# Did German bombers make a different sound and why?



## pattle (Nov 5, 2013)

I often hear that German bombers made a different sound to British aircraft during the blitz, my mum and others tell me the German planes made a woo woo woo sound while the British aircraft made more of a roar. Going by the amount of accounts and witnesses there seems little doubt that German aircraft actually did make this sound and I have heard a number of explanations of why this happened which include the following.

1) That the sound was caused by a large number of aircraft in formation that had engines running at different rpm's.
2) That twin engine German aircraft had each engine set at a different rpm to either frighten civilians, confuse radar or because the engines were tired and could not be synchronised correctly.
3) That the pilots themselves de-synchronised the engines while in flight to confuse the anti aircraft defences.

I would have thought that de-synchronised engines would have been a bad thing for both crew and aircraft.


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## pbehn (Nov 5, 2013)

I believe it is called the doppler effect on twin engines


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## stona (Nov 5, 2013)

My grand mother would confirm the uneven sound of German aircraft engines.
She said that it sounded as if the bombers were asking..."where do you want it?......where do you want it?......where do you want it?"
Cheers
Steve

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## FLYBOYJ (Nov 5, 2013)

I don't think early WW2 twin engine bombers had effective propeller synchrophasers.

Propeller synchronization - Wikipedia, the free encyclopedia

Here's a little chat on the same subject...

http://www.pprune.org/archive/index.php/t-135198.html


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## GrauGeist (Nov 5, 2013)

Have you ever heard numerous engines of the same type operating in the same area?

And example would be riding in a B-17. You can hear the engines creating a low frequency "wow wow wow" sound. When you multiply these similiar engines, all set to comparable RPMs, (add distance or other accoustic adjustments) you'll get harmonic sounds like the ones being discussed here.


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## stona (Nov 5, 2013)

In 1942 BBC engineers were attempting to record Nightingale song in a garden in Surrey when Bomber Command passed overhead. Consequently they started to record the sound of the bombers.

There is a link to the recording on this page (play recording). You can clearly here the aircraft as well as a beautiful Nightingale song, remarkable and from such a dowdy looking little bird







The British stream of four engine bombers makes a constant droning sound quite unlike described by people who also heard German aircraft pass overhead. My grand mother was quite sure she could tell "ours" from "theirs". Living in Kent she would certainly have heard "theirs" often enough.

Cheers

Steve


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## silence (Nov 5, 2013)

If you play two guitar strings that are just slightly out of tune with each other, say at 300Hz and 303Hz, you'll get that beating sound.

To get a good demonstration, pick up a guitar and play a harmonic on the A-string at the fifth fret and a harmonic on the D-string at the 7the fret (using harmonics make the effect far easier to hear). If the two strings are properly in tune with each other, there will not be a "beating" sound. However, if they are just slightly out of tune with each other you'll hear that beating sound, and the more out of tune they are the faster the beating sound. 

Its a very simple and quick way to get the strings on a guitar (or bass) in tune with each other.


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## OldSkeptic (Nov 5, 2013)

There are 2 theories, one to confuse sound locators. The other by Stllpepper was that in their 109s they were constantly switching propeller pitch (which changed the revs) to gain boost at high altitudes. 
They'd change to get more revs, hence more boost, then back to cruise setting.


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## stona (Nov 5, 2013)

I reckon it has already been answered above by FLYBOYJ. It seems a lack of synchronisation between the_ two engines _on Luftwaffe types is the most likely cause of "where do you want it?.....where do you want it?" as perceived by people on the ground.
Just my hunch 
Cheers
Steve

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## pattle (Nov 5, 2013)

The British stream of four engine bombers makes a constant droning sound quite unlike described by people who also heard German aircraft pass overhead. My grand mother was quite sure she could tell "ours" from "theirs". Living in Kent she would certainly have heard "theirs" often enough.

Cheers

Steve[/QUOTE]

Yes that is exactly what I have been told and the same goes for large American formations, my Dad lived in Derby and used to see the Americans practice flying in vast formations that seemed to take for ever to pass over, He tells me they were incredibly noisy but had a much more even sound than the Germans. From what I can gather it was possible for the Germans to synchronise a HE111's engines but it was not possible to synchronise one He111's engines to another He111, while I am led to believe that with the Lancaster and Halifaxfor example it was.
I think this will be one of those threads where lots of people confidently post opposite opinions leaving me none the wiser.


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## gumbyk (Nov 5, 2013)

Synchronising engines between two different aircraft would be near impossible. How would one pilot be able to hear another aircraft's engines over the noise of his own aircraft?

