Close formation flight control - with applications in commercial aviation

Close formation flight control - with applications in commercial aviation

Van der Kleij, C.A.

Van Kampen, E.J. (mentor)

Aerospace Engineering

Control & Operations

Control & Simulation

2012-10-05

Ever since the beginning of manned flight, engineers have been inspired by nature in many ways. Birds have been flying in formation for as long as man remember and military aircraft followed suit. In the light of rising fuel prices, crowded airspace and stringent environmental regulations, formation flight could just be another leap forward in commercial aviation as well. This study aims to provide an insight in the implications and prerequisites of close formation flight in commercial aviation. In this research, a wake vortex model for the Boeing 747 commercial jet is developed. The optimum separation between aircraft in a formation is determined. The location of the sweet spot and the drag reduction that are determined with the wake vortex model, are in good agreement with previous research. The location of the sweet spot can however differ from off-line predictions due to e.g. wind and simplifications in the model. It is found that the classic autopilot of the B-747 is not suitable for formation flight. A new autopilot is therefore developed and evaluated. The new autopilot is based on a multiple loop architecture and is developed for a linearized model of the B-747 in cruise condition. It is shown that both in the linearized and the nonlinear model, the controller design complies with regulations and the aircraft successfully tracks the sweet spot under the influence of wake vortex effects. To circumvent the problem of an uncertain sweet spot location, the autopilot is extended with extremum seeking capability. By estimation and maximization of the induced angle of attack, the aircraft automatically finds and tracks the location in which maximum drag reduction is achieved. For applications in commercial aviation, a number of practical issues is finally considered. Different strategies for sweet spot approach, formation flight in a turbulent atmosphere and multiple aircraft formations are considered and it is investigated how passenger comfort is affected. A considerable mean thrust reduction is achieved with the new autopilot set to extremum seeking, without causing disturbances to the passengers.

formation flight
wake vortex
fuel saving
extremum seeking
gradient descent
passenger comfort
boeing 747

http://resolver.tudelft.nl/uuid:eaab3e0d-f836-49ca-902d-1a62b0997012

2016-06-01

Student theses

master thesis

(c) 2012 Van der Kleij, C.A.