6 May 1935: At Buffalo, New York, the prototype Curtiss-Wright Model 75, NX17Y, serial number 11923, made its first flight.
Designed by Donovan Reese Berlin, the airplane was a modern design of all metal construction, with fabric covered control surfaces. The Model 75 was a single-seat, single-engine low wing monoplane with retractable landing gear.
In its original configuration, the Model 75 was powered by an air-cooled, supercharged 1,666.860 cubic inch displacement (27.315 liter) Wright Aeronautical Division GR1670A1 two-row 14-cylinder radial engine. The GR1670A1 was a developmental engine with a compression ratio of 6.75:1. It was rated at 775 horsepower at 2,400 r.p.m. at Sea Level, and 830 horsepower at 2,600 horsepower for takeoff, burning 87-octane gasoline. The engine was 3 feet, 9 inches (1.143 meters) in diameter, 4 feet, 4–25/32 inches (1.341 meters) long, and weighed 1,160 pounds (526 kilograms). The GR1670A1 drove a three-bladed Curtiss Electric constant-speed propeller through a 16:11 gear reduction.
The GR1670A1 was also used in the Seversky SEV-S1, NR18Y, a record-setting experimental variant of the rival Seversky P-35.
Registration issued 1 June 1936, cancelled 26 April 1937.
The Curtiss-Wright Model 75 would be developed into the P-36 Hawk fighter for the U.S. Army Air Corps. France ordered it as the H75A-1, and in British service, it was known as the Mohawk Mk.I.
The tenth production P-36 was modified with a liquid-cooled Allison V-1710 V-12 engine to become the prototype XP-40.
26 April 1939: The United States Army Air Corps placed an order for 524 Curtiss-Wright P-40 Warhawks. This was the largest production order for any U.S.-built fighter since World War I. The total cost was $12,872,398.¹
The order was authorized by the Air Corps Expansion Act, approved by Congress 3 April, and signed by President Roosevelt on 26 April 1939.
The Curtiss-Wright Corporation Hawk 81 (P-40 Warhawk) was a single-seat, single-engine pursuit, designed by Chief Engineer Donovan Reese Berlin. It was developed from Berlin’s radial-engine P-36 Hawk. The P-40 was a low-wing monoplane of all-metal construction and used flush riveting to reduce aerodynamic drag. It had an enclosed cockpit and retractable landing gear (including the tail wheel). Extensive wind tunnel testing at the NACA Langley laboratories refined the airplane’s design, significantly increasing the top speed.
The new fighter was 31 feet, 8-9/16 inches (9.666 meters) long with a wingspan of 37 feet, 3½ inches (11.366 meters) and overall height of 9 feet, 7 inches (2.921 meters). The P-40’s empty weight was 5,376 pounds (2,438.5 kilograms) and gross weight was 6,787 pounds (3,078.5 kilograms).
The P-40 was powered by a liquid-cooled, supercharged, 1,710.597-cubic-inch-displacement (28.032 liter) Allison Engineering Co. V-1710-C15 (V-1710-33). This was a single overhead cam (SOHC) 60° V-12 engine designed by Harold Caminez, Allison’s chief engineer. The V-1710-33 had a compression ratio of 6.65:1. It was rated at 930 horsepower at 2,600 r.p.m. at 12,800 feet (3,901 meters), and 1,040 horsepower at 2,800 r.p.m. for takeoff, burning 100-octane gasoline. The engine turned a three-bladed Curtiss Electric constant-speed propeller through a 2:1 gear reduction. The V-1710-33 was 8 feet, 2.54 inches (2.503 meters) long, 3 feet, 5.88 inches (1.064 meters) high, and 2 feet, 5.29 inches (0.744 meters) wide. It weighed 1,340 pounds (607.8 kilograms).
The cruising speed of the P-40 was 272 miles per hour (438 kilometers per hour) and the maximum speed was 357 miles per hour (575 kilometers per hour) at 15,000 feet (4,572 meters). The Warhawk had a service ceiling of 30,600 feet (9,327 meters) and the absolute ceiling was 31,600 feet (9,632 meters). The range was 950 miles (1,529 kilometers) at 250 miles per hour (402 kilometers per hour).
The fighter (at the time, the Air Corps designated this type as a “pursuit”) was armed with two air-cooled Browning AN-M2 .50-caliber machine guns on the engine cowl, synchronized to fire through the propeller, with 380 rounds of ammunition per gun. Provisions were included for one Browning M2 .30-caliber aircraft machine gun, with 500 rounds of ammunition, in each wing.
The first production P-40 Warhawk, 39-156, made its first flight 4 April 1940. The 8th Pursuit Group at Langley Field, Virginia, was the first Army Air Corps unit to be equipped with the P-40.
After 200 P-40s were produced for the Air Corps, production was interrupted to allow Curtiss-Wright to build 100 Hawk 85A-1 export variants for the French Armée de l’air, then engaged with the invading forces of Nazi Germany. When France surrendered 22 June 1940, none of these airplanes had been delivered. The order was then assumed by the British Royal Air Force as the Tomahawk I.
U.S. Warhawk production resumed as the improved P-40B, and the remainder of the P-40 order was cancelled.
12 February 1935: The United States Navy rigid airship USS Macon (ZRS-5), under the command of Lieutenant Commander Herbert Victor Wiley, crashed into the Pacific Ocean off Monterey Bay, on the central California coastline. The airship soon sank to the sea floor, approximately 1,500 feet (457 meters) below. Of the crew of 76 men, 74 survived.
