P-51D vs. Spitfire IX

[BiffF15]

Greetings Pat303,

There is a difference between Range and Combat Radius. Summarizing from documents over on World War II Aircraft Performance, Range is the farthest an aircraft can fly in a given configuration. In the footnotes for calculating range it is noted that when calculating range no fuel is used for warm up, taxi, take-off, and climb to altitude. The best range I can find for a Spit Mk XIV is 861 miles. Combat Radius of Action is calculated with factors for warm up, taxi, take-off, climb to altitude, and a factor for combat action (duration at WEP). Since I have the calculations for the P-51H handy, this can be demonstrated with the P-51H range being 2514 miles and combat radius for the same configuration is 1024 miles. If you want to do a simple ratio to get a rough idea of the Spitfire's combat radius we can use 40% based on P-51H numbers. The Combat radius for the Spit XIV calculates as 861 x 40% = 344 miles. My guess is that this number is a little high as the percentage of fuel used for WEP goes up with the shorter the range of the fighter.

Going back to my original post, my question really wasn't about which fighter was better, but was questioning a myth that the Spitfire was always more maneuverable or better. This came from references to the Mustang's best combat performance being at higher speeds and the energy maneuvering chart I had come across that showed the Mustang had an advantage at higher speeds. To illustrate, here is a similar chart comparing the F-18 and F-16.

View attachment 594277

and the chart from my original post with a similar shading showing the envelope where the Spit Mk IX has a definitive advantage and where the Mustang has an advantage.

View attachment 594279

Aircraft behave differently at different speeds and altitudes and while one aircraft might be "better' in one situation another might outperform it in a different situation. To me, the discussion should be a more nuanced comparison. As Rochie has stated, they are both great aircraft and should be appreciated as such.

NevadaK,

Your EM charts are a bit different from what I've looked at before. However, looking at the F18 F16 chart it appears that the Hornet has limit of 9Gs same as the F16. In reality the Hornet is a 7.3G jet. No exceptions that I'm aware of other than the occasional over G. The F16 has a unique chart as well due to its FBW and slats.

Cheers,
Biff

 

[Clayton Magnet]

For equity purposes lets keep it with the P-51D/Spitfire Mk IX comparison. If you want to go Spitfire Mk XIV then you need to go with the comparable generating Mustang the P-51H.

A comparable Mustang to the Spitfire Mk.IX would be the Mustang Mk.I, or Mk.II (P-51A), as they both entered service in early 1942.
The P-51H is comparable to the 20 series Spitfires, or even the Spiteful.

 

[GregP]

Hi PAT 303,

I don't believe anybody dogfights with drop tanks on unless they get jumped and get off a few shots before or as they drop tanks. It isn't from thinking the tanks might break off in maneuvering as much as from the effect on flight characteristics with the extra weight and the effect on performance.

If we have a full 150-U.S. gallon drop tank that weighs 25 pounds, and if it is held on by four 1/4" - 28 bolts, we have a theoretical limit of 11 g's or so if we use yield strength rather than tensile strength, but most WWII pilots didn't spend the time to calculate the reserve strength, the effect on stall speed, or on rolling ability. They'd drop tanks because they were going into combat with an enemy who might not have drop tanks installed and didn't want to lose performance while in combat. It was dangerous enough without unnecessarily giving away performance.

 

[pbehn]

Hi PAT 303,

I don't believe anybody dogfights with drop tanks on unless they get jumped and get off a few shots before or as they drop tanks. It isn't from thinking the tanks might break off in maneuvering as much as from the effect on flight characteristics with the extra weight and the effect on performance.

If we have a full 150-U.S. gallon drop tank that weighs 25 pounds, and if it is held on by four 1/4" - 28 bolts, we have a theoretical limit of 11 g's or so if we use yield strength rather than tensile strength, but most WWII pilots didn't spend the time to calculate the reserve strength, the effect on stall speed, or on rolling ability. They'd drop tanks because they were going into combat with an enemy who might not have drop tanks installed and didn't want to lose performance while in combat. It was dangerous enough without unnecessarily giving away performance.

Someone here did recall a P51 fighting with one tank on, simply because it refused to drop off.

 

[fastmongrel]

I don't believe anybody dogfights with drop tanks on

Spitfires did fight with the slipper tank in place possibly because dropping it would mean getting out and pushing the last few miles home.

 

[pbehn]

Spitfires did fight with the slipper tank in place possibly because dropping it would mean getting out and pushing the last few miles home.

P-51s just have to fly further to run out of fuel, waste of effort.

 

[GregP]

There are always extenuating circumstances. I'd much rather fight with tanks than walk home and I'd fight rather than get shot down if the tanks wouldn't drop.

I was talking about normal circumstances where it was pilot's choice, which is usually when you are a section leader or flight leader. Usually, then pilot in charge of the two to six airplanes would call for tank drop, and it would be pilot's choice if that's YOU. I'd assume everyone in the flight knew where the point of no return without tanks was and wouldn't drop if they were going to walk home or take a swim.

 

[PAT303]

I don't believe anybody dogfights with drop tanks on unless they get jumped and get off a few shots before or as they drop tanks. It isn't from thinking the tanks might break off in maneuvering as much as from the effect on flight characteristics with the extra weight and the effect on performance.

And while I agree with you it's performance with the tank fitted still made it effective against the opposition.

