Generally considered the best fighter of WWII
By Stephen Sherman, Apr. 2002. Updated Sept. 26, 2012.
North American Aviation originally designed theMustang in response to a British specification. They agreed to producethe first prototype only 4 months after signing the contract in April1940.
By the end of 1941 North American had delivered the first Mustangto England for test flights. These first Mustangs were powered by theAllison V-1710 engine, a good engine, but one which didn't operate wellat high altitudes.
A Better Engine
In April, 1942, a British test pilot, Ronald Harker,flew theMustang and was very impressed by it. He suggested that the new planewould be a natural fit with the Rolls Royce Merlin 60-series engine,well-suited to high altitudes. At the prodding of Major Thomash*tchco*ck, the Americans began working along the same lines (using thePackard license-built version of the Merlin), and the firstMerlin-equipped Mustang, the P-51B, flew in November, 1942. The resultswere impressive, to say the least. At 30,000 feet, the improved Mustangreached 440 MPH, almost 100 MPH faster than theAllison-equipped Mustang at that altitude.
Both Robert Goebel and Bud Anderson flew Mustangs. Theircomments follow.
Bob Goebel on the P-51:
Robert Goebel flew Mustangs with the 31st Fighter Group, based at SanSevero, Italy, in the MTO (Mediterranean Theater of Operations). LikeBud Anderson, he had flown P-39s earlier on. At San Severo in Spring1944, he got his first crack at the P-51:
We soon found out that the P-51 Mustang was indeed adifferent breed of airplane. It was fast, for one thing. ... The P-51was red-lined at 505 and, though it was no Spitfire, its turning abilitywasn't bad at all - especially if you sneaked down 10 degrees of flaps.It was pretty good in the climbing department too, and accelerated veryfast in a dive. But the thing that really set the Mustang apart fromany other fighter, friend or foe, was its range. With a 75-gallon tankslung under each wing, it could perform the unheard-of: It could fly six-hourmissions.
Physically, it was pleasing to the eye and looked fast, evensitting on the ground. Power was provided by a V-1650 Rolls-RoyceMerlin engine built under license in the States by Packard, the luxuryautomobile company. The V-1650 was a fine engine and could be taken upto 61 inches of manifold pressure at 3,000 RPM for take-off or, ifneeded in combat, 67 inches for up to five minutes in Emergency Power.Normally aspirated engines tended to run out of power as altitudeincreased, usually between 15,000 and 20,000 feet.
The P-51 had atwo-stage blower in the induction system that was controlledautomatically with a barometric switch. Around 17,000 feet, when thethrottle had been advanced almost all the way forward just to maintainnormal cruise, the blower would kick into high, the manifold pressurewould jump up, and the climb could be continued to 30,000 feet. TheP-51 could be taken a lot higher than that, but above 30,000 feet thepower was way down and the controls had to be handled gingerly.
See AlsoNorth American P-51 Mustang | The National WWII Museum | New OrleansP-51 Mustang: The Untamed Beast of the SkiesThe P-51 Mustang Was the Quintessential Aircraft of the World War II EraThe North American P-51 Mustang: A “Little Friend” with a Big Impact | The National WWII Museum | New Orleans
quoted from MustangAce available at Amazon.com
Bud Anderson on the P-51:
When Bud Anderson arrived at Raydon Wood in England, with the 357thFighter Group, he was introduced to the Mustang, which was a lotdifferent from the P-39. The Mustang was a tail-dragger with a longnose blocking the pilot's forward view, requiring him to make sweeping"S" turns to see where he was going. The P-51 was a lot more powerful,and had a big four-blade paddle propeller. Take-offs and landing were abit tricky, but in the air:
[The Mustang] was pleasant and forgiving to fly. Best of all, it wentlike Hell. The Merlin had great gobs of power, and was equally at homehigh or low, thanks to a two-stage, two-speed supercharger. The Mustangcarried fuel enough to pursue and destroy the enemy once you'd flown tothe target, and it could turn on a dime. It was crucial to keep it ittrim but, as we gained experience with the plane, that becameautomatic. We sensed it was special, even before we measured it againstwhat the enemy pilots were flying.
quoted from ToFly and Fight, Memoirs of a Triple Ace, by Clarence 'Bud' Anderson
The Mustang's range and combat capabilities permitted it to escortthe heavy USAAF bombers (B-17s mostly) on massive daylight bombingraids over Germany. Some have argued that it was a "war-winning"weapon. It certainly was a decisive factor in the aerial Battle ofGermany. After World War Two, the Mustang continued to serve with theUSAF and other Western air forces, including distinguished service inthe Korean War.
