the Boeing Model 377 Stratocruiser, on which the Guppies were based. The reason for considering producing such an aircraft was the desire of NASA to possess a means of transporting first stage of the Saturn V rocket by air, if this were possible, to Cape Canaveral; the ability for the aircraft to conduct a water landing would also be advantageous for proximity landing at sea, or on nearby lakes in Florida. Ultimately, this plan was deemed to be impractical, though the existing Guppies continued to function throughout the Apollo program as efficient air transport of the outsize hardware used in these missions. Conroy quipped that the British were "offended when we named our aircraft 'The Pregnant Guppy'. Man, can you imagine what they would have said if we produced 'The Pregnant Princess' !" Design The SR.45 Princess was a large flying boat, being the largest all-metal flying boat to have ever been constructed. The Princess featured a rounded, bulbous, "double-bubble" pressurized fuselage which contained two full passenger decks; these decks had sufficient room to accommodate up to 105 passengers in great comfort. The planing bottom of the hull had only a slight step in the keel to minimize drag in the air. The Princess was powered by an arrangement of ten Bristol Proteus turboprop engines. These engines drove six sets of four-bladed propellers; of these, the inner four propellers were double, contra-rotating propellers which were driven by a twin version of the Proteus, named the Bristol Coupled Proteus, each engine drove one of the propellers. The two outer propellers were single and each powered by a single engine. The cockpit of the Princess was designed to be operated by a pair of pilots, two flight engineers, a navigator, and a radio operator. Early on, it had been intended for the aircraft to be outfitted with some form of powered flight controls, including an early fly-by-wire implementation, in order that pilots would be able to effectively actuate its large control surfaces, which would have to overcome equally larger forces. However, it was decided to opt for a traditional mechanical linkage approach that was augmented by a series of electrically driven power assist units to effectively support actuation instead. The ailerons and rudder were split into multiple sections in order that, if a part of the servo-powered control system were to fail, a faulty section could be "trailed" so that it did