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|P-51 Mustang||HISTORY SPECIFICATIONS DRAWINGS DETAILS
COMBAT ADVENTURE SIDE VIEWS
NA-73 PROTOTYPE MUSTANG I P-51B AND -C
P-51D AND -K P-51H P/F-82 TWIN MUSTANG
THE "BEST" OF THE WAR?
In the early months of 1940, America's entry into World War II was still nearly two years away. But on the European continent, nothing seemed to be able to slow the onslaught of the German military as one country after another came under Nazi control. It appeared to be only a matter of time, and perhaps a very short time, before England would be facing the German war machine alone.
Great Britain needed the weapons and materials of war in great quantity, and it needed them quickly. Nothing was of higher priority than fighter planes to defend the island nation, and in January 1940, before the fall of France, the Anglo French Purchasing Commission came to America hoping to acquire additional P-40s. But the Curtiss production lines were operating at capacity, so some "back room" discussions sent them to see James H. "Dutch" Kindelberger, the president of North American Aviation.
The British had purchased aircraft from North American before, but they had been trainers, not the fighters they now so desperately needed. In fact, up to that time, North American had never produced a true fighter design. During World War II, it would later become common for one company to produce another's design. Vega and Douglas would build Boeing's B-17, Goodyear would build Vought's Corsair, General Motors would build Grumman's Wildcat and Avenger, and Curtiss would even build Republic's Thunderbolts. But in 1940, North American was not interested in producing Curtiss P-40s for the British.
Instead, North American informed the British that it could produce an even better fighter plane than the P40 while still using the same Allison V-171 0 inline engine. Reports have been published stating that North American stipulated in the contract that this would be accomplished in only 120 days, but in fact, there was no such guarantee in the contract. Nevertheless, North American did assure the British that the plane could be designed and produced very quickly.
Asked to name the American military personnel who made significant contributions to victory in World War II, men like Dwight Eisenhower, George Patton, Douglas MacArthur and Chester Nimitz would be on most lists. But a very good argument could also be made to include First Lieutenant Benjamin S. Kelsey. Lt. Kelsey was head of the Army Air Corps Pursuit Projects Office at Wright Field, and he was the single most important man in the acquisition of what would eventually become the P51 Mustang fighter. With a degree in aeronautical engineering from M.I.T., Kelsey was qualified in aircraft design and performance, and he ingeniously found the means and the money to keep the program going until America's entry into the war ensured its success.
On May 4, 1940, when North American obtained release to sell the NA-73 to the British, Kelsey had included the stipulation that two aircraft from the first production batch would be turned over to Wright Field for testing. This meant that the British would buy the U.S. Army two aircraft which it did not then have the funds to purchase for itself.
Kelsey also knew of the National Advisory Committee on Aeronautics' (the forerunner to NASA) studies on the laminar flow airfoil, and as an aeronautical engineer, he understood its importance to new aircraft design and performance. As a result, NACA's Eastman Jacobs was assigned to North American's team that was working on the new fighter for the British. Raymond H. Rice was North American's chief engineer, Edgar Schmued their chief of design, and Ed Horkey was the aerodynamicist. Along with Jacobs, they worked day and night, seven days a week, to produce the new fighter as quickly as possible.
Curtiss had been ordered to turn over its design studies and other pertinent information on the XP-46. This included the radiator scoop originally intended for installation under the fuselage of the P-40. This scoop, which provided cooling air for glycol and oil cooling, was also to have a hot air exit ramp which would create thrust that more than offset the drag caused by the frontal cross-section for the scoop. Though never fitted operationally to the P-40, it held promise and was one of the features incorporated in the design of the NA-73. Just how much the data from Curtiss was used is subject to debate. Curtiss engineers state that it was almost total, while those at North American claim that little of the information was used. The truth is probably somewhere between these two extremes. Clearly, the NA-73 had a lot in common with the XP-46, and a rational analysis would indicate that the NA-73 could not have been engineered in such a short period of time without considerable use of the Curtiss data. But equally as clear is the original thinking added by the North American design team. Among the most important changes was the addition of the laminar flow wing.
On September 9, 1940, only 102 days after the contract had been signed, the NA-73X prototype was rolled out though still waiting for its engine. The new fighter was named Mustang by the British, and the first British version was designated Mustang I. As soon as it was available, the 1,120hp Allison V-171 0-39 powerplant was installed, and engine and taxi tests began. On 26 October, Vance Breese lifted the aircraft off the runway for a maiden flight. Testing continued until Paul Balfour was forced to make a deadstick landing. The NA73X flipped over on its back, and it took six weeks to make repairs and get the aircraft ready to fly again. The first production Mustang I soon joined the repaired prototype in the test program, and shortly other Mustangs were heading for England.