57. Even with the 90 gallon tank, the Spitfire XIV can equal or outclass the FW.190 (BMW.801D) and the Me.109G in every respect. Its main advantages remain the tight turn and maximum climb.

 

[PAT303]

Spitfires did fight with the slipper tank in place possibly because dropping it would mean getting out and pushing the last few miles home.

Spitfires had plenty of range if fitted out for long range work http://www.spitfireperformance.com/spitfire9-fuelsystem-lr.jpg

 

[Milosh]

What was the combat radius? A ballpark number is 1/3 of range.

 

[Peter Gunn]

There are always extenuating circumstances. I'd much rather fight with tanks than walk home and I'd fight rather than get shot down if the tanks wouldn't drop.

I was talking about normal circumstances where it was pilot's choice, which is usually when you are a section leader or flight leader. Usually, then pilot in charge of the two to six airplanes would call for tank drop, and it would be pilot's choice if that's YOU. I'd assume everyone in the flight knew where the point of no return without tanks was and wouldn't drop if they were going to walk home or take a swim.

I agree, but interestingly enough (or maybe not) I remember reading some encounter reports I think from a 4th FG jock where they engaged without dropping tanks, it's here ( Mustang Encounter Reports ) somewhere but I'll wager it was a once in a hundred happenstance.

 

[SaparotRob]

Great link! Thanks for that.

 

[spicmart]

The 20 series Spitfires had a new sturdier wing which rectified its elasticity problems at very high speeds and made the Spit one of the best rollers in that realm.
After solving its handling issues it might well have been the best dogfighter in the class of the latest super props. It was not among the fastest though.
Only the F8F could compete with it in terms of agility and climb.
What do yo guys think?

 

[pbehn]

The 20 series Spitfires had a new sturdier wing which rectified its elasticity problems at very high speeds and made the Spit one of the best rollers in that realm.
After solving its handling issues it might well have been the best dogfighter in the class of the latest super props. It was not among the fastest though.

The Spitfires roll rate problem was purely relative. It had a good rate of roll compared to most but one plane noticeably better was the one it met most across the Channel, the Fw 190. This put it second in a two horse race.

 

[pbehn]

I agree, but interestingly enough (or maybe not) I remember reading some encounter reports I think from a 4th FG jock where they engaged without dropping tanks, it's here ( Mustang Encounter Reports ) somewhere but I'll wager it was a once in a hundred happenstance.

I believe the LW did try engaging escorts early to try to get them to drop tanks, not a success, probably because as you said, they didn't actually have to to be at least partially effective.

 

[BiffF15]

There are times when you can get away with it and times when you can't. When you can comes with high situational awareness, the element of surprise, and or a big enough advantage.

If offensive, and need the gas to get home then you are hamstrung a bit and better commence the attack, if necessary, with a clearly defined stop (how bad will I let things possibly get before I leave).

Or if you get bounced, and need the gas to get home, (then you probably shouldn't be there to begin with) then you jettison now, fight, and only walk / swim a little bit of the way home. Or you keep the tank on and fight. This requires you to be good or in a position that can be won because if you lose your walk is much longer.

There are also times you can get away with it but don't because you make an execution error. Think Tommy McGuire. He had a position of both advantage and numbers. Or so he thought. He was an outstanding leader and pilot who paid full price for one small mistake.

Thomas McGuire - America's 2nd Highest-Scoring Ace, Medal of Honor Recipient

 

[GregP]

When I look at Pilot Operating Handbooks, most if not all say that with drop tanks, no aerobatics are permitted. In the P-51 POH, for instance, it says: "When the airplane is carrying droppable fuel tanks, only normal flying attitudes are permitted. Don't try anything but normal climbing turns and let-downs when you're carrying extra wing tanks." It also cautions against any aerobatics with more than 25 gallons in the fuselage tank. Most other POH have similar cautions against hard maneuvering with drop tanks on.

The Spitfire XVI manual states that the airplane becomes very difficult to fly with 90-gallon (or 170-gallon) drop tanks and is restricted to straight flying and gentle maneuvers. Aerobatics are not permitted when carry any external stores or when the read fuselage tank contains any fuel. Other Spitfire marks are similar so far as I have looked. As such, I am tending to doubt intentional combat with drop tanks installed.

Combat maneuvers when you can't drop them or don't have a choice for some reason is another story. It's ALWAYS better to fight than to get shot down.

 

[drgondog]

Someone here did recall a P51 fighting with one tank on, simply because it refused to drop off.

My father had trouble losing both tanks and engaged with 1 108 gal tank hung halfway into the fight...

 

[pbehn]

My father had trouble losing both tanks and engaged with 1 108 gal tank hung halfway into the fight...

Yes Bill you (or rather your father) were that someone, I just couldn't find it in a search to get the exact details.

 

[drgondog]

The Tempest was actually heavier than the P-51, at 9,000 pounds clean compared to the P-51 clean:
B/C at 6,985 pounds
D/K at 7,635 pounds.

Dave - by 'clean' weren't you targeting Empty (with empty 85 gal fus tank and GFE only)? P-51A = 6433, P-5B/C = 6988, P-51D = 7150 or Basic Wt (with guns, bomb racks - no fuel/oil or ammo or pilot) A=6806, B/C=7422, D= 7,728

As good a job as Dean did, he probably didn't have access to the NAA 'P-51A, B and D Airplane Specifications'

Source - NAA P-51A, B and D Specifications. I did extract from the Specs to put in the Appendices of the new book. Hope I did the math right.