One of a Kind
XP-37: Beautiful Beast
The sleek, long-nosed, Curtiss XP-37 bore a similarity to some of the most successful, high-powered aircraft that competed in the National Air Races from 1935 to 1937. But while air racers were only required to fly a few times per year, the extreme rearward position of the cockpit and corresponding lack of pilot visibility were going to be a major problem for a fighter.
Don Berlin, one of the great aircraft designers, with successful products for Douglas and Northrop, eventually found his way to Curtiss-Wright in 1934. The company was fortunate to enjoy considerable success with his P-36 and, later, the P-40 fighters.
In 1936–37, fighter designers in Europe and the United States were attempting to improve performance with better streamlining. With war looming, Roll-Royce, Mercedes, Packard, and others made good use of their decades of aviation powerplant leadership. The United States invested more than a half million dollars to develop a new liquid-cooled, streamlined engine: the Allison V-1710. The military challenged the aircraft manufacturers to come up with planes that were best suited for it.
Curtiss took its prototype Model 75D airframe and mounted the 1150hp, turbo-supercharged Allison V-12 on the front, with a beautifully streamlined cowling. Ordered on February 16, 1937, it first flew in April 1937. It was Army serial # 37-375. It seems like a possible afterthought that the engine length became a challenging problem, when the cockpit had to have a major relocation, rearward, to accommodate the massive turbo-supercharger and three radiators. The long nose and cowling as well as the main wing not only obstructed pilot visibility in the air but also (even worse) on the ground.
An additional unfortunate development resulted when the early supercharger materials proved incapable of withstanding the stresses required. Failures were routine. But the military was much impressed with the high-speed performance of 340mph (about 20mph faster than the standard P-36), which seemed to justify ordering another 13 to be modified and constructed as service test aircraft. There was a considerable addition to the length of the fuselage behind the cockpit, and the superchargers were improved, though still not reliable. The strong negative assessments by pilots as well as the unreliability factor sunk any plans for production and service. It was not long before the planes were transferred to mechanical-training facilities.
Taking note of the positives and negatives, Berlin took another P-36 and worked on the forward engine compartment, with numerous revisions of radiator positioning; extended the fuselage by some 4 feet; and restored the cockpit location to a more standard configuration. In the ongoing, frenzied pace of aircraft development, this became the XP-40, leading to the long and successful use of the classic P-40 fighters, the third-most-produced American fighter of World War II. The influential link of the XP-37 between the P-36 and the eventual P-40 fighter development was a noteworthy contribution.
“This original photo from the Curtiss Company archival files illustrates the glaringly obvious major problem of lack of pilot visibility.”