109's inverted engine ?

[taffy2jeffmorgan]

Hi All, I have been doing some research into German fighters, I know that the DB 601 was fitted inverted [ upside down ] and the main reason put forward by the Messerschmitt engineers for this configuration was to improve center of gravity, others were, ease of maintenance, reduces exhaust port glare, can anyone else add to this list ? 

 

I did read somewhere that with the original 109 design [ large engine/small airframe ] there was a centre of gravity problem which was temporally overcome by placing a small concrete block behind the pilot seat which could be moved backward and forward, i'm sure this would have been sorted by the time they went to war !!

[=FEW=fernando11]

Hi.

Off the top of my head, ease of mantenance and visibility was part of the reasons.

 

I you have not seen this video, is worth your time and a very good channel in my opinion.

 

 

[[DBS]Browning]

I don't think they had a good design reason.

Germany hadn't been making military aircraft for some time when the 108/109 project started and of the few civilian aircraft they where making, many had inverted engines. They just went with what worked before.

[Elem]

1 hour ago, [DBS]Browning said:

I don't think they had a good design reason.

Everything in aircraft design is done for a very good reason! Early in-line engines were mounted upright due to the simple oil systems they had, which resulted in the engine cylinders being in the pilots line of sight. Once this was improved with separate oil tanks and scavenge pumps then they were able to invert the engine to improve pilot view and the aerodynamics with improved thrust line position to achieve balanced flight...

https://flying-school.com/straight-and-level-flight/

 

Edited August 8, 2019 by Elem
More info

[=FEW=fernando11]

Well. I respectfully desagree.

they had to " start from scratch" with prety much everything afther the desarmament of 1919-20

Why would they stay doing the same if they had no reasons? No stockpile of any kind of weapon/machines...

If anything look at the Alied designs, they thend to keep on doing what they were doing before, ofcourse improuving things through the years.

 

Germany developed a new (universal) machinegun,  new engine tipe for new line of aircraft, new construction technique for armour on tanks. They developed a radicaly diferent set up for their tanks compared to what they used during WWI...

[taffy2jeffmorgan]

Also in my research, I found out that in 1935 Willy Messerschmitt obtained a few Rolls Royce Kestrel V12 engines from the British government to test the 109's air frame as the DB 601 was not available, Junkers also used the Kestrel to test fly their JU 87   " Ironic is it not "

[CrazyDuck]

3 hours ago, taffy2jeffmorgan said:

Hi All, I have been doing some research into German fighters, I know that the DB 601 was fitted inverted [ upside down ]

 

Engine was fitted normally as intented and as designed, not inverted. Engine configuration of this type however bears the name "inverted V" (due to similarity with "normal" V engines, only inverted). In could have been named an "A" type (without any reference to "invertedness"). Bottom line - it's just semantics, engine was not mounted "upside down".

Edited August 8, 2019 by CrazyDuck

[[DBS]Browning]

A key question is: Was the engine (or it's direct predecessor) designed before the 109's airframe?

 

If it was, then it's likely they where just using the best engine they had available, regardless of it's orientation.

[JtD]

Which designer would deliberately use the second best engine available?

 

That said, the first Bf109 was powered by a Rolls-Royce, then Jumo, then DB60x.

Edited August 8, 2019 by JtD

[[DBS]Browning]

1 hour ago, JtD said:

Which designer would deliberately use the second best engine available?

 

That said, the first Bf109 was powered by a Rolls-Royce, then Jumo, then DB60x.

 

A designer who decided that the engine must be inverted  in order to *insert reasons for inverted engine here * might take the second best engine just because it meets the inverted criteria. 

 

I don't think that is the case with the 109.

Edited August 8, 2019 by [DBS]Browning

[ZachariasX]

23 minutes ago, [DBS]Browning said:

A designer who decided 

It was the RLM that decided it wanted V-12 „A“ configuration aero engines for military purposes. Not the designers. Whoever wanted to sell to the Luftwaffe needed to have that configuration.

 

It was a decision based on bureaucratic maintenance assumptions, not much else. Better view maybe, but if that was a reason, you could still use traditional V configurations on twin engine aircraft and they didn‘t, despite the Germans were eventually producing several different engine blocks.

