Supercharger Intake Locations

[silence]

So I was looking at some cutaway drawings...

Looks like the P-47's supercharger intake is directly under the engine right in front, correct?

But I can't find for sure the location for the same on the Spitfire, unless its the little bitty scoop above the starboard exhaust pipes.

And I have no idea where the Mustang's is.

 

[swampyankee]

Well, here's a cutaway: http://www.flightglobal.com/airspac...images/10752/supermarine-spitfire-cutaway.jpg and another: http://mustang51.com/dwgs/p51b_1_3v_c_cutaway.jpg

 

[razor1uk]

The little scoop on one side of a Spitfires cowling, is for (partial) cockpit pressurisation using a roots type blower - after the war many were used for supercharging drag bikes due to its small size. The carb/supercharger intake is the under nose roughly inline with the wings leading edge on Spits, in Mustangs (with Merlins/Packhards), its by the tip of the nose, or when cold or dusty, fed by the perforated plates behind the spinner.

 

[silence]

Ah, so on the Spit the intake is shared. Okay, that makes sense.

So the Mustangs' would be the small chin scoop?

 

[nuuumannn]

The Spitfire's is the carburettor intake at the wing leading edge under its nose; it's not shared with anything. That's what its for:

So the Mustangs' would be the small chin scoop?

Yep.

 

[GregP]

The Allison had a downdraft carb and so the intake for the carb is on top in the P-51A. The Merlin has an updraft carb and so the intale is under the spinner on the P-51.

The intake for the P-38 is a small stand-alone scoop under the traling edge of the wing on the booms. In modern P-38's, nobody is running the turbochargers and the carb intake is in the middle where the intercooler intake used to be.

Actually, there is now ONE P-38 out there running an operational pair of turbochargers and ONE P-47 also running a turbo.

 

[wuzak]

The Allison had a downdraft carb and so the intake for the carb is on top in the P-51A. The Merlin has an updraft carb and so the intale is under the spinner on the P-51.

The intake for the P-38 is a small stand-alone scoop under the traling edge of the wing on the booms. In modern P-38's, nobody is running the turbochargers and the carb intake is in the middle where the intercooler intake used to be.

The P-38 also had a system which drew air in from the wheel well.

 

[silence]

It seems (to me) that razor1uk and nuuumannn are in disagreement.

 

[Milosh]

It seems (to me) that razor1uk and nuuumannn are in disagreement.

They both said the same thing:

razor1uk: The carb/supercharger intake is the under nose roughly inline with the wings leading edge on Spits

nuuumann: the carburettor intake at the wing leading edge under its nose; it's not shared with anything.

Did you actually look for an answer before asking the question?

 

[razor1uk]

Thanks Milosh Sorry Silence English meanings can be usually be written in at least 2 or more ways and still mean the same, this can make translating difficult sometimes, but for those who write books, they find it useful being less bored, or end up with a bigger writers block. Mind due those who read, can find that it is hard at times and sometimes too much.

 

[silence]

I think my confusion may be resulting from ignorance on just how the supercharger and carburetor interact with the engine.

The carburetor mixes air and fuel for the engine. The supercharger is an air compressor used to increase the pressure, temperature, and density of air supplied to an internal combustion engine (per wiki). Therefore the supercharger (my fingers seem to HATE to type that!) feeds INTO the carburetor to keep its air supply at the levels it needs.

This, coupled with previous posts, leads me to conclude that the supercharger is in front of the carburetor and maintains a strong airflow to the carburetor. (Please excuse me if I'm stating the obvious: typing it out helps my thought processes.) The intake does not feed both simultaneously, but rather the one with then, in turn, feeds the other - a system in series rather than in parallel.

If this is correct, then it appears that for whatever reason I was thinking (apparently not too well!) that the carb and supercharger operated side-by-side, simultaneously drawing from the same air supply at the same time. I think that rates a big "whoops"!

 

[Shortround6]

Yes and no. The Merlins had a system in which air went from the carburetor to the supercharger and from the supercharger to the intake manifold. Most Allisons did too. German engines used direct fuel injection into the cylinders. Air from the intake went to the supercharger, it was compressed and flowed to the cylinders. French Hispanos ( and Russian VK-105 engines) took air from the intake to the supercharger, blew it through pipes to six carburetors ( one carb fed two cylinders) and then to the cylinders.
Some engines had one supercharger blowing air into a carburetor mounted on a second supercharger.

They ALL operate in series except the engine on a F4U Corsair which had a changeable intake. It had two superchargers in series but it could by pass the first one. Not really operating in parallel.

A number of planes had alternate air intakes like the P-38 in which one faced forward and picked up "ram" pressure from forward speed but was liable to ingest sand, dirt and debris and another intake for use while taking off/landing that was more sheltered or filtered but they joined BEFORE the carb or supercharger.