Shown here with a tan and olive green camouflage scheme and with American national insignias, the first Mustang I of the second production batch can be identified by the British serial, AL958, painted on the side of its fuselage. The second production order of Mustang Is was given the North American model number NA-83, while the Mustang Is of the original order were North American model NA-73.
As expected, the evaluation of the flight test aircraft showed that the NA-73 was indeed superior to the P-40 Warhawk which was considered to be the best single-engine fighter in the U.S. Army Air Corps inventory at the time. A lot of criticism has been written about the AAC's initial lack of interest and subsequent slowness to act concerning acquiring Mustangs for its own use. This simply is not so. All evidence is to the contrary, particularly considering the political and economic situation in America at that time. Here again Lt. Benjamin Kelsey was the man who deserves the credit.
As stated earlier, Kelsey saw to it that two aircraft from the original British order were supplied to Wright Field for testing, but his efforts did not stop there. Kelsey was able to place an order for 150 P-51s on July 7, 1941, and this was before the first XP-51 even arrived in Ohio. It was a small order for the first U.S. version, but it was all that funding would allow at that time.
The P-51 was very similar to the Mustang I, with the main difference being the replacement of the mixed machine gun armament of the British version with four 20mm cannon. Clearly, the USAAC had a genuine interest in the NA-73, even before it had a chance to obtain one. The situation in Europe would cause 93 of the P51s to be sent to the Royal Air Force where they were called Mustang IAs.
With an order from the U.S. Army, North American chose the nickname "Apache" for the U.S. aircraft. But by then the British name, Mustang, had taken root, and it became the official nickname of the USAAC.
With no funds available for pursuit aircraft, as fighters were then called, Lt. Kelsey came up with a way to beat the system and get some additional Mustangs on order for the USAAC. Using some remaining funds for attack aircraft, Kelsey asked North American to develop a dive-bomber version of the NA-73. Choosing A-36, which was the next available attack designation, Kelsey ordered 500 of these dive-bomber versions on April 16, 1942. Ironically, the North American name, "Apache," was commonly used with the A-36 but never officially recognized by the newly renamed U.S. Army Air Forces.
About a month and a half after the order for 150 P-51s had been made on July 7, 1941, the first XP-51 arrived at Wright Field on August 24. The second did not join the first until December 16. In between these deliveries, the Japanese had caused everything in the United States to change with their attack at Pearl Harbor. No one could claim any longer that this was Mr. Hitler and Mr. Churchill's war. It was World War II.
In numerous accounts about the development of the Allison-powered Mustang, it has been stated that its poor performance at high altitudes was a surprise and a disappointment to the British and to the USAAF as well. This simply is not so. The aircraft designers of that day had more than sufficient knowledge of powerplants, and they were capable of determining that the Allison engine and supercharger combination installed in the aircraft would have a drop in performance above 15,000 feet. Clear evidence of this is that two of the P-51s, ordered even before the flight of the first XP-51, were reserved for testing with a Packard-built Rolls Royce Merlin engine. They knew that the Allison-powered Mustangs would be low-Ievel fighters, while the Merlin-powered aircraft would be the high-altitude versions. By comparison, Mustangs with the Allison engine could outperform the Merlin-powered variants below 15,000 feet, but no writer has criticized the P-51B, -C, -D, or -K for having less performance at low altitudes. It has been claimed that the Merlin engine is what allowed the Mustang to reach its potential. If only high-altitude performance is considered, this would be true. But a more correct assessment would be that both the Allison and Merlin-powered versions performed very well at the altitudes where they were designed and intended to operate.
P-51B AND -C
The first production version of the Mustang to be equipped with the Merlin engine was the P-51B. Identical airframes were produced at North American's Dallas plant and were designated P-51Cs. By the time these variants were ordered, America was in a full wartime economy, and production numbers of these Mustangs were in the thousands instead of the hundreds. The British received these two variants as well and named them Mustang Ills. Seventy-one P-51Bs and twenty P-51Cs were fitted with cameras and designated F-6Cs.
