Fuel system

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Tomas Linnet
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Re: Fuel system

Post by Tomas Linnet »

I was 100% sure that it was in the manual, but now I'm 100% sure that I've been studying the P-51' fuel system to understand what was going on, But you have a point Rob, it is very strange that it isn't mentioned in the original pilots handbook.
Kind Regards
Tomas

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MkIV Hvd
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Re: Fuel system

Post by MkIV Hvd »

Thank you very much Dudley, THAT was all I've been looking for since the start of the "investigation". :D

Thomas, the fact that it is not mentioned is not as strange as the fact that the RAF manual advises a fuel management technique that will apparently result in a significant loss of fuel through a full left main tank...for three hours or more... :?

Cheers,
Rob
Rob Wilkinson
A2A: Civilian Mustang, T-6, Bonanza, Comanche, Cub, C182, Spitfire, P-40, Cherokee, P-51 - VATSIM P4 and some other stuff...

Tomas Linnet
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Re: Fuel system

Post by Tomas Linnet »

MkIV Hvd wrote: 12 Mar 2021, 08:48
that will apparently result in a significant loss of fuel through a full left main tank...for three hours or more... :?

Cheers,
Rob
Rhob, this is the strange part ;-) I mean...why just dump fuel??
Kind Regards
Tomas

Sim: FSX SE
Accu-Sim aircraft in my hangar:
C172, C182, P51 Civ, P51 Mil, B17, Spitfire, P47, B377 COTS,
J3 Cub, T6, Connie, P-40, V35B
A2A Accu-Sim Avro Lancaster Loading:............0.000003% complete, please wait.

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MkIV Hvd
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Re: Fuel system

Post by MkIV Hvd »

Tomas Linnet wrote: 12 Mar 2021, 09:43
MkIV Hvd wrote: 12 Mar 2021, 08:48
that will apparently result in a significant loss of fuel through a full left main tank...for three hours or more... :?

Cheers,
Rob
Rhob, this is the strange part ;-) I mean...why just dump fuel??
Yep, still confused Sir, but whatever... :roll: :lol:
Rob Wilkinson
A2A: Civilian Mustang, T-6, Bonanza, Comanche, Cub, C182, Spitfire, P-40, Cherokee, P-51 - VATSIM P4 and some other stuff...

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DHenriques_
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Re: Fuel system

Post by DHenriques_ »

Tomas Linnet wrote: 12 Mar 2021, 09:43
MkIV Hvd wrote: 12 Mar 2021, 08:48
that will apparently result in a significant loss of fuel through a full left main tank...for three hours or more... :?

Cheers,
Rob
Rhob, this is the strange part ;-) I mean...why just dump fuel??
You don't "just dump fuel". The entire design concept for the return line is based on NOT dumping fuel.
The carb can only "absorb" so much of the vaporized fuel that it is sent by the fuel system. The "extra" vapors have to go somewhere. As fuel is used by the left tank (Or the fuselage tank if the line goes there) room becomes available for the returning fuel which comes back to the tank via a return line running from the carb to the tank. The return line simply dumps whatever is being returned back into the tank.
If the tank was full and had no room for the returning fuel..........THEN and only THEN would the returning fuel be exited through an exit port.
So the whole idea is based on SAVING the unused fuel as opposed to "dumping it".
Hope this helps.
Dudley Henriques

Tomas Linnet
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Re: Fuel system

Post by Tomas Linnet »

I know, that is why it's strange that the pilot handbook tells the pilot to take of on the fuselage tank instead and not mentioning the fact that fuel will be lost if the left tank is full.
Kind Regards
Tomas

Sim: FSX SE
Accu-Sim aircraft in my hangar:
C172, C182, P51 Civ, P51 Mil, B17, Spitfire, P47, B377 COTS,
J3 Cub, T6, Connie, P-40, V35B
A2A Accu-Sim Avro Lancaster Loading:............0.000003% complete, please wait.

