Why did Germany use inverted engines?

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phylo_roadking
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Re: Why did Germany use inverted engines?

Post by phylo_roadking » 15 Nov 2008 23:42

I wouldn't think that the weight of the engine block, cylinders, pistons, heads, camshaft(s), valves, valve train, induction system, and fuel and oil systems would be more than the single crankshaft.


That's my point exactly.

Also, some of the propellers had a gun shooting through the hub, and having the engine in the inverted configuration would allow the gun to be more in line with the pilot's view


Take a look at a cutaway of the DB600 family. Sitting in the inverted vee, the gun would be somewhere down around the pilot's kneecaps...!

In this configuration, the propeller would need a gear drive of some sort, which would lower the center of gravity still more, since the motor would sit even lower in the fuselage.


It did have. But in the case of the Me109 - it brings the centre of the prop down in line with the cylinder gallery.

The only think I can think of off the top of my head is some role the inverted vee plays in centering the floating cylinder liners on assembly....?

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Re: Why did Germany use inverted engines?

Post by jbaum » 16 Nov 2008 00:47

In editing my previous reply, I misstated my intention. I think that the other parts of the motor WOULD weigh more than the single piece of crankshaft. While the crankshaft may be the heaviest single part, the other parts together would weigh more than the crankshaft.
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phylo_roadking
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Re: Why did Germany use inverted engines?

Post by phylo_roadking » 16 Nov 2008 01:24

Heaviest single part...PLUS the weight of the crank webs, two-thirds of the reciprocating weight of the conrods, and crankcase, the gear train for the prop...don't forget the cylinder heads are "light" alloy (well, dural IS heavy but not as heavy as steel LMAO) I think that if we had a breakdown of the engine and components by weight, we'll find the "bottom end" of the engine - in this case the TOP end - IS heavier. We also have "circumstantial evidence" of topheaviness, it was one of the contributary factors to the groundlooping. Once the 109 started to lift, there was a VERY top-heavy weight carrying the rest of the aircraft "over centre"...

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Re: Why did Germany use inverted engines?

Post by Kurfürst » 16 Nov 2008 18:46

phylo_roadking wrote:I found the original performance specs for the DB600 family buried in Hooton's Phoenix triumphant...but no indication that any specific layout was laid down in 1930.


The immidiate precedessors of the DB 600 series with inverteed vee configuration and 30 liter displacement were developed from 1929 onwards by Daimler Benz as a private venture, following the RLMs guidelines. These were followed by the F4, two of which run in 1931; the F4 B prototype became basis for the DB 600 of 33.7 liter displacement, for the which the firm received a contract for the completition of six engines. These were followed by the F4 E prototype, the first one with fuel injection, that became the DB 601, and run in 1935. 150 examples ordered in February 1936, series production beginning in November 1937.

The Junkers 210 series show a similiar story, a private venture following RLM guidelines, developed from 1931.

phylo_roadking wrote:We also have "circumstantial evidence" of topheaviness, it was one of the contributary factors to the groundlooping.


Never heard or read of any that, nor did I see any implication of the 109 being 'top heavy'. The aircraft was tail heavy.

The most likely reasons for using an inverted Vee layout were the advantages offered: better view over the (narrower) cowling, and easier everyday maintanance, and their development of direct fuel injection systems. R-R was considering inverted Vees as well, the probable reason they eventually didn't was their lack willingness/possibility to use direct fuel injection (fuel trapping in cylinders), and preferred carburrators instead.

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Re: Why did Germany use inverted engines?

Post by Ome_Joop » 16 Nov 2008 20:45

Looking at the pictures of Spitfire engine mouns i wonder if it's easier to mount an engine inverted?
Spitfire engine mounts seem to be a bit crude :wink:

http://www.spitfirespares.com/SpitfireS ... ators.html

that was just a model...real thing can be found here:
http://www.spitfire.dk/chapter4.htm
The HA-1112 buchon (Spannish 109G with merlin engine) does look a bit bigger than a DB-605 engined 109G while the Merlin is a smaller engine (less displacement) than the Db-605

http://www.taphilo.com/JG26/index.shtml
http://www.taphilo.com/jg26/bf109-db605 ... 260002.JPG
http://www.taphilo.com/jg26/bf109-db605 ... 260002.JPG
http://www.richard-seaman.com/Aircraft/ ... oClock.jpg
http://www.taphilo.com/Photo/Pictures/B ... 2-Taxi.jpg
http://www.zap16.com/Duxford%202007/IMG ... G-BWUE.jpg

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phylo_roadking
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Re: Why did Germany use inverted engines?

Post by phylo_roadking » 16 Nov 2008 22:28

O-J, not crude; I was looking at them both in situ last night. if you think about it - the Merlin with its configuration and heavier crankcase to the bottom requires MORE bracing, including mounting cradle extensions supporting the crankcase. The Me109 however gets away with a much lighter design, basically "hanging" the engine from a pair of braced rails - completely in line with the design ethos Hooton puts behind the Me109's design as the modern, lightweight, high wingload fighter solution to the problem of Germany at the start of the 1930s not being able to build high performance engines yet - and so, as designers NOW call the process - they "added lightness".

