The Boeing Model 307 pressurized cabin allowed the airplane to soar (220 mph cruising speed) above rough weather at an altitude of 20,000 feet -- higher than any other transport of its time. With names like Rainbow, Comet, Flying Cloud and Apache, the Stratoliner set new standards for speed and comfort. The Stratoliner was the first airplane with hydraulically boosted control surfaces (elevators and rudder) and the first airliner with geared two speed engine superchargers. Boeing built 10 Model 307s.