What's the difference.....?

[Smokey Stover]

Just a quick one before i really start a debate going. Ok, so the RR/Packard PV12 merlin engine. And two examples of a/c equipped with this legendary engine. The Spitfire & the P-51D. Both have almost exactly the same engine (simply tuned differently) but still no distinction between them. Idk how many of the avid air enthusiasts here have heard both these warbirds in flight (particularly in a dive) but even listening to a recording its easy to distinguish how different they sound. The P-51 for example has a whistling sound very much like that of the F4U corsair. While the Spitfire keeps a continuous warble/deep growling sound. Why? They are powered by the same engine (Once the US entered the peak of production most merlin engines were Packard built. The Spitfire it not alone in its unique sound, the Mosquito, Hurricane and Lancaster all have that merlin sound. So my question is, what makes the P-51 the exception? And just to give a clue to any novice airmen not to mention eliminating the obvious suggestions. It has nothing to do with the supercharger, the radiator intake, coolant system or any other source related to the engine.

No googling please. General knowledge only

 

[jetcal1]

It could be nothing more than a difference caused by the airfoil. (Or even the air passing over an opening like the slot for the rear canopy guide.)
From past experience;
A Phalanx M61 sounds more like canvas ripping than it does when it's installed in an airframe
A sailplane in a low, high speed pass sounds like a loud jet.
These were not sounds you would expect to hear!

 

[Smokey Stover]

It could be nothing more than a difference caused by the airfoil. (Or even the air passing over an opening like the slot for the rear canopy guide.)
From past experience;
A Phalanx M61 sounds more like canvas ripping than it does when it's installed in an airframe
A sailplane in a low, high speed pass sounds like a loud jet.
These were not sounds you would expect to hear!

Good try but no cigar im afraid. Although your not far off. But it's not the airframe.
Btw, i did enquire as to where this subject matter should be posted. Evidently i was given wrong or conflicting advice. No problem

 

[MIflyer]

The Mustang used the same engine but the prop was a whole lot bigger.

 

[Smokey Stover]

The Mustang used the same engine but the prop was a whole lot bigger.

True, the P-51K did have a slightly different spec but the prop is not the source of the whistling.

 

[GrauGeist]

A clue would be that the "whistle" only occurs on the "D" model, it also occurs whether the gun ports are covered or uncovered - as some people have speculated it was the airflow over the inboard gun ports.

 

[Smokey Stover]

A clue would be that the "whistle" only occurs on the "D" model, it also occurs whether the gun ports are covered or uncovered - as some people have speculated it was the airflow over the inboard gun ports.

You are correct sir. But the fault actually lies with the barrel/50cal, and is the same reason the F4U experiences the same anomaly. Although some refuse to admit it. But there is a simple test that can be done. Blow compressed air through the gun barrel and you have yourself a deadly wind chime... I've seen it done at RAF Duxford

 

[jetcal1]

Good try but no cigar im afraid. Although your not far off. But it's not the airframe.
Btw, i did enquire as to where this subject matter should be posted. Evidently i was given wrong or conflicting advice. No problem

Hmmm, well you did say that "It has nothing to do with the supercharger, the radiator intake, coolant system or any other source related to the engine." which I find confusing since you say it not's the "airframe".

So,I'll sit back and wait to see what makes a whistling noise on a Mustang that is not a "source related to the engine", and "not the airframe".

 

[Smokey Stover]

Hmmm, well you did say that "It has nothing to do with the supercharger, the radiator intake, coolant system or any other source related to the engine." which I find confusing since you say it not's the "airframe".

So,I'll sit back and wait to see what makes a whistling noise on a Mustang that is not a "source related to the engine", and "not the airframe".

The source of the noise is air being forced at high pressure through the 50cal barrel jacket. Do you consider the machine gun sleeve to be part of the engine or airframe? If the answer is yes (with all due respect) you are an idiot. Or you are just looking to make someone you know nothing about to be a fool. Either way it's rather immature....

Btw, anytime you want a private general knowledge test let me know.

 

[Crimea_River]

Well that' rather rude...."with all due respect".

 

[jetcal1]

The source of the noise is air being forced at high pressure through the 50cal barrel jacket. Do you consider the machine gun sleeve to be part of the engine or airframe? If the answer is yes (with all due respect) you are an idiot. Or you are just looking to make someone you know nothing about to be a fool. Either way it's rather immature....

Btw, anytime you want a private general knowledge test let me know.

Generally I would consider ordnance/fixed mount guns physically bolted to aircraft structure to be part of the airframe as opposed to pylon mounted ordnance. Especially if it's a serialized item that transfers with the aircraft.

 

[Marcel]

The source of the noise is air being forced at high pressure through the 50cal barrel jacket. Do you consider the machine gun sleeve to be part of the engine or airframe? If the answer is yes (with all due respect) you are an idiot. Or you are just looking to make someone you know nothing about to be a fool. Either way it's rather immature....

