraft was destroyed in an air crash on 4 June 1921. While flying in bad weather, the crew of por.pil. Stefan Berezowski and por. obs. Mieczyslaw Danecki lost their bearings and made an emergency landing in Germany. The aircraft overturned upon touchdown and por. Danecki suffered a serious head injury, from which he died two days later. Parts of the aircraft were brought back to Poland and struck off charge.


Halberstadt Cl.IV (w/n 1770)

  This aircraft was probably captured on 2 January 1919, at the airship hangar in Poznan. It appears for the first time in surviving documentation on 7 April 1920 (that day it was transferred from the Stacja Lotnicza Lawica to the inventory of the 2. EW). It reached the unit, based at Rivne, on 16 April. Presumably it was damaged during a test flight and transferred for repairs to the II RPL on 26 April. In July 1920, it went, less its engine, to the CWL. Its repair was not undertaken, however, and it was struck off charge.



Halberstadt CI.IV Aircraft in Poland
German Serial Type and Manufacturer Works number Polish serial Code number Engine type (works number)
5894/18 CI.IV no data none none Benz Bz.IV (34127, 35266)
Mercedes D.III (33123)
no data C1.IV no data 525/18 none Mercedes D.III (34145)
no data C1.IV 1770 none none Mercedes D.III (37272)

Журнал Flight

Flight, December 12, 1918.

THE HALBERSTADT TWO-SEATER TYPE C.L. IV
[Issued By Technical Department (Aircraft Production), Ministry of Munitions]

   THIS machine, which is allotted G/5Bdr./22, landed near Chipilly on August 23rd, 1918. Dates stamped on the main planes give the date of construction as July, 1918.
   It is very similar in design and construction to the C.L. II type, which has already been fully reported upon (see issue of "FLIGHT" for October 10th), but many detail differences are incorporated.
   Below is a comparative list of the principal dimensions of both C.L. II and C.L. IV types :-

   C.L. IV C.L. II
Span of upper plane 35 ft. 2 1/4 in. 35 ft. 3 1/4 in.
Span of lower plane 34 ft. 9 1/4 in. 34 ft. 11 in.
Chord of upper plane 5 ft. 2 5/8 in. 5 ft. 3 1/4 in.
Chord of lower plane 4 ft. 3 1/2 in. 4 ft. 3 1/2 in.
Gap, maximum 4 ft. 4 in. 4 ft. 0 in.
Gap, minimum 4 ft. 0 in. 3 ft. 8 1/2 in.
Dihedral angle of lower plane 2 deg. 2 deg.
Horizontal dihedral of main planes 4 deg. 4 deg.
Total area of main planes 308 sq. ft. 310 sq. ft.
Area of each aileron 12 sq. ft. 12 sq. ft.
Area of aileron balance 2.0 sq. ft. 2.0 sq. ft.
Area of tail planes 16 sq. ft. 13.6 sq. ft.
Area of elevator 13.6 sq. ft. 12.4 sq. ft.
Area of fin 11.4 sq. ft. 6.4 sq. ft.
Area of rudder 7.9 sq. ft. 7.9 sq. ft.
Area of rudder balance 1.0 sq. ft. 1.0 sq. ft.
Horizontal area of body 36 sq. ft. 44 sq. ft.
Vertical area of body 41 sq. ft. 52.8 sq. ft.
Length overall 20 ft. 11 1/2 in. 24 sq. ft. 0 in.
Engine 180 Merc. 180 Merc.
Capacity of petrol tanks 34 galls. 34 galls.
Capacity of oil system 4 galls. 4 galls.
Crew Two Two
Guns One fixed and one movable

Wings
   The wings, both in disposition and construction, are substantially the same as in the former machine. The characteristic wash-out at the root of the lower planes is even more pronounced than was the case in the C.L. II machine. It will be seen from photograph A that the rear spar is bent and twisted by this wash-out. The exact shape of the trailing edge of one of the lower planes is shown in the scale drawings.
   Fig. 1 gives a section of the upper wing drawn to scale, and Fig. 2 a comparison of the upper aerofoil of the C.L. IV with the R.A.F. 14 section, which is dotted. From Fig. 1 it will be noticed that the 3-ply surrounds to the spars are still employed. They are drawn to scale in Fig. 3.
   The ailerons remain unaltered in the C.L. IV machine, and this is also true of the interplane and centre section struts.
   The attachment of upper wings to centre section and of lower wings to fuselage are unaltered, except that the tube which, in the earlier machine, passed right across the fuselage and connected the spars of the port and starboard lower wings is no longer found. Its place is taken by two fuselage fittings of the type shown in Fig. 4.