"Li'l Kitten" was a P-51B flown by Lt. Louis Fechet of the 357th Fighter Group. When Mustangs began to be delivered to operational squadrons in a natural metal finish, they were often painted by unit personnel. This was because many pilots did not think it was healthy to be flashing around the sky in a silver airplane. Standard U.S. colors were used on many occasions, but British paints were also seen on U.S. aircraft. If a camouflaged aircraft had its data block stencilled on a bare metal area as is the case here, it was a sure bet that the aircraft had been delivered without camouflage and was then painted in the field by unit personnel. To avoid having to restencil the entire data block, the stencilling was masked off, then the rest of the aircraft was painted. An important modification to some Mustangs fitted with the flush canopy was the Malcolm hood. This semi-bubble canopy provided much improved visibility, and because it slid aft, it allowed for easier access to the cockpit from both sides.
During the second half of 1942 and much of 1943, U.S. heavy bombers suffered great losses as they flew unescorted, daylight missions over enemy territory. The new, high-altitude versions of the Mustang have been heralded as the savior of the bombing campaign. But it must be understood that the reason the bombers were not escorted by fighters during the early months of America's involvement in the European theater was a matter of choice and not because of a lack of adequate fighters.
When he was in command of the 8th Air Force, General Ira Eaker did not believe the bombers needed escort. He thought that the bombers' defensive armament would be protection enough. High rates of losses never deterred him from this belief. Accordingly, Eaker turned down the P-38 Lightnings provided him to protect his bombers. The P-38s, with enough range to escort the bombers to any of their targets, spent time in England with relatively little to do, and many were subsequently sent to Africa.
By mid-1944, P-51 Mustangs were fast replacing other types of fighters in the USAAF. The early variants with Allison powerplants were combat veterans and had proven to be superior in performance over any other allied fighter below 15,000 feet. The Merlin-powered P-51B and P-51C possessed outstanding high-altitude performance that made them formidable adversaries to any enemy aircraft above 12,000 feet. Additionally, all Mustang variants had great range capabilities which exceeded most other fighter aircraft of World War II.
P-51D AND -K
But as good as the Mustang was, there were several problems with the design, and complaints about two shortcomings in particular resulted in the development of the P-51D and subsequent versions. First, the visibility from the original standard canopy was very restricted. In combat, the pilot who saw his adversary first had a decided advantage, and more often than not, the first indication a fighter pilot had that he was under attack was the impact of bullets on his aircraft. Although the British Malcolm canopy had been fitted to many early Mustangs, it was an interim solution which was not available in sufficient quantities for all aircraft.
"Butch Baby" was Jullian H. Bertram's Mustang, and it was assigned to the 357th Fighter Group. P-51Ds were delivered in a natural metal and silver dope finish, but the 357th FG painted many of its P-51Ds in the field. At times regulation U5AAF Olive Drab and Neutral Gray were used, but British greens and grays were often used as well. "Butch Baby" was painted with British Dark Green over U.S. Neutral Gray. The small orange object with the silver surround on the side of the fuselage is a formation light. A second light was located near the center of the national insignia. Formation lights were also on the opposite side of the fuselage, but they were installed on relatively few Mustangs. Note also that this aircraft is fitted with the ANI AP5-13 tail warning radar antenna which remains natural metal.
The second complaint about the Mustang that required correcting was that the four .50-caliber machine guns were not sufficient for the average pilot. Further, they were subject to jamming, and this was due in part because they were mounted at an angle.
To correct the visibility problem, two P-51Bs were modified with a cut down, aft fuselage section and a full bubble canopy. This provided excellent visibility all around and above the aircraft. Beginning with the P-51D and the nearly identical P-51K, all future Mustang variants were designed and fitted with full bubble canopies.
For more firepower, the number of machine guns was increased from four to six. This was a rather simple matter because the gun bays in previous Mustangs had always been large enough for an extra gun in each wing. To reduce chances of jamming, the guns were mounted upright instead of at a slant. Additionally, they were installed along the dihedral of the wing rather than being parallel to the ground line as they were in earlier variants. The P-51D and all subsequent production versions had six internal machine guns. Ammunition capacities for the guns were also increased, and a K-14B gyro-computing gunsight replaced the reflector sights during the P-51D production run.
During the second half of 1944, P-51Ds and P-51Ks were arriving in both the European and Pacific theaters in considerable numbers. Although they served in combat during World War II for less than a year, their numbers exceeded all previous versions combined. They scored impressively against all types of enemy aircraft, although admittedly, the German and Japanese air forces were significantly reduced in both quality and quantity during the last 12 months of combat.
Even the early versions of the Mustangs were considered to have substantial eye appeal with their sleek aerodynamic lines, due in part to the streamlined nose which housed the inline, liquid-cooled engine. But with the introduction of the bubble canopy on the P-51D and P-51K, there were few who would argue that these Mustangs were not among the most handsome fighter designs ever produced. This undoubtedly lead to the Mustang's overall popularity among pilots and aviation enthusiasts alike.
