WW2 Turbochargers why not used by all?

[MIflyer]

Also realize that the two stage supercharged Merlin used mainly an Aftercooler, but also used a partial Intercooler by the way they routed the coolant internal to the engine.

It is amazing that the two stage supercharged Merlin began as a quick lash up, using the Merlin engine, which was already deemed too small for front line fighters, combined with the first stage supercharger from the failed Vulture engine and a stroke of real brilliance, the liquid cooled aftercooler, Note that Stanley Hooker was a theoretical aerodynamicist, and "not much of an engineer" so seizing liquid cooling as an answer was stepping outside his comfort zone.

See the attached article.

 

[MIflyer]

Attached is a nice diagram that shows some of the complexities of a turbosupercharged aircraft engine.

 

[mad_max]

As for Thrust from the Jug I have only seen estimates, but this months AIR CLASSIC has an article on the J Model Superbolt that states at 1770 HP level speed it produces 400lb of thrust. , which it says is actually more than the inlines of the USA. For the old version the the CH turbo I'd est. 250-300 lbs., since it turned at less rpm.

As for the "problem" of high inlet temperatures; Flight tests proved that when using 100-150 fuel there wasn't any issues. You need to remember at high alt. the air is in the neg numbers for temps.

150 Grade Fuel

P-47D AIRPLANE, AAF NO. 42-26167
USING 44-1 FUEL

I Introduction

Flight tests have been conducted at Wright Field on the P-47D airplane, AAF NO. 42-26167, at the request of the Power Plant Laboratory, Engineering Division. These tests were made to determine the increased performance of the airplane using the higher powers allowable by use of 44-1 fuel as compared with powers allowable with the standard fuel, grade 100/130, Spec. No. AN-F-28. From 15 April to 30 June 1944 approximately 30 hours were flown by Captain R. B. Johnston.

The P-47D is a single engine, high altitude fighter. It is equipped with a Pratt & Whitney R-2800-63 engine furnished with a water injection system and a four-bladed Curtiss Electric controllable propeller, blade design No. 836-2C2-18.

II Summary

Preliminary tests were run to clear the airplane for performance with higher powers with and without water injection. Detonation equipment was installed to determine if any flight condition became marginal as to detonation, cooling or improper operation of auxiliary parts. No detonation was observed in level flight up to 65.0" Hg. without water and 70.0" with water. No detonation was observed in climb up to 65" Hg. without water. Detonation occurred at 65.0" with water in climb but was remedied by using a No. 18 water jet. Cylinder head and carburetor air temperatures remained below the limits in level flight. Excessive cylinder head and carburetor air temperatures were encountered in climbs, limiting the duration of any climb to a point where limits are reached.

The airplane and engine handled well at all altitudes at the higher powers. At 70.0" Hg., water injection, a maximum speed of 444 MPH was obtained at 23,200 feet. At 65.0" Hg., with water a high speed of 439 MPH at 25,200 feet and a maximum rate of climb of 3260 ft/min. at 10,000 feet were obtained. At 65.0" Hg., without water a high speed of 430 MPH at 25,400 feet and a maximum rate of climb of 2850 ft/min. at 12,000 feet were obtained. At 56.0" Hg. without water a high speed of 418 MPH at 29,600 feet and a maximum rate of climb of 2330 ft/min. at 12,000 feet were obtained. At 52.0" Hg. without water a high speed of 412 MPH at 31,400 feet and a maximum rate of climb of 2030 ft/min. at 12,000 feet were obtained.

Here are some good articles on the Jug:

Air Force Magazine
http://rwebs.net/avhistory/history/p-47.htm

Most Civil airliners cruised at 20,000 ft +/-, so a single stage 2 speed supercharging system was quite adequate for the purpose. The Connie's ceiling was 24,000ft and it was the premier airliner in the time.