Siemens Schuckert D.IIILtn Ernst UdetJasta 4Metz AerodromeSeptember 1918

Ultimate successor of the S.S.W. D I was the D.III/ D.IV

series, which appeared almost a year later, after development

through a series of D.II prototypes, and represented a line of

advanced and original thought from the drawing-board of Dipl. Ing.

Harald Wolff (who was appointed chief designer after Steffen was

killed) and his assistant, a young engineer named Hauck.

With the relative success of the various D.II prototypes a pre-

production order for 20 D.IIIs was placed by Idflieg during the last

weeks of 1917; followed by an order for 30 more in February 1918.

During April and May some 41 S.S.W. D.IIIs were channeled to the

Western Front for operational trials. Most were received by

Jagdstaffel 15 of the Jagdgeschwader 11 commanded by Haupt.

Rudolph Berthold. A good deal of trouble was experienced with

piston seizure, and it became obvious the Siemens-Halske Sh.III

engine with which these D.IIIs were fitted was not yet ready for

operational service. This shortcoming was seized upon by

opponents of the D.III, one of whom had been Hermann Goring, in

an endeavor to discredit it completely and have it condemned.

Berthold none the less had achieved several victories on the D.III

and saw its potentialities; it was largely through his intelligent and

objective report on the type that development continued.

The Siemens-Halske Sh.III engine was a more powerful,

eleven-cylinder development of the earlier Sh.I engine, retaining the

same characteristic of crankshaft rotating in one direction at 900

rpm. and the crankcase and cylinders rotating in the reverse direction

also at 900 rpm., thereby achieving an actual engine speed of 1,800

rpm. Although advantageous in some respects, this system had its

disadvantages. Being a more powerful and bigger engine than the Sh

I, the Sh III tended to run a lot hotter, and this effect was magnified by

the slow speed at which the cylinders rotated, compared with a

normal rotary, resulting in a considerable reduction in the amount of

air cooling. Coupled with the low-grade castor oil available to the

Germans at this period of the war, recurrent piston seizure after some

seven to ten hours running seemed inevitable. The redeeming

feature of the engine was that its power did not drop off at high

altitude and held good prospects. The D.IIIs were withdrawn from

the Front during May 1918 for the fitting of improved engines and

some airframe modifications.

One such re-engined D.III, with a Rhemag built Sh IIIs, was

piloted by the Siemens test pilot Rodschinka, to the extraordinary

height of 8,100 m. (26,568 ft.) in exactly 36 min. These aircraft were

then returned to operational service during July 1918, when, by

virtue of their superb climbing powers, they were used mainly as

interceptors by Kampfeinsitzer Staffeln 4a, 4b, 5, 6 and 8 for defense

of the Fatherland.

Fritz Beckhardt, a friend of the late A. R. Weyl, flew

Siemens-Schuckert fighters to good account with Kest (the

abbreviated Kampfeinsitzer Staffel) 5, his aircraft being

characterized by the painting on the fuselage sides of a large

Hakenkreuze (swastika). On a single sortie during September 1918

he managed to shoot down a pair of French Breguet B 14s operating

at a height of more than 23,000 ft. The Breguets were by no means

sitting ducks, as Ernst Udet was able to testify when he had been shot

down by one earlier in the year and was only saved by his parachute.

When in December 1917 Idflieg gave the first D.III order, it

also requested development of the D.IV and placed an order for three

prototypes. A D.V development was similarly requested, but as this

was virtually a two-bay version of the D.IV, and offered no

improvement, it proceeded no further. Although the S.S.W. D.III had

excellent climbing abilities, its maximum level speed was not

comparable, being only about 180 km.h. (112-5 m.p.h.). In an

endeavor to achieve improved performance a redesigned top wing of

new section and reduced chord was experimentally fitted, and in this

guise the aircraft was re-designated D.IV. There was also some

revision to the cowling arrangement, in which the lower half was

almost completely cut away to give additional cooling to the

cylinders. The spinner was also impressed with four cooling louvers

in order to scoop cooling air on to the crankcase. Apart from these

modifications, the two types differed little. In performance an

immediate increase in level speed to 118 m.p.h. was obtained and the

rate of climb substantially improved. By March 1918 a production

order had been given for the D.IV, but it was not until August of that

year that it became operational; first deliveries went to Jasta 14 and

to the Marine Jagdgeschwader commanded by Osterkamp. Later

Kest 2 and Jasta 22 received some D.IVs, but production rate was

largely controlled by engine availability, and by the Armistice not all

the 280 machines that had been ordered had been delivered. Not

even the famous Richthofen Geschwader (after an initial antipathy)

had been able to get its belated request for the type fulfilled.

