The Martin B-10 two-engined bomber seemed to fill the Army requirements. It was a low-wing monoplane capable of carrying a ton of bombs a thousand miles at a speed of nearly 200 miles per hour. It became the Army’s standard bomber in 1934. In the same year ten Martin B-10’s, under the command of (then) Lieutenant Colonel Henry H. Arnold, made an historic flight to Alaska. This Alaskan trip was climaxed by a nonstop flight from Juneau, Alaska, to Seattle, Washington, 943 miles over water in five hours and forty minutes. Alaska’s nearness became apparent and American airpower was needed to defend it. Army officials and top air strategists went to work. The answer was a call for bigger bombers with greater range, greater bomb capacity, and greater speed. The Boeing Company, whose B-9 all-metal, low-wing, two-engined bomber had proved sensational in 1932, produced the answer to the Army’s problem of 1935. The answer was the giant four-engined model 299, America’s first four-engined bomber. It was a mid-wing, all-metal monoplane with a wingspan of 104 feet. With a top speed of over 250 miles per hour its performance was more than sensational. [Illustration: 1935-1939 WINGSPAN 105 FEET LENGTH 70 FEET THE BOEING 299. THE _FLYING FORTRESS_, WAS AMERICA’S FIRST ALL-METAL, LONG-RANGE, HIGH-ALTITUDE, FOUR-ENGINED “BATTLESHIP OF THE AIR.” POWER FOUR 9-CYLINDER 750-HP. RADIAL ENGINES THE FIRST _FORTRESS_ WAS POWERED WITH PRATT & WHITNEY 750-HP. RADIAL ENGINES. LATER MODELS USED 1,000-HP. WRIGHT CYCLONES. SPEED ONE HOUR 230 MILES RANGE 2,000 MILES CEILING 20,000 FEET PAYLOAD 9 CREW MEMBERS, ONE TON OF BOMBS, AND FIVE 30-CALIBER MACHINE GUNS. THE 299, OFFICIALLY DESIGNATED THE XB-17, WEIGHED 16 TONS. ITS GREAT WINGS WERE CONSTRUCTED OF ALUMINUM ALLOY METAL BRACED INTERNALLY BY A BRIDGE-LIKE TRUSS STRUCTURE. THE 299 WAS HIGHLY STREAMLINED AND ITS LANDING GEAR RETRACTED INTO WELLS IN THE ENGINE NACELLES. ITS ENGINES WHIRLED 3-BLADED CONSTANT-SPEED PROPELLERS. IT WAS EQUIPPED WITH WING FLAPS TO REDUCE ITS LANDING SPEED. GUNNERS WERE PROTECTED BY PLASTIC GUN BLISTERS AND BOMBS WERE CARRIED INSIDE THE FUSELAGE. THE INTRODUCTION OF THE _FLYING FORTRESS_ MARKED A GREAT STEP FORWARD IN THE DESIGN OF BIG MILITARY AIRPLANES. IT CAME AS THE RESULT OF THE BOEING COMPANY’S DEVELOPMENT OF LOW-WING, ALL-METAL, MULTI-ENGINED PLANES. IT ALSO PROVED THAT PROPER STREAMLINING REDUCED _DRAG_ AND INCREASED SPEED.] [Illustration] The pioneering of unusual airplanes like the _Monomail_, the B-9, and the 247 transport were steps toward the Boeing 299. It was a courageous step from two-engined to four-engined bombers, but the Boeing Company made it so successfully that almost instantly the United States Army Air Corps won world leadership in long-range, heavy bombardment aviation.