IS THE TILTROTOR WORTHY FOR CIVILIAN TRANSPORTATION BETWEEN GREAT CITIES? A CASE STUDY INVOLVING BRAZILIAN IMPORTANT CITIES

摘要

Brazilian executive transportation has grown significantly facing the challenge of avoiding the traffic jam of great cities and lack of satisfactory airport infrastructure. There are travel ranges which are too far for helicopters and too close for fixed-wing aircrafts, where the tiltrotor-type solution, that now enters the civilian market, may bring better relation between time and cost to the user. The objective of this study is to examine the tiltrotor's feasibility and its worthiness against other available market options for executive transportation between Brazilian great cities. Tiltrotors are supposed to use the large helicopter landing sites, sometimes far from cities airports. Therefore, the IFR (Instrument Flight Rules) operation is a concern because of the transition to the VFR (Visual Flight Rules) and the following flight to the landing site that, if performed at low speed, will raise the specific fuel consumption because the engines would not be completely tilted forward. Today, the tiltrotor speed would be limited to 80 knots inside some helicopters visual corridors of these cities. The tiltrotor would flight more economically in the fixed-wing corridors, unless the rules for the helicopter corridors are adapted to it. That's why the certification and safety issues are analyzed. ANAC (Brazilian Civil Aviation Agency, under the Civil Aviation Secretariat, a species of Ministry directly attached to Brazil's Presidency) is set to play a major role in definition of the requirements to certify or accept the FAA (Federal Aviation Administration) certification of tiltrotors because, rigorously, it does not fit in any of the present standards. Meanwhile, DECEA (Brazilian Airspace Control Department, under the Air Command, which is linked directly to the Defense Ministry) is expected to define the IFR and visual corridors rules. Typical flights departing from Sao Paulo city (Capital of Sao Paulo State) and arriving in many Brazilian great cities are simulated. These cities are 46 to 658 NM apart and there are roads and airways connecting them. Shorter distances represent an advantage to helicopters while bigger distances would be more adequate to fixed-wing aircraft. To compare the tiltrotor with its competitors it was chosen one jet aircraft, one helicopter and one car "competing" with the tiltrotor Agusta Westland AW-609. The simulation considers departure and arrivals in places that have landing sites that support the operation of the AW-609 and helicopters with similar gross weight. For the jet aircraft solution, the time and costs data are added with the taxi transportation between the leaving and arriving points and the closest airport in each city. Aircraft manufacturer data, such as specific fuel consumption and cruise speed, are used for the comparison whose results are based on the necessary time and cost to perform this travel carrying seven passengers. The cost of the fuel is based on the rates used in Brazil in the beginning of 2012. As conclusion one verifies that the tiltrotor solution is a fast option, thanks to the ability of performing point-to-point transportation at a cruise speed significantly higher than the helicopters' currently available in the market, though the tiltrotor be an expensive option, even taking into account its optimum range. The car is the cheapest solution but takes more time to reach destination. The jet aircraft had its time extended because of the need of taxi support in departing and arriving cities. The helicopter showed itself cheaper than the tiltrotor but significantly slower. The minutes to be saved with the tiltrotor option and the associated extra costs are to play the key role in defining the worthiness of this transportation according to the customer needs.