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FlyingShark

Difference between P51 B and P51 C

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Hi,

 

This is probably one of the most stupid questions you have ever heard but, as the title says, can anybody tell me difference between the P51 B and the P51 C?

They're mostly named in the same breath and I can't find anything about the difference on the net either.

 

Have a nice day.

 

:salute:

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Just where they were built - that's it. It's also the only difference between a B-25C and B-25D.

Edited by LukeFF
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Minor trivia:

The last of the C's built came from the factory with the fin leading edge strake (much like the later D's).  The B's and earlier C's had strake* field kits available to update them but not so many were installed.  The P-51B Impatient Virgin? is one that was so updated.  This was to correct for the move from a three blade prop to four.

 

*Or leading edge extension, whatever.

Edited by chuter

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I always thought it was to correct for the loss of stability that happened when going from the razor back to the bubble canopy.

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14 minutes ago, BlitzPig_EL said:

I always thought it was to correct for the loss of stability that happened when going from the razor back to the bubble canopy.

Thats what I've always read but who knows.

You can see it added to the P-51B/C in some photos. Had to have some effect for them to add it.

 

EDIT: Trying to find a wartime photo with one but can't seem to find one. 

 

lopes-hope-air-to-air__75677.1533055887.

Edited by Legioneod

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The primary cause of the lack of stability in the Mustang was the switch from the lighter, lower powered single stage Allison with it's 3 bladed prop, to the heavier and more powerful two stage merlin with the 4 bladed prop.  Cutting back the fueselage for the bubble canopy made it worse, but all Merlin engined Mustangs had marginal yaw stability.

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I recall the fin modifications took place in non-bubble canopy versions... but I'm remembering forum posts from ten years ago here (so grain of salt).

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4 hours ago, 4thFG_Cpt_D_S_Gentile said:

The C was 50 some pounds lighter

 

More than that. To my knowledge it didn't have a fuselage tank, and it only had four guns. E: Apparently, P-51Cs from the C-3 on did indeed have a fuselage tank.

4 hours ago, Legioneod said:

Thats what I've always read but who knows.

You can see it added to the P-51B/C in some photos. Had to have some effect for them to add it.

 

EDIT: Trying to find a wartime photo with one but can't seem to find one. 

 

<snip>

 

Here's one, complete with Malcolm hood: 

 

p-51C_001&f=1&nofb=1

 

E: Link to source http://www.ww2incolor.com/us-air-force/p-51C_001.html

"P-51C-10-NT S/N 43-25050 of the 503rd FS, 339th FG, 8th AF assigned to 1st Lt. Esteban A. Terrats who was KIA in this aircraft on the March 2,1945 during an escort mission to Ruhland,Germany.Photo taken at RAF Fowlmere, England."

This picture was almost certainly taken during the winter of '44/'45, as the 339th FG transitioned to the P-51 only in April '44.

Edited by PainGod85
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The link of photo is broken, I suppose it was this one:

144797039_P51B-Cdorsfin3.thumb.PNG.7a12fe260e1b0be10269e53246a05f67.PNG

 

I found these others ones:

 

334th Fighter Squadron, 4th Fighter Group

81872669_P51B-Cdorsfin.PNG.c6ae4004b2440e816e0d053a0d401b57.PNG

353th Fighter Squadron, 354th fighter Group

1337973051_P51B-Cdorsfin2.thumb.PNG.390af6fdef5f273d1ccbba9044cc1b13.PNG

 

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This site gives a reasonable description of all the P-51s, http://joebaugher.com/usaf_fighters/p51.html

 

Initially, the P-51B and C had the Packard V-1560-3 engine rated at 1400 hp for takeoff and 1450 hp at 19,800 feet and carried four 0.50-inch machine guns with a total of 1260 rounds. There were four hundred P-51B-1-NAs and 250 P-51C-1-NTs built.

