I have been searching high and low for the companion volume to my FIGHTER COMBAT COMPARISON No.1: P-40C versus A6M2 Zero.
I found this excerpt online at IL-2 and tried to contact the poster with no results so here it is for your information.
FIGHTER COMBAT COMPARISON No.2: Messerschmitt Bf109E-3 versus Supermarine Spitfire Mk.IA, Tacitus Publications, M Rubenstein, 1973. The data were generated by a USAF a/c performance computer modeling program developed by John Boyd during his tenure at the USAF Fighter School, Nellis AFB, Las Vegas NV. This is the same program which demonstrated the combat superiority of Russian fighter aircraft over their US counterparts and was also employed in the conception and design of the F16.
Aircraft Design Comparison
..................Bf109E-3............Spitfire Mk.IA
Engine............DB601Aa.............R/R Merlin III
Output (t/o).... [email protected]@3000rpm
[email protected]@3000rpm
..................@14765ft (no ram)...@16250ft (no ram)
Red Gear Ratio....0.53:1..............0.477:1
Ram Recovery......37.5%...............50%
Propeller.........3-blade VDM.........3-blade Rotol
..................constant speed......constant speed
Empty Weight......4189 lbs............4810 lbs
Normal Loaded.....5875 lbs............6200 lbs
Combat Weight.....5479 lbs............5811 lbs
Length............28ft 4.25 in........29ft 11in
Span..............32ft 4.50in.........36ft 10in
Height............8ft 2.33in..........12ft 7.75in
Wing Area.........176.53 sq ft........242 sq ft
Aspect Ratio......5.94................5.61
Wing Loading......31.0 lb/sqft........24.0 lb/sqft
Power Loading.....4.66 lb/hp..........5.64lb/hp
Prof Drag Area....4.975 sq ft.........5.182 sq ft
Max [email protected]@18500ft
Max Climb Rate....3730 ft/min.........3240 ft/min
Range.............410 miles...........575 miles
Service Ceiling...35600 ft............37000 ft
On Wing Loading and Turning Performance -
"On paper, the wing loading of the Spitfire was far less than the Emil. Except that the Emil had slats. Although the slats reduced the advantage of the Spitfire in turning ability, it didn't eliminate it completely. The difference in wing loading was just too great. But the slats endowed the Messerschmitt with another important characteristic. They gave the pilot ample stall warning. Spitfire pilots weren't so lucky. If, in combat with the enemy, a Spitfire pilot pulled too tight a maneuver and stalled, he lost all control and became easy pickings for a fighter on his tail. As a result, many top German pilots believed that the Emil could turn inside the Spitfire. This is because they had fought RAF pilots who were afraid to extract the last ounce of turn capability from their mounts. With the slats preventing vicious stall and the wing giving the Luftwaffe pilots ample warning of impending stall, the German pilots could rack the Emil through the tightest possible maneuver."
Powerplants -
The earliest Spitfires, circa Battle of France, with the Watts wooden 2-bladed fixed-pitch propeller, and even the deHavilland 3-bladed two-position propeller, were inferior to the 109E-3 in both climb and ceiling performance. It was not until the Rotol variable-pitch constant speed propeller was fitted that Spitfire was substantially improved.
TheDB601Aa offered a significant improvement in critical altitude, from the 12140 ft of the old DB601A to 14765 ft.
"A cardinal fault of the Bf109E - one which was corrected in the F and G models - was the design of the supercharger air intake. The unit on the Emil was close to the fuselage and ingested the "dirty" boundary layer air which scrubbed along the cowling surface. As a result, the supercharger ram recovery was 37.5% compared with the Spitfire's 50%. The lower ram recovery meant that the critical altitude was reached at a lower altitude. Had the later design been used on the Bf109E, as much as 1000 ft may have been gained in ceiling and in best combat altitude. This would have nullified much of the Spitfire's performance advantage at height."
"Another important difference between the Bf109E and the Spitfire Mk.IA lay in the supercharger design. The early Merlin engines were equipped with gear-driven single-speed, single-stage units. The supercharger had to be throttles back at low altitude to avoid over-boosting the engine. As altitude increased, more and more of the supercharger capability was used and engine horsepower continued to increase until critical altitude was reached, after which power fell off rapidly.