Edited August 8, 2019 by ZachariasX
Edit: Engine history... was always „A“

[=FEW=fernando11]

9 minutes ago, ZachariasX said:

It was the RLM that decided it wanted V-12 „A“ configuration aero engines for military purposes. Not the designers. Whoever wanted to sell to the Luftwaffe needed to have that configuration. The DB-600 series started out in the traditional V configuration but quickly had to change that in order not to remain in the shelves.

 

It was a decision based on bureaucratic maintenance assumptions, not much else. Better view maybe, but if that was a reason, you could still use traditional V configurations on twin engine aircraft and they didn‘t, despite the Germans were eventually producing several different engine blocks.

You just beated me to it!

[Elem]

5 minutes ago, ZachariasX said:

The DB-600 series started out in the traditional V configuration but quickly had to change that in order not to remain in the shelves.

And what configuration did they change into?

[SCG_OpticFlow]

23 minutes ago, ZachariasX said:

It was the RLM that decided it wanted V-12 „A“ configuration aero engines for military purposes. Not the designers. Whoever wanted to sell to the Luftwaffe needed to have that configuration.

  

It was a decision based on bureaucratic maintenance assumptions, not much else. Better view maybe, but if that was a reason, you could still use traditional V configurations on twin engine aircraft and they didn‘t, despite the Germans were eventually producing several different engine blocks. 

 

From German Wikipedia (quoting an article from MTU):

 

Quote

Bereits Anfang der 1930er-Jahre wurden die deutschen Motorenhersteller vom Reichsverkehrsministerium zur Entwicklung eines 800-PS-Flugmotors aufgefordert, der als V-Motor mit „hängenden“ Zylindern (Kurbelwelle oben) konzipiert werden sollte und sich für militärische und zivile Zwecke eignete. Daimler-Benz entwarf aufgrund dieser Vorgabe den Daimler-Benz F4A mit 30 Litern Hubraum. Von dem Zwölfzylinder-V-Motor mit 60°-Bankwinkel und zwei mechanischen Radialladern waren 1932 zwei Prototypen fertiggestellt.[2]

Der F4A wurde zum DB 600 weiter entwickelt, dessen erste Probeläufe im Spätsommer 1935 erfolgten.

 

https://de.wikipedia.org/wiki/Daimler-Benz_DB_600

 

http://www.mtu.de/e-papers/MTU_ePaper/Marketing/MTU_Museum/epaper/ausgabe.pdf

Edited August 8, 2019 by SCG_OpticFlow

[ZachariasX]

50 minutes ago, Elem said:

And what configuration did they change into?

I think I remembered it wrongly, the images of the DB in traditional V configuration seemed to have been printed upside down (for whatever reason) after taking another closer look.

 

It was always the hanging V, or „A“ configuration. And it was due to spec requirement. Power output is largely agnostic to cylinder configuration. V, A, inline upright or hanging, boxer... these are decisions driven by ulterior motives rather than power output.

[JG1_Vonrd]

Most radial engines have to be rotated by hand (pulled through) to get rid of accumulated oil pooling in the bottom cylinders while the engine was sitting for a while. If not done, hydraulic lock could damage the engine's rotating components when the starter was engaged. Did the DB require this also with it's cylinders inverted?

[ZachariasX]

1 hour ago, II./JG1_Vonrd said:

Most radial engines have to be rotated by hand (pulled through) to get rid of accumulated oil pooling in the bottom cylinders while the engine was sitting for a while. If not done, hydraulic lock could damage the engine's rotating components when the starter was engaged. Did the DB require this also with it's cylinders inverted?

Yes. Also see here:

 

„ [...] Uniquely for a V12 engine, the “inverted vee” design of the DB 600 series causes oiling issues in the lowermost engine components, requiring considerably more preventive maintenance than contemporary power plants such as the Rolls-Royce Merlin.  If the Bf 109E has sat idly on the ground for some time, oil will have dissipated into the cylinder heads and a hydraulic lock on start-up, whereby the piston hits oil settled in the cylinder, may be symptomatic and can inflict long-term damage on the engine.  To mitigate against this, pre-flight preparation includes removing the plugs at the end of the induction tubing and turning the propeller through by hand to drain oil from the system. [...]“

 

It is generally a good idea to hand crank such engines a couple of turns before a cold start. Especially if the crate sat idle for prolonged time.