Fuselage
   Although the fuselage of the C.L. IV machine is very like that of the C.L. II type, the machine now being described has a body which is practically 3 feet shorter than that of the earlier machine.

Tail planes and Skid
   It is in these components that the greatest differences between the two types are found. The tail plane is now in one piece, and is laid across the rear of the fuselage, and attached there by the bolts shown in Fig. 6. The undivided elevator is now balanced, and the aspect ratio of the whole horizontal tail is larger than was the case in the earlier model. Besides this the actual area is greater. (It has been remarked that the C.L. IV body is 3 feet shorter.)
   The fin and rudder were not salved, and comparison is therefore not possible, but it is clear from the fuselage design that the fin is a separate unit simply attached to the body, and not an integral part of it. It is also established that the rudder post is now found in the same vertical plane as the leading edge of the elevator. It will be remembered that the rudder post, in the C.L. II type, was fixed more than a foot forward of the elevator fulcrum.
   The inverted camber of the C.L. II tail plane is now abolished, and a symmetrical camber substituted, and the rather elaborate tail skid of the earlier model has been simplified to the type found in the modern L.V.G. biplanes. In this type the skid is entirely exposed, and is pivoted on the lower edge of a small triangular fin under the tail plane. (See photograph and general arrangement drawings.)

Undercarriage
   The landing gear is substantially the same as in the C.L. II machine, but, as may be seen in Fig. 5, two compression tubes now run parallel to the axle, instead of one, as before.

Fittings
   The gun ring has been additionally stayed in front, but otherwise remains the same. It was fitted with a Parabellum gun.
   Two fixed guns of the Spandau type are arranged for, one each side of the camshaft, but only the one on the starboard side was fitted at the time of capture.
   A ten-loop Very cartridge belt is tacked to the top of the fuselage just behind the cockpit - it may be seen in the photograph - and a total of twelve light hand grenades may be carried in the wooden racks, one of which may be seen on either side of the fuselage.
   The practice of enclosing the control wires in the cockpit is still continued, but aluminium shields are used instead of the more permanent three-ply construction.
   The machine is internally wired, but no wireless apparatus was on board at the time of capture. The dynamo bracket is no longer to be found alongside the engine, but is now on the front port undercarriage strut, and is driven by a propeller.
   The pilot's seat is a shallow three-ply bucket, which rests on two cross pieces of wood supported on ribbed brass strips sweated to the top of the petrol tank, thus providing a fair amount of adjustment. This is the subject of a sketch (Fig. 7).
   The fabric is throughout of the usual colour-printed type.

Schedule of Weights, Halberstadt, C.L. IV.
   lbs. ozs.
Body, with undercarriage, engine,
   Spandau gun, petrol tank, gauges, and
   controls 1220 0
Engine (dry), 180 Mercedes 635 0
Upper wing, complete (no bracing wires) 70 8
Lower wing, complete (with bracing wires) 64 0
Centre section, complete (with struts and
   wiring) 108 8
Gravity petrol tank 11 4
Radiator 36 0
Centre section strut (Vee) 5 3
Centre section strut (straight) 2 4
Interplane strut (front), with cable 4 8
Interplane strut (rear), with cable 4 0
Undercarriage, complete, approximately 112 0
Shock absorber (one) 4 6
Axle, with bobbins and caps 14 8
Wheel, complete with tyre 20 4
Tyre and tube 8 12
Leading spar of wings (per foot run) 1 4
Trailing spar of wings (per foot run) 0 14 1/2
Tail plane and elevator (covered) 25 0

   The aeroplane is in the Enemy Aircraft View Rooms, Islington, and may be seen on production of a pass, to be obtained by writing to :- The Controller, Technical Department, Ap.D. (L.), Central House, Kingsway, W.C. 2 .