Inverted V engine vs. V engine

[B-17engineer]

Just curious what the inverted V's do as opposed to having the pistons aligned in a V?

Also what difference does fuel injection make? As opposed to say the P-51D with the air scoop?

Thanks in advance.

 

[wuzak]

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.

 

[wuzak]

Btw, some consideration was mad by Rolls-Royce in making the PV-12/Merlin an inverted V12, but the idea was rejected, IIRC, by the RAF and/or the airframe manufacturers.

 

[Kryten]

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

 

[davebender]

Radial aircraft engines would have a similiar problem for half the pistons.

 

[B-17engineer]

Appreciate the responses guys, really helpful!

 

[michaelmaltby]

Do inverted V's offer better (more rigid) platform for mounting nose armaments ...?

MM

 

[Readie]

There is a 'right' way to have an engine and a 'wrong' way.
Inversion is the wrong way.
Cheers
John

 

[DonL]

There is a 'right' way to have an engine and a 'wrong' way.
Inversion is the wrong way.

Arguments?

I don't think that the DB 601, 605, 603 and Jumo 211 and 213 were outclased from RR engines.
Of the Allison we didn't need to talk that this engine could outclass any german engine of the same timeline.

So please some arguments and no phrases.

 

[Aaron Brooks Wolters]

Carburated aircraft would tend to stall out in some maneuvers do to loss of fuel over the needle and seat in the carb bowl whereas and injected aircraft had constant fuel pressure regardless of its attitude in the air.

 

[Shortround6]

Btw, some consideration was mad by Rolls-Royce in making the PV-12/Merlin an inverted V12, but the idea was rejected, IIRC, by the RAF and/or the airframe manufacturers.

There is a story that R-R went as far as making a full sized mock-up of an inverted V-12 which a group of visiting German engineers were allowed to see.

Truth or fiction?

 

[Readie]

Arguments?

I don't think that the DB 601, 605, 603 and Jumo 211 and 213 were outclased from RR engines.
Of the Allison we didn't need to talk that this engine could outclass any german engine of the same timeline.

So please some arguments and no phrases.

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.

The Allison is a worthy effort, but in the power stakes it is not in the same league as a RR Merlin.

If inversion was so brilliant why has no major manufacturer followed suit?

Cheers
John

 

[Readie]

There is a story that R-R went as far as making a full sized mock-up of an inverted V-12 which a group of visiting German engineers were allowed to see.

Truth or fiction?

GGGGermans at Rolls Royce? Good lord. I hope they checked the spanners afterwards. You can never tell with these types.

The United States had the experimental Continental IV-1430 inverted V12 engine under development, with a higher power-to-weight ratio than any of the initial versions of the German WW II inverted V12s, but was never developed to production status, with only 23 examples of the Continental inverted V12 ever being built.

So, why was that I wonder?
Cheers
John

 

[Readie]

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

Remote oil tank, dry sump and high suction collection. Often done in rally cars to avoid protruding sumps.
Cheers
john

 

[Shortround6]

GGGGermans at Rolls Royce? Good lord. I hope they checked the spanners afterwards. You can never tell with these types.

The United States had the experimental Continental IV-1430 inverted V12 engine under development, with a higher power-to-weight ratio than any of the initial versions of the German WW II inverted V12s, but was never developed to production status, with only 23 examples of the Continental inverted V12 ever being built.

So, why was that I wonder?
Cheers
John

Too many changes, not enough money and questionable design practices.

Continental was often acting as a contract shop for an Army design team, making bits and pieces and performing tests for a number of years. Literally, While both the displacement changed and the planned configuration ( it was originally a flat 12, the better to be mounted inside wings) only single cylinder test rigs were built for a number of years. Design work started in the very early 30s but a complete 12 cylinder engine was only run in 1939 or 40 I believe? This obviously pushed the timing even later than the Allison. The questionable design was that it used individual cylinders instead of cylinder blocks which made for a longer engine than needed and a less rigid engine than an engine using cylinder blocks. Power was to be achieved using high rpm and high boost.

 

[Readie]

Too many changes, not enough money and questionable design practices.

Continental was often acting as a contract shop for an Army design team, making bits and pieces and performing tests for a number of years. Literally, While both the displacement changed and the planned configuration ( it was originally a flat 12, the better to be mounted inside wings) only single cylinder test rigs were built for a number of years. Design work started in the very early 30s but a complete 12 cylinder engine was only run in 1939 or 40 I believe? This obviously pushed the timing even later than the Allison. The questionable design was that it used individual cylinders instead of cylinder blocks which made for a longer engine than needed and a less rigid engine than an engine using cylinder blocks. Power was to be achieved using high rpm and high boost.

Thanks SR, I have learnt something tonight.
Cheers
John

 

[B-17engineer]

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.

But if the Germans were such good engineers why did they stick with it?

Just curious, if from an engineering standpoint its 'the wrong way' what are the disadvantages?

 

[wuzak]

If inversion was so brilliant why has no major manufacturer followed suit?

If you ar ereferring to car manufacturers then it is clear that there is no advantage in an inverted engine. In fact it is at a disadvantage because you need the dry sump (most road cars have wet sumps) and the crank is placed high, meaning the gearbox would need to be too - bad in a car.

 

[wuzak]

Do inverted V's offer better (more rigid) platform for mounting nose armaments ...?

MM

No, I wouldn't think so.

 

[DonL]

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.

LOL!

And an boxer is not designed to run on the west and the east/ or on the left and right side?
To my opinion this statement is absurd, because a Jumo 213 could manage 3250 rpm as normal piston speed. I don't see any oil control problems!
Or could you tell me why on earth a late DB 605 could manage 1.8 ata and the Jumo 213 E was equal/could match with any RR Merlin or Griffon ever produce in the same timeline?

If inversion was so brilliant why has no major manufacturer followed suit?

Very easy germany lost the war!
Or do you know any other invert piston engine state of the art?

Edit:

The only advantage was in the availability of special alloys and high performance fuel (150 octane), but nothing else!
There was no technology advantage of the Allies piston engines by comparison to german invert inline engines!