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

Siemens-Schuckert D I
  
   Siemens-Halske O.H. was founded in 1847 to manufacture telegraphic equipment. It was not until 1873 that the more famous Siemens-Schuckert Werke title was adopted on the merging with the Schuckert works of Nurnberg to form the giant electrical combine.
   The firm made a tentative excursion into the aircraft manufacturing field in 1907, when a non-rigid military airship was constructed at the request of the German General Staff. From 1909 to 1911 three original aircraft were built, the last bearing a close resemblance to the Bleriot monoplanes. Interest in aircraft manufacture then ceased until 1914, when, in response to urgent requests for aeroplanes from the German military forces, the aircraft department was reopened on a new footing under the direction of Dr. Walter Reichel, assisted by Dr. Hugo Natalis, Wolff, the Steffen brothers (Franz and Bruno) and Forssman.
   Initially "Giant" R (Riesenflugzeug) aircraft were designed and built, apart from the "Bulldog" monoplane, but towards the end of 1915 appeared the S.S.W. E 1, a neat shoulder-wing monoplane. It was accepted by Idflieg (Inspectorate of Flying Troops), and a small batch was built to bolster supplies of Fokker and Pfalz monoplanes. At this time the first French Nieuport scouts were enjoying a considerable success on the Western Front, and as there was no immediate prospect of Germany having a superior machine forthcoming, Idflieg requested the Albatros, Euler and S.S.W. firms to produce quickly an improved copy of the Nieuport as a means of obtaining parity with their opponents. Captured Nieuports were supplied to the firms as models, but Albatros did not make such a close copy of the French machine as did Siemens-Schuckert. Their machine closely resembled the Nieuports XI and XVII, differing noticeably only in the engine installation and, later, the tailskid arrangement. In October 1916 Bruno Steffen climbed to an altitude of 5,000 m. in 45 min. on the prototype Siemens-Schuckert D.I.
   The D.I was accepted for production, and on 25th November 1916 an initial order for 150 machines was placed. Production was somewhat tardy, airframes being held up for their engines-which were by way of being something new in geared rotaries-and a later order (21st March 1917) for 100 machines was cancelled, as it was found that by mid 1917 performance of the S.S.W. D.I was no longer up to requirements. Eventually only 95 aircraft of the original order were completed; 22 by the Berlin factory and 73 at Nurnberg. A further 55 uncovered airframes were delivered to Adlershof.
   Power unit of the D.I was the Siemens-Halske Sh.I geared rotary, which had been developed by yet another branch of the Siemens combine. This was an engine of considerable mechanical ingenuity, in which the crankcase rotated in one direction at about 900 r.p.m. and the crankshaft in the opposite direction at the same speed, thereby achieving a virtual engine speed of 1,800 r.p.m. for an airscrew speed of only 900 r.p.m. This resulted in greater propeller efficiency. The engine was mounted in an open-fronted horse-shoe-type cowling, which incorporated a front bearer spider and was cut away almost completely in the lower half to allow free escape of exhaust. The fuselage, based on four main longerons, was a slab-sided braced box-girder. The top decking was rounded both fore and aft of the cockpit, with light formers and stringers. With the lower longerons being set closer together than the upper pair, the sides tapered in, exactly as in the Nieuport model The foremost bay of the fuselage sides was covered with slightly bulged metal panels, which were embossed with large vertical ventilation louvers, the remainder was fabric covered.
   Tail surfaces were all of steel-tube framing and fabric covered, the trapezoidal tailplane and unbalanced elevators being mounted directly on top of the top longerons. The balanced rudder was hinged to the sternpost and was of flattened comma profile. At a later date the underside of the tailplane was braced to the lower longerons with two steel-tube struts on either side.
   The sesquiplane layout and swept-wing plan form of the original French machine was retained, although the center panel of the upper wing was simplified somewhat and the four center-section struts were vertical in both side and front views. The wings were a normal braced structure based on two (upper) and one (lower) box spars; ribs in the upper wing panels being strengthened where necessary to act also as compression members. Ailerons were of light-gauge steel tube and of inverse taper; they were operated through a torque tube connected to bell cranks in the center section. Both interplane and center-section struts were of steel tube enclosed with wooden fairings.
   A conventional vee-type undercarriage chassis was fitted, made up from streamlined steel tube and with the axle sprung with elastic shock cord. A hockey-stick type tailskid, pivoted about the lower longerons and internally sprung, was fitted to the first machines. Later the arrangement was modified and the tailskid attached to an inverted steel-tube pylon.
   A further modification to the later production aircraft was the enclosing of the airscrew hub in a large pointed spinner, which considerably enhanced the lines of this already elegant aeroplane even though it did not materially improve its performance.
   The only subsequent development of the S.S.W. D.I was a single D.Ia D3768/16, which had an increased wing area totaling 15.7 sq.m. Of the two D.Ibs which had one-piece upper wings, D1230/17 had a further increase in total area to 16.2 sq.m., and D1231/17 was fitted with a high compression Sh I engine, developing about 140 h.p. Area was again increased, to 19.2 sq.m., in an endeavor to achieve a good climb and altitude performance.
   Many of the S.S.W. D.Is were used by the flying schools, although small numbers appeared on the Western Front with Jastas 1-5 and 7, 9, 11 and 14. Two machines were delivered to the "Armee-Flugpark Sud"
  
