Although the Netherlands had been neutral until the German invasion in May, the first Dutch casualties had occurred immediately after the German invasion of Poland. On 13 September 1939 a German flying boat shot down a Dutch Fokker T.VIIIw/G seaplane. The German crew claimed that they had misidentified the T.VIII as British or French, having confused the Dutch red, white, blue and orange roundel with those of the Entente. In response the Netherlands adopted the orange and black triangle as their roundel both in Europe and overseas. In the aftermath of the German invasion, the Netherlands retained the orange triangle as their military symbol.
The Netherlands was the country most damaged by the War, with heavy fighting over her central and eastern provinces, and enormous damage having been further wrought by the inundations. The Dutch industrial heartland was still mostly intact and functional although supply problems negatively effected production capacity. The return of the Dutch royal family from Britain was positive in raising Dutch spirits, and the return of an imperial family to German gave the Dutch hopes for a more positive future relationship with their eastern neighbour. As a demonstration of that, the Dornier Do 215B-2’s ordered immediately before the war were delivered to the Netherlands.
Like most other manufacturing nations in Europe, pre-war military production had been ramped up but had not reached its required output. The Dutch now had a damaged nation and a military that had been lost most of its land and air vehicles. And even more so, the Dutch had the requirements for defence of the Netherlands East Indies. But the real stumbling block for aviation production was the supply of aero-engines. France was not even able to supply sufficient engines for its own needs before the war, and had resorted to American imports of both engines and completed aircraft. Britain was still expanding its domestic aircraft construction programme leading to an increasing delay in foreign engine deliveries. American engines were still available, but at prices that were steadily increasing with demand. Into this environment Germany agreed to supply engines and other resources to the Dutch.
The most significant destruction to Dutch military construction infrastructure was the complete destruction of the Koolhoven Aeroplanes facility at Rotterdam. In the initial German assault the airfield at Waalhaven, Rotterdam had been targeted and Koolhoven had been reduced to ashes; all aircraft , equipment, tooling and documentation destroyed. Koolhoven had been producing F.K.58 fighters for both French and Dutch contracts. In the aftermath of the invasion the French order was cancelled, but the Dutch order was redirected to Fokker.
The Fokker T.VIII seaplanes were already on the production line, which had been halted with the invasion. Initial Dutch deliveries had been for the T.VIIIw/G mixed construction model, with the all metal T.VIIIw/M model slated for the Netherlands East Indies. Production now shifted to all aircraft being assembled as /M models. Experience of the war now led to the aircraft being fitted with a machine gun in the bombardier’s nose glazing. Additionally production of the Finnish T.VIIIw/C continued, without the nose gun, and the aircraft were exported.
The prototype Fokker T.IX had flown only days after the German invasion of Poland, and had suffered a landing accident in early March. With the Germans gone the aircraft was repaired and production commenced. The T.IX was Fokker’s first break with mixed materials construction and was all-metal from the outset. Planned initially for the Netherlands East Indies, American-sourced aircraft had already begun to fill their requirements. Instead the T.IX was repurposed for Dutch home service. Taking cognisance of the effect that the Manchesters had had on invading armour, Fokker engineers started work on the original prototype, developing a heavy 4-cannon turret to convert the bomber into an anti-armour “pantserjager”.
Although not a casualty of the war, development of the promising Fokker D.XXIII was cancelled. With other urgent projects, the stumbling blocks of engine cooling and safe pilot ejection were considered just too time-consuming to solve and the single prototype was eventually scrapped.
Instead work progressed on the Fokker G.I. Production continued on the Dutch G.I “Wasp” version, with design work continuing with the updated all-metal version for the NEI. International sales customers for the G.I had not deserted the design, but Fokker was in no position to build for export. Instead the Danes, who had established a production line for their licence-built aircraft, were granted additional licences to produce the aircraft for international sales.
As design work progressed the engine requirement from the NEI changed from the Pratt & Whitney Wasp Junior to the Curtis Cyclone, for standardisation with their newly adopted Lockheed Hudson’s. This led to a model with a further modified tail section, the G.I “Cyclone”. The additional horsepower available now also allowed additional armament in the form of a removable belly cannon pack, designed for air-ground action. The G.I bis was considered overpowered and too expensive for European operations and although trialled, were not accepted for Dutch European service.
All work on the Fokker G.2 design ceased, although the project was not cancelled. The G.3 fighter for Europe, with much comonality with the metalised G.1 and the T.IX, moved into the design background while work continued on the features required to update its stablemates. But Fokker was not just concerned with military orders. Development of the Fokker F.XXXX Intercontinental airliner continued, albeit at a lower priority, but Fokker was looking at future production once the military production bubble was over.
The destruction of Koolhoven and their F.K.58 led to an increase in the order for the Fokker D.XXI. Fokker also continued its work on the advanced retractable-gear version, the D.XXIV, now to be equipped with German Daimler Benz DB 601 engines.
The De Schelde shipbuilding company were also involved in aircraft design and manufacture, having built the De Schelde S.20 utility and training aircraft, and were working on the construction of the S.21 fighter before the invasion. Designed from the outset to use Daimler Benz engines, the availability of additional DB 601’s worked very much in the design’s favour. A novel design with a nose mounted heavy canon the S.20, fit easily into the new concept of ground attack aircraft and the Dutch military appreciated the potential of a small, cheap heavy fighter. An initial Dutch contract was awarded for 20 aircraft, and international interest was also shown from Finland.
But the biggest Dutch pre-war construction project was the construction of Dornier Do 24 flying boats at Aviolanda. Originally designed by Dornier for the Netherlands construction had been started by the Dornier subsidiary in Switzerland and by Dornier themselves in Germany, before being taken over by Aviolanda. The aircraft was for use in the Netherlands East Indies, with 37 of a planned 72 been already been sent to the NEI before the German invasion – the 37th aircraft had been shipped only 2 days before the German invasion. The production line recommenced on the longer-range Do 24 K-2 model with American Curtis Wright R 1820 engines. The potential of the Do 24 to take on a rescue role had been noted by other nations, and Denmark requested a non-combat version of the aircraft. With no capacity for additional design work or manufacture Aviolanda turned back to Dornier re-engineer and market the Do 24 internationally. Dornier’s Swiss subsidiary took back the design, and having failed to secure addition supplies of American engines commenced production of the Do 24 T with BMW Bramo 323 engines.
In the aftermath of the invasion Dutch civil aviation had no immediate need for either modernisation or expansion. Before the war KLM had required a pressurised airliner to service the Netherlands East Indies, a need that Focke-Wulf was to fill with a pressurised model of the Fw 200 Condor. Focke-Wulf had put the KLM Condor model at a relatively low priority due to their own commitments to both Lufthansa and the Luftwaffe, which actually caused no disruption to KLM as they were in no financial position to take on new aircraft in 1940.
Military production also continued for land forces. The spectacular success of Dutch armoured car units in defeating the German airborne invasion led the Dutch military planners to accelerate production of the DAF M.39 Pantserwagon who’s production had only just commenced before the invasion. The remaining Landsverk M.36 and M.38 vehicles remained in service, although relegated to secondary roles as the M.39’s replaced them. Additionally DAF started work on modifying the M.39 for service in the Netherlands East Indies