With enough aircraft flying in close proximity, all of the various beat frequencies would virtually eliminate each other. (what would the possible resonant frequency of 100 engines, all at slightly different RPM's be?)
However, with aircraft a bit more spaced out, it may be that a beat frequency would be heard due to interference between aircraft. 

This could be an explanation. Are there any reports of this from the other side of the Channel?


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## GrauGeist (Nov 5, 2013)

The dynamics of the engine's operation creates a certain frequency. When you multiply that many times over, you have interaction of these frequencies. These harmonics will create a wide range of audible effects.

The best example I can think of, that most can relate to, would be a passing train. Especially if it's moving slowly and has several locomotives coupled. You can clearly hear (and feel, in this case) the low sound frequencies falling in and out of sync. Even if the engine RPMs are matched exactly, you'll hear the soundwaves hitting each other, creating a change in pitch, or a "warbling" as those frequencies try and cancel each other out.

Think of it as ripples in a pond from two identical stones tossed in. The ripples will be identical until they hit each other. When they do collide, they alter themselves to a certain degree. Now toss hundreds of those same stones in the pool and you'll have a better idea of what was going on in the skies over England.

I'm sure that if the Allied bombers were operating at the same altitudes over Europe that the Germans were operating at, over England, people on the ground would have heard the same effect.


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## Cave Tonitrum (Nov 6, 2013)

It's as simple as different engines sounding different. A Spitfire sounds different than a Bf-109. A P-47 sounds different than a P-40. Why would formations of British as opposed to German bombers be any different?


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## stona (Nov 6, 2013)

Cave Tonitrum said:


> It's as simple as different engines sounding different. A Spitfire sounds different than a Bf-109. A P-47 sounds different than a P-40. Why would formations of British as opposed to German bombers be any different?



It's not that simple.

A Spitfire does sound different to a Bf 109 but not in that way and the difference is actually quite subtle. Unless you are lucky enough to have heard both at the same (or similar) time they are virtually indistinguishable. If either aircraft flew alone past me, wearing a blindfold, I doubt I could be certain of which it was and I have heard both engines. I would be even more dubious of anyone claiming to be able to tell the difference between the sounds of formations of the two types.

The asynchronous drone or beat of formations of German twins is often commented on. I've heard such comments first hand from several "civilians" including my own grandmother. It is something quite different from a general difference in sound.

Cheers

Steve


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## Cave Tonitrum (Nov 6, 2013)

I have heard both. (Spitfire and Bf-109) Seen both do flyby's but not together. They do sound different and I could easily distinguish the two. 

I would expect a concentration of 100 BMW-801's to sound different from a concentration of 100 Rolls Royce Merlins (both featuring different propeller designs) irrespective of the synchronization issue. There were likely also other differences between concentrations of German and British bombers heard by good British folk that might have contributed to perceived differences in sound. Was the altitude and speed of German bombers, hot en route to and escaping from bombing runs the same as British bombers, over friendly territory, departing and returning home? 

I'm interested in other thoughts on whether there would be a perceived difference merely on the basis of the different engines / propellers.


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## stona (Nov 6, 2013)

I've heard both too and I did say they sound different. The argument is not about our ability to identify aircraft by engine noise when flown past a blindfolded listener on its own. I admire your confidence though 

The Luftwaffe formations undoubtedly made a distinctive sound. This "woo....wooo....wooo" or "where do you want it" as described in contemporary accounts was quite different to British formations. I think that FLYBOYJ hit the nail on the head. His explanation matches others I have heard over the years, all referring to the unsynchronised engines on German twins.

My grandmother certainly couldn't distinguish single engine types. She told me that she and a friend, when fruit picking, once waved cheerily at two aircraft passing at low level moments before they strafed a train station (which one I'd have to check)

Cheers

Steve

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## s1chris (Nov 6, 2013)

I agree that there would be a difference between Allied and German bombers based on engine type.
It has to be comparable to the difference between 100 Ferrari's and 100 jaguar XK's for example. Very distinguishable as an individual machine but amplified when en masse. 

My grandma to this day remembers the distinctive sound of the German bombers compared to when large groups of allied aircraft were flying overhead in preparation for overlord. My Grandad said the same when he was alive.

Edit : I think more than one factor is responsible for the distinctive sound.


