Conference Papers: RAeS Future of Aerodynamics Conference - July 2018

I shall be attending the RAeS Future of Aerodynamics conference in Bristol in July 2018. The full programme is available here: RAes Future of Aerodynamics

I shall be presenting two papers

i) 'The Practical Realities of Reduced Design Range, Aerial Refuelling and Reduced Cruise Mach number'

ii) ' Aerodynamic Challenges of Hybrid-Electric and Electric Propulsion Systems on transport aircraft'

The 'Practical Realities...' paper considers three transport aircraft 'Top Level Aircraft Requirements' (TLARs) that have been proposed, in several previous research, as a means to reduce aircraft fuel burn and the associated emissions. The widely held, at least publicised, claim that aircraft are rarely operated close to their certificated capabilities is challenged.

The actual benefits of reduced design range is assessed for two scenarios based on different TLAR sets are assessed using my RAWAvCon design suite. Further, the operational and economic challenges imposed by reduced design range are discussed.

Aerial Refuelling addresses some of the reduced design range operational challenges but introduces its own. These are discussed.

Finally, the benefits of reduced design cruise Mach number are discussed as well as their impact on aircraft scheduling.

The 'Aerodynamic Challenges ...' paper considers where applied aerodynamics will be required to maximise the benefits available for the Hybrid Electric and All Electric propulsion concepts that are currently receiving substantial industry and academic interest.

Specifically, the replacement of kerosene with battery energy storage results in aircraft with higher landing weights (no fuel burn off) and possibly higher take-off weights (battery mass). Hence, low speed aerodynamics will be an important consideration for this technology to deliver the claimed benefits.

The increasing use of battery energy storage will also reduce the weight variation of a given aircraft type at different mission lengths and throughout an individual mission. This will reduce the scatter of optimum cruise altitudes compared to a kerosene powered aircraft type. This may drive a need for less 'peaky' L/D characteristics to reduce the penalty for sub-optimal cruise altitudes.

An electric powered system should have significantly less 'waste heat' than a turbine engine. However, the battery, cabling and power management systems will all generate waste heat that needs to be managed with venting or cooling flows. These require inlets and outlets that will have associated drag and thrust recovery characteristics.

I now need to finish these papers to get them submitted