  
Description: Single-seat fighter.
Manufacturer: Siemens-Schuckert Werke G.m.b.H. Siemensstadt, Berlin und Nurnberg (Ssw.).
Power Plant: One 110 h.p. Siemens-Halske Sh I 9 cylinder geared rotary engine.
Dimensions:
   Span 7.50 m. (24 ft. 7 3/8 in.)
   Length 6.0 m. (19 ft. 8 1/4 in.)
   Area 14.4 sq.m. (155.52 sq.ft.)
Weights:
   Empty 430 kg. (946 lb)
   Loaded 675 kg. (1,485 lb.)
Performance:
   Max speed 155 km.h. (96.875 m.p.h.)
   Climb to
   1,000 m. 3.5 min
   2,000 m. 8.0 min.
   3,000 m. 14.5 min.
   4,000 m. 24.3 min.
   Duration 2 1/3 hr.
Armament: One fixed Spandau machine-gun firing forward.
   Later twin machineguns were fitted.
  
  
Siemens-Schuckert D Ia
   This machine differed little from the production D I, and when orders for that machine were cancelled development of the D Ia was discontinued. Only one was built, No. 3768/16. It had reduced gap and increased area as compared with the D I; the undercarriage differed slightly and the tailskid arrangement noticeably. Engine, 110 h.p. Siemens-Halske Sh I. Span, 7.5 m. (24 ft. 7 3/8 in.). Length, 6.0 m. (19 ft. 8 1/4 in). Area, 15.7 sq.m. (169 sq.ft.). Weights: Empty, 430 kg. (946 lb.). Loaded, 640 kg. (1,408 lb.). Speed, 140 km.hr. (87.5 m.p.h.). Climb, 4,000 m. (13,120 ft.) in 25 min. Duration, 14 hr. Armament, twin Spandau machine-guns.

J.Herris Siemens-Schuckert Aircraft of WWI (A Centennial Perspective on Great War Airplanes 12)

