Greatest aviation myth this site “de-bunked”.

[Elvis]

But the YP-37 was never actually fielded by the USAAF, since the turbo-compound supercharger was large and complicated and it pushed the pilot so far back in the fuselage that it made it hard to see past the part of the plane that was in front of them.

 

[Reluctant Poster]

But the YP-37 was never actually fielded by the USAAF, since the turbo-compound supercharger was large and complicated and it pushed the pilot so far back in the fuselage that it made it hard to see past the part of the plane that was in front of them.

It wasn't a turbo compound.

 

[Elvis]

It wasn't a turbo compound.

Apologies. What was that supercharger called then?

 

[GregP]

Today we call it "turbocharged."

In WWII, they called it turbo-supercharged.

Same compressor, but the supercharger is driven vy the crankshaft and the turbocharger is driven by exhaust gases.

 

[MiTasol]

and turbo compound is where the exhaust driven turbine(s) help drive the propeller by feeding power in to the crankshaft through the back of the engine.

 

[pbehn]

and turbo compound is where the exhaust driven turbine(s) help drive the propeller by feeding power in to the crankshaft through the back of the engine.

It could also be called a turbo prop with the least efficient combustion and power recovery known to aviation or science.

 

[Thumpalumpacus]

At any rate, it was an inline GeeBee, for our purposes here. Imagine trying to pull lead in that thing.

 

[Zippythehog]

Centrifugal superchargers are commonly referred to as turbochargers. Turbochargers are spun by spent exhaust gases. Roots type superchargers are usually driven on aircraft engines with a gearbox turned by the crankshaft. Both are superchargers.

A turboprop usually refers to a turbine engine that drives a propeller through some type of a reduction system.

 

[ThomasP]

re

Centrifugal superchargers are commonly referred to as turbochargers.

?

In WWII centrifugal superchargers referred to the type of mechanically driven impeller (or compressor setup) that was used, usually driven by the crankshaft through a gear train.

The supercharger on the Napier Sabre II is diagramed below, note that the impeller drive shaft is driven by gearing from the crankshaft.

 

[tomo pauk]

To expand on what is said in the post above.

Centrifugal superchargers are commonly referred to as turbochargers. Turbochargers are spun by spent exhaust gases.

Turbocharger ('turbo' as the shorthand) consists from turbine (that is indeed spun by the exhaust gasses) and compressor (predominantly of the centrifugal type), with a shaft connecting the two.
The vast majority of the superchargers on the ww2 was gear-driven (ie. by the engine itself), not turbine driven. Includes the RR, Bristol, DB and Jumo engines, V-1710, R-1820, R-2800, Sakae, Homare, AM-38 - you name it. When people were adding the turbochargers to the existing engines, the gear-driven superchargers were still retained; both S/Cs working in series. That meant that such engines have had two stages of supercharging - 1st stage now being the turbocharger, second stage being the gear-driven S/C. Most notable installations being the American ones - includes but not limited to P-38, P-47, B-17, B-24.
Engines with 2 stages of supercharing were excellent at very high altitudes, talk above 20000 ft. let alone above 25000 ft.

There was a way to have 2 stages of supercharging with both stages being gear-driven. RR system used common shaft for both stages (on Merlin 60, 70, 80, 100 and 130 series, as well as on Packard Merlin V-1650-3, -7, -9 etc; also on the Griffon 65 and similar), Allison used the additional variable-speed drive for the auxiliary stage. P&W used clutch to engage the aux stage on their 2-stage engines. Benefit vs. the turboed engines was that installation was more compact, shortcoming was that the turboed versions of the same engine were sometimes better at the very high altitudes.

Nomenclature back in 1930s and 40s was not set in stone, the turbo being often called 'supercharger', while the engine-driven S/C was often called 'blower'. This is before we discuss the nomenclature of the countries not using English language.

In the 1980s-2000s, the gear-driven S/C was used on the VW Golf 60 and Corrado 60, on Polo 40, on Mercedes 200 Kompressor, on Jaguar XKR - just to name a few. Engines that employ only the turbo and no gear-driven S/C are far more common, especially the so-called 'turbo diesels' in Europe, as well as on many gas-fueled Japanese cars, plus on the European ones.
(American cars are not my cup of tea, sorry)
Some high-end car engines use (used) the 2-stage system (turbo feeding the gear-driven S/C).