 

With the introduction of the P-51C-5-NT onto the Dallas production line and the P-51B-15-NA in the Inglewood production line, the Packard V-1560-7 engine was adopted as standard. It offered 1450 hp for take off and a war emergency rating of 1695 hp at 10,300 feet. Maximum speed at 20,000 feet was reduced from 440 to 435 mph, but increased from 430 to 439 mph at 25,000 feet. 398 P-51B-10-NAs, 390 P-51B-15-NAs, and 1350 P-51C-10-NTs were built, all powered by the V-1650-7 engine.

 

Fuselage fuel tank

The last 550 P-51B-5-NAs were fitted with this extra tank, becoming P-51B-7-NAs, and into P-51C-1-NTs, becoming P-51C-3-NT.

 

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11 hours ago, MiloMorai said:

This site gives a reasonable description of all the P-51s, http://joebaugher.com/usaf_fighters/p51.html

 

Initially, the P-51B and C had the Packard V-1560-3 engine rated at 1400 hp for takeoff and 1450 hp at 19,800 feet and carried four 0.50-inch machine guns with a total of 1260 rounds. There were four hundred P-51B-1-NAs and 250 P-51C-1-NTs built.

 

With the introduction of the P-51C-5-NT onto the Dallas production line and the P-51B-15-NA in the Inglewood production line, the Packard V-1560-7 engine was adopted as standard. It offered 1450 hp for take off and a war emergency rating of 1695 hp at 10,300 feet. Maximum speed at 20,000 feet was reduced from 440 to 435 mph, but increased from 430 to 439 mph at 25,000 feet. 398 P-51B-10-NAs, 390 P-51B-15-NAs, and 1350 P-51C-10-NTs were built, all powered by the V-1650-7 engine.

 

Fuselage fuel tank

The last 550 P-51B-5-NAs were fitted with this extra tank, becoming P-51B-7-NAs, and into P-51C-1-NTs, becoming P-51C-3-NT.

 

 

Both the V-1650-3 and -7 were rated for 75" Hg of MAP in US service, and the full +25 PSI / 81" Hg in British service.

 

Instructions for the modification of both engines:

http://www.wwiiaircraftperformance.org/mustang/ppf-p-51-mods.pdf

 

+25 PSI cleared:

http://www.wwiiaircraftperformance.org/150grade/Packard_V-1650_Engine_Performance_data.pdf

 

It's not surprising, the engines were exactly the same with the exception of the supercharger gearing, for which there was a modification kit. Either engine could be turned into the other in the field.

 

E: Actually missed this on my first readthrough of the +25 PSI document. The rating wasn't officially cleared because at the start of the -3 engines' production run, they were using single girder pistons. This was rectified in the later -3 engine batches, and virtually all later -7 engines came with them as standard as well. Even then, the rating was available to pilots.

E2: By September '44, both the -3 and -7 were officially rated to +25 PSI.

 

Re-rating_V-1650-7_6sept44.jpg

Edited by PainGod85

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3 minutes ago, Trooper117 said:

RAF version with the Malcolm Hood

So much this.

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18 hours ago, KW_1979 said:

Cutting back the fueselage for the bubble canopy made it worse, but all Merlin engined Mustangs had marginal yaw stability.

Just curious, how does cutting back the fuselage like that reduce stability? Is it something like turbulence aft of the cockpit?

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5 hours ago, Kataphrakt said:

Just curious, how does cutting back the fuselage like that reduce stability? Is it something like turbulence aft of the cockpit?

 

Look at the fuselage behind the center of gravity as an airfoil. By cutting it back, you're effectively reducing its chord without changing its span. Overall you lose wing area, which means the plane has less area behind the CoG to push the tail in line with the direction of flight.

 

The fin fillet they introduced later on remedied that by effectively acting as a leading edge root extension. It turned the rudder so effective the TO describing how to install it also mandated its servo tab be turned into an anti-service tab - increasing rudder control forces instead of reducing them.

 

(The same principle can actually be seen on the Boeing 737-300 and later. The engineers would've had to use an unreasonably high rudder leading to issues with hangar size if they hadn't gone with a vortex generator.)

E: I actually forgot to mention it, but the fillet naturally also increased the chord and with that the fuselage's area as well.

Edited by PainGod85
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