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## pattle (Nov 6, 2013)

I'm almost certain that the distinctive woo woo woo sound applied to lone German twin engine bombers as well as those in groups. My confidence in saying this comes from what I have been told and read, common examples include accounts of lone German bombers being first heard and then sighted, a common theme in these accounts is that these bombers have for whatever reason become detached from the main body of aircraft and have gone off course whilst returning from a raid, in such accounts I have heard of these aircraft dropping their bombs on handy targets before returning home, another common theme in accounts describe low flying German bombers appearing and being followed by RAF fighters. It has occurred to me that these lone aircraft may have been damaged and certainly some were actually seen to be shot down.
In the case of night time accounts witnesses are confident of having heard a lone aircraft which was often being fired at by anti aircraft guns, of course it was difficult to see these aircraft in darkness. Night time attacks from what I understand would not have been conducted by formations of aircraft like in daytime but aircraft in a stream, accounts from RAF night fighter pilots generally describe lone aircraft not groups of aircraft.


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## Cave Tonitrum (Nov 6, 2013)

Stona, I don't think we're having an argument but to the extent that you are characterizing it as such, it is *you* who argued that you (and by extension, others) would not be able to distinguish between a Spitfire and Bf-109 if blindfolded. I merely pointed out that I could. Your admiration is easily purchased but thank you nonetheless.

I'm certainly not saying that the lack of synchronization between engines wouldn't lend an additional character to the symphony of sound emitted. I'm just pointing out that formations of German bombers would likely sound different from formations of British bombers (as individual aircraft do) for simpler, more obvious reasons. Perhaps that could account for the woo, woo, woo. Perhaps not.


Edited to add: (as individual aircraft do)


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## MikeGazdik (Nov 7, 2013)

Apples to Oranges, but..... When I was in the U.S. Army in Germany in the mid 80's, 2 friends and I were the very best at identifying the sound of the aircraft overhead without seeing the plane first. That was a time when A-10's, F4 Phantoms,, F-16's, F-15's, F-111's, Tornado's and F-18 Hornets (Canadian, with the false canopy painted on the belly), a few F104's, flew everyday and all day. We could tell them all by sound. The hardest to distinguish was the Eagle and the Falcon, because of the same engines, but the twins in the Eagle , to the careful listener, was identifiable.


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## silence (Nov 7, 2013)

Cave Tonitrum said:


> Stona, I don't think we're having an argument but to the extent that you are characterizing it as such, it is *you* who argued that you (and by extension, others) would not be able to distinguish between a Spitfire and Bf-109 if blindfolded. I merely pointed out that I could. Your admiration is easily purchased but thank you nonetheless.
> 
> I'm certainly not saying that the lack of synchronization between engines wouldn't lend an additional character to the symphony of sound emitted. I'm just pointing out that formations of German bombers would likely sound different from formations of British bombers (as individual aircraft do) for simpler, more obvious reasons. Perhaps that could account for the woo, woo, woo. Perhaps not.
> 
> ...



Very true. If I hear my sister just walking I know its her. Depending on recording quality, I can also sometimes tell the difference between an analog and digital recording, but that's a tough one.

Really, all hearing these differences comes down to is simply having enough exposure to the sound(s) in question coupled with active listening. Anyone with "some" experience as a musician could probably do it to at least a reasonable degree. Even someone with damaged hearing could, depending on the damage.


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## pattle (Nov 7, 2013)

One thing is for sure, it is difficult to mistake the sound of a Chinook.


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## N4521U (Nov 7, 2013)

Besides, the German pilots made a different Vah-room noise when at the controls!

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## pbehn (Nov 7, 2013)

I was with my uncle in Yorkshire when we heard a planes engines, "Its a Dac" he said. A few minutes later a Dacota came in sight, I asked him how he knew he said "I would recognise that sound anywhere. He was in the ROC so it was his job to identify aircraft and sound is one way to do it, admittedly not foolproof. I believe the sound comes from the engine noise end the propeller speed and pitch. Dunno if German bombers had different combinations of RPM and propeller size and pitch but I imagine they would (maybe others can answer).


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## Cave Tonitrum (Nov 7, 2013)

N4521U said:


> Besides, the German pilots made a different Vah-room noise when at the controls!



Funny! That was a good one.


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## soulezoo (Nov 17, 2014)

N4521U said:


> Besides, the German pilots made a different Vah-room noise when at the controls!



It was the accent.


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## Edgar Brooks (Nov 17, 2014)

Years ago we were told that the RAF engineers made a conscious effort to synchronise the note from their four engines, because otherwise, inside the fuselage, the noise could be maddening. With only two engines, the Germans never seem to have bothered.