The DB601Aa engine, on the other hand, was equipped with a single-stage supercharger with a hydraulic or fluid clutch. While heavier and more complex than the gear-driven clutch, this unit had the capability of operating at an infinite number of speed ratios. This meant that the supercharger could be slowed down without choking it and far more power was delivered at lower altitudes. As the Bf109 flew higher, an aneroid control caused the supercharger to run faster to compensate for the decreased density of the air. The variable speed characteristics of this supercharger are obtained through slippage, so it was necessary for the Bf109 cooling system to contain more oil for cooling.
At low levels, the variable-speed supercharger of the DB601Aa allowed some 200 hp more to be delivered to the Bf109. To a great extent, this was the measure of the low altitude superiority of the Messerschmitt fighter."
Armaments -
The Bf109E-3 was equipped with three 20mm Oerlikon MG FF/M (two wing mounted with 60 rpg and one in the prop hub with 200 rpg) plus two 7.9mm Rheinmetall Borsig MG17 in the cowling with 500 rpg. The MG ff/M fired a 115 gram projectile at 350 rpm with a muzzle velocity of 1919 ft/sec. The MG17 fired an 11.6 gram projectile at 1100 rpm with a muzzle velocity of 2600 ft/sec. Total weight of fire for the 109E-3 was 322 lbs/min
The Spitfire Mk.IA was equipped with eight .303 in Browning Mk.II machine guns firing 11.2 gram ball and 11.1 gram AP projectiles at 1350 rpm with a muzzle velocity of 2600 ft/sec. total weight of fire for the Spitfire was 266.7 lbs/min.
"While the Spitfire armament was very adequate against the Heinkel and Dornier bombers ... , it proved to be disappointing ... against the Emils. The German fighter's guns outranged those of the Spitfire. Its cannon were more lethal ..."
Profile Drag -
"...the equivalent profile drag area of the Bf109E was slightly less than that of the Spitfire Mk.IA. This would lead one to believe that the streamlining of the Messerschmitt was better than that of the English fighter. This just wasn't so. The Spitfire was, physically, a larger airplane. It was slightly longer, had a greater wing area, and was deeper. That the drag coefficients were so close could only mean that it was the Spitfire that had the more refined contours.
Energy / Maneuverability -
Maximum Climb Rate...Bf109E-3.........Spitfire Mk.IA
Sea level............3730 ft/min......2900 ft/min
14765 ft.............3300 ft.min......3200 ft/min
16200 ft.............3050 ft/min......3250 ft/min
24000 ft.............1875 ft/min......2150 ft/min
30000 ft.............1000 ft/min......1250 ft/min
Maximum Speed........Bf109E-3.........Spitfire Mk.IA
Sea level............305 mph..........280 mph
5000 ft..............322 mph..........301 mph
10000 ft.............336 mph..........324 mph
15000 ft.............350 mph..........346 mph
16400 ft.............355 mph..........350 mph
18500 ft.............350 mph..........362 mph
20000 ft.............347 mph..........358 mph
25000 ft.............336 mph..........349 mph
30000 ft.............315 mph..........335 mph
35000 ft.............276 mph..........309 mph
Level flight Acceleration -
Sea level............Bf109 superior by +/- 1.5 mph/sec
15000 ft.............practically equal
25000 ft.............Spitfire superior by +/- 0.25 mph/sec
Maneuverability -
At any airspeed, the Spitfire was superior in maximum instantaneous maneuverability, the advantage ranging from about +0.50G at 140 mph up to a full 1.0G or slightly more at 260mph plus.
In terms of maneuverability in the sustained 1G condition, the advantage lay heavily with the Bf109E up to about 18000 ft. Above that altitude, the Spitfire held a modest advantage. In the sustained 2G maneuvering case, the Bf109E was superior up to about 12000 ft, with the Spitfire superior above that altitude. In the 3G condition, the Bf109E was superior up to about 8,000 ft by my best analysis of the graph.
Conclusions -
"...against the Spitfire, the Emil could slash and dive away. At the lower altitudes where the Bf109 was unable to dive, it was capable of outperforming the Spit Mk.IA
At altitudes of about 20,000 feet or more, the Spitfire could outperform the Emil in everything except the dive. Nor could the Spitfire be intercepted effectively at the higher altitudes, since it owned a speed advantage.
British radar prevented the Luftwaffe from jumping the RAF fighter units. Spitfires were forced to descend from the upper altitudes which favored them in order to join battle with invading German aircraft at lower - and less favorable - altitudes.
