Benefits and challenges of a civil air to air refuelling network analysed in a traffic simulation

The project REsearch on a CRuiser Enabled Air Transport Environment (RECREATE) is about the introduction and airworthiness of cruiser-feeder operations for civil aircraft. Cruiser-feeder operations are investigated as a promising pioneering idea for the air transport of the future. The top level objective of the project is to demonstrate on a preliminary design level that cruiser-feeder operations (as a concept to reduce fuel burn and CO2 emission levels) can be shown to comply with the airworthiness requirements for civil aircraft. (The project is funded through the Seventh Framework Programme of the European Commission.) Air-to-air refuelling operations are an example of this concept. Currently Air-to-air refuelling operations are primary used to extend range of aircrafts in military operation. However some research has been done in the past to estimate fuel saving capabilities of air-to-air refuelling in both military and civil operations. Most of these estimations give highly positive results on the fuel saving capabilities. Nevertheless these results mainly based on a small number of optimised cases. This paper will discuss the effect of the introduction of air-to-air refuelling operations in the civil air transportation system. A traffic scenario based on Eurocontrol-Data containing one day of traffic over Europe serves as basis for a transatlantic Scenario. The traffic scenarios used in the paper will exchange current flights due flight with air to air refuelling somewhere on the route. The aircrafts used on these routes will be exchanged to RECREATE specific aircrafts as aircrafts who use air to air refuelling have a much lower design range than the aircrafts they replace. As reference the same routes will be flown by aircrafts without air to air refuelling and a higher design range. These aircrafts have the same technology level as the RECREATE Aircraft. Also the reference aircrafts will use direct routes while the aircrafts with air to air refuelling will use fuel optimized routes with one or more refuelling operations. The third aircraft type used in the traffic simulation is the Feeder aircraft. The Feeder aircraft will take off from a specific Feeder base and refuel a number of cruiser aircrafts depending on the size of the feeder. The Feeder will then land on the same Feeder base. The main parameters for the Feeder are the Feeder size, the Feeder range and the Feeder efficiency. The Scenario includes 2776 connections between Europe and North-America. In this Transatlantic Scenario 8 Feeder bases have been chosen to serve as take-off and landing airport for the feeder aircrafts. The location of these feeder bases orientates at the optimal refuelling position for these connections. The resulting fuel savings will be shown as the main benefits for air to air refuelling in the traffic system. The driving parameters on the fuel savings will be shown. Furthermore the paper will show the differences in routings with high concentration at the feeder bases and the effects of the main parameters on the network. Thus the traffic loads on the feeder bases will be part of the analyses