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I used to wonder why there where no engine exhaust stacks from the massive PW R-2800 engine on the P-47?
Your question is a little ambiguos in that you could mean was it the only turbocharged fighter (no, so was the P-38) or the only one with the wastegates between the engine and the turbocharger, which is probably correct as I cannot think of another built that way.
Why is it so? My guess would be that having the wastegate forward of the cockpit was necessary to keep the cockpit cool in hot climates. Reducing the volume of the exhaust passing below cockpit would significantly reduce the radiant heat on the cockpit and the resulting cooling needed but the down side is that when instant power is called for the lag between closing the wastegates and the turbo speeding up would be significantly longer than on an installation where the wastegate is downstream of the turbo. Two wastegates also doubles the chances of failure.
I do not know if you have the P-47 PTM so I am attaching one version and a P-38 version so you can see how the "normal" layout (P-38/B-17/B-24) is. In all those cases there is no exhaust near the cockpit.
I can add another, later, P-47 PTM if you want.
I was under the impression that if a Turbocharged engine has a wastegate, it is always located between the engine and the Turbocharger. The job of the wastegate is to regulate the flow of exhaust gasses to the Turbocharger. It not only to limits the total flow to prevent over-boost, but reduces back-pressure in the exhaust manifold during acceleration caused by turbo lag in some applications.Your question is a little ambiguos in that you could mean was it the only turbocharged fighter (no, so was the P-38) or the only one with the wastegates between the engine and the turbocharger, which is probably correct as I cannot think of another built that way.
B-17, B-24, P-38, P-43, B-29. perhaps some others.Can you sight an example of any powerplant that uses a wastegate after the turbocharger instead of before?
Can you sight an example of any powerplant that uses a wastegate after the turbocharger instead of before?
As you can see in the picture from Shortround, there is no exhaust ducting or wastegate after the turbine on the P-38.
Yes the wastegate dumps the exhaust before it passes through the turbocharger.I was under the impression that if a Turbocharged engine has a wastegate, it is always located between the engine and the Turbocharger. The job of the wastegate is to regulate the flow of exhaust gasses to the Turbocharger. It not only to limits the total flow to prevent over-boost, but reduces back-pressure in the exhaust manifold during acceleration caused by turbo lag in some applications.
While I suppose some of this could be accomplished by placing the wastegate after the Turbocharger, through back-pressure, that seems incredibly inefficient. Can you sight an example of any powerplant that uses a wastegate after the turbocharger instead of before?
The wastegate on the B-series turbos was in the housing and released exhaust before the turbine.
As you can see in the picture from Shortround, there is no exhaust ducting or wastegate after the turbine on the P-38.
Actually the wastegate is in the photo provided by Shortround. The arrow points to the pivot shaft for the wastegate as shown in the graphic from the manual below it.
Yes the wastegate dumps the exhaust before it passes through the turbocharger.
great visuals. thanks.The P-38, the prototype P-39, B-17, B-24, B-29 for beginners.
P-38 (from the Allison service school handbook)
View attachment 588639
From the GE Turbocharger handbook
View attachment 588641
From the -2 (E&M) manual
View attachment 588648
B-17 (from the B-17 Pilot Training Manual.)
View attachment 588636
B-24 (from the B-24 Pilot Training Manual). Yes the B-24 uses the twin row R-1830 but this is the diagram in the B-24 manual.
View attachment 588635
B-29 (from the GE Turbocharger handbook)
View attachment 588640