You're probably right. Sorry for my English. In Polish turbosupercharger is in fact "turbosprezarka" but I thought that "sprezarka" is simply charger.
BTW I have another idea of never-were aircraft - medium bomber for RAF, a slightly bigger Canberra with 2 Centauruses.
Regards
In the UK a supercharger is driven from the engine and a Turbocharger driven from the exhaust. As with all things it is easy to say and not so easy to do.
There is a difference between two stage and two speed, heres some wiki info on the merlin.
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Central to the success of the Merlin was the supercharger. A.C. Lovesey, an engineer who was a key figure in the design of the Merlin, delivered a lecture on the development of the Merlin in 1946; in this extract he explained the importance of the supercharger:
"Coming now to specific development items we can ... divide them into three general classes:
Improvement of the supercharger.
Improved fuels.
Development of mechanical features to take care of the improvements afforded by (1) and (2).
Dealing with (1) it can be said that the supercharger determines the capacity, or ... the output, of the engine. The impression still prevails that the static capacity known as the swept volume is the basis of comparison of the possible power output for different types of engine, but this is not the case because the output of the engine depends solely on the mass of air it can be made to consume efficiently, and in this respect the supercharger plays the most important role ... the engine has to be capable of dealing with the greater mass flows with respect to cooling, freedom from detonation and capable of withstanding high gas and inertia loads ... During the course of research and development on superchargers it became apparent to us that any further increase in the altitude performance of the Merlin engine necessitated the employment of a two-stage supercharger."[26]
As the Merlin evolved so too did the supercharger; the latter fitting into three broad categories:[27]
Single-stage, single-speed gearbox: Merlin I to III, XII, 30, 40, and 50 series (1937–1942).[nb 3]
Single-stage, two-speed gearbox: experimental Merlin X (1938), production Merlin XX (1940–1945).
Two-stage, two-speed gearbox with intercooler: mainly Merlin 60, 70, and 80 series (1942–1946).
The Merlin supercharger was originally designed to allow the engine to generate maximum power at an altitude of about 16,000 feet (5,000 m). In 1938 Stanley Hooker, an Oxford graduate in applied mathematics, explained "... I soon became very familiar with the construction of the Merlin supercharger and carburettor ... Since the supercharger was at the rear of the engine it had come in for pretty severe design treatment, and the air intake duct to the impeller looked very squashed ..." Tests conducted by Hooker showed the original intake design was inefficient, limiting the performance of the supercharger.[28][nb 4] Hooker subsequently designed a new air intake duct with improved flow characteristics which increased maximum power at a higher altitude of over 19,000 feet (5,800 m); and also improved the design of both the impeller, and the diffuser which controlled the airflow to it. These modifications led to the development of the single-stage Merlin XX and 45 series.[29]
A significant advance in supercharger design was the incorporation in 1938 of a two-speed drive (designed by the French company Farman) to the impeller of the Merlin X.[30][nb 5] The later Merlin XX incorporated the two-speed drive as well as several improvements that enabled the production rate of Merlins to be increased.[32] The low-ratio gear, which operated from take-off to an altitude of 10,000 feet (3,050 m), drove the impeller at 21,597 rpm and developed 1,240 horsepower (925 kW) at that height; while the high gear's (25,148 rpm) power rating was 1,175 horsepower (876 kW) at 18,000 feet (5,490 m). These figures were achieved at 2,850 rpm engine speed using +9 pounds per square inch (1.66 atm) boost.[33]
In 1940 Rolls-Royce considered adapting the Merlin to use an exhaust-driven turbocharger to increase the power of the Merlin. Although a lower fuel consumption was an advantage, the turbocharger was rejected in favour of a two-stage supercharger.[34] The basic design, first tested in September 1941, used a modified Vulture supercharger for the first stage while a Merlin 46 supercharger was used for the second.[35] A liquid-cooled intercooler on top of the supercharger casing was used to prevent the compressed air/fuel mixture from becoming too hot.[nb 6] Fitted with the two-stage two-speed supercharger, the Merlin 60 series gained 300 horsepower (224 kW) at 30,000 feet (9,144 m) over the Merlin 45 series,[35] at which altitude a Spitfire IX was nearly 70 miles per hour (113 km/h) faster than a Spitfire V.[36]