 

 

[danielprates]

I heard years ago in a conversation that one of the reasons for an inverted design was that the cranckshaft would sit higher up, thus making it easier to position the propeller with higher clearence from the ground. A "normal" engine would have a lower shaft so the propeller shaft would either result too low, or would have to be raised higher up by the means of gears, which raised weight, mechanic complexity etc.

 

At the time I took that as the main reason. Now I am not so sure if that checks out. Is this correct?

[taffy2jeffmorgan]

Thanks Fernando 11, that video you posted was very interesting

[Art-J]

2 hours ago, danielprates said:

I heard years ago in a conversation that one of the reasons for an inverted design was that the cranckshaft would sit higher up, thus making it easier to position the propeller with higher clearence from the ground. A "normal" engine would have a lower shaft so the propeller shaft would either result too low, or would have to be raised higher up by the means of gears, which raised weight, mechanic complexity etc.

 

At the time I took that as the main reason. Now I am not so sure if that checks out. Is this correct?

 

That might indeed be the case in the early years of aviation when all props were direct-driven. Certainly not later, though, when reduction gears lowered the prop shaft anyway.

[Elem]

4 hours ago, danielprates said:

t the time I took that as the main reason. Now I am not so sure if that checks out. Is this correct?

Yes, it is another of the many design considerations and advantages of inverted in-line engines.

 

9 hours ago, ZachariasX said:

It is generally a good idea to hand crank such engines a couple of turns before a cold start. Especially if the crate sat idle for prolonged time.

This is good to essential practice for all aero piston engines regardless of configuration, in-line or radial.

[Heliopause]

"Although the aircraft had been designed around the 610hp Jumo 210 12 cil. inverted-Vee liquid cooled engine, one was not available at that time and

the prototype took off powered by a 695 hp Rolls-Royce Kestrel imported from Britain".

[LizLemon]

19 hours ago, ZachariasX said:

It was the RLM that decided it wanted V-12 „A“ configuration aero engines for military purposes. Not the designers. Whoever wanted to sell to the Luftwaffe needed to have that configuration.

 

It was a decision based on bureaucratic maintenance assumptions, not much else. Better view maybe, but if that was a reason, you could still use traditional V configurations on twin engine aircraft and they didn‘t, despite the Germans were eventually producing several different engine blocks.

 

There was a big study done by the RLMs predecessor organization that was tasked with figuring out the 'ideal' engines for future aircraft.

 

One of the big drivers was actually use of the engines in zepplins, and on that count an inverted v-12 offered some big advantages over upright when it came to in-flight maintenance.

 

As far as planes go a couple points were identified the inverted arrangement as being superior. One was the CG argument, so was easier access to spark plugs. Prop clearance was a plus. But they also thought the lower location of the exhausts would minimize the flames causing visibility issues in low light conditions. The visibility benefit was also noted, but it was at the bottom of the list from what I remember.  However all of this was secondary to the supposed advantages in airships.

[=FEW=fernando11]

15 hours ago, danielprates said:

I heard years ago in a conversation that one of the reasons for an inverted design was that the cranckshaft would sit higher up, thus making it easier to position the propeller with higher clearence from the ground. A "normal" engine would have a lower shaft so the propeller shaft would either result too low, or would have to be raised higher up by the means of gears, which raised weight, mechanic complexity etc.

 

At the time I took that as the main reason. Now I am not so sure if that checks out. Is this correct?

Its not correct

 

Againg, if any of you have Time, check this video, and channel, out

 

 

TlDR

On small planes with low Power engines, this Is the case, but on WWII warbirds the engines are so powerfull that the props need to be geared to a lower RPM than the engine anyway, so on "upright" engines the prop is moved up through this gearing, and on the "inverted"  BD 60X engines (bf109 engine) the prop is moved down. 

So it is not done for prop clearing porpuses.

[danielprates]

1 hour ago, =FEW=fernando11 said:

but on WWII warbirds the engines are so powerfull that the props need to be geared to a lower RPM than the engine anyway, so on "upright" engines the prop is moved up through this gearing, and on the "inverted"  BD 60X engines (bf109 engine) the prop is moved down. 

So it is not done for prop clearing porpuses.

 

 Yeah, that makes sense. Someone else said above that it was the case with older engines but not mid-30s and onwards, which I think makes total sense.