SSW D.I

   During the spring and summer of 1916 the Nieuport 11 and D.H.2 biplanes wrested air superiority from the Fokker and Pfalz monoplanes due to their superior performance and maneuverability. Since the new Halberstadt, Fokker, and Albatros biplane fighters had barely started to arrive at the Front and had not yet proved themselves, Idflieg decided that one way to quickly redress the balance would be to produce improved copies of the Nieuport fighters, which clearly had more performance and development potential than the D.H.2 pusher. Idflieg therefore provided captured Nieuport fighters to the Albatros, Euler, Fokker, Pfalz, and Siemens-Schuckert companies and encouraged them to create new fighters based on Nieuport technology.
   Albatros adapted the Nieuport sesquiplane wing design to their new D.II fighter to develop their Albatros D.III and later D.V and D.Va fighters. Pfalz adopted the wing planform for their D.III fighter but retained the stronger two-spar lower wing, avoiding the structural problems experienced by Nieuport and Albatros. Euler produced a near copy of the Nieuport, while Fokker pursued his own designs. Siemens-Schuckert, already involved in building giant bombers, chose to reduce development time by producing a near copy of the Nieuport.
   Other than its use of a 9-cylinder, 110 hp Siemens-Halske Sh.I rotary engine, the SSW response, designed by Franz Steffen shortly before his fatal crash in the E.II and designated the SSW D.I, was essentially a copy of the Nieuport 17. The engine cowling and propeller differed from the Nieuport due to the different engine. The slow-turning Sh.I enabled a larger, more efficient propeller to be used, which in turn required a longer undercarriage for clearance. The Sh.I also required front bearing supports in the cowling. The center section appeared a little more compact with slightly reduced gap between the wings, giving the SSW D.I a more aggressive appearance than the Nieuport. Wing area was slightly less than the Nieuport original, and a single synchronized Spandau machine gun was mounted just to the right of centerline ahead of the pilot. After the first few production machines were built, a spinner was added to improve streamlining.
   The prototype SSW D.I, 3503/16, was first test flown between 4-10 October 1916 by Bruno Steffen; during tests it climbed to 5,000 meters in 45 minutes, a reasonable performance for the time. The Typenprufung (type test) was flown on October 26, 1916 and the SSW D.I was accepted pending successful static load testing. The second D.I, 3504/16, was tested to destruction during 25-27 January 1917.
   A total of 250 D.I aircraft were ordered, the initial order (206615 Kr.16) for 150 being placed on November 25, 1916 and the second order for 100 aircraft (371724 Kr.17) on March 21, 1917. The order dates, Siemens order numbers, quantities, and associated military serial numbers are given in the table.
   However, only 95 of the original order were completed (22 at Berlin and 73 at Nurnberg) as production was seriously delayed by slow engine deliveries. In the meantime the Albatros D.II and D.III, with their more reliable and powerful engines and twin Spandau guns, had demonstrated their superiority. Therefore SSW D.I production was terminated by Idflieg in July 1917. The Nurnberg plant shipped an additional 55 partially completed airframes to Adlershof for instructional use in aviation mechanics' schools.
   Photographs show the various D.I production batches had some distinguishing features:
- Prototype: No louvers, no spinner, straight tailskid, light plain finish, no camouflage. Small crosses on white fields on top wing surface, underneath lower wing surface, and on fuselage. Cross on rudder also on white field. Engine air intake on starboard side
- Early Production: Four louvers, no spinner, fabric covered center section of top wing, curved tailskid, three-color camouflage, crosses on white fields, crosses under upper wings, engine air intake on port side, rigging diagram on port side below cockpit.
- Mid-Production: Three louvers, spinner, plywood covered center section of top wing, curved tailskid, two-color camouflage, crosses with borders, no crosses under upper wings, engine air intake on starboard side.
- Late Production: Three louvers, spinner more sharply pointed than earlier spinner, plywood covered center section of top wing, outer-braced tailskid, two-color camouflage, crosses with borders, no crosses under top wings, engine air intake on starboard side.
   The SSW D.I was used only in small numbers and no Jasta was ever fully equipped with the type. Units which received the SSW D.I included Jastas 1, 2, 3, 4, 5, 7, 9, 11, and 14, two went to Armee Flugpark Sud in Galicia. The D.I had excellent flying qualities (Lt. Kurt Student praised it as having the best flying qualities of any fighter at the front at that time) but modest performance, so many were delivered to fighter schools.

SSW D.l Development

   A number of modifications were tried to improve D.I performance, including enlarged wing area and up-rated engines. D.I 3576/16 was tested with a Siemens-designed supercharger, making several successful factory flights in August-September 1918 before going to Adlershof for additional testing. Three aircraft with more wing area were built at the Berlin factory. First was SSW D.Ia (3768/16) with two guns and 15.7 m2 wing area,- delivered in July 1917, it had an empty weight of 430 kg and reached 4,000 meters in 25 minutes. There were two variants of the D.Ib, both with two guns, one-piece upper wings, and a length of 6 meters. The first D.Ib, 1230/17, had a span of 8.7 m, wing area of 16.2 m2, empty weight of 410 kg, and reached 5,000 meters in 29.8 minutes. The second D.Ib, 1231/17, had a larger wing spanning 11.1m with 19.2 m2 wing area, empty weight of 430 kg, and an over-compressed 140 hp Sh.Ia engine. It demonstrated excellent climb, reaching 5,000 meters in 20.5 minutes, less than half the time required by the D.I.
   Despite its excellent climb, the D.Ib was not fast enough to see production in late 1917. The basic Nieuport sesquiplane configuration had reached the limit of its development potential, and subsequent SSW fighters featured conventional two-spar wings and the more powerful 11-cylinder Sh.III engine.
   The proposed D.Ic, a parasol monoplane with 8.2 meters span, 560 kg empty weight, and 160 hp Sh.III engine remained a project, but inspired the later SSW D.VI parasol monoplane fighter.