 

[silence]

NOW I get it!

Thank you all!

 

[GregP]

All Allisons except some unsupercharged PT boat and tank engines had a carburetor that fed the air fuel mixture directly into the supercharger impeller and was compressed and routed to the cylinder via the intake manifold system. Supercharged Merlins, both single and muilti-stage, were the same except the Allison has a downdraft carb (carb sticks up ... so air intake is routed above the engine and turns downward into the carb) and the Merlin has a updraft carb (carb sticks down ... so air is routed under the engine and turns upward into the carb).

That's why the ALlison-powered P-51A has the carb intake above the spinner and Merlin-powered units have the carb intake below the spinner.

The -147 and -149 Allisons (the G9R and G8L for the F-82) had fuel injection, but the supercharger was in the same place with the air being routed to it instead, bypassing the space where the carburetor used to be.

 

[nuuumannn]

Perhaps this confused you, Silence.

The little scoop on one side of a Spitfires cowling, is for (partial) cockpit pressurisation using a roots type blower

What Razor is referring to here is the intake just below the exhaust ports on the nose above the guy's head, he is obscurting the carburettor intake. This is a PR.XIX photographic reconnaissance Spit.

 

[silence]

Actually it was another portside scoop I saw on an online drawing. My confusion, I think, really just boils down to the complexity of the English language. I tend to read very literally.

Damn, those are some BIG underwing radiator scoop thinigies!

 

[nuuumannn]

Yep, its got a big engine to keep cool; 36.7 lt two-speed two-stage supercharged Griffon 65.

 

[sotaro]

All Allisons except some unsupercharged PT boat and tank engines had a carburetor that fed the air fuel mixture directly into the supercharger impeller and was compressed and routed to the cylinder via the intake manifold system. Supercharged Merlins, both single and muilti-stage, were the same except the Allison has a downdraft carb (carb sticks up ... so air intake is routed above the engine and turns downward into the carb) and the Merlin has a updraft carb (carb sticks down ... so air is routed under the engine and turns upward into the carb).

That's why the ALlison-powered P-51A has the carb intake above the spinner and Merlin-powered units have the carb intake below the spinner.

The -147 and -149 Allisons (the G9R and G8L for the F-82) had fuel injection, but the supercharger was in the same place with the air being routed to it instead, bypassing the space where the carburetor used to be.

On a separate question, since you seem to have a lot of knowledge of the Allison engine, was the Allison every used in WWII combat without a supercharger in an airplane? I am having a debate on Quora who alleges the Mustang I used by the British did not have a supercharger. He writes that supercharged Allison engines were not allowed to be exported from the U.S.. This I assume to be a misreading of his literature. thank you.

 

[pbehn]

On a separate question, since you seem to have a lot of knowledge of the Allison engine, was the Allison every used in WWII combat without a supercharger in an airplane? I am having a debate on Quora who alleges the Mustang I used by the British did not have a supercharger. He writes that supercharged Allison engines were not allowed to be exported from the U.S.. This I assume to be a misreading of his literature. thank you.

Early P-38s were ordered without the turbo charger by the British and French, but I don't think that was because of a "ban" they wanted all the engines to be the same as I understand. There was some sort of embargo on selling turbos abroad which lasted into the 70s but I read about that with regard to aftermarket bolt ons for motorcycles.

 

[tomo pauk]

Two things (at least) can point out that V-1710 on the Mustang I have had a supercharger. For example, a quick look at here shows this line:
"3. Climb data, propeller set for 3000 R.P.M. for first five mins. with throttle open to 44" Hg. manifold pressure or wide open when below."
(my emphasis)
Manifold pressure above 29.92in Hg is generated either by a supercharger, or by pixie dust. Now, since nobody actually used pixie dust to increase the manifold pressure, it got to be a supercharger.
Second quick proof can be seen by looking at test reports for aircraft that used non-turbo V-1710s, like P-40 or P-39 - here. Always supercharged.
A look at manual for the Mustang I also disproves the notion that it was without supercharger - here. On pg. 30 the boost is again mentioned - no superchager, there will be no boost. Or at pg. 44, boost up to 44.5in Hg is stated. Altitude power chart at pg. 56 is also of interest. reding the manuals for P-40s or P-39s reveals the same thing.
People today ofted don't know that other types of supercharging are/were used, apart from use of turbochargers. And USA was exporting turbocharged engines (installed on aircraft) to the UK already in 1941, while contracts were been made in 1940. Unfortunately, most of the people that will state that V-1710 was non-supercharged came from Europe.

After all of this, there is a question of logic: why would anyone sane design a non-supercharged engine for military aircraft in 1930s?
BTW - since when quora became a fountain of knowledge?