Lieutenant Commander Wiley was a 1915 graduate of the United States Naval Academy, Annapolis, Maryland. He had previously served aboard the U.S. Navy’s first rigid airship, USS Shenandoah (ZR-1) and then commanded USS Los Angeles (ZR-3), 1929–1930. He had been assigned as executive officer of USS Akron (ZRS-4) and had been one of only 3 crew members to survive the wreck of that airship off the coast of New Jersey, 4 April 1933. He took command of USS Macon in June 1934.
During World War II, Captain Wiley commanded Destroyer Squadron 29 (consisting of thirteen Clemson-class “flush-deck” destroyers) with the Asiatic Fleet, and later, the Colorado-class battleship USS West Virginia (BB-48). He rose to the rank of rear admiral before retiring in 1947.
USS Macon was built by the Goodyear-Zeppelin Corporation at Akron, Ohio. It was launched 21 April 1933, and commissioned 23 June 1933.
Macon was constructed of duralumin ring frames and girders, covered with a fabric envelope. The rigid airship was 785 feet (239.3 meters) long with a maximum diameter of 132 feet, 10 inches (40.488 meters). The overall height was 146 feet, 2 inches (44.552 meters). The airship displaced 7,401,260 cubic feet of air (209,580 cubic meters). Lift was provided by 6,500,000 cubic feet (184,060 cubic meters) of non-flammable helium gas contained in 12 rubberized fabric gas cells.
Macon had a dead weight of 108.2 tons (98,157 kilograms) and a useful lift of 160,644 pounds (72,867 kilograms).
Propulsion was provided by eight water-cooled, fuel-injected, 33.251 liter (2,029.077-cubic-inch-displacement) Maybach VL-2 overhead valve 60° V-12 gasoline engines producing a maximum 570 horsepower at 1,600 r.p.m., each, or 450 horsepower at 1,400 r.p.m. for cruise. In addition to gasoline, the VL-2 could also use blau gas (similar to propane) as fuel. The engines were reversible and drove Allison Engineering Co. out-drives, which turned three-bladed fixed-pitch, rotatable propellers. The VL-2 is 6 feet, 5 inches (1.96 meters) long, 3 feet, 0 inches (0.91 meters) wide and 3 feet, 2 inches (0.97 meters) high. It weighs 2,530 pounds (1,148 kilograms).
The airship had a maximum speed of 75.6 knots (87.0 miles per hour, 140.0 kilometers per hour).
USS Macon was armed with eight Browning .30-caliber machine guns for defense. It also carried five Curtiss-Wright Airplane Division F9C-2 Sparrowhawk reconnaissance airplanes in an internal hangar bay. These were small single-place, single-engine biplanes, with a length of 20 feet, 7 inches (6.274 meters) and wingspan of 25 feet, 5 inches (7.747 meters). The Sparrowhawk had an empty weight of 2,114 pounds (959 kilograms) and loaded weight of 2,776 pounds (1,259 kilograms).
The F9C-2 was powered by an air-cooled, supercharged, 971.930-cubic-inch displacement (15.927 liter) Wright Aeronautical Division Whirlwind R-975E-3 (R-975-11, -24 or -26) nine-cylinder radial engine with a compression ratio of 6.3:1. The R-975E-3 had a normal power rating of 420 horsepower at 2,200 r.p.m., and 440 to 450 horsepower at 2,250 r.p.m. for takeoff, depending on variant. These were direct drive engines which turned two-bladed propellers. They were 3 feet, 7.00 inches to 3 feet, 7.47 inches (1.092–1.104 meters) long, 3 feet, 11 inches to 3 feet, 11.25 inches (1.143–1.149 meters) in diameter, and weighed from 660 to 700 pounds (299–317.5 kilograms).
The Sparrowhawk had a maximum speed of 176 miles per hour (283 kilometers per hour), a range of 297 miles (478 kilometers) and a service ceiling of 19,200 feet (5,852 meters).
The airplane was armed with two fixed Browning .30-caliber machine guns, synchronized to fire forward through the propeller arc.
Four of Macon‘s fighters, Bureau of Aeronautics serial numbers A9058–A9061, were lost when the airship went down.
During an earlier transcontinental flight, USS Macon had encountered severe turbulence while crossing mountains in Arizona. A diagonal girder in one of the ring frames failed. Temporary repairs were made, but permanent repairs were deferred until the next scheduled overhaul.
On 12 February 1935, the airship flew into a storm near Point Sur, California. The ring frame failed and the upper vertical fin was lost. Pieces of broken girders punctured several of the aft helium cells.
With the loss of helium, Macon lost rear buoyancy and began to settle. To compensate, all engines were run at full power and ballast was released. The airship began to climb with a nose-up pitch angle. When it passed 2,800 feet (853.4 meters) altitude, it reached its Pressure Altitude Limit. At this point, expanding helium began to vent from the gas cells. Macon continued rising until reaching 4,850 feet (1,478.3 meters), by which time it had lost so much helium that the engines could no longer keep it airborne and it again began to settle toward the ocean’s surface. The descent took twenty minutes.
One sailor jumped from the airship, but did not survive the fall. Another swam back to the sinking ship to collect personal belongings and drowned. The rest of the crew was rescued by the light cruiser USS Richmond (CL-9).
USS Macon was the U.S. Navy’s last rigid airship. For the next twenty years, all lighter-than-air craft were non-rigid “blimps”.