The D.III/ D.IV fighter series, the first-and last-S.S.W.

original rotary engined design to see service with the German Air

Force, differed radically in appearance from all previous production

fighters. Its stocky, barrel-like fuselage was of considerable strength

and continued the circular section dictated by the engine throughout

its length. In the initial production machines the Sh.III engine was

completely enclosed in a close-fitting circular cowl, and the four-

bladed propeller-of fairly coarse pitch-was fitted with a large

diameter spinner. This combination left an insufficient aperture for

the entry of cooling air, and later the cowling was drastically cut

away in the lower half, thereby exposing the front engine-bearer

spider frame. The fuselage consisted of a basic structure of spruce

longerons and circular plywood bulkheads additionally reinforced

with diagonally mounted ply formers, which, when the three-ply

skin was attached, resulted in an extremely strong structure. The

by either struts or wires. As in the steering surfaces, they were of

welded steel tube and covered with fabric.

A conventional vee-type undercarriage was fitted, although

the vee struts were fabricated from alloy tube instead of the more

usual steel tube, and were wrapped with alloy sheet fairings. The

wheels were sprung with spiral steel springs. A substantial ash

tailskid was hinged to the under fin and bound at its upper end with

elastic cord. Interplane struts were of wood and wrapped with fabric

for additional strength, as

were also the center section

struts.

F l i g h t

characteristics of the series

were such as to demand

constant vigilance from the

pilot; there was no stall

warning and a spin rapidly

developed. Nevertheless,

although with such a

powerful engine the torque

was considerable, it could

be handled by any pilot of

good average skill. The

counter-rotation of the

crankshaft and cylinders did

nothing to lessen torque (as has been supposed), but did compensate

the gyroscopic reaction. This was extremely beneficial, as it gave no

fore-and-aft change of trim between right- and left-hand turns, as

was normally the case with rotary-engined fighters.

Without doubt these Schuckert machines were the best

German fighters to reach operational status, yet they were probably

the least known. For some odd reason, manufacture of the type did

not cease until the summer of 1919, and one D.IV survived in

Germany until as late as 1926.

panel between the front undercarriage legs was of sheet metal

liberally endowed with louvers to allow the exhaust to escape; the

top panel between the center-section struts was similarly covered.

Handgrips adjacent to the cockpit and tail plane were fashioned by

the simple expedient of cutting away a small rectangle of the

plywood skin and exposing the longeron, which could be grasped.

All fin surfaces were of wooden framing and constructed integrally

with the fuselage, and were likewise plywood skinned. The vertical

fin was of asymmetrical

section, which helped to

counteract a tendency to

swing on take-off as a result

of the considerable torque

moment of the big engine.

The balanced, angular

rudder and the one-piece

balanced elevator were of

w e l d e d s t e e l - t u b e

construction and covered

with fabric.

In the D.III the upper

wing was of considerably

greater chord than the lower.

Both were based on twin

hollow box-spars, and the

plywood ribs with pine capping strips were closely spaced and, with

the plywood sheeting of the leading edge back to the front spar,

dispensed with the necessity for false ribs to preserve the aerofoil

section. In the D.IV an improved aerofoil section was introduced and

the upper wing reduced in chord to 1 m.: the same as the lower wing.

Overhung, horn-balanced ailerons, of parallel chord (those of the

D.IV were slightly tapered towards the tips) were fitted at all four

wingtips and imparted a brisk rate of roll to the machine. They were

operated through torque tubes in all wing panels by a positive

linkage which made it unnecessary for them to be linked externally

Description:Manufacturer:Power Plants:

Span:

Weights:

Performance:

Climb to:

Ceiling:Duration:Armament:

Single-seat fighter Siemens-Schuckert Werke G.m.b.H. Siemensstadt, Berlin and Nurnberg (SSW.)One 160 h.p. Siemens-Halske Sh III and IIIa 11 cylinder geared rotary engine.

..............................................................................................8.43 m. (27 ft. 7 3/8 in.) Length: ...........................................................................................5.7 m. (18 ft. 8 1/2 in.) Height: ............................................................................................2.8 m. (9 ft. 2 1/4 in.) Area: ...............................................................................................18.82 sq.m. (203.5 sq.ft.)

Empty: ............................................................................................534 kg. (1,175 lb.)Loaded:...........................................................................................725 kg. (1,595 lb.)

Max speed: .....................................................................................180 km.h. (112.5 m.p.h.)

1,000 m. ..........................................................................................1.75 min2,000 m. ..........................................................................................3.75 min 3,000 m. ..........................................................................................6.0 min 4,000 m. ..........................................................................................9.0 min5,000 m. ..........................................................................................13.0 min 6,000 m. ..........................................................................................20.0 min

...........................................................................................8,000 m ........................................................................................2 hr. Two fixed Spandau machineguns firing forward

Dimensions:

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