Inverted aero engines

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Re: Inverted aero engines

Post by user-17438 »

Frankshaft wrote: Mon Sep 10, 2018 3:22 pm
mk e wrote: Mon Sep 10, 2018 2:06 pm
Frankshaft wrote: Mon Sep 10, 2018 12:56 pm
Would you have to raise the floor and lower the roof when porting?
I'm pretty sure you just do what you always do, then flip the engine over, connect the breather to the oil pan and return pump to the valve covers...I'm pretty sure it was a dump setup with a pickup or 2 in each cover.

I remember him telling me he was worried about oil in the pistons and oil consumption but was very pleasantly surprised when it run fine. It was port fuel injected.
I was just trying to be comedic.
I bet transient throttle response is better.
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Re: Inverted aero engines

Post by volodkovich »

The bigger question is why the 90deg drive for the centrifugal supercharger? I am led to believe they used variable speed fluid coupling for the drive too.
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Re: Inverted aero engines

Post by rfoll »

Whenever I see one of these, I wonder about pistons running full of oil.
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Re: Inverted aero engines

Post by SupStk »

I'm interested in the DB600 series engines also. From what I understand the the BF109s inverted engine had the auto canon on the pan. There had to be a gear drive to the prop so the canon could shoot through the propeller hub.
The Diamler-Benz's supercharger was driven hydraulically with automatic variable speeds. The Merlin had a two speed supercharger but the pilot had to control it based on altitude and manifold pressure. Can imagine a pilots hands were full without having to adjust engine controls during a climbing and diving dogfight.
At 2500 RPM I doubt a dry sump.system cares what position the engine is. The oil wouldn't be sitting in the pistons at that point.
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Re: Inverted aero engines

Post by peejay »

hoodeng wrote: Mon Sep 10, 2018 1:38 am One benefit of inverted engines was that it allowed for lower mounted machine guns grouped in the pilots line of sight ,so there was no need for a convergence zone required by wing mount guns,

Image

Of course, the American solution involved more power :) But then we had somewhat different priorities.

I "get" all the reasons for doing an inverted engine like having an easier time getting the prop's thrust axis in a beneficial spot. But how did they get around the problem of oil collecting in the "tops" of the chambers after the engine sat for a while? On a radial you have to pull the bottom plugs and turn the engine over by hand, before starting. Did they have to remove ALL of the plugs before a cold start or did they have some sort of workaround?
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Re: Inverted aero engines

Post by ptuomov »

The think the exhaust valves were forced open during the time when the plane was standing with the models that had exhaust ports in the V.

Due to superior engineering, the axis planes were better than allied planes, in all respects bar one: production numbers.
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Re: Inverted aero engines

Post by peejay »

ptuomov wrote: Mon Sep 10, 2018 7:07 pm The think the exhaust valves were forced open during the time when the plane was standing with the models that had exhaust ports in the V.

Due to superior engineering, the axis planes were better than allied planes, in all respects bar one: production numbers.
That's not what I'd read about the Me109. It's been a while, but from what I remember Allied pilots bitching about when they got to sample them, the controls got really heavy at higher speeds, they had a variable prop but it was manually adjusted so you had to keep your head in the cockpit so to speak, and they had a laughably small range. Under an hour of flight time. (The low range did mesh well with the doctrine of shooting down Allied bombers over German soil for civilian morale reasons. Not a good way to win a war though)

The Zero was a fine plane in the 1930s. Unfortunately for Japan, they didn't really move past that.

In both cases, a concentrated effort on destroying manufacturing infrastructure helped stifle innovation. Lack of available resources, especially oil, did the rest.
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Re: Inverted aero engines

Post by Truckedup »

ptuomov wrote: Mon Sep 10, 2018 7:07 pm The think the exhaust valves were forced open during the time when the plane was standing with the models that had exhaust ports in the V.

