The Siemens-Schuckert D.IV; Best Fighter of the First World War?

June 3, 2023

When it comes to aircraft of great potential, those of the First World War are often overlooked. And while the dogfights between aircraft like the Sopwith Camel, the Fokker Dr.1 triplane and the SPAD XIII are often the source for historical recollection, this tends to obscure the fact that towards the war’s ending in late 1918, new aircraft of far more formidable capability were in the air and fighting the last, desperate actions.

A great example of this is the Fokker D.VII.

This formidable fighter was considered such a threat that, of all the various weapons systems that the Allies required be turned over to them at the German surrender, the Fokker D.VII is the only one that was explicitly named and the entire number in existence demanded be handed over.

But though the D.VII is perhaps not as well remembered as it should be, there was another fighter that the Germans had began to field in the last few months of the war that was, according to the pilots who fought in it, even more formidable.

The Siemens-Schuckert D.IV.

And ironically, the foundations of this remarkable fighter were laid by copying a captured French aircraft.

Siemen-Schuckert’s aeronautic efforts during the War primarily revolved around building some of the massive “R-Class” bombers, but they also made an effort at building fighters as well.

In mid-1915 they built a couple of monoplane designs, but these were soon rendered obsolete by the rapid advances in fighter designs that the war was engendering, so in 1916 they were provided with a captured example of the French Nieuport 17 with a request to “study” it.

This aircraft was one of the most formidable flying at the time and Siemens-Schuckhert figured they might as well not worry on trying to improve on this.

Simply building a copy of the aircraft but fitted with their own engine, the Siemens-Halske Sh.I rotary, the new Siemens-Schuckert D.I started the line of biplane fighters for the company.

Ironically though, by the time this entered service in mid-1917 the aircraft was already obsolete, and the ninety-five delivered served as trainers. But the aircraft laid the basis for further development, and after building several variants of the D.II for testing, in late 1917 Siemens-Schuckhert flew the D.III.

This entered service with the German army’s air arm in April 1918 and initially proved extremely successful.

But problems rapidly came to light with the new aircraft’s engine. This, the Siemens-Halske Sh.III, was an eleven-cylinder counter-rotary design that was one of the most advanced rotary engines to be designed.

While rotary engines had been largely standard for fighter design throughout the war, by 1917 they were approaching the limits of what they could deliver on. In short, to improve performance as the demands for better aircraft accelerated, engines needed to deliver more revolutions-per-minute (RPM) to compete. In inline engines this was possible, but for rotary’s, as revolutions went up, the efficiency dropped markedly as more energy was spent spinning the engine than providing usable power to the propellor. Siemen’s got around this by creating a counter rotary design in the Sh.III. This used a bevel gearing system to rotate the crankshaft in the opposite direction to the rest of the engine which, cutting to the basics, allowed it to deliver more power to the prop.

The problem was that by this point in the war, the German’s had massive issues getting hold of supplies of castor oil which was critical for running rotary engines. They implemented a mineral oil substitute, but this really didn’t agree with the Sh.III at all, and they began to fail regularly after just ten hours of running.

The D.IIIs were therefore swiftly recalled, normally replaced with the Fokker D.VII. Despite this, the pilots who flew the aircraft were reportedly very keen to get the Siemens Schuckhert back if the engine issues could be resolved.

But in fact Siemen’s had further plans for the type. While working to resolve the engine issues, they also sort to improve the airframe, leading to the D.IV.

This fitted an improved engine, combined with a huge four-bladed propellor and with the lefthand wing being slightly longer to counteract the torque from it. Armed with twin 8mm synchronized machine guns, the new design seems to have been a real winner. The engine may only have produced 160hp but the greater power efficiency of the design, combined with the big prop, meant that the D.IV could outclimb just about anything else.

For example, the Fokker D.VII with the 185hp BMW IIIa engine, the aircraft that filled allied flyers with dread, could get to 1,000m (3,281ft) in 4 minutes and 15 seconds and to 6,000m (19,685ft) in 18 minutes and 45 seconds.

The Sopwith Snipe, which was to become the Royal Air Forces primary fighter after the First World War, well, I couldn’t find exact comparisons, but this formidable aircraft could get to 2,000m (6,500 ft) in 5 minutes 10 seconds, 3,050m (10,000ft) in 9 minutes 25 seconds and 4,600m (15,000 feet) 18 minutes and 50 seconds.

The Siemens Schuckhert D.IV could get to 1,000 m (3,281 ft) in 1 minutes 54 seconds and 6,000 m (19,685 ft) in 15 minutes 30 seconds. The damn thing was an absolute rocket!

It matched this with a top speed of 120mph (190km/h) which was broadly in line with the other aircraft, but could maintain a far higher altitude, with a listed maximum ceiling of 8,000m (26,600 feet). Though operating at this height would require special measures, it was still more than a 1,000m higher than the Fokker D.VII could manage.

So, the D.IV combined good agility with excellent climb and a superior operational ceiling, while being comparable in speed to its primary contemporaries. All in all, it had immense potential, and this was soon recognised. Pilots that got to fly the new aircraft waxed lyrical about it and requested more.

Indeed, the D.IV managed to repair the poor reputation that the aircraft had received from its prior models and even Jagdgeschwader I, the famed Flying Circus that had been commanded by the equally famous “Red Baron”, began to request an allocation of the fearsome new fighter.

But that was not to be as the D.IV arrived just too late to make its impact fully felt. Deliveries began to units in August 1918, and though several hundred were ordered in quick succession as the capabilities of the aircraft became apparent, in fact only perhaps sixty managed to get to combat units before the collapse of the German army and the signing of the armistice on the 11th of November 1918 that marked the cessation of hostilities.

One of the issues with the slow production, other than the near collapse of the German war economy after four years of blockade, was that the D.IV was an indication of the future that aircraft were taking, with its plywood skinned fuselage being more complicated to build than the fabric-wrapped construction of most previous fighter aircraft of the war.

The end of the war also meant largely the end of the aircraft, though some were to find new lives with the air forces of Switzerland, Belgium and Lithuania, though only in tiny numbers. And that marked the end of the Siemens-Schuckert D.IV; potentially the best fighter of the First World War.



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