Merlin Two Stage Supercharger Sketches

[MIflyer]

Here are a couple of the better drawings I have seen showing the Merlin 2-stage supercharger. The sectioned complete engine is the Merlin 130.
These are from the book "Merlin Power."

 

[GrumpyOldCrewChief]

Great find for this drawing! Not trying to start a "flame fight" here, but isn't the "inter-cooler" in this instance more properly an "after-cooler"? As in, an inter-cooler should be placed between the stages of supercharger compression, (i.e., between a turbocharger compressor, and the engine-driven compressor) and this item is after all stages of supercharger. Often, technical terms are used interchangeably, when they should not, or with insufficient clarity. FAA A & P days will haunt you...

 

[Sid327]

Great find for this drawing! Not trying to start a "flame fight" here, but isn't the "inter-cooler" in this instance more properly an "after-cooler"? As in, an inter-cooler should be placed between the stages of supercharger compression, (i.e., between a turbocharger compressor, and the engine-driven compressor) and this item is after all stages of supercharger. Often, technical terms are used interchangeably, when they should not, or with insufficient clarity. FAA A & P days will haunt you...

Agree.

There was an inter cooler between the first and second stage of the Merlin's supercharger and as you said, the after cooler was the ''square box'' mounted at the back of the engine.
The word inter cooler is now in common use for what are technically after coolers.

 

[tomo pauk]

Great find for this drawing! Not trying to start a "flame fight" here, but isn't the "inter-cooler" in this instance more properly an "after-cooler"? As in, an inter-cooler should be placed between the stages of supercharger compression, (i.e., between a turbocharger compressor, and the engine-driven compressor) and this item is after all stages of supercharger. Often, technical terms are used interchangeably, when they should not, or with insufficient clarity. FAA A & P days will haunt you...

Seems like this inter-cooler was located between something, after all - between supercharger and cylinders of an engine?

 

[MIflyer]

You are right about that big box on the back - but in fact the Merlin was both intercooled and aftercooled. The routing of the fluid to the Aftercooler also did some Intercooling along the way.

Over at Kissimee they have a Merlin on display that has been sectioned and you can see inside like the drawing. I need to fly over there and take some photos of that.

 

[Zipper730]

It's interesting how the airflow goes from the radiator to flow between the casing prior to cooling off the airflow off the second stage of the supercharger. I knew the design used cooling of the casing, I just didn't know the flow pathway. It seems that the coldest coolant would cool the casing a little and warm up a skosh, then absorb the hot air off the second stage and heat up a whole lot, then from there, go to the header, and down through the radiator.

I also never would have thought the coolant flow would have gone from the hot radiator to the header: I figured it would have went from the header to the cooler, then to the radiator.

 

[MIflyer]

Header tanks typically have "Sniffle Valves" that allow excess pressure to vent, usually along with a little bit of fluid - just like an automobile radiator cap does. That would allow air in the system to vent and not enter the pump.