Inverted V engine vs. V engine

[wuzak]

Nice job Tartle.

 

[Shortround6]

Thank you Tartle.

 

[P-40K-5]

' I'm not arguing, I'm stating an engineering fact. The piston engine was not designed to run upside down.
Oil control being one reason. '

ha! not if it was designed too. ever hear of dry sump oiling? look at a boxer engine, no problems there.
vacuum makes the engine round and round, not gravity. the engine dosn't care how it sits.

 

[fibus]

The inverted Vee engine is the same as a Vee engine, but turned upside down, so that the crank sits at the top and the heads at the bottom. The thory is, for single engined aircraft at least, that the inverted Vee allows the pilot a better view over the nose. If you look at a Spitfire you can see the cam covers make the top of the cowling wider at the front, particularly on Griffon engined models. If the engine was inverted then the top of the cowling coud be narrower, theoretically giving the pilot a better view.

The P-51D air scoop as little to do with fuel injection or lack thereof. The belly scoop is purely for the radiator group, while the chin scoop feeds air back to the engine.

Fuel injection is far superior to carburettors now because of the sophisticated electronic managment systems that are used. But in the time of WW2 injection was all mechanically operated.

The German engines, Daimler Benz's at least, used direct fuel injection - fuel is injected directly into the cylinder. This has the advantage of the supercharger only having to compress the intake air, and not the fuel. But it has the disadvantage that the effect of the fuel vapourising in the intake system is lost, and thus the intake air is hotter.

Some US and British aircraft used fuel injection, but I believe that these injected fuel into the eye of the supercharger impeller. In this instance the injection offers better metering with the cooling effect of the fuel, and is otherwise the same as a carburettor.

Direct injection systems also reduce the possiblity of backfires in the engine, as there is no fuel/air mix in the intake ducts.

Comapred to earlier carburettors, fuel injection was able to deal with negative G manouevres better. Egines fitted with earlier carburettors would cut out when negative Gs were encountered - something the Germans would exploit in the battle of Britain. Later carburettors solved this problem, however.

carburettor cut out? google miss schillings orifice.

 

[fibus]

always been curious as to how you prevent oil collecting in the skirts of the pistons on an inverted V engine?

Oil collects. So you turn the engine by battery or apu counting the number of blades, say 16 on a Wright radial and a similar number on inverted engines. This clears the bottom cylinders of standing oil by forcing it out the exhaust. Then you start the engine. If you don't clear the engine you would have hydraulic shock, oil is incompressible, so you would have bent connecting rods etc.

 

[wuzak]

carburettor cut out? google miss schillings orifice.

I know of this device, but it was not until after the BoB that the device was invented and fitted to frontline aircraft. And even then it wasn't a complete cure.

 

[Tartle]

The anniversary edition of ' Aeroplane Monthly', I believe the June edition had a description of the various improvements to carburation of the Merlin... I raed it in the newsagent and when I returned to buy it they had all gone! However it was a very good article that explained the steps from Miss Schilling to a more robust solution. It was of course a design choice for the original carb'r and is nothing to do with \/ or /\! However the cooling effect of the fuel is worth a great deal... I'll dig out the figures. (does anyone want to post the article?)

 

[P-40K-5]

'On a further point of interest regarding CRs, J.J. notes, quite correctly, the 8.3/9.5 figures that pertain to the left and right cylinder banks of the Daimler-Benz 603 when running on 100 octane fuel.'

it was 8.3/8.5:1 when running 100oct fuel. these engines could also run on 87oct too.

2) The DB 600 series V-12s were never fitted with anything but fork and blade con-rod pairs! '

I don't think so! NOT a fork/blade design!

'Theory two centers on the fact that the supercharger on the DB 600 V-12s as located on the left hand side of the engine and, thus, from such position would naturally provide mere "huff" to the cylinder bank nearest to it. In order not to (relatively) over-boost the left hand bank, the CR would have to be lowered slightly on that side.'

what difference does it make where the s/c is located? the s/c outlet connects to the rear center of the intake plenium. no different then when you install a supercharger to a Chevy LS series engine.

 

[Kryten]

I know of this device, but it was not until after the BoB that the device was invented and fitted to frontline aircraft. And even then it wasn't a complete cure.

the device did not cure the problem entirely but it made the aircraft considerably less sensitive to negative G, to the point only pitching the aircraft into a steep dive resulted in fuel starvation, unlike the original problem which caused the problem in even a minor bunt could see the engine splutter!

 

[Kryten]

'On a further point of interest regarding CRs, J.J. notes, quite correctly, the 8.3/9.5 figures that pertain to the left and right cylinder banks of the Daimler-Benz 603 when running on 100 octane fuel.'

it was 8.3/8.5:1 when running 100oct fuel. these engines could also run on 87oct too.

2) The DB 600 series V-12s were never fitted with anything but fork and blade con-rod pairs! '

I don't think so! NOT a fork/blade design!

'Theory two centers on the fact that the supercharger on the DB 600 V-12s as located on the left hand side of the engine and, thus, from such position would naturally provide mere "huff" to the cylinder bank nearest to it. In order not to (relatively) over-boost the left hand bank, the CR would have to be lowered slightly on that side.'

what difference does it make where the s/c is located? the s/c outlet connects to the rear center of the intake plenium. no different then when you install a supercharger to a Chevy LS series engine.

study the problems associated with air pressure fluctuation accross a centrally mounted V8 plenum and you appreciate how the longer plenum on an aircraft engine can most definatly have an adverse effect on cylinder filling!

 

[P-40K-5]

yes, but also take into account the firing order. kinda equalizes everything, not perfectly mind you. still, it will not pressurize one bank more then the other bank.
that design holds fast even today.. austin martins, dodge vipers, ferraris, all use the same principle when supercharging.

 

[Kryten]

yes they do, but thier centrally mounted plenum is designed in such a way as to have equal pressure drop on throttle opening accross the whole plenum, the aircraft engine cant achieve this due to packaging, imagine a spitfire with a bonnet bulge!!!

 

[P-40K-5]

haha no kidding lol. but still, for 1940's technology, it was most impressive!

 

[P-40K-5]

@ Tartle's excellent posts,

it amazes me to no end how so called " experts " (ie: the authers of the article) can make such grievous
mistakes.

 

[wuzak]

2) The DB 600 series V-12s were never fitted with anything but fork and blade con-rod pairs! '

I don't think so! NOT a fork/blade design!

What sort of rod design did they have?

 

[fastmongrel]

@ Tartle's excellent posts,

it amazes me to no end how so called " experts " (ie: the authers of the article) can make such grievous
mistakes.

Would it be possible to list the mistakes made

 

[Readie]

Would it be possible to list the mistakes made

Only one mistake mate.
Turning an aeroengine upside down in the first place

 

[tyrodtom]

Only one mistake mate.
Turning an aeroengine upside down in the first place

Ranger, Argus, DeHavilland,Hirth,Menasco,Alfa , Renault, and several other aircraft engine manufactors all made the same mistake.

 

[Readie]

Ranger, Argus, DeHavilland,Hirth,Menasco,Alfa , Renault, and several other aircraft engine manufactors all made the same mistake.

It was my feeble attempt at mirth...

 

[Kryten]

I'm still not fully comprehending the reasoning to invert the engine, as it does seem to produce more issues than an upright installation, and offers little if any realistic advantage?