Why is it upside down???

[PWR4360-59B]

The mention of ease of service having the cylinders inverted, is highly arguable. Having some experience wrenching on radials, I much prefer the upper section of cylinders when doing wrench turning on them. And to reiterate, cylinders placed in the down ish position are very prone to oil accumulation and hydraulic locking problems. Saying nothing about massivly oil fouled spark plugs, some interesting lubricating issues, with the pistons constantly pumping oil around in the crankcase, creating windage losses etc. of course this is standard pratice in the radial world, but why promote it, if there is really no reason to do so?
All this talk about visibility and or what ever else is in my opinion nonsense, why? Look at the top of the line American recip WWII fighters, P51 to start.

 

[jerryw]

Some research information on this topic.

View attachment Inverted V12..doc

 

[vanir]

For some reason I always only get a weird screen capture of the site homepage on a word doc when I download word attachments here, though I use a download manager on this system because of rotten connection speed to my area. It's necessary.

 

[GregP]

Velius, the Bf 109 V-31 had inward-retracting landing gear as a trial. It was an F-series airframe used to test the concept in 1941. An extendable belly radiator ws installed and served as preliminary designs for the Me 309. Could have been adopted anytime but wasn't. Unbelievable in retrospect.

As an aside, the Bf 109X, based on an E-series airframe, had an American Twin Wasp (R-1830 as installed in the B-17) installed with a cut-down rear fuselage and bubble canopy. It flew VERY well and had modified wings. It flew 18 Aug 1938. Handled well. Should have been developed with a German radial engine.

Pictures in "Willy Messerschmitt: Pioneer of Aviation Design. by Hans Ebert, Johann Kaiser, and Klaus Peters."

 

[Denniss]

Bf 109 V31 was a heavily modified F-4 airframe used as Me 309 testbed in 1942/43 - nothing was easily adoptable for Bf 109 production

 

[pressurized]

the bottom line is that the idea was to place the majority of the engine below the crankshaft cenerline in order to improve pilot visibility over the nose in flight. no guess work, just fact.

 

[PWR4360-59B]

the bottom line is that the idea was to place the majority of the engine below the crankshaft cenerline in order to improve pilot visibility over the nose in flight. no guess work, just fact.

Problem with that is most all high powered aircraft engines use a reduction gear assembly. So actually something like a P51 will have as good or better visability as anything with an iverted engine. Unless your talking caving in the upper portion of the engine cowling closer to the crankcase and oil pan/crankcase cover.

 

[tyrodtom]

The rocker arm or cam covers are much farther from the crankshaft center than the oil pan bottom. The reduction gear assembly can be orientated in any direction you want from the crankshaft center.

 

[tyrodtom]

You only have to look at some of the sideviews of aircraft posted on this forum, to see the better forward view on the Me-109 vs the P-51.

On the Mustang the fuselage contines forward of the cockpit several feet, before it begins a downward slope. On the Me. the fuselage begins a immediate downward slope forward of the cockpit. It may just be a few degrees better in forward-down view, but when it comes to foeward visibility, every little bit helps.

 

[machine shop tom]

The German V engines weren't upside-down.

Everbody else's were.

tom

 

[Frantish]

A few of other technical reasons to to piston down, could be support for go with this config with the visibility advantage.:

1. Oil to the piston pins is very difficult, to drill oil paths in the connecting rod to pin is expensive.
2. Cooling piston with longer contact time between oil and piston.
3. Lower temperature differential over engine, naturally heat rises, heat from cylinder head travels up.
4. Easier restarts of hot engines. The fuel will vaporize in injection lines, the less heat exposed, less bubbles, easier start.

Some down sides exist in piston down, but on balance I think it has a small advantage to pistons up.

 

[PWR4360-59B]

A few of other technical reasons to to piston down, could be support for go with this config with the visibility advantage.:

1. Oil to the piston pins is very difficult, to drill oil paths in the connecting rod to pin is expensive.
2. Cooling piston with longer contact time between oil and piston.
3. Lower temperature differential over engine, naturally heat rises, heat from cylinder head travels up.
4. Easier restarts of hot engines. The fuel will vaporize in injection lines, the less heat exposed, less bubbles, easier start.

Some down sides exist in piston down, but on balance I think it has a small advantage to pistons up.

More difficult to scavenge oil, easier to hydraulic lock. Increase in windage, and oil splash.