In the air, the Mustang could hold its own against any other propeller-driven aircraft of World War II. But in the closing months of the war, particularly in Europe, there were decreasing opportunities for aerial combat with enemy fighters. Instead, Allied fighters were used more and more for strafing missions against the German army on the ground, airfields, rail yards and other ground targets. These were usually well defended by a considerable number of antiaircraft weapons ranging from machine guns to the famous German 88mm gun. A single hit to the liquid cooling system would bring a Mustang down, and because the critical components of this cooling system were in the forward and lower sections of the fuselage, the Mustang proved more vulnerable to ground fire than it was to enemy aircraft. As a result, the ratio of losses to missions flown was higher on these ground attack missions for the P-51 than they were for the P-47 Thunderbolt with its air-cooled engine. The vulnerability of the liquid-cooled engine to ground fire would surface again as a problem for the F-51D in Korea where losses were very high.
The P-51H, which first flew on February 3, 1945, may appear to be nearly identical to the previous P-51D. However, the fuselage, wing and tail section were all redesigned. Even the main landing gear was changed from that on all previous Mustangs. This redesign was accomplished in order to correct some balance problems as well as to lighten the airframe and thereby improve performance. Both empty and gross weights of the P-51H were 500 pounds lighter than the P-51D, and maximum speed increased between 50 and 86mph depending on altitude and the configuration of the aircraft. The lines of the P-51H were cleaner, and even the exhaust shroud was more streamlined in order to reduce drag.
The Packard Merlin V-1650-9 engine was equipped with water injection to provide in excess of 2,000hp in a wartime emergency. The standard dry rating was 1,380 horsepower. The engine turned an Aeroproducts A-542-B1 or B2 uncuffed propeller which was 11 feet 1 inch in diameter.
With a top speed of 487mph in a clean configuration, the P-51H was the fastest propeller-driven aircraft produced during World War II. However, production was so late that the war ended before any of these hot-rod Mustangs saw combat service. At the end of the war, defense orders were cut across the board, and the P-51H was no exception. The initial order of 2,000 aircraft was cut to just 555 examples. In addition to being faster in the air, improvements were made to make the P-51H easier and faster to maintain on the ground. The internal armament of six .50-caliber machine guns was retained, but the ammunition was loaded in removable boxes that made rearming the weapons much simpler and quicker.
As World War II ended, the P-51H began replacing P-51Ds in regular Air Force squadrons, and the older versions were passed on to the Air National Guard, bulldozed into the ground, or cut up and burned without ever returning back to the U.S. at war's end. As excellent as the performance of the P-51H was, its days of service with the regular Air Force were limited as the F-80s, F-84s and F-86 jet fighters began to take their place on the flightlines. The P-51H followed the D into the Guard units but were retained there for even a shorter time than many of the older versions.
P/F-82 TWIN MUSTANG
In January of 1944, the USAAF ordered four prototypes of the P-82 Twin Mustang. This unusual fighter would have a maximum range of 2,600 miles, which was 300 miles more than the P-51D, and over the Pacific Ocean every mile would be precious. More importantly, the P-82 carried two pilots who could relieve each other during missions that might last as long as nine hours. But it is interesting to note that only the pilot in the left fuselage had full IFR instruments. On such missions in the "soup," the second pilot would be able to provide little in the way of relief.
North American joined two modified and lengthened P-51H fuselages with constant cord center wing and tail sections. The outer wing panels remained similar to what was on the P-51H, although there were several noticeable differences. The six .50-caliber machine guns were moved to the center wing section to concentrate their fire, and the main landing gear folded into wells under the two fuselages.
Although the order was cut to only two XP-82 prototypes, work continued, and the first flight was made on April 15, 1945. It was powered by two Packard Merlin V1650-23 or -25 engines, and performance was equal to that of a P-51D. Although no P-82As were built, 500 P-828s were ordered in June 1944, long before either prototype flew. But the end of the war caused production to be cut to only 20 aircraft, and none of these ever saw combat.
The USAAF did see some promise in the design because a radar observer could replace the second pilot. This made the Twin Mustang a good candidate for all-weather and night operations. Accordingly, the USAAF ordered two of the P-828s to be converted to night-fighter prototypes. P-82B-1-NA, 44-65169 became the P-82C, and P-828-1-NA, 44-65170 became the P-82D. These first flew on March 27 and 29, 1946, respectively, and they served as developmental aircraft for the later P-82F, P-82G, and P-82H.
