Me 109 inverted engine

[taffy2jeffmorgan]

Hi, Could someone tell me why the Daimler-Benz 601 was fitted into the airframe upside down, was it to maintain the correct centre of gravity / ease of maintenance/  ? and where there others with the same configuration ?

 

Cheers

[PikAss]

So the crankshaft was on top, that way the cylinder head and ignition plug was easier to maintain.

[SCG_OpticFlow]

The Junkers engines in Ju-87, Ju-88, Fw-190, etc. are all inverted V-12.

 

The benefit is flatter top (improved visibility) and having the exhaust blow the wings upper side instead of the pilots face (less noise, smoke and flashes).

[Dakpilot]

Both Daimler Benz and Junkers would ideally have preferred to build their engines in conventional manner (from post war discussions) but German Air ministry had already called for inverted layout in future programs in 1928, citing many of the advantages mentioned above. 

 

Interestingly one of the prototype Merlin engines was of an inverted design (being quite common in the 30's) 

 

Cheers, Dakpilot 

[Ehret]

The inverted V engine has some cons as well - it tends to leak oil and proven problematic in twin configuration for the He177 which included fires. Basically it seems most suited for single engine fighters.

Edited July 1, 2018 by Ehret

[Wolfram-Harms]

49 minutes ago, Ehret said:

The inverted V engine has some cons as well - it tends to leak oil ...

 

Not more than the British fighters with the "normal" build, I guess...

 

 

[Ehret]

2 hours ago, Wolfram-Harms said:

Not more than the British fighters with the "normal" build, I guess...

 

Well... according to the Günther Rall American ones had to be much better built as the captured P-51 did not leak.

 

 

Edited July 1, 2018 by Ehret

[Finkeren]

It also had the effect of moving the crankshaft closer to the centerline of the fuselage. Not sure exactly what the effect of that is, but my uneducated guess would be, that it would help a bit with directional stability.

[Hirachi]

1. The engine gets a lower center of gravity, and makes the plane's weight distribution come closer to the wing line throughout the entire plane rather than being "significantly" higher in the nose. This has some marginal effect on the design and efficiency of the wings, horizontal stabilizer, and elevator and the way reinforcing struts can be designed.

 

2. It keeps the thrust line low while keeping the narrow part of the engine in the pilot's view, rather than keeping the broad part in the pilot's view. You want the thrust line to be as close to the height of the center of gravity as possible to avoid tendencies to nose up/down as the thrust (generally the throttle) is increased/decreased, and a significant portion of a plane's weight is in the undercarriage and the wings (which on most monoplane fighters means a lot of weight is at the bottom of the plane). Compare to for example a Spitfire which both has more view obstruction from the top-width of the engine, as well as high-riding propeller causing a higher thrust line.

 

3. It raises the crankshaft which makes it easier to fit all the nose armament. With a low crankshaft you'd be forced to place an eventual engine-cannon somewhat higher (fires between the crankshaft and cylinders) and subsequently would have greater trouble fitting the two MG 17s above the engine-cannon without seriously impacting the pilot's line of sight. It'd necessitate a higher cockpit, which would make the plane taller, which'd make it less aerodynamic (although arguably the 109 could have needed a taller cockpit for the pilot's sake, but that's a different discussion entirely).

 

4. The engine becomes more powerful by not having the crankshaft in the oil sump. Any engine with a wet sump loses some power by having to move parts through the oil. It did however make the lubrication system more complex and more difficult to maintain.

 

5. It made maintenance and replacement of spark plugs, fuel lines, and the water cooling easier since you could reach a lot of it from the ground.

 

6. Lowers the engine exhaust which much better hides it from the pilot's view. Helps a lot with maintaining good sight for the pilot in low-light conditions. This was probably more a happy accident than a conscious decision though, seeing the 109 is a daytime-fighter.

 

 

Edited July 1, 2018 by Simba

[Finkeren]

2 minutes ago, Simba said:

i hear it was more of less so they can fit the cannon in it

 

I seriously doubt that. Why would inventing the engine make it easier to install a motorkanone? Plenty of normal V-engines had engine mounted guns.