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DHenriques_
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Re: Fuel system

Post by DHenriques_ »

Tomas Linnet wrote: 12 Mar 2021, 14:00 I know, that is why it's strange that the pilot handbook tells the pilot to take of on the fuselage tank instead and not mentioning the fact that fuel will be lost if the left tank is full.
Some squadrons did a "field mod" on the 51 where long range cruise to the combat area was involved. They rerouted the return line to the fuselage tank REMOVING it from the left main. The reasoning for this was that it was considered wise to use up as much of the fuselage fuel as possible before entering enemy airspace due to the fact that with fuel in that tank when engaged the Mustang could have serious issues maneuvering. If engaged by the enemy with a lot of fuel in the fuselage tank it affected the cg on the Mustang and made hard maneuvering very difficult and in some cases impossible. The Mustang pilots were well aware of this and had their crew chiefs reroute the line to the fuselage tank. This served a double purpose; first being the making of room in that tank for the returning fuel from the carb and second using up the fuel from the fuselage tank first to bring the cg into maneuvering range if engaged.
Dudley Henriques

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Paughco
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Re: Fuel system

Post by Paughco »

Here is a link to a P-51 Pilot's Manual from WW2. https://ww2aircraft.net/forum/threads/p ... ual.22715/. The manual download link is a tan rectangle with an Adobe sign in it that says P-51 D/K Manual.pdf, in a post by Deac. Download it and check out Pages 21 and 22. Also, there's a lot of really good information on landing, starting on Page 56.

The P-51 fuel pump pumps more fuel than the carburetor needs, mainly because it would be really bad if it pumps less then the carb needs. The unused fuel (vapor or liquid - semantics) goes back to a fuel tank. The manual says that which tank varies from squadron to squadron, but it goes to a tank, either the left, fuselage, or right. As the book says, check with your Engineering Officer. Our A2A P-51's return vent is to the left tank.



Seeya
ATB
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Tomas Linnet
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Re: Fuel system

Post by Tomas Linnet »

Paughco wrote: 12 Mar 2021, 19:52 Here is a link to a P-51 Pilot's Manual from WW2. https://ww2aircraft.net/forum/threads/p ... ual.22715/. The manual download link is a tan rectangle with an Adobe sign in it that says P-51 D/K Manual.pdf, in a post by Deac. Download it and check out Pages 21 and 22. Also, there's a lot of really good information on landing, starting on Page 56.

The P-51 fuel pump pumps more fuel than the carburetor needs, mainly because it would be really bad if it pumps less then the carb needs. The unused fuel (vapor or liquid - semantics) goes back to a fuel tank. The manual says that which tank varies from squadron to squadron, but it goes to a tank, either the left, fuselage, or right. As the book says, check with your Engineering Officer. Our A2A P-51's return vent is to the left tank.



Seeya
ATB
I have read this manual when I was new in the :a2a: P-51D, this must why I was 100% sure the return line was mentioned in the :a2a: manual.

I really enjoy geeking(not sure this is an actual word, but...) around in stuff like this :D
Kind Regards
Tomas

Sim: FSX SE
Accu-Sim aircraft in my hangar:
C172, C182, P51 Civ, P51 Mil, B17, Spitfire, P47, B377 COTS,
J3 Cub, T6, Connie, P-40, V35B
A2A Accu-Sim Avro Lancaster Loading:............0.000003% complete, please wait.

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MkIV Hvd
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Re: Fuel system

Post by MkIV Hvd »

Paughco wrote: 12 Mar 2021, 19:52 Here is a link to a P-51 Pilot's Manual from WW2. https://ww2aircraft.net/forum/threads/p ... ual.22715/. The manual download link is a tan rectangle with an Adobe sign in it that says P-51 D/K Manual.pdf, in a post by Deac. Download it and check out Pages 21 and 22.

Seeya
ATB
Thanks for the link Paughco! That's the best overview I've seen and weirdly, I have a paper copy of that one on the way from Amazon that's set for delivery tomorrow...love Amazon, but it can be a dangerous place :mrgreen:

The thing that's still very strange is the fuel management procedure laid out in the RAF Mustang manual that would result in a significant amount of fuel loss if followed. I mean, I know the English do things slightly differently at times, but... :?

By the way, the difference between vapor and fuel is not semantics...it's science and chemistry I think... :lol:

Over and out!
Rob
Rob Wilkinson
A2A: Civilian Mustang, T-6, Bonanza, Comanche, Cub, C182, Spitfire, P-40, Cherokee, P-51 - VATSIM P4 and some other stuff...

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