Even before the outbreak of the Second World War in 1939, the Finns recognised that what they needed was an indigenous up-to-date fighter aircraft for their air force. Unfortunately, and as I covered in my article on the VL Myrsky, circumstances got in the way.
And things would only get worse. When the Soviets didn’t collapse after the invasion by Nazi Germany and their allies, including Finland, in 1941, it suddenly became apparent that the war was going on for the foreseeable future.
The Soviets also, after the devastating losses they suffered to their air forces in the first six months of the new war, began to field large numbers of rapidly improving aircraft. By contrast, the Finnish Air Force found itself using a hodgepodge of fighters that pretty much every other combatant had consigned to non-combat duties, or even scrapped.
Despite this, they managed to achieve a quite remarkable amount of success, but this didn’t fool the Finns into thinking that all was well. They appreciated that they were essentially scraping by with these old aircraft and as a result, they were constantly desperate to get more first-rate fighters.
The delays experienced with developing the Myrsky meant that even before it got into service it was recognised that it was going to be obsolescent in short order. The only alleviation was purchasing Bf 109Gs from Germany, with deliveries of this type to the Finns starting in March 1943.
But even before this began the Finns started taking steps to, once again, begin development of an up-to-date fighter that could be built in the Finnish State Aircraft Factory from locally available materials.
The VL Pyörremyrsky
In November 1942 the State Factory (VL for short) was instructed to begin development of a new fighter that was as comparable to the Bf 109G as could be whilst using as much local material in its construction as possible. And that meant wood – lots and lots of wood.
The Pyörremyrsky would use the same VDM propellor and Daimler Benz DB 605A-1 liquid cooled engine as the Bf 109G, and that is probably why some people think the two aircraft are visually very similar. But in fact, they were very different.
In contrast to the Messerschmitt, the Pyörremyrsky used metal extremely sparingly, with the forward fuselage being built with a welded steel tube structure with detachable metal panels for skinning. But the rear fuselage was a of wooden monocoque construction, being built of pine and plywood, and the wings were built of the same materials. The fuel tank was mounted in the fuselage behind the pilot and protected by a 10mm armoured plate.
One very useful change the Finns made was to the landing gear. The Pyörremyrsky used the same components as the Bf 109, but in essence reversed them, mounting them out in the wings and making them retract toward the fuselage. This gave the Pyörremyrsky a wide gauge gear and resolved one of the major issues that the Bf 109 had. The tailwheel was also fully retractable.
Armament was intended to two synchronized 12.7 mm LKK-42 machine guns and one 20 mm MG 151 motor cannon firing through the propeller hub.
The Pyörremyrsky was actually bigger than the Bf 109G, having a wingspan 18-inches (46 cm) wider. It also weighed 372 kgs (820lbs) more than the Bf 109, an increase of 16.5% which is substantial on a lightweight fighter aircraft.
But despite this, and having the same engine which produced 1,475hp as the -109Gs, the Pyörremyrsky proved to have lighter wing loading and excellent performance. In testing the aircraft demonstrated a top speed of 400mph (645km/h) which matched that of the -109G.
But perhaps more impressively when it was flown against the German fighter, which was hardly a slouch in air combat, the Pyörremyrsky apparently demonstrated excellent agility and had a superior climb to the Messerschmitt.
Overall, the various test pilots rated that the -109G was the better aircraft, but not by much and the Pyörremyrsky was considered a fair match. That’s pretty impressive when one considers both the amount of development the Messerschmitt had received by that point, as well as the respective experience of the two companies.
But there were a number of problems that the Pyörremyrsky faced. For starters, despite the excellent showing it gave on test flights, these were conducted without armament, which would have impeded the aircraft’s actual combat performance, albeit probably not too significantly.
Secondly, the Pyörremyrsky was also constructed using many of the same techniques used in the previous Myrsky design – including the poor-quality glue. Although the Pyörremyrsky was put through its paces by multiple pilots during its testing and seems to have come out extremely well with only a few hiccups, it would likely have experienced the same issues that blighted the Myrsky of the wooden skins peeling off during flight if not rigorously maintained.
But the third, and most critical element in killing off the aircraft, was timing.
Because, just like the Myrsky, the pressures of war meant that despite the desperate need for the Pyörremyrsky, other even more critical work kept the VL factory running effectively at capacity for the entire conflict.
When the Finns signed a ceasefire with the Soviets in September 1944, the Pyörremyrsky was still under construction. The peace deal that followed saw the need for a new fighter evaporate, compounded by limits on what the Finnish Air Force was allowed to fly in terms of numbers anyway.
As a result, orders for a second prototype and forty production Pyörremyrsky’s were cancelled, leaving just the single one being built to be completed. It wasn’t actually until the 21st of November 1945, several months after the end of the war that the first flight took place. The aircraft would perform a total of 31 test flights over the next two years, before being put into storage.
With sufficient -109s for their short-term needs, and the new jets showing clearly that the age of the piston-engine fighter was done, the Finnish Air Force wasn’t foolish enough to consider the Pyörremyrsky more than a novelty at that point.
But thanks to their foresight, the Pyörremyrsky was not scrapped and is still to be seen, preserved at the Finnish Air Force Museum located at Jyväskylä.