SSW D.I Production Orders
Order Date Siemens # Quantity Military # Notes
25 Nov. 1916 9733 1 D3503/16
25 Nov. 1916 9762 4 D3504-3507/16
25 Nov. 1916 9772 6 D3508-3513/16
25 Nov. 1916 9798 122 D3514-3635/16
25 Nov. 1916 9777 16 D3552-3767/16
25 Nov. 1916 9866 1 D3768/16 D.Ia
21 March 1917 9899 1 D1230/17 D.Ib
21 March 1917 9916 1 D1231/17 D.Ib
21 March 1917 9922 98 D1232- 1329/17 D.Ib, not built
A total of 250 D.I aircraft were ordered, the initial order (206615 Kr.16) for 150 being placed on 25 November 1916 and the second order for 100 aircraft (371724 Kr.17) on 21 March 1917.

M.Dusing German Aviation Industry in WWI. Volume 2 (A Centennial Perspective on Great War Airplanes 85)

Siemens-Schuckert-Werke, Abt. Flugzeugbau, Siemensstadt b. Berlin (SSW)

Aircraft Development:

Siemensstadt:

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  Siemens-Schuckert-Werke achieved its first major successes with the development of a single-seater based on the Nieuport model - the SSW D.I with a 110 hp Siemens- Halske Sh.I rotary engine. This type was accepted by Idflieg in August 1916 and an order was placed for the delivery of 150 + 250 aircraft, of which, however, only 95 were realized, as the Army administration wanted the development of an aircraft with improved performance using a 160 hp Siemens- Halske engine (Sh.III).
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Transformatorenwerk Nuremberg

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  In October 1916, an order for the production of 6 Nieuport-type "D.I" biplanes was placed on a test basis by the Inspectorate of Aviation Troops (Idflieg), and the monthly output was increased somewhat. Towards the end of 1916, another order was placed, initially for the accelerated completion of 150 units with Siemens rotary engines. Parallel to this, as already mentioned, the factory premises were expanded by May 1917.
  In the meantime, the series production of the D airplanes, which had been developed in the rooms of the transformer plant during the months of January to the end of April 1917 and which amounted to 15 units per month, and which was brought to the required level of 50 airplanes per month in June, had to be aborted suddenly, since the type had been classified as obsolete in the meantime. The biplane, now in series production, met the same fate. The existing contract for the delivery of 100 aircraft and the current order were cancelled, so that only the parts already manufactured could be accepted.
  As compensation for the cancelled contracts, Idflieg offered Siemens-Schuckert Werke in Nuremberg to turn its attention to aircraft repair. The monthly output was set at 30 to 40 B- or C-type Albatros or LVG aircraft. Although an average of 25 repair orders were still received at the plant between June and July 1917, it soon became apparent that the existing workshop capacity was underutilized. In September, only 18 repair aircraft were delivered, and in October through December 1917, an average of only 5 to 6 aircraft were delivered. For this reason, Idflieg, in order to again keep the plant fully occupied, placed a new series order on Alb C.IIIs and additionally contracted the company to repair SSW aircraft built at the parent company.
  Although the Transformatorenwerk was able to absorb a large part of the workforce of the aircraft construction department as a result of the constantly changing order situation, it could not be avoided that a large part of the employees of the aircraft construction department had to be furloughed or laid off for several weeks.