Btw, anytime you want a private general knowledge test let me know.

If you are talking like this, you are rude yourself and rather immature. Please respect other people .

 

[DerAdlerIstGelandet]

Sigh...

 

[Vintageaeroengines]

Just a quick one before i really start a debate going. Ok, so the RR/Packard PV12 merlin engine. And two examples of a/c equipped with this legendary engine. The Spitfire & the P-51D. Both have almost exactly the same engine (simply tuned differently) but still no distinction between them. Idk how many of the avid air enthusiasts here have heard both these warbirds in flight (particularly in a dive) but even listening to a recording its easy to distinguish how different they sound. The P-51 for example has a whistling sound very much like that of the F4U corsair. While the Spitfire keeps a continuous warble/deep growling sound. Why? They are powered by the same engine (Once the US entered the peak of production most merlin engines were Packard built. The Spitfire it not alone in its unique sound, the Mosquito, Hurricane and Lancaster all have that merlin sound. So my question is, what makes the P-51 the exception? And just to give a clue to any novice airmen not to mention eliminating the obvious suggestions. It has nothing to do with the supercharger, the radiator intake, coolant system or any other source related to the engine.

No googling please. General knowledge only

Propeller, exhaust stacks and Camshafts:
Propellers are very different in shape and make a different sound.
Exhausts stacks vary in shape, angle and opening size.
Cams have 3 major changes in duration and overlap. Early Rolls/Packard -7, Later Rolls through _500/Packard -9 and Rolls -620 to-724
every once in a while I have found engines with two different cams. That really make for some interesting sound and harmonics when running.
Then add in an engine with the slower reduction gears from a transport engine and it all changes again.
Mike

 

[mikewint]

private general knowledge test

OKey Doke: What US President was almost involved in a war crime and what was the crime?

 

[Smokey Stover]

Well that' rather rude...."with all due respect".

Rather rude you say? With all due respect i dont think ive made a single post on this site that hasnt had half a dozen people try to pull apart. The phrase too many chiefs springs to mind.
And i dont quite understand why everyone think the gun barrels are a part of the airframe. Does that mean the landing gear is a part of the airframe too? Or maybe the pilots parachute perhaps....Oh please, dont accuse me of being rude just because you need your ego stroking. And that goes for everyone, with maybe two exceptions. Ive been about as welcome here as a dose of ebola. Time for me to leave for skies of blue.. Its a little too grey and black here for me. Adios

 

[jetcal1]

The barrel is a sub-assembly of a serialized item that is hard mounted to aircraft structure. In one case, my aircraft required ballast to fly without it's airframe mounted gun. In another case, an aircraft I supported could not fly without its gun as it (the gun) carried structural airframe loads. The only time the gun (+ barrel) did not fly (Or transfer with the aircraft.) with the aircraft were the pintle mounted crew served weapons on my helicopters. And yes, while the landing gear is attached to the airplane it is part of the airframe as a sub assembly. and will remain so until, (like the machine gun) it is removed from the airframe at which point it becomes an end item. The exception to this rule would be engines and propellers as they have their own logbooks.

 

[Marcel]

Ive been about as welcome here as a dose of ebola. Time for me to leave for skies of blue.. Its a little too grey and black here for me. Adios

Bye

 

[rochie]

Rather rude you say? With all due respect i dont think ive made a single post on this site that hasnt had half a dozen people try to pull apart. The phrase too many chiefs springs to mind.
And i dont quite understand why everyone think the gun barrels are a part of the airframe. Does that mean the landing gear is a part of the airframe too? Or maybe the pilots parachute perhaps....Oh please, dont accuse me of being rude just because you need your ego stroking. And that goes for everyone, with maybe two exceptions. Ive been about as welcome here as a dose of ebola. Time for me to leave for skies of blue.. Its a little too grey and black here for me. Adios

People pulled your posts apart because they were random pictures from the internet that you seemed to know very little about or were obviously pictures of models or video game screen grabs that you tried to pass off as real.
You were then a total arsehole to anyone that checked you on them.

No loss to the forum so adios !

 

[DerAdlerIstGelandet]

Rather rude you say? With all due respect i dont think ive made a single post on this site that hasnt had half a dozen people try to pull apart. The phrase too many chiefs springs to mind.
And i dont quite understand why everyone think the gun barrels are a part of the airframe. Does that mean the landing gear is a part of the airframe too? Or maybe the pilots parachute perhaps....Oh please, dont accuse me of being rude just because you need your ego stroking. And that goes for everyone, with maybe two exceptions. Ive been about as welcome here as a dose of ebola. Time for me to leave for skies of blue.. Its a little too grey and black here for me. Adios

Well that is your choice. Bye. Maybe you should think about how you present yourself. People might welcome you more...