I found this excerpt online at IL-2 and tried to contact the poster with no results so here it is for your information.
FIGHTER COMBAT COMPARISON No.2: Messerschmitt Bf109E-3 versus Supermarine Spitfire Mk.IA, Tacitus Publications, M Rubenstein, 1973. The data were generated by a USAF a/c performance computer modeling program developed by John Boyd during his tenure at the USAF Fighter School, Nellis AFB, Las Vegas NV. This is the same program which demonstrated the combat superiority of Russian fighter aircraft over their US counterparts and was also employed in the conception and design of the F16.
Aircraft Design Comparison
..................Bf109E-3............Spitfire Mk.IA
Engine............DB601Aa.............R/R Merlin III
Output (t/o).... [email protected]@3000rpm
[email protected]@3000rpm
..................@14765ft (no ram)...@16250ft (no ram)
Red Gear Ratio....0.53:1..............0.477:1
Ram Recovery......37.5%...............50%
Propeller.........3-blade VDM.........3-blade Rotol
..................constant speed......constant speed
Empty Weight......4189 lbs............4810 lbs
Normal Loaded.....5875 lbs............6200 lbs
Combat Weight.....5479 lbs............5811 lbs
Length............28ft 4.25 in........29ft 11in
Span..............32ft 4.50in.........36ft 10in
Height............8ft 2.33in..........12ft 7.75in
Wing Area.........176.53 sq ft........242 sq ft
Aspect Ratio......5.94................5.61
Wing Loading......31.0 lb/sqft........24.0 lb/sqft
Power Loading.....4.66 lb/hp..........5.64lb/hp
Prof Drag Area....4.975 sq ft.........5.182 sq ft
Max [email protected]@18500ft
Max Climb Rate....3730 ft/min.........3240 ft/min
Range.............410 miles...........575 miles
Service Ceiling...35600 ft............37000 ft
On Wing Loading and Turning Performance -
"On paper, the wing loading of the Spitfire was far less than the Emil. Except that the Emil had slats. Although the slats reduced the advantage of the Spitfire in turning ability, it didn't eliminate it completely. The difference in wing loading was just too great. But the slats endowed the Messerschmitt with another important characteristic. They gave the pilot ample stall warning. Spitfire pilots weren't so lucky. If, in combat with the enemy, a Spitfire pilot pulled too tight a maneuver and stalled, he lost all control and became easy pickings for a fighter on his tail. As a result, many top German pilots believed that the Emil could turn inside the Spitfire. This is because they had fought RAF pilots who were afraid to extract the last ounce of turn capability from their mounts. With the slats preventing vicious stall and the wing giving the Luftwaffe pilots ample warning of impending stall, the German pilots could rack the Emil through the tightest possible maneuver."
Powerplants -
The earliest Spitfires, circa Battle of France, with the Watts wooden 2-bladed fixed-pitch propeller, and even the deHavilland 3-bladed two-position propeller, were inferior to the 109E-3 in both climb and ceiling performance. It was not until the Rotol variable-pitch constant speed propeller was fitted that Spitfire was substantially improved.
TheDB601Aa offered a significant improvement in critical altitude, from the 12140 ft of the old DB601A to 14765 ft.
"A cardinal fault of the Bf109E - one which was corrected in the F and G models - was the design of the supercharger air intake. The unit on the Emil was close to the fuselage and ingested the "dirty" boundary layer air which scrubbed along the cowling surface. As a result, the supercharger ram recovery was 37.5% compared with the Spitfire's 50%. The lower ram recovery meant that the critical altitude was reached at a lower altitude. Had the later design been used on the Bf109E, as much as 1000 ft may have been gained in ceiling and in best combat altitude. This would have nullified much of the Spitfire's performance advantage at height."
"Another important difference between the Bf109E and the Spitfire Mk.IA lay in the supercharger design. The early Merlin engines were equipped with gear-driven single-speed, single-stage units. The supercharger had to be throttles back at low altitude to avoid over-boosting the engine. As altitude increased, more and more of the supercharger capability was used and engine horsepower continued to increase until critical altitude was reached, after which power fell off rapidly.