[CrazyDuck]

6 hours ago, taffy2jeffmorgan said:

Hi, Could someone tell me why the Daimler-Benz 601 was fitted into the airframe upside down

 

I assume you are under impression that the DB was actually mounted upside down compared at how it was designed. It wasn't, it was designed from the beginning as an "inverted V" design, and was supposed to be oriented like this in normal flight. It's just semantics, this design was named "inverted" for some reason, probably it turned up later than the normal V design and got named like this.

Edited July 1, 2018 by CrazyDuck

[BlitzPig_EL]

The Merlin and Allison V1710 did not mount the crank in the sump, as they, like the DB and Junkers engines were of the "dry sump" design, with separate oil tanks mounted away from the engine.   I'm wondering if hydraulic lock of the DB engines was a problem, what with the oil that was not removed by the scavenge pumps laying in the bores of the engine and eventually working past the rings and into the combustion chambers?

[Art-J]

Simba, you're quite stretching it with your arguments No. 3, 4 and 5. There's nothing more difficult with fitting mixed nose armament in conventional design, as Russian experiences show, even with calibers of 37 mm and up. Dry sump lubrication was common in all aero engines of the era as well , like BP noted above, no matter what layout. Maintenance was questionable advantage too, as easier access doesn't change the fact that oil leaked into bottom cylinders requiring additional work, like on radials.

[Siegfried]

28 minutes ago, Finkeren said:

 

I seriously doubt that. Why would inventing the engine make it easier to install a motorkanone? Plenty of normal V-engines had engine mounted guns.

 

I think that canon weight higher because the barrel goes between cilinders. 109 pilots had canon in the floor, with higher mounted cannon you would need longer nose too. 

[SCG_OpticFlow]

BTW the first Jumo 210 series inverted V-12 engines were used in the Arado 68, an open cockpit biplane. Only few years later the 109 were made, using the same engine initially...

[Finkeren]

16 minutes ago, Siegfried said:

 

I think that canon weight higher because the barrel goes between cilinders. 109 pilots had canon in the floor, with higher mounted cannon you would need longer nose too. 

 

Not necesarilly. You can also move the cockpit backwards, as was done with Yak-9T.

 

Again: This didn’t seem like a problem to other aircraft designers. And also the Junkers Jumo was made with the same configuration as the DB and to my knowledge was never fitted with a Motorkanone.

[LukeFF]

1 hour ago, Finkeren said:

And also the Junkers Jumo was made with the same configuration as the DB and to my knowledge was never fitted with a Motorkanone.

 

Ta 152 H

[Hirachi]

2 hours ago, Art-J said:

Simba, you're quite stretching it with your arguments No. 3, 4 and 5. There's nothing more difficult with fitting mixed nose armament in conventional design, as Russian experiences show, even with calibers of 37 mm and up. Dry sump lubrication was common in all aero engines of the era as well , like BP noted above, no matter what layout. Maintenance was questionable advantage too, as easier access doesn't change the fact that oil leaked into bottom cylinders requiring additional work, like on radials.

well from my experience working on a inverted straight 4 on a Gipsy  Major the maintenance is easier for me ... but then again it does leak and you have to watch for hydraulic lock. Now the the inverted did provide a better forward vis at least for me then some of the bigger radials....

[Finkeren]

24 minutes ago, LukeFF said:

 

Ta 152 H

 

Ok you’re right, but I think we can safely say, that the Jumo wasn’t designed that way with engine armament in mind.

[taffy2jeffmorgan]

Thanks for all the replies, i now have a good idea why the engine was installed inverted.

 

Cheers

[Wolfram-Harms]

On 7/1/2018 at 10:15 PM, CrazyDuck said:

... it was designed from the beginning as an "inverted V" design, and was supposed to be oriented like this in normal flight. It's just semantics, this design was named "inverted"...

 

According to the German article on that engine in WIKI, this is correct. An "inverted" V-engine was called A-Motor in Germany.

 

If not chosen for other good reasons, the better pilot vision forward down was an important one.

Paul Day, Spitfire Memorial Pilot in Britain, mentions the bad forward down vision for Spitfire pilots in his comparison of both fighters.

 

 

Edited July 4, 2018 by Wolfram-Harms