When removing the Pratt & Whitney Twin Wasp R-1830-SC3G engine from the fuselage of the J 22, we were surprised to find a data plate written in French !
With help from Lionel Persyn, author of the book “Les Curtiss H-75 de l’Armée de l’Air” edited by Lela Presse, we managed to get the answer. This story starts in September 1938…
As Sweden wasn’t producing any engine that was powerful enough to equip its J 22s, the country soon decided to look abroad for available engines.
All the main aircraft engine manufacturers were located in the USA, UK or Germany. Of course the engine produced were then all restricted to war use only, and couldn’t be sold to a neutral country such as Sweden.
Meanwhile in France…
Facing the growing threat represented by Nazi Germany, the French considered getting US material to increase their military capacities. After the first technical missions to the Northern America, and seeing that the US Army Air Corps had just orderd the new Curtiss P-36A fighter, the French Air Ministry decided to buy this airplane, from Curtiss Wright Corporation, based at Buffalo, New York. The aircraft received the designation Hawk H-75.
The fighters were ordered on 3 different contracts :
• Contract No 1035/8, on September 9th 1938, for an order of 100 H-75A-1.
• Contract No 1544/9, on March 5th 1939, for an order of 100 H-75A-2.
• Contract No 173/0, on October 5th 1939, for an order of 400 H-75A-3.
Those 3 first contracts were of course, associated with orders of P&W R-1830 engines from United Aircraft Corporation, located at East Hartford, Connecticut. Those orders were devided as follows :
• Contract No 1034/8, on August 27th 1938, for an order of 150 R-1830 SCG along with associated spare parts.
• Contract No 3, on February 14th 1939, for an order of 795 R-1830 SC3G.
• Contract No 10, on June 16th 1939, for an order of 350 R-1830 SC3G, along with 350 Halmiton Standard propellers
Our engine is the : P&W R-1830 SC3G c/n 3637, which was ordered on Contract No 10. The material ordered on this contract was shipped aboard the French “De Grasse” destroyer on March 6th 1940, heading for France. The SC3G version of the P&W R-1830 differed from the SCG version in its new Bendix-Stromberg carburettor.
All H-75A1 and H-75A-2 aircrafts were re-assembled, equipped and tested at the SNCAC, in Bourges in 1939. However a part of the H-75A-3 fighters and their engines still bundled into boxes were sent to the ARAA (Atelier de Réparation de l’Armée de l’Air) in Toulouse, as Bourges factory was already saturated at the end of May 1940.
On June 22nd 1940 an armistice was signed by the French. At that time, the Twin Wasp c/n 3637 was, of course, stored at Toulouse-Francazal, in the “Free zone”. This avoided the engine to be captured by the Germans, unlike the material that was located in the “Occupied zone”.
Between June 1940 and November 1942, the wokshop of Toulouse delivered and repaired a few H-75 and R-1830 engines for the Vichy’s Armée de l’Air in North Africa.
Buying engines from the French
A note from the Armée de l’Air’s headquarters, dated July 20th 1942, confirms that some countries such as Sweden are interested in buying engines and aircrafts that Vichy’s government has no use of.
This note approves the sale of 50 R-1830 SC3G engines to Sweden. The country was apparently willing to buy even more engines.
We now know that a total of 115 French engines were finally delivered to Sweden before July-August 1943.
The first contract must have been signed and delivered very quickly, under observation of the German armistice commission, because after the British-American invasion of North Africa in November 1942, this sale couldn’t have been approved. Indeed, after the Torch Operation in North Africa, the “Free zone” of France was invaded by the Germans as well.
In this regard, about 15 H-75 stored with their spare parts in Toulouse, now occupied, were sold to Finland in 1943, as the Germans had already done it in 1941 with captured H-75.
Producing engines in Sweden
A total of 115 “French” engines were bought and delivered before July-August 1943. On the 198 J 22 built, 113 were delivered with engines coming from France. The 2 remaining engines were mounted on SAAB’s bomber B 18A c/n18102 that was completely destroyed on January 8th 1944 near SAAB’s factory at Linköping.
Those 115 “French” engines allowed Sweden to prepare their own production of a “Swedish” R-1830 SC3G (the country would later acquire an official production license) named STW C3. In January 1945, 50 J 22 were already powered with “Swedish” engines. The 113 first J 22s delivered (starting in October 1943) were, of course, equipped with “French” engines, including our Twin Wasp c/n 3637 !
This concludes the unusual history of this engine, produced in the USA, for France and intended to be fitted on a French H-75. But History decided otherwise…