Convair B-36 Peacemaker variants

On 1941 April 11, the AAC issued a design competition for an aircraft with a 275 mph (445 km/h) cruising speed, a service ceiling of 45,000 ft (14,000 m), capable of delivering 10,000 lb (4,500 kg) of bombs to targets 5,000 miles (8,000 km) away.

By the time the first XB-36 was delivered, the design had been changed to a huge single tail, and the wingspan increased to 230 ft (70 m), an unprecedented size.

The maiden flight revealed problems with the flap actuating system, engine cooling, and the reliability of the aluminum wiring.

In particular, inadequate engine cooling kept its service ceiling under 30,000 ft (9,000 m), much less than that called for in the original contract.

References: The YB-36A, a conversion of the original XB-36, was turned over to the United States Air Force in June 1948, a week before the production B-36A was scheduled to be delivered.

Later it was idle for several years, then employed in the Carswell Air Force Base firefighting program.

The first B-36A ever built was destroyed by a series of brutal stress tests, consisting mainly of applying more and more load to various parts of the aircraft until they disintegrated.

On April 8, 1948, a B-36A made a 6,922 mile (11,140 km) flight of 33 hours, shuttling between Fort Worth and San Diego three times without landing, and carrying a 10,000 lb (4,500 kg) bomb load.

It was an explicitly interim plane used by the 7th Bomb Group at Carswell Air Force Base in Texas for the sole purpose of flight testing and transitional crew training.