Due to superior engineering, the axis planes were better than allied planes, in all respects bar one: production numbers.
The USA used superior engineering to design aircraft suited to mass production by women and auto workers,rugged construction to absorb combat damage and get the pilot back to base, high top speeds with many fast firing machine guns suited to less experienced pilots..
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Re: Inverted aero engines

Post by Keith Morganstein »

On the big radial engines I’ve seen, they have suction tubes to evacuate (or scavenge ) the oil out of the pistons. I don’t see that on the inverted vee engines.
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Re: Inverted aero engines

Post by mfdcar51 »

Roller bearings..
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Re: Inverted aero engines

Post by ptuomov »

peejay wrote: Mon Sep 10, 2018 7:16 pm
ptuomov wrote: Mon Sep 10, 2018 7:07 pm The think the exhaust valves were forced open during the time when the plane was standing with the models that had exhaust ports in the V.

Due to superior engineering, the axis planes were better than allied planes, in all respects bar one: production numbers.
That's not what I'd read about the Me109. It's been a while, but from what I remember Allied pilots bitching about when they got to sample them, the controls got really heavy at higher speeds, they had a variable prop but it was manually adjusted so you had to keep your head in the cockpit so to speak, and they had a laughably small range. Under an hour of flight time. (The low range did mesh well with the doctrine of shooting down Allied bombers over German soil for civilian morale reasons. Not a good way to win a war though)

The Zero was a fine plane in the 1930s. Unfortunately for Japan, they didn't really move past that.

In both cases, a concentrated effort on destroying manufacturing infrastructure helped stifle innovation. Lack of available resources, especially oil, did the rest.
I don’t think there was a better plane on the allied side than Messerschmidt ME-262. That plane obsoleted all propeller fighters.

Once the Americans (including head of technical staff at Boeing) saw the German research materials on airplanes in 1945, including the experimental data from a supersonic wind tunnel and the equations explaining the data, they telegraphed home “Stop the design!” That’s how B-47 Stratojet become to exist.

The German wing design of B-47 survived to B-52. B-52 might end up being in service until 2050.

Americans perfected the radar and radar targeting system, the proximity fuse, and the atomic bomb, so I’m just talking about planes here, not overall technological superiority. Those three technologies really moved the needle on the Pacific.
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Re: Inverted aero engines

Post by ptuomov »

Truckedup wrote: Mon Sep 10, 2018 7:50 pm
ptuomov wrote: Mon Sep 10, 2018 7:07 pm The think the exhaust valves were forced open during the time when the plane was standing with the models that had exhaust ports in the V.

Due to superior engineering, the axis planes were better than allied planes, in all respects bar one: production numbers.
The USA used superior engineering to design aircraft suited to mass production by women and auto workers,rugged construction to absorb combat damage and get the pilot back to base, high top speeds with many fast firing machine guns suited to less experienced pilots..
Exactly correct on mass production from standardized parts by regular skilled labor.

This was even more evident in shipbuilding, where ships used to be like houses, each one a little different. Then the US standardized everything and started cranking out 1.25 million tons of shipping capacity per month in 1943.
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Re: Inverted aero engines

Post by hoodeng »

Usually in an inverted engine [also radials]there are collection channels distributed throughout the engine and drain back points that oil collects in and is scavenged to the oil tank.

Cheers.
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Re: Inverted aero engines

Post by Kevin Johnson »

hoodeng wrote: Tue Sep 11, 2018 1:48 am Usually in an inverted engine [also radials]there are collection channels distributed throughout the engine and drain back points that oil collects in and is scavenged to the oil tank.

Cheers.
DB_601_1.gif
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For higher quality images: https://ww2aircraft.net/forum/threads/d ... als.38202/

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Comment: The 601 handbook uses Fraktur (older stylized German writing); the 603 uses a more accessible font for English readers. If you do not know what a German term means, Google will translate it for you. A similar exercise could be performed for a particular radial engine of interest. Good luck.
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Re: Inverted aero engines

Post by plovett »

Maybe the biggest disadvantage the Germans had in aircraft engine design was the lack of high octane gas. I'm making up numbers, but they had something in the range of 87 to 100 octane. The Americans had up to 150 octane. This allowed much higher manifold pressures. Again making up numbers, but maybe over 70" on 150 octane and a little over 40" on 90 something octane.

The Germans compensated by using larger displacements (P&W R2800 not withstanding), and using chemical charge cooling, like N2O and water/methanol mixtures. But the allies could add those to their already higher boosted engines, too.

The fuel octane is probably the biggest factor, in my opinion.

Since jet engines could use very low octane fuel, that was a game changer for them.

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