Roots type superchargers are usually driven on aircraft engines with a gearbox turned by the crankshaft.

Roots-type S/Cs were not installed on service-worthy aero engines, at least not in the 1930s-40s.

A turboprop usually refers to a turbine engine that drives a propeller through some type of a reduction system.

Very true.

 

[Reluctant Poster]

The aircraft engine historical society has several articles on superchargers. An example deals with US developments between wars

Supercharger Development in the U.S. During the Inter-War Period

Also I have attached is very informative paper by NACA on superchargers

 

[Elvis]

Today we call it "turbocharged."

In WWII, they called it turbo-supercharged.

Same compressor, but the supercharger is driven vy the crankshaft and the turbocharger is driven by exhaust gases.

Then why did they need to dedicate so much of the fuselage to it?

 

[Elvis]

Centrifugal superchargers are commonly referred to as turbochargers. Turbochargers are spun by spent exhaust gases. Roots type superchargers are usually driven on aircraft engines with a gearbox turned by the crankshaft. Both are superchargers.

A turboprop usually refers to a turbine engine that drives a propeller through some type of a reduction system.

When you mentioned "Rootes type superchargers", you mean a supercharger that is similar to one found on a Detroit Diesel Engine, right?

 

[Reluctant Poster]

Then why did they need to dedicate so much of the fuselage to it?

The cooling system was in the fuselage behind the engine . A unique arrangement to say the least

 

[Reluctant Poster]

When you mentioned "Rootes type superchargers", you mean a supercharger that is similar to one found on a Detroit Diesel Engine, right?

Correct

 

[GregP]

Centrifugal superchargers are commonly referred to as turbochargers. Turbochargers are spun by spent exhaust gases. Roots type superchargers are usually driven on aircraft engines with a gearbox turned by the crankshaft. Both are superchargers.

A turboprop usually refers to a turbine engine that drives a propeller through some type of a reduction system.

Disagree, rather completely.

The difference is drive.

If the compressor is driven by the crankshaft, it is today and was in WWII called a supercharger. If it is driven by exhaust gases, it is today called a turbocharger, but was known then as a turbosupercharger.

This confusion is the source of commonly held but incorrect belief that a WWII Allison V-1710 was not supercharged. In fact, all Allisons for aircraft were supercharged, but only the P-38 Allison V-1710 got turbocharged. The rest were simple, single-stage supercharged that basically started giving up at about 15,000 or so feet.

 

[pbehn]

Then why did they need to dedicate so much of the fuselage to it?

Regardless of what you do on a single engined fighter the prop is in front of the engine and any supercharger / turbo charger system goes behind. An exhaust driven turbo was discounted by Rolls Royce for the high altitude Wellington engine because it couldnt be fitted to a Spitfire even though it would have been OK in a Wellington as it was in US bombers.

 

[Zippythehog]

Disagree, rather completely.

The difference is drive.

If the compressor is driven by the crankshaft, it is today and was in WWII called a supercharger. If it is driven by exhaust gases, it is today called a turbocharger, but was known them as a turbosupercharger.

This confusion is the source of commonly held but incorrect belief that a WWII Allison V-1710 was not supercharged. In fact, all Allisons for aircraft were supercharged, but only the P-38 Allison V-1710 got turbocharged. The rest were simple, single-stage supercharged that basically started giving up at about 15,000 or so feet.

OK. I'm not an engineer. They don't even let me blow the whistle or ring the bell. However, in Edward F Obert's book, Internal Combustion Engines Analysis and Practice, first published in 1944, he defines "supercharging as any assistance given to the intake process by a supplementary fan, blower, or compressor."

AFAIK, turbine engines are the motive force that turns propellers on airplanes. At least that was the case for the King Airs I've flown.

 

[Zippythehog]

When you mentioned "Rootes type superchargers", you mean a supercharger that is similar to one found on a Detroit Diesel Engine, right?

Yup

 

[Zippythehog]

BTW, GregP, is that a Van on your avatar?