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## Milosh (Nov 17, 2014)

If one hears the sound of certain a/c continuously one can learn to distinguish between types.

In Europe, troops on the ground said they could tell the difference between German and Allied types.


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## bobbysocks (Nov 17, 2014)

that is true. when i worked the ramp for the airlines i could tell which of the 4 turbo-prop planes was coming my way before they came around the building. right now they would all probably sound the same to me....


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## syscom3 (Nov 17, 2014)

Could it be due to the exhaust manifold designs for a radial engine vs. an inline type?


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## bobbysocks (Nov 17, 2014)

the design of the exhaust has a lot to do with the signature of its sound. blower will add something as well. when i sold auto parts changing the style and type of muffler and tuning the pipes could make a car sound a lot different. but generally you you have more options with an auto than ac due to room, cowlings, drag, etc.


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## norab (Nov 18, 2014)

Just a random thought, could the shape of formation play a part? The US flew combat boxes, the RAF flew in streams, but the Luftwaffe flew V' s, at least during the BOB.


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## Capt. Vick (Nov 18, 2014)

I remember reading a fictional short story in junior high about an RAF fighter pilot that was shot down and wakes up in a hospital with a leg missing. Anyway, spoiler alert, he is really a captive of the Luftwaffe but doesn’t know it UNTIL he hears the distinctive engine noise of a Heinkel bomber from outside!

Does anyone remember it?


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## stona (Nov 18, 2014)

It seems there was a belief amongst air forces of WW2 that the throbbing of unsynchronised engines could confuse the sound locating equipment used by most nations at the time. I have seen it suggested that it became standard procedure for the Luftwaffe to run engines unsynchronised for this reason.

Ken Rees' in his book 'Lie in the Dark and Listen' wrote that his squadron's Wellingtons would do the same thing 'over there'.

It has also been suggested that the Luftwaffe unsynchronised their engines as a psychological tactic (not impossible for people who attached sirens to dive bombers) or to give the impression that formations were larger than they were.
Intentional or not, the psychological aspect certainly worked as I have read and heard first hand accounts of the dread that the throbbing of German engines instilled in prople on the ground.

Whether any of that is true or not the Luftwaffe formations certainly did have a distinctive sound.

Modern aircraft auto-synchronise their engines for precisely the reason highlighted by Edgar above, the oscillations could be bloody annoying for the crew and unacceptable to paying passengers. Unsynchronised engines could also set up annoying vibrations.

Cheers

Steve


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## Capt. Vick (Nov 18, 2014)

Found it!

Beware of the Dog is a 1944 World War II story by *Roald Dahl* which was originally published in Harper's Magazine and later appeared in his Over to You collection. It was made into the movie 36 Hours in 1964.[1]


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## rogerwilko (Nov 18, 2014)

Anyone have a sample soundtrack of unsynchronised engines?


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## GregP (Nov 19, 2014)

The sound of ANY V-12 can be made different by firing order and exhaust manifold length, shape, and diameter.

Many of the early Merlins had 2-into-1 exhaust manifolds and they sound different from the individual 1-into-1 pipes adopted by others. A Griffon in a Fairely Firefly sounds WAY different froma Merlin, and it is almost entirely due to exhaust manifolds. The one around here has night-fighter shields and, while the flames may be attenuated or not, it sounds like a series of explosions flying by due to sound reflections off the flame shields.

This is the one:







Doesn't sound ANYTHING like a Merlin but, in fact, is quite similar.


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## wuzak (Nov 19, 2014)

Greg, teh Griffon has a differnet firing order than the Merlin, which is teh main cause of the sound difference.

Other reasons are that the Griffon cylinders are 37% larger than the Merlin's and the Griffon operates at lower rpm, reducing the frequency (300rpm at max rpm is 10% difference. Cruise for a Merlin is 2650rpm while it is 2400rpm for the Griffon).


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## Snautzer01 (Nov 27, 2014)

The engines of the He111 were synchronized with the rev counter of both engines to the same value and if needed adjusted on hearing. I have an old LP with different air plane noises recorded standing, taxi fly-by and a night attack on London. Will see if i can make a mp3 file of it.


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## Capt. Vick (Nov 27, 2014)

I have this, but I don't know how to post it here.


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## GrauGeist (Nov 27, 2014)

Capt. Vick said:


> I have this, but I don't know how to post it here.


That is an awesome collection of engine recordings! 

Not sure how large of an audio file it would be, but if it were converted to MP3, it can be uploaded by way of the Advanced Reply, under "Manage Attachments".

