Large Passenger Aircraft

Large Commercial Aircraft – or in the Clean Sky lexicon Large Passenger Aircraft, are generally considered to be aircraft carrying over roughly 100 passengers or an equivalent cargo loading across short/medium up to very long distances. This includes today’s “narrow-body” aircraft which are usually designed and configured around the median of 150 seats, twin-aisle aircraft for medium (200 – 300 seats) and large capacity (roughly 300 – 400 seats) for both mid and long range trips; and “very large” aircraft with two passenger decks and generally over 400 seats. It should be noted that the largest (sometimes stretched models) of regional aircraft might carry the same amount of passengers as the shortened versions of airliners (the Airbus A318, the shortest aircraft in the A320 family, has approximately 100 seats). One point of difference though is the fact that regional aircraft are mainly for short haul flights, whereas Large Passenger Aircraft can be for short, medium, and long-haul missions.

The challenges? From a market perspective, there's fierce competition – not just between the main manufacturers and global leaders (such as Airbus and Boeing) but from what are often mistakenly referred to as "emerging markets" - which in fact are not "emerging" but are actually nations with well established aerospace industries, especially in Russia and China, with the ability to produce aircraft that are capable of capturing market-share (especially in their home markets) – albeit with products that technologically are until now comparable to the legacy level of the global leaders, using conventional configurations. Nevertheless these aircraft can be produced and supplied very competitive cost levels and the competition for technology and innovation is certain to increase.

The challenge for Clean Sky 2's Large Passenger Aircraft Programme is to further mature technologies tackled in Clean Sky 1, such as the integration of CROR propulsion systems (a radical new type of aero-engine without a nacelle which can ingest air and produce thrust more efficiently than today's conventional engines), and to validate other key technologies such as wings and empennages (the aircraft tail), making use of advanced and hybrid laminar airflow wing developments, as well as an all-new next generation fuselage cabin and cockpit-navigation. It's an approach that builds on the positive experience in Smart Fixed Wing Aircraft (SFWA) Programme of Clean Sky 1.

The Contra Rotating Open Rotor (CROR) combines the best characteristics of a conventional turbofan and a turboprop. Thanks to the crescent shaped rotor blades, cruising speeds can be attained equal to those of a passenger jet. The diameter of the rotor is no longer restricted by the dimensions of the engine nacelle, and the introduction of a second rotor can reduce swirl, which is the loss of power inherent to propeller-based propulsion. Fuel consumption and thus CO2 emission are markedly lower than those of an aircraft propelled by conventional turbofans. New computer models can map out and forecast the characteristics of CROR, such as rotor vibration, noise emission and forces on specific components. This knowledge may be essential in identifying adjustments to the CROR concept, so that it complies with current and prospective noise limits. The accrual of knowledge on CROR enables the air transport industry to make reliable decisions on the application of new propulsion technologies in a new generation of medium-haul aircraft, of which airlines currently have thousands in service.

For Clean Sky 2, the Large Passenger Aircraft goal is high-TRL demonstration of the best technologies to accomplish the combined key ACARE goals with respect to the environment, fulfilling future market needs and improving the competitiveness of Europe's aeronautical industries.

The plan for the Large Passenger Aircraft Programme is to develop these new technologies by streaming them in to three parallel workload platforms, focusing on new propulsion systems and their integration in future aircraft; the future of the fuselage and aircraft systems concepts for possible next generation cabin architectures; and the ‘cockpit of the future’. These three platforms will include large scale demonstrators, test rigs and flight test demonstration for the first one.

Platform 1: Advanced Engine and Aircraft Configurations - will provide the environment to explore and validate the integration of the most fuel-efficient propulsion concept for next-generation short and medium range aircraft: the CROR engine. Large scale demonstration will include extensive flight testing with a full size demo engine mounted on the Airbus A340-600 test aircraft, and a full size rear end structural ground demonstrator.

Two demonstrators are planned to mature the concept of “hybrid laminar flow” targeting substantial aerodynamic drag reduction for next generation long range aircraft.

A further demonstration is planned for a comprehensive exploration of the concept of dynamically scaled flight testing. The target is to examine the representativeness of dynamically scaled testing for technology demonstration with highly unconventional aircraft configuration, which means flight test demonstrations that are virtually impossible with modified “standard” test aircraft. The scaling of these tests could allow for important cost reduction and an acceleration in the discovery and validation of radical new aircraft configurations, even allowing a “plug and play” insertion of different aircraft wing or body shapes and breaking new ground in aerodynamics, in flight control and also in flight mechanics.

Platform 2 Innovative Physical Integration Cabin – System – Structure - aims to develop, mature, and demonstrate an entirely new and advanced fuselage structural concept developed in full alignment with next-generation cabin-cargo architectures, including all relevant principal aircraft systems.

Platform 3 Next Generation Aircraft Systems, Cockpit and Avionics has a dedicated focus on developing and demonstrating a next generation cockpit and navigation suite. Based on the results of a number of research programmes that are currently ongoing or to be started shortly, platform 3 shall allow the Programme to integrate and validate all functions and features which are emerging from individual developments into a disruptive new concept in a major demonstrator suite.