The DB601Aa engine, on the other hand, was equipped with a single-stage supercharger with a hydraulic or fluid clutch. While heavier and more complex than the gear-driven clutch, this unit had the capability of operating at an infinite number of speed ratios. This meant that the supercharger could be slowed down without choking it and far more power was delivered at lower altitudes. As the Bf109 flew higher, an aneroid control caused the supercharger to run faster to compensate for the decreased density of the air. The variable speed characteristics of this supercharger are obtained through slippage, so it was necessary for the Bf109 cooling system to contain more oil for cooling.
At low levels, the variable-speed supercharger of the DB601Aa allowed some 200 hp more to be delivered to the Bf109. To a great extent, this was the measure of the low altitude superiority of the Messerschmitt fighter."
Armaments -
The Bf109E-3 was equipped with three 20mm Oerlikon MG FF/M (two wing mounted with 60 rpg and one in the prop hub with 200 rpg) plus two 7.9mm Rheinmetall Borsig MG17 in the cowling with 500 rpg. The MG ff/M fired a 115 gram projectile at 350 rpm with a muzzle velocity of 1919 ft/sec. The MG17 fired an 11.6 gram projectile at 1100 rpm with a muzzle velocity of 2600 ft/sec. Total weight of fire for the 109E-3 was 322 lbs/min
The Spitfire Mk.IA was equipped with eight .303 in Browning Mk.II machine guns firing 11.2 gram ball and 11.1 gram AP projectiles at 1350 rpm with a muzzle velocity of 2600 ft/sec. total weight of fire for the Spitfire was 266.7 lbs/min.
"While the Spitfire armament was very adequate against the Heinkel and Dornier bombers ... , it proved to be disappointing ... against the Emils. The German fighter's guns outranged those of the Spitfire. Its cannon were more lethal ..."
Profile Drag -
"...the equivalent profile drag area of the Bf109E was slightly less than that of the Spitfire Mk.IA. This would lead one to believe that the streamlining of the Messerschmitt was better than that of the English fighter. This just wasn't so. The Spitfire was, physically, a larger airplane. It was slightly longer, had a greater wing area, and was deeper. That the drag coefficients were so close could only mean that it was the Spitfire that had the more refined contours.
Energy / Maneuverability -
Maximum Climb Rate...Bf109E-3.........Spitfire Mk.IA
Sea level............3730 ft/min......2900 ft/min
14765 ft.............3300 ft.min......3200 ft/min
16200 ft.............3050 ft/min......3250 ft/min
24000 ft.............1875 ft/min......2150 ft/min
30000 ft.............1000 ft/min......1250 ft/min
Maximum Speed........Bf109E-3.........Spitfire Mk.IA
Sea level............305 mph..........280 mph
5000 ft..............322 mph..........301 mph
10000 ft.............336 mph..........324 mph
15000 ft.............350 mph..........346 mph
16400 ft.............355 mph..........350 mph
18500 ft.............350 mph..........362 mph
20000 ft.............347 mph..........358 mph
25000 ft.............336 mph..........349 mph
30000 ft.............315 mph..........335 mph
35000 ft.............276 mph..........309 mph
Level flight Acceleration -
Sea level............Bf109 superior by +/- 1.5 mph/sec
15000 ft.............practically equal
25000 ft.............Spitfire superior by +/- 0.25 mph/sec
Maneuverability -
At any airspeed, the Spitfire was superior in maximum instantaneous maneuverability, the advantage ranging from about +0.50G at 140 mph up to a full 1.0G or slightly more at 260mph plus.
In terms of maneuverability in the sustained 1G condition, the advantage lay heavily with the Bf109E up to about 18000 ft. Above that altitude, the Spitfire held a modest advantage. In the sustained 2G maneuvering case, the Bf109E was superior up to about 12000 ft, with the Spitfire superior above that altitude. In the 3G condition, the Bf109E was superior up to about 8,000 ft by my best analysis of the graph.
Conclusions -
"...against the Spitfire, the Emil could slash and dive away. At the lower altitudes where the Bf109 was unable to dive, it was capable of outperforming the Spit Mk.IA
At altitudes of about 20,000 feet or more, the Spitfire could outperform the Emil in everything except the dive. Nor could the Spitfire be intercepted effectively at the higher altitudes, since it owned a speed advantage.
British radar prevented the Luftwaffe from jumping the RAF fighter units. Spitfires were forced to descend from the upper altitudes which favored them in order to join battle with invading German aircraft at lower - and less favorable - altitudes.