Mustang Chronology
June '40 - British Request
In the Spring of 1940, the British Purchasing Commission, headed by SirHenry Self, visiting the U.S. asked Dutch Kindelberger, head of NorthAmerican Aviation, to build Curtiss-designed P-40's for them. While hiscompany had never built a fighter, Kindelberger's designers, led byEdgar Schmued had started design work on a modern fighter. Already, in1940, the Curtiss P-40 and the Bell P-39 were inferior to aircraftbeing flown by Germany and Britain. Kindelberger offered to design andbuild the first prototype of the new fighter in 120 days. They signedthe contract for 300 of the aircraft in late May.
The new fighter incorporated many of the latest developments inaeronautics, notably the laminar flow wing, a wing that was relativelysymmetrical and offered less drag at high speed. The wings weredesigned to be easy to manufacture, with only two spars. As specifiedby the British requirement, the new airplane, designated the NA-73X,employed an in-line engine; the Allison V-1710 fit the bill, althoughit lacked a turbo-supercharger for high-altitude performance. The mainwheels were set twelve feet apart, for good stability on landing.
In the original design, the British required eight machine guns:four .30 caliber and four .50 caliber. Ultimately, most Mustangs wouldcarry the usual American weaponry of six .50 caliber Brownings. Itcarried twice as much internal fuel as a Spitfire, 180 gallons inself-sealing wing tanks.
102 days after contract signing, in Sept. 1940, the protoype NA-73Xrolled out. Apparently no one quibbled over the fact that it didn'thave an engine, nor brakes, nor paint, nor actual gun mounts.
Oct. '40 - Flight of NA-73X Prototype
Oct. '41 - Mustang Mark I Reaches Britain
While North American (NAA) had developed the prototype quickly, thefirst stage of production moved along more slowly. The first NA-73production aircraft did not fly until April 23, 1941, six months after NA-73X.It carried no weapons and was kept by NAA for testing and development.The second production airplane (armed with four .30's and four .50's)arrived in Liverpool in October, 1941 - a year after the prototype'sfirst flight.
Nonetheless, the Mustang was so promising that in late 1941 the RAFordered another 300 and the USAAF 150. As the exigencies of wardemanded, 93 of these 150 (factory designated NA-91) ended upin British service, as Mustang IA's, equipped with four 20mmcannon. The remaining 57, equipped with four .50 caliber machine guns,and known as P-51's, ended up in US service.
Feb. '42 - Tactical Recon: No. 26 Sqn Issued Mark I's
These early Allison-powered Mustangs were fast, strongly constructed,had a long range, and packed a wallop with their eight guns. But theirpoor high-altitude performance relegated them to the low-level tacticalreconnaissance role with British Army Cooperation Command (ACC).Outfitted with a K24 camera behind the pilot, the Mark I Mustangs couldphotograph enemy dispositions, provide ground support, and fight theirway out of a jam. And they could do so better than the ACC's existingTomahawks and Lysanders. By summer 1942, 15 RAF squadrons were flyingthe Mark I, photographing invasion targets, shooting up trains,barge-busting, and probing German defenses.
July '42 - First Long Range Recon Mission
On July 27, sixteen RAF Mustangs undertook a long-range reconnaissancemission, photographing the Dortmund-Ems Canal.
Aug. '42 - Dieppe Raid
The "reconnaissance in force" on August 19 gained little for theAllies, except the expensive and bloody lesson in how tough the Germandefenses were, both on the ground and in the air. The raid, Operation Jubilee,introduced the Typhoon and the Spitfire Mk. IX, and marked the firstMustang aerial victory.Four Mustang squadrons, No. 26, 239, 400, and 414, provided tacticalrecon for the ground troops.
Flight Officer Hollis "Holly" Hills, an American serving with No.414 Sqn of the RCAF, took off from Gatwick in the pre-dawn darkness, as"weaver" (wingman) to Flt. Lt. Freddie Clarke. Flying at wavetop level,the glow from the searchlights and AA fire at Dieppe permitted him tostay with his leader. Once over the target, they were promptlyseparated; both returned safely. On the second mission that morning,they saw a huge dogfight filling the sky over Dieppe, and Hills spottedfour Fw 190s off to their right. With his radio out and unaware of theGerman fighters, Flt. Lt. Clarke left himself open and was hit. ThenHollis caught one of the FW's with a deflection burst. It startedsmoking and flaming, then the canopy popped off. Hollis fired again,and the plane fell to ground. He headed for home, shepherding Clarke ashe went, dueling another Fw 190 for miles. In his fight with the Fw's,he lost sight of Clarke. After that, Hollis flew home uneventfully, toa dinner made rather somber by Clarke's apparent loss. But nextmorning, Clarke re-appeared over Hollis' bunk, smelling of seaweed; hehad ditched off Dieppe and been rescued. He had witnessed and couldofficially confirm Hollis' victory over the Focke-Wulf, the first ofmany aerial victories for the Mustang. And Clarke had the dubious honorof being the first combat Mustang to be shot down in the war by theGermans.
