The Curtiss O-52 Owl was a large, advanced two-man observation aircraft that had been made obsolete by the nature of the fighting in the Low Countries and France in 1940, and mainly saw use as a trainer.
The O-52 was developed in response to a request for a two-seat observation aircraft. Curtiss produced a two-seat high wing monoplane, with single bracing struts for the main wing. The two man cockpit was extensively glazed, and the wing was mounted on top of the cockpit glazing. It had a retractable undercarriage, with the wheels pulling back into wells in the side of the fuselage. In order to give it good low speed handling it had full length automatic leading edge slots, which were linked to wide-span trailing edge flaps that operated whenever the slots were extended. It had dual controls, and doors in the floor of the cockpit to use a camera. It was armed with one fixed forward firing machine gun and one flexibly mounted machine gun in the observer’s position. It had a retractable turtle back, first developed for the SOC Seagull, which improved the observer’s field of fire. It was powered by a Pratt & Whitney Wasp radial engine.
The O-52 was ordered into production in 1939, before the prototype had been tested. A total of 203 were built, with the first aircraft delivered in 1940. Internally it was known as the Curtiss Model 85.
By the time the O-52 entered production it was already obsolete. There had been a long debate in the USAAF about the correct type of aircraft for the observation role, with a split between those who thought that only aircraft resembling fast light bombers could perform the task and those who preferred the slow flying light aircraft. At the start of 1939 the USAAF launched a contest to find a light, slow, short range liaison aircraft, which was eventually won by the Stinson O-49/ L-1 Vigilant. The fighting in the Low Countries and France in 1940 demonstrated that this concept was correct, with the Fieseler Storch performing very well. The O-49/ L-1 took so long to develop that the Army Ground Forces rented their own commercial light aircraft for the 1941 manoeuvres, and these light aircraft would become the mainstay of US wartime liaison and artillery observation units (the Taylorcraft O-57/ L-2 Grasshopper, Aeronca O-58/ L-3 Grasshopper and Piper O-59/ L-4 Grasshopper). Although the O-52 resembled these aircraft in appearance, it was much heavier, larger and faster, more complex to maintain and fly, and couldn’t operate from the unimproved fields required by the sometimes fast moving armies.
To put this in more context, the O-52 used a 600hp engine, had an empty weight of 4,231lb and a top speed of 220mp. The O-49, which also turned out to be too large, had a 295hp engine, empty weight of 2,670lb and a top speed of 129mph. The Piper L-4 Grasshopper had a 65hp engine, empty weight of 740lb and a top speed of 87mph. These smaller, lighter aircraft, with their impressive STOL capabilities, turned out to be much more suited to the direct army liaison role, operating right up to the front line, while the longer range reconnaissance role was taken over by much faster conversions of front line fighters.
A handful of O-52s had been sent to the Pacific theatre by December 1941. Some were also delivered to the Soviets, but the majority were used as training aircraft within the continental United States.
Although it wasn’t used in its original role, the O-52 was one of the few O series observation aircraft to be used in any numbers by the USAAF during the Second World War (along with the Douglas O-46 and North American O-47).
Engine: Pratt & Whitney R-1340-51 Wasp
Span: 40ft 9in
Length: 26ft 4.75in
Height: 9ft 11.5in
Empty equipped weight: 4,231lb
Maximum take-off weight: 5,364lb
Max speed: 220mph
Cruising speed: 192mph
Climb Rate: 10,000ft in 8.2 minutes
Service ceiling: 21,000ft
Range: 700 miles
Armament: Two 0.3in machine guns - one fixed forward firing and one flexibly mounted
Bomb load: None