M.Sc Thesis

M.Sc StudentGael Amouyal
SubjectPeriodic Flight in the Transonic Regime for Energy Saving
DepartmentDepartment of Aerospace Engineering
Supervisor Research Professor E Weihs Daniel
Full Thesis textFull thesis text - English Version


Saving energy has always been one of the major goals in the aerospace development and research. The aim of this study is to show a possible energetic superiority of a periodic flight over a steady level flight in the transonic regime (M=0.7 to M=1.3). The trajectory of the aircraft is no longer steady but shows a periodic behavior consisting of repeated cycles. Other studies [2-9,11-13] show the advantage of a periodic trajectory in aerospace and in other area. Due to a high increase of the drag force, the transonic speed is the worse region to flight in. Consequently it is essential to develop a way of saving energy in this region.

This study looks at two cases of periodic flight using one standard full body aircraft wind tunnel model, the AGARD Model “B”. For both cases numerical simulations and wind tunnel experiments have been made and compared with the steady level flight.

The first one is a periodic flight with altitude variation. The trajectory of the aircraft is no longer rectilinear but shows sinusoidal path. The results showed similarities between the numerical simulation and the wind tunnel test. It confirmed the superiority of the periodic flight over the steady level flight up to 26% of energy gain.

The second case is a periodic flight with constant altitude. The trajectory consists of an accelerated motion and a powerless gliding in a periodic manner. The results show in both numerical simulation and in wind tunnel test that under certain conditions the periodic cruise can be better than the steady level flight up to 11% of energy gain.

These results don’t represent an optimum but only show a possible way of saving energy at transonic regime.