P-51D vs XP-51F/G & P-51H aero tweaks.

[BarnOwlLover]

I know of the radiator ducting and wing profile changes, as well as other elements (such as modifying the supercharger intake), but what other elements changed as far as aero refinements? After all, the XP-51F was about 25mph or so faster than the D on the same power, so what other refinements did North American use on the F/G and H?

 

[Bigmerle]

The H was 600 lbs lighter and 50 mph faster than the D.

 

[ThomasP]

I have only been able to find ~215 lbs difference between the D and H models. Weights for both aircraft with 265/13 USgal fuel/oil, 6x .50 cal w/1820 rpg, comparable radio/electronics fits (might be 40-50lbs difference). Both clean with wing DT/bomb racks.

P-51D_____9700 lbs
P-51H_____9485 lbs

If anyone has weight and loading diagrams/charts that contradict the above weights to any degree, I would very much appreciate if you would post them.

 

[BarnOwlLover]

I've been able to find SAC data for the P-51H that gives weights, power/supercharger boost ratings and such for various configurations (standard combat, interceptor, ferrying, etc) at World War II aircraft performance, but not for the B/D, at least for later in the war when 75-80" was approved (the H data had ratings for 80" and 90", 90" with ADI).

But from said data, the P-51H in interceptor trim weighed as low as 8450 lbs take off. Also, drgondog has made mention of P-51D at 67" on half fuel and set up as an interceptor (8900 lbs TO weight) getting 452 mph at I believe about 22,000 ft and a 4200+ fpm initial climb rate.

But I'm not necessarily talking weight here (the XP-51F/G could weigh between 7200 and 7900 lbs depending on set up when tested). I'm asking more about aero tweaks and differences between the models, since aero played a much bigger role in top speed for the same power outputs. Weight does however govern climb rate for a given power output.

 

[drgondog]

I have only been able to find ~215 lbs difference between the D and H models. Weights for both aircraft with 265/13 USgal fuel/oil, 6x .50 cal w/1820 rpg, comparable radio/electronics fits (might be 40-50lbs difference). Both clean with wing DT/bomb racks.

P-51D_____9700 lbs
P-51H_____9485 lbs

If anyone has weight and loading diagrams/charts that contradict the above weights to any degree, I would very much appreciate if you would post them.

P-51D full combat load out ~10,135 lbs with 269gal fuel; Basic Wt. = 7635 pounds, without racks
P-51H full combat load out ~ 9450 lbs with 255 gal fuel; Basic Weight = 7146 pounds without racks
P-51H had 240 rounds less of 50 cal = 1820 to 2060 rnds = 76 pounds delta
P-51H had 14 gal less fuel
P-51H bomb racks 44 pounds; P-51D racks 32 pounds.(22 and 15 each, respectively


Source P-51D-5 and P-51H-1 Specifications and NAA Performance Calculations reports for each.

 

[BarnOwlLover]

I thought that the D had 1880 rounds of ammo for 6 .50s (2x400, 4x270)?

Also, are those take off weights vs combat weights?

 

[ThomasP]

The early P-51D could carry 2080 rounds (2x500 + 4x270). The later P-51D had 1880 rounds (2x400 + 4x270). Sometimes the total for the earlier aircraft is listed as 2060 rounds (2x490 + 4x270).

 

[drgondog]

I thought that the D had 1880 rounds of ammo for 6 .50s (2x400, 4x270)?

Also, are those take off weights vs combat weights?

'Combat weights' without external fuel tanks. Essentially max internal load out, but including wing racks - but not rocket stubs.

Whenever the phrase 'take off weight' is posed, the answer is 'it depends'.

External loads adding to 'combat loadout - clean' could include bombs, rockets, chemical canisters, napalm, cluster bombs, combat tanks, ferry tanks or any combination.

 

[BarnOwlLover]

Then, what weights would we be looking at (at least intended weights) for actual combat as far as typical or max combat weight for engagement?

 

[Tom Fey]

The Merlin V-1650-9 in the P-51H made 2,270 horsepower wet and used the high activity factor, H20 series Aeroproducts propeller blade which is the same blade family as used on the Bearcat. The oil cooling used a liquid-liquid heat exchanger instead of an oil radiator and ducting. All this helps the top end. P-51H owner/pilot Steven Coutches talks about the -H here: H Is For Heirloom

 

[drgondog]

The Merlin V-1650-9 in the P-51H made 2,270 horsepower wet and used the high activity factor, H20 series Aeroproducts propeller blade which is the same blade family as used on the Bearcat. The oil cooling used a liquid-liquid heat exchanger instead of an oil radiator and ducting. All this helps the top end. P-51H owner/pilot Steven Coutches talks about the -H here: H Is For Heirloom

Thanks Tom.

 

[BarnOwlLover]

I wonder if I'm imagining things or it's actually true. But it looks like (at least from some angles that the P-51H and the XP-82/P-82B have the engine cowling wrapped tighter around the front of the engine than on say the D or even the F/G models. Is this an illusion, or is there something to it?

 

[BarnOwlLover]

A small question about a particular dimension. I remember that the Allison Mustangs may've had a smaller diameter spinner vs the B/D models. But what about the H vs the B/D as far as that goes?

 

[drgondog]

I doubt the difference between H and D but I do no know for sure.