Read more about Clarke's and Hills' mission in this email from Clarke's son.
Mustang Aces of the Ninth and Fifteenth Air Forces andthe RAF tells more about Dieppe and the RAF's use of theMustang.
Oct. '42 - the Merlin Engine
As early as May, 1942, Ronald Harker, a Rolls Royce test pilot, firstrecommended mating the Mustang airframe to the Merlin engine, an ideawhich would transform the P-51 into a decisive weapon, capable ofescorting American bombers all the way to Berlin. Harker test-flew anRAF Mustang on April 30, 1942, and noted that it was 30 MPH faster thanthe Spitfire Mk V and had almost double the range. Harker's memorecommending the Merlin-Mustang combination (in which he erroneouslyidentified Edgar Schmued as a former Messerschmitt employee) got theattention of Rolls Royce management, who borrowed five RAF Mustangs totest the idea. The British flight-tested the Mustang X in October, andfound that the experimental craft significantly out-performed theAllison at high altitudes, generating 200 more horsepower at 20,000feet and almost 500 more HP at 30,000 feet. While the British researchwas valuable, the American Merlin Mustang program proceeded almostindependently.
In the summer of 1942, Packard Motors was negotiating with RollsRoyce to license-build the Merlin engine at its Detroit plant. Learningof Rolls Royce' Merlin-Mustang plans, Major Thomas Hitchco*ck, theAmerican military attache in London, and others, pushed for thedevelopment of a Mustang powered by the Packard-built Merlin.Authorized in July, 1942, North American began its Merlin Mustangdevelopment in August.
The XP-51B included these changes:
- a Packard Merlin engine, instead of the Allison V-1710
- a four-bladed propeller
- stronger underwing racks
- a strengthened airframe
- a relocated carburetor air intake, from above to below the nose, asshown below
©Osprey Publishing Ltd, www.ospreypublishing.com - an intercooler radiator
- larger ducts and doors for the radiator system
- a deeper scoop under the rear fuselage
- removal of the nose-mounted guns - (see illustration above)
First flown on November 30, 1942, the XP-51B's performanceexceeded the engineers' expectations. At 29,800 feet, it made 440 MPHin level flight, 100 MPH better than the Allison models.
The USAAF, desperately needing a long-range bomber escort,contracted for 2200 P-51B's. North American geared up forMustang production, moving the B-25 program to Kansas City, dedicatingthe Inglewood plant to the Mustang, and expanding the Dallas plant forthe Mustang (Dallas-built versions of the -B model weredesignated P-51C). P-51B's began rolling out ofInglewood in May, 1943; eventually 1,990 of the -B models wouldbe made. The first of 1,750 P-51C's produced at Dallas flew inAugust.
After production of the B/C model began, three more changesappeared:
- an up-rated Packard Merlin engine, the 1650-7 replacing the1650-3, for a small increase in HP
- an 85 gallon fuel tank installed behind the pilot, givingcritically longer reach, but moving the center of gravity aft, thusreducing directional stability until most of the fuel was consumed
- the bulbous Malcolm hood, giving much better all-aroundvisibility (a field modification), as shown below
©Osprey Publishing Ltd, www.ospreypublishing.com
June '43 - A-36's with USAAF in MTO, Sicily
The first U.S. unit to fly the Mustang in combat was the Morocco-based154th Observation Squadron, which used 35 P-51-2NA's for a few weeks inApril-May, 1943.
300 A-36A's (a variant of the Mustang known as "Apache" and"Invader") made a larger impact, when the 27th and 86th BombardmentGroups began flying them. In June, 1943, the 27th BG flew missionsagainst Pantelleria, in the build-up for the Sicily invasion. Divebombing was a challenge, the recommended technique being a dive from8,000 - 10,000 feet at 90 degrees, with dive brakes extended to keepspeed below 400 MPH. At 3,000 feet, the pilot dropped two 500-poundbombs and pulled out at 1,500 feet. With this extended straight-in bombrun, they were vulnerable to anti-aircraft fire.
German and Italian fighters engaged also engaged them. One A-36pilot, Lt. Mike Russo of the 27th BG, made ace, the only man to do sowhile flying an Allison-powered Mustang. He counted four differenttypes among his five aerial victories: two Fw-190's, a Bf-109, a Ju-52,and a Fieseler Storch.
The 27th and 86th were reduced to three squadrons each in September,due to the heavy losses they had incurred. As the Italian campaignprogressed, they increasingly used strafing and glide bombing tactics,which reduced their losses to flak. In early 1944, both Groupstransitioned to P-47's and turned over their A-36's for training.
