By the early 1930s, the Army Air Corps was no longer interested in the “ancient technology” of biplane fighters. For a very short while, the Army Air Corp thought they had the ultimate fighter on their hands. The P-40 was sleek and fast and carried an assortment of machine guns above its nose and in the wings. By the time 1942 was in full swing, the P-40 was basically shoved aside as newer fighter models were coming on line at a rapid rate. But none of that stopped the Curtiss Company from trying to make the P-40 even better.
P-40s followed the alphabet and began producing P-40Bs with a 1,150-horsepower Allison engine giving it a top speed of right around 345mph. The P-40B/C weighed in at just over 5,800 pounds empty with a max weight of over 8,000 pounds. The armament package tripled from that of the P-36 with a pair of machine guns in each wing and another pair above the nose. Just shy of 32 feet long, its wingspan came in at just over 37 feet. The P-40B held the line early on over Pearl Harbor and the skies over China with the AVG “Flying Tigers.”
Curtiss forged ahead and created the P-40D next. This time, the guns above the nose were removed and added to the wings. This was also the beginning of the more familiar shorter nose, with a much more pronounced chin. This was due in part to the radiator being moved forward slightly and increased in size. The D model also increased in weight by more than 600 pounds.
The P-40E called for more guns in the wings, bringing the total to six .50 caliber machine guns. The Allison V-1710-39 twelve-cylinder liquid-cooled engine still produced 1,150 horsepower with a max speed of 335mph at 5,000 feet. Of all the P-40 short fuselage survivors, the E model is the most prevalent.
Next came the P-40F with a 1,300-horsepower Rolls-Royce Merlin engine replacing the Allison. The designers had hoped to get more altitude and airspeed out of the P-40F but were sorely disappointed with the results—a max speed of 364mph at 10,000 feet. The F model was the beginning of the longer nose P-40s by adding two more feet to the fuselage length and having its rudder and fin moved back as well. To Curtiss birdwatchers, the giveaway to the different fuselage design is that the rudder hinge line no longer lines up with the elevator hinge line, but is a significant distance farther aft. Because of these factors, many pilots commented about better-handling control during landings and takeoffs. Over 1,300 Fs were produced.
When the P-40K came out, it switched back over to an even more powerful 1,325-horsepower Allison engine, one with automatic boost control, and it retained the overall length of the P-40F. Because of the extra power and the tendency for the nose to swing on takeoff, a dorsal fin was added to later K models, another birdwatcher giveaway.
Curtiss became a stickler on weight and stripped the P-40L down by removing two of the six guns, reducing the fuel capacity and removing some protective armor plating. For all of this weight loss, it certainly could have been proclaimed “the biggest loser” because it only picked up an additional 4mph. The P-40M returned with three machine guns in each wing and added a perforated cooling grille near the exhaust stack.
The P-40N went through a weight-loss program as well and this time it seemed to do wonders. Not only was this model the fastest of the bunch, topping out at 378mph with a 1,200-horsepower Allison engine, the N also received a canopy rework that gave the pilot a much greater view at his 6 o’clock. Another birdwatcher ID feature, the turtledeck being cut back at an angle and covered by Plexiglas screens “N.” The N model also had the distinction of being the most widely produced version of the P-40 pedigree with over 5,200 examples produced.
But Curtiss wasn’t satisfied and tried one more time with the P-40Q, which looked like no other P-40. The Q was modified with a bubble-top hood, à la P-51 Mustang, a four-bladed propeller powering a 1,425-horsepower Allison engine. But probably the most striking difference was the almost complete removal of the trademark chin. With its wingtips clipped by over two feet it was finally able to break the 400mph mark—but it still couldn’t catch a P-47 or P-51, so the Q never saw the light of combat.
With over 13,700 Curtiss P-40s of various models produced, even the naysayers have to tip their hat to this workhorse that bore the brunt of the action during the early, darkest days of the war. Many of the newly ordained fighter pilots cut their teeth on the P-40 before they transitioned into Thunderbolts and Mustangs. Some will call it a dog, while others will say it was a sweetheart. However, all will agree that the Curtiss P-40 was one tough old bird.
By James P. Busha
The real reason for the shorter nose going from the P-40B/C to the P-40D was a change in the Allison V-1710 sub-type used. The engine in the B/C and earlier had a planetary reduction gear, which was long but relatively small in diameter. It was thought that this would improve streamlining and result in higher speed. The D model and later changed to an Allison with more common spur gear reduction which was relatively shorter in length but taller.
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