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Re: Why did Germany use inverted engines?

Post by Seppo Koivisto » 16 Nov 2008 23:24

The inverted V-form was chosen for the predecessors of the DB 600 and Jumo 210, because of the better visibility over the engine and the easier maintenance. I think this was part of the RLM guidelines.

In a geared inverted engine the propeller is moved lower, thus decreasing the ground clearance of the prop, which is clearly a drawback.

The location of the center of gravity was probably not an issue, because its effect on the lateral stability could be compensated by increasing dihedral for example.

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Re: Why did Germany use inverted engines?

Post by Topspeed » 20 Nov 2008 18:27

Me 109 was a good climber..also this fuselage form was due to the engine lay-out.

Definitely with 20 mm cannon arrangement and two machineguns were easier to install in this arrangement..and with the cannon CG stayed lower..or the distribution of the weight was kept on the longitudal centerline..making rolls faster etc.

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Re: Why did Germany use inverted engines?

Post by Ome_Joop » 21 Nov 2008 23:32

I was under the impression that the predecessors (the F2 and F4) of the Db600 were all "normal" V12's and the DB600 was the first Daimler Benz inverted (V12) one.
Can someone here enlighten me on this (provide some info)?
It's hard to find some good resource/info/photo's on this.

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Re: Why did Germany use inverted engines?

Post by Seppo Koivisto » 22 Nov 2008 17:22

F2 was a "normal" V engine, but F4 was the first inverted Daimler-Benz V12. My source is the book Flugmotoren und Strahltriebwerke by Gersdorff and Grasmann.

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Re: Why did Germany use inverted engines?

Post by Wehrmann » 23 Nov 2008 00:17

In the museum of MTU aero engines you can find the last existing Daimler Benz F4A.

Regards Wehrmann

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Tim Smith
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Re: Why did Germany use inverted engines?

Post by Tim Smith » 24 Nov 2008 13:16

jbaum wrote:Having a lower center of gravity in a fighter would be very important. The inherent stability of an airplane which has sustained damage in battle might make the difference whether the aircraft could return home or crash.

Designing a stable aircraft has always been a problem with any fighter, because often the traits which provide quick maneuverability detract from stability. The Sopwith Camel biplane of WW1 was said to have had more losses during landing and take-off than in combat.

The ability of an airplane to be easy (stable) to fly, by a pilot who often had limited experience, during the most difficult of maneuvers, in a life and death situation, and return home to land with damaged control surfaces (and possibly wounded himself), would certainly rank as one of the top considerations during design of the aircraft. If something as simple as inverting the engine would help, or using a gull-wing design for the wings (as in the F4U Corsair and the Stuka Dive Bomber) to effectively raise the roll axis and thus provide a lower center of gravity (adding to stability), then the results would always be worth the effort.

Affection for an airplane which is easy to fly is always one of the things mentioned in interviews of the surviving pilots after the war.


Hmm.....

Hawker Hurricane - extremely easy to fly (even for a novice.)

Messerschmitt Bf 109 - extremely difficult to fly (especially for a novice).

One of the few advantages the Hurricane had over the 109.....

Even the Spitfire was easier to fly than the 109.

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Re: Why did Germany use inverted engines?

Post by Kurfürst » 24 Nov 2008 14:30

Tim Smith wrote:Hawker Hurricane - extremely easy to fly (even for a novice.)
Messerschmitt Bf 109 - extremely difficult to fly (especially for a novice).
One of the few advantages the Hurricane had over the 109.....

Even the Spitfire was easier to fly than the 109.


I think this 'popular knowledge' is true, practically every primary source and evaluation describes the Me 109 as a very simple to fly plane with benign handling characteristics, and virtually no incentive to stall or flat spin. Take off and landing has been considered more difficult than on the Spit and Hurri.

ie.

Conclusion

10. The Me.109F, altough very similiar in appearance to the Me.109E is much superior in all-round performance. The fac that the airscrew is fully automatic, and the oil and coolant temperatures thermostatically controlled, helps to make the aircraft a simple fighting machine, as the only things then occupying the pilot's attention in combat are his throttle, flying controls and guns.

http://www.kurfurst.org/Tactical_trials ... _AFDU.html

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Tim Smith
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Re: Why did Germany use inverted engines?

Post by Tim Smith » 24 Nov 2008 16:11

By 'flying' I include take-off and landing. The two most dangerous parts of any flight (excluding combat).

In order to fly, you have to be able to take off first. And every take-off means a landing, so you have to know how to do that too.

Any idiot, even me, could 'fly' a Bf 109 in level flight. But could I get it off the ground without killing myself? No. Nor could I land it safely even if I got it into the air.

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Re: Why did Germany use inverted engines?

Post by Ome_Joop » 25 Nov 2008 02:55

Any idiot, even me, could 'fly' a Bf 109 in level flight. But could I get it off the ground without killing myself? No. Nor could I land it safely even if I got it into the air.


This would probably count for every high performance fighter aircraft and is not a typical 109 treat....in other words an idiot would also die in a hurricane without any proper training(or do i mean Primary Training?)
I don't think many pilots started in a Huricane when they got into the air for the first time

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