ABSTRACT The Tilt Rotor is a VTOL concept which is being evaluated in the NASA/Army/Bell Tilt Rotor Research Aircraft Program. The concept is described and the test results of the XV-IS Program are presented in an analysis and discussion of the benefits of Tilt Rotor aircraft in offshore/remote area transportation. The relative cost per passenger mile of the Tilt Rotor and advanced helicopters is compared for trips of various lengths. Other advantages of the Tilt Rotor in offshore oil support missions are described. INTRODUCTION The Tilt Rotor is a VTOL aircraft that combines helicopter-like hover capability with turboprop airplane cruise speed and efficiency. Wingtip-mounted rotors provide efficient lift and precise control in helicopter ode as shown in Figure 1. The rotors are then tilted in flight until they operate as propellers in airplane mode, with the lift being provided by the wing, as shown in Figure 2. This unique combination of rotors and wing eliminates the drag of the rotor in forward flight which limits the helicopter's cruise speed and efficiency. As depicted in Figure 3, the Tilt Rotor can fly twice as fast, twice as far, compared to a helicopter on the same amount of fuel. This provides a significant increase in productivity and range with a dramatic decrease in cost per passenger mile. Demonstration of the benefits of the Tilt Rotor concept is being accomplished using two XV-15 Tilt Rotor Research Aircraft. This program was initiated in 1972 as a joint Army and NASA effort to provide an evaluation of the Tilt Rotor concept in both military and civil applications. The results of over 420 XV-15 test hours to date provide the confidence that the Tilt Rotor has significant benefits in offshore/remote area exploration and production of natural resources. BENEFITS TO OPERATORS - ECONOMIC The XV-15 has been flown at a cruise speed of 300 knots at altitudes of 16-20,000 feet. It has demonstrated fuel efficiency equal to twice the miles per gallon of an equivalent helicopter. Because of its cruise speed and efficiency, the Tilt Rotor?s cost per passenger mile is lower than that of a helicopter. The Tilt Rotor?s competitive advantage increases as the range increases. Two specific Tilt Rotor designs were compared to conventional helicopters to determine this. The designs were:16-passenger aircraft with a gross weight of 20,000 pounds (Figure 4)40-passenger aircraft with a gross weight of 40,000 pounds (Figure 5) Both Tilt Rotors were required to have one-engine-inoperative hover capability using existing engines. Both were designed to have a 300 nautical mile radius of operation (600 nm range) with all seats filled. Both were equipped with radar, anti-icing, and pressurization for all-weather operation at altitude. Both had airline style seating consistent with current standards of comfort. Since these Tilt Rotors were to be compared on a cost per mile standpoint with existing helicopters, advanced structural and systems technology which would reduce weight and/or increase performance was not incorporated. In addition, relatively conservative cost assumptions were used to estimate initial and operating costs for the Tilt Rotor.