Meanwhile, the P-82E was developed as a long-range escort fighter. It was similar to the previous P-828, but it was powered with Allison 1710-143 or -145 engines. This Allison powerplant would be installed on all subsequent P/F-82 versions. One hundred P-82Es were built, and these became the Strategic Air Command's first long-range escort fighters for the B-29, B-36 and B-50. The 27th Fighter Escort Group (SAC) was the first unit to become operational with any Twin Mustang variant.
The P-82F made its first flight on March 11, 1948, and three months later, the pursuit type was replaced by the fighter type as the U.S. Army Air Forces became the United States Air Force. All aircraft designated previously with a P prefix were changed to an F prefix. Thus, the P82 became the F-82, and the P-51 became the F-51.
Most F-82s were produced as all-weather night fighters, with the first being the F-82F. This version was equipped with the AN/APG-28 tracking radar, and a total of 91 were built. These were followed by 45 F-82Gs, which carried the SCR-720C search radar that had been previously proven in the P-61 Black Widow. In both types, the right cockpit was modified with the necessary controls and displays for operation of the radar. The last nine F-82Fs ordered (44-496 through 44-504) and the last five F-82Gs (44-384 through 44-388) were winterized for service in Alaska and redesignated as F-82Hs.
Although the Twin Mustang's service with the USAF was limited, it did leave some indelible marks on aviation history. A specially modified P-828 named Betty Jo establish a non-stop unrefueled distance record by flying from Hickam Field, Hawaii, to Mitchell Field, New York, in 1946. This record still stands today as the greatest distance flown by an unrefueled fighter.
On June 27, 1950, shortly after the beginning of the Korean War, an F-82G from the 68th F(AW)S of the 8th Fighter Bomber Wing shot down a North Korean Yak fighter near Kimpo Air Field north of Seoul. This became the first aerial kill of the war and the first scored by a pilot in the United States Air Force. The F-82G was flown by Lt. William Hudson, and the radar observer was Lt. Carl Fraser. In addition to this first, the Twin Mustang became the last propeller-driven fighter ordered into production by the United States Air Force.
THE "BEST" OF THE WAR?
Without question, the P-51 Mustang was one of the great aircraft designs of all time. It will forever be considered a classic among all aircraft ever built. But a disservice has been paid to it by those who would make unrealistic claims about its performance and contributions to the victory in World War II. Often, the world "best" has been attributed to the Mustang. But "best" must be qualified to the point that it becomes practically meaningless. When applied to a fighter aircraft, "best" is usually related to performance figures. Certainly, the Me-262 jet fighter was superior in many ways to the Mustang, so it is often written that the Mustang was the best propeller-driven fighter ever built. But the Germans had several types of propeller-driven fighters under development that were clearly superior, and the U.S. Navy's FBF Bearcat proved to be a much better fighter in almost every respect except range. So the claim is made that it was the best propeller-driven fighter that served in World War II, or sometimes this is even further qualified to state that it was the best propeller-driven Allied fighter of the war. Very justifiable arguments can be made that the P-47 Thunderbolt or the F4U Corsair were better in some respects or even overall, but it is really not possible to objectively call any one fighter the best of World War II.
Likewise, it has been written that the P-51 was the fighter that "won the war." This is also a ludicrous contention. Everyone from generals to the man on the street have claimed that one weapon or another won the war. Eisenhower said that the artillery won the war. Many have said that the atomic bomb won the war, or the aircraft carrier did, or the heavy bomber did. No weapon won the war. The war was won by people. This included the soldier with a rifle, the driver of a tank, the sailor on a ship and the pilot and crewmen in an aircraft. It included the people who built the machines and weapons of war and those who delivered this equipment to the ones who used them. It included the people who made the decisions and dictated the tactics, and it included the ones that carried them out.
The Mustang's combat record is generally considered to consist of: 4,950 air kills, 4,131 ground kills and 230 V-1 kills, with an 11:1 "kill ratio".
Of the machines and weapons of war, some played a more important part than others, and indeed, a few played a very critical part. But it was a combination of all of them that resulted in victory. No single weapon system decided the outcome of the entire war. Many credit the Mustang with winning the war in Europe because it had the range to escort the bombers all the way to their targets in the heartland of Germany. But this capability was always there, even before the P-51 became available. The fact that long-range fighters were not used earlier was a tactical decision rather than because such fighters did not exist.
Unless otherwise noted, text and photos in this section were excerpted from Bert Kinzey's P-51 Mustang In Detail & Scale volumes, published by Squadron/Signal.
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