Audio files acceptable to upload are: MP3, WAV and WMA


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## Capt. Vick (Nov 27, 2014)

I'll try when I get a chance.


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## N4521U (Nov 28, 2014)

Was it the Ital;ian bombers that went "whooooooshkah"?
or was it the VVS?


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## KiwiBiggles (Nov 28, 2014)

I believe Japanese bombers tended to go 'wooof'.


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## Capt. Vick (Dec 9, 2014)

Sorry guys. I can't figure out how to do it.


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## oops (Oct 16, 2016)

pattle said:


> I often hear that German bombers made a different sound to British aircraft during the blitz, my mum and others tell me the German planes made a woo woo woo sound while the British aircraft made more of a roar. Going by the amount of accounts and witnesses there seems little doubt that German aircraft actually did make this sound and I have heard a number of explanations of why this happened which include the following.
> 
> 1) That the sound was caused by a large number of aircraft in formation that had engines running at different rpm's.
> 2) That twin engine German aircraft had each engine set at a different rpm to either frighten civilians, confuse radar or because the engines were tired and could not be synchronised correctly.
> ...


My mom lived in Hull during the war. She was recently telling me that she knew when the German bombers were overhead - she heard a very low pulsing sound - she often mentions the sound they made - she is now 92 yrs.


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## Lefa (Oct 17, 2016)

_View: https://www.youtube.com/watch?v=aeva7zWZJAg_


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## Old Wizard (Oct 17, 2016)




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## XBe02Drvr (Mar 10, 2017)

At a chief flight instructor seminar in the early 80s I was told of an old ex-LW pilot who was working as an instuctor/charter pilot at a large FBO in New England. He reportedly said they used to make the many small corrections to hold formation using the prop governor, as the throttle friction lock was a clunky PITA and very tiring to use, and had to be cinched down after every tiny thrust adjustment. Apparently throttle response was non-linear and the throttles subject to vibration creep if the friction lock wasn't TIGHT. Can you imagine what a formation all jockeying their prop speeds would sound like? Like wow-wow, man!
Cheers,
Wes


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## rinkol (Mar 10, 2017)

XBe02Drvr said:


> At a chief flight instructor seminar in the early 80s I was told of an old ex-LW pilot who was working as an instuctor/charter pilot at a large FBO in New England. He reportedly said they used to make the many small corrections to hold formation using the prop governor, as the throttle friction lock was a clunky PITA and very tiring to use, and had to be cinched down after every tiny thrust adjustment. Apparently throttle response was non-linear and the throttles subject to vibration creep if the friction lock wasn't TIGHT. Can you imagine what a formation all jockeying their prop speeds would sound like? Like wow-wow, man!
> Cheers,
> Wes


This could be correct. I do recall seeing something in one of Green's books that mentioned the He111s having a distinctive sound because of the difficulty in synchronizing the engines. The other possibility would be that the German engine control systems (fuel injection and, in the case of planes with DB engines, the supercharger speed control, included feedback loops whose operation might not have been completely stable.

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## XBe02Drvr (Mar 10, 2017)

rinkol said:


> This could be correct. I do recall seeing something in one of Green's books that mentioned the He111s having a distinctive sound because of the difficulty in synchronizing the engines. The other possibility would be that the German engine control systems (fuel injection and, in the case of planes with DB engines, the supercharger speed control, included feedback loops whose operation might not have been completely stable.


In a large formation nothing is stable except the leader. Everybody else is constantly jockeying to stay in position. If the prop synchronizers are a little sloppy and everybody is trying to make vernier thrust corrections with prop RPM because the throttles are clunky and the supercharger controller feedback is getting into the act, it's gotta sound downright symphonic! An orchestra without a conductor. "....and the beat goes on, la de da de dee, la de da de dah"
Cheers,
Wes


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## XBe02Drvr (Mar 10, 2017)

Our engines instructor at mech school, a round engines guy dating back to 8th AF, told us that our planes had sychrophasers, while the bad guys only had synchronizers, as their bombers were a generation older technology. A synchronizer merely matches the RPM of the slave engine(s) to the master. A synchrophaser not only matches speed but also keeps the props in the same phase relationship. A stop action photo would show all props aligned evenly with each other. He said this tremendously extended the fatigue life of the airframe, especially the engine mounts, by reducing beat frequencies and harmonic vibrations. "She's only givin me good vibrations, I'm not getting any excitations; Good, good good, good vibrations!"
Cheers,
Wes

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