Way Forward to Step Jumps for Highly Efficient & Greener Civil Aviation

We are going to have an exctiting seminar on 'Way Forward to Step Jumps for Highly Efficient & Greener Civil Aviation' with a focus on Air-to-Air Refuilling and Close Formation Flying, on the 20th of January 2015, Tuesday, given by Dr Raj Nangia, Consultant Engineer, Bristol, UK.

Abstract is given below.

Date & Time: 2:00-3:00 PM, 20th of Jan 2015, Tuesday
Venue: Room 526, Seminar room in the CDT suite, James Watt South Building 





Context: Over three generations, the civil aviation industry has dominated world transport. Growth has been upwards - bigger, farther and faster on an economic productivity basis. With increasing concerns of environmental issues and volatility of in the fuel price, the NASA and ACARE (Europe) objectives imply reduction of Aviation’s environmental impact (fuel burn, noise, emissions) by 50% or more in 25 years.

Metrics: A new set of “unified” Efficiency performance metrics relate the maximum and design Payloads, Fuel consumed and Unit Costs as functions of Range. These demonstrate how efficiencies decrease dramatically as range increases.

Evolution vs Step-Jump: As aviation matures, the propulsive, aerodynamic and structural efficiencies show smaller increments. The environmental objectives on an evolutionary basis become very costly and challenging. The pace of Research is however, increasing. With some lateral thinking, can we envisage a “step jump” by changing focus towards operational strategies?  The pros and cons will be discussed.

How, Efficient Aviation: Towards achieving a more efficient Commercial Aviation industry, Air-to-Air Refuelling (AAR), “multi-stage operations” and Close Formation Flying (CFF, drag reduction) are proposed, all have significant possibilities. It will be interesting to know / explore how these technologies may co-exist and compare with evolutionary technologies.

With AAR, by using smaller, efficient (greener) aircraft optimised for 2500-3000 nm range to fulfil long-range routes, considerable savings in fuel burn and noise arise. Essentially less metal is in the air!  For shorter ranges, fully loaded aircraft could take-off “light”, with minimum fuel and a planned AAR a few minutes into the flight. AAR can enable Laminar flow Aircraft development. So there is a considerable scope for Special Purpose Aircraft (SPA) to emerge either by modification or new types – Commercial Aircraft and generally smaller tankers. Initially there will be certification / Airworthiness issues.

With AAR, also implied is a greater usage of smaller airports, relieving congestion and ATC demands on Hub airports.

Problems due to shed vortices at airports are reduced. Smaller engines will be needed. With CFF, 10-15% fuel savings have been demonstrated.

Goals: For moderate to longer ranges, the operational AAR and CFF, in concert, go most of the way towards satisfying NASA / ACARE objectives. We need to work towards practical demonstrations. (recent C-17 programme on CFF). These technologies provide benefits over and above the evolutionary trends and complement the work on synthetic / biomass fuels, prop-fans, laminar flow etc.



First published: 24 October 2013