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

SIEMENS-SCHUCKERT (SSW) D I Germany

   The debut of the Nieuport 11 on the Western Front came as a serious blow to Germany, and, with no immediate prospect of a superior fighter forthcoming from the German aircraft industry, the Idflieg requested Albatros, Euler and SSW to produce improved copies of the Nie 11 with the utmost urgency. The SSW version, designed by Franz Steffen shortly before his death in the E II, was powered by a 110 hp Siemens-Halske Sh I rotary and armed with a single synchronised 7,9-mm LMG 08/15 machine gun, but was in most other respects virtually identical to the French fighter. In October 1916, Bruno Steffen, brother of the designer, made a noteworthy climb to 16,405 ft (5 000 m) in 45 min in the prototype of the SSW version of the Nie 11, and, on 25 November, a contract was placed for 150 aircraft under the designation D I. In the event, production tempo was slowed by delays in deliveries of the geared rotary engine, and as, by mid 1917, the SSW D I had been overtaken in performance by other types, only 95 were completed (the remaining 55 airframes being delivered uncovered to Adlershof). An order for a further 100 placed on 21 March 1917 had meanwhile been cancelled. Only small numbers of SSW D Is appeared on the Western Front, most being assigned to flying schools. Attempts to improve the basic fighter resulted in a single D Ia and two D Ib aircraft. The D Ia featured a twin-gun armament and a 14-sq ft (1,30-m2) increase in wing area, and the D Ib’s had one-piece upper wings, one having a further increase in wing area to 174.38 sq ft (16,20 m2) and the other having a high-compression version of the Sh I engine affording 140 hp and enabling the fighter to attain 16,405 ft (5 000 m) in 20.5 min.

Max speed, 96 mph (155 km/h).
Time to 3,280 ft (1 000 m), 3.5 min.
Endurance, 2.3 hrs.
Empty weight, 979 lb (444 kg).
Loaded weight, 1,442 lb (654 kg).
Span, 24 ft 7 1/4 in (7,50 m).
Length, 19 ft 8 1/4 in (6,00 m).
Height, 8 ft 5 7/8 in (2,59 m).
Wing area, 155 sqft (14,40 m2).

Журнал Flight

Flight, September 26, 1918.

A NEW GERMAN "CHASER."
THE SIEMENS-SCHUCKERT BIPLANE.

   THE following is a translation of an article published in Le Matin of August 18th :-
   "The reverses which the Germans have suffered with their 'chasers,' which since last March have been very much inferior to those of the Allies, have led them to venture into new designs.
   "Some time ago we have remarked upon the new Fokker D VII biplane, whose fighting value is far below that of the Allies' fighting 'planes. Our enemies have also put into service the Halberstadt C II fitted with a 160 h.p. motor (Mercedes). They hoped to make a record with this machine, but they were forced to recognise that the relatively slow speed of the machine - 165 kilometres per hour - its great weight of 45 kgs. per square metre of carrying surface, made it inferior to our machines in speed and handiness.
   "For some little time the Germans have placed in their fighting squadrons a few of the new Siemens-Schuckert biplanes, fitted with a rotary motor, eleven cylindered, and giving 260 h.p.
   "The Siemens-Schuckert workshops which are producing this new chaser also construct large bombing machines of the Lizenz type with three or five motors.
   "This 'chaser,' with a span of 7 metres and 6 metres in length, is short and squat in appearance. To obtain stability it has been necessary to fit a fixed plane to the tail, and to have an elevator of large dimensions.
   "The upper and lower planes are of the same span, and balanced ailerons are fitted to both planes. The upper plane is rectangular in shape; it is made in one piece, but cut away to allow the pilot a better view. The lower plane is staggered to the rear, but it is of smaller chord than the upper wing.
   "The rotary motor of 260 h.p. moves a four-bladed propeller after the English fashion. Certain 'planes of the same type are fitted with the modified 260 h.p. Mercedes.
   "The armament consists of two machine-guns firing together or separately, through the propeller.
   "The Germans say that this aeroplane is very easy on controls and that it 'stunts,' and in particular 'cartwheels' and 'loops' with surprising ease. They also say that its climbing speed is excellent, and that it climbs to 6,000 metres in 15 minutes. They have said the same of their Pfalz, their Fokkers, and their Halberstadts, that one is tempted to believe that they take their ideals for realities!
   "But what must be remembered is the haste with which the Germans have tried to invent and to construct new machines in order to recover a little of the prestige of their air services which has been in a bad way for the last six months. The construction and transport has not been without difficulty. Witness the orders for the 40th Division :-
   "'The slowness which is found in the replacing of aeroplanes and in the repair of existing machines, and the everincreasing difficulty of recruiting the personnel of the air services, oblige us to economise in our air forces. The forces will be directed with the distinct intention of refusing to participate in any mission which is not of primary importance in the war. This severe discipline, necessary because of the artillery action (which ought not to be held up for an instant during the present artillery duel), will not permit the use of battle planes for a moment longer than is absolutely necessary.'"