Civil Aircraft Component Geometries
Previous sections discussed statistical relationships of weight and geometries for a complete aircraft. Section 2.4.1 provides familiarization with typical civil aircraft and its components. The next level of information pertains to the aircraft component geometries available, as building blocks, to shape a new aircraft. There is a wide range of options available from which to choose. The choices are not arbitrary – definite reasons are associated with the choices made (see Chapter 6). This section provides pertinent information on the fuselage, wing, empennage, and nacelle groups, which are required to configure civil aircraft designs.
1. Fuselage Group. This