Was the Republic P-47's turbo-supercharger system unique to only the P-47?

Dash119 said:

Butterfly valve is a much better description than flapper valve...

I think only one of the flying P-38's actually has functioning turbos, not sure about the flyable P-47's.

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I only know of one P-47 with a functioning turbo and that is Hun Hunter. All the rest are just using the single speed supercharger only as that's good for 10K alt.

P-47D

Gentlemen, The waste gate on B turbos as mounted on B-17, B-24 and P-38 is located after the turbine. The turbos are the same for these 3 aircraft and they were made by either by GE or Allis-Chalmers. We use P-38 turbos on our B-17. The P-38 has one turbo per engine, the B-29 two. Re the P-47: There are always exhaust gases that go through the exhaust system and turbine, even when the waste gate is completely open. Thus the duct under the cockpit will always be "hot". I believe that the only reason that the waste gate was installed where it is at is the desire to "dump" much of the exhaust gases outboard as close to the engine as possible when boost is not needed.

By the way, when it comes to exhaust stacks, one shouldn't forget the glare from the flames coming out of the exhaust at night. That was one of the main reasons for placing the stacks where they sometimes wound up at.

Big Jake said:

Gentlemen, The waste gate on B turbos as mounted on B-17, B-24 and P-38 is located after the turbine.

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No, it is not. The wastegate relieves the exhaust before it passes through the turbine.

On the B-series the wastegate is integral with the turbine housing, which directs the exhaust through the turbine.

Physically the wastegate is behind the turbine on those machines, but it could be placed in any orientation. In terms of the exhaust flow, the wastegate is before the turbine.

wuzak said:

No, it is not. The wastegate relieves the exhaust before it passes through the turbine.

Before it passes through the turbine? See below.

On the B-series the wastegate is integral with the turbine housing, which directs the exhaust through the turbine.

It's not integral. You can unbolt and remove it.

Physically the wastegate is behind the turbine on those machines, but it could be placed in any orientation. In terms of the exhaust flow, the wastegate is before the turbine.

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So now it's behind the turbine?

As someone who has personally replaced turbos on B-17 on a number of times, I should know my turbos... The wastegate is behind the turbine and after it is nothing - in a preflight inspection, you stick your hand into the wastegate and make sure that the flapper valve is loose and free. I do it often enough...

Big Jake said:

So now it's behind the turbine?

As someone who has personally replaced turbos on B-17 on a number of times, I should know my turbos... The wastegate is behind the turbine and after it is nothing - in a preflight inspection, you stick your hand into the wastegate and make sure that the flapper valve is loose and free. I do it often enough...

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The exhaust that exits the wastegate does not go, and has not been, through the turbine. It works exactly the same as the wastegates on the P-47, which are not mounted behind the turbine.

The wastegate is operationally between the engine and the turbine, even if physically is not.

If you turn the turbo 90° around its axis, is the wastegate now to the side?

Big Jake said:

So now it's behind the turbine?

As someone who has personally replaced turbos on B-17 on a number of times, I should know my turbos... The wastegate is behind the turbine and after it is nothing - in a preflight inspection, you stick your hand into the wastegate and make sure that the flapper valve is loose and free. I do it often enough...

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The B series Turbo-Supercharger contains an integrated wastegate, not a separate wastegate like the C series found in the P-47. As wuzak points out above, while the butterfly valve of the wastegate and it's exhaust port are located at the back end of the unit, in operation it controls the flow of exhaust gases into the exhaust turbine. This was not clear to me or other members until wuzak explained the actual operation, so he gets the credit for the following.

The circular manifold which culminates in the wastegate has pathways to the exhaust turbine of the Turbo-Supercharger. So when the wastegate is closed, the exhaust gases are forced through the exhaust turbine and out the bottom of the Turbo-Supercharger itself. When the wastegate is open, the back pressure inherent in the exhaust turbine of the Turbo-Supercharger causes most of the exhaust gases to flow out past the butterfly valve.

So despite its physical location, the integrated wastegate on the B series Turbo-Supercharger provides a bypass and regulates the flow of exhaust gases into the exhaust turbine. All the wastegates I have ever heard of, in any application, control boost by regulating the flow of exhaust gasses to the inlet side of the exhaust turbine not the outlet side. Trying to control boost by regulating the flow of exhaust from the outlet side of the exhaust turbine creates a whole litany of issues, and would be very inefficient.

See the image of the B-24 manual in post #8 of this thread for a better visual. The B-17 manual image is somewhat deceptive as it doesn't show the flow out the bottom of the Turbo-Supercharger as it should.

Dash119 said:

Trying to control boost by regulating the flow of exhaust from the outlet side of the exhaust turbine creates a whole litany of issues, and would be very inefficient.

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That would be the Variable Discharge Turbine (VDT) that Pratt & Whitney tried for the R-2800 and R-4360, but abandoned due to control issues (and the coming of jets).