| 摘要 |
An aircraft comprises at least one jet engine having a surrounding, open-ended duct coaxial with the engine and spaced therefrom radially to define a passage of annular cross-section. The casing or duct extends upstream and downstream of the jet engine and tapers internally in the forward direction over a region, in which a leading edge of a casing of the jet engine is disposed. Upstream of the tapering region, the interior of the duct forms a cylindrical entry section of the passage through the duct, in which an axially displayable open-ended tube is disposed, spaced radially from the wall of the entry section of the duct passage. The duct is mounted for axial movement relative to the jet engine whereby the width of the annular gap defined between the leading edged of the casing of the jet engine and the tapering portion of the passage through the duct can be varied to control the amount of air bypassing the jet engine within the duct, and thereby adapt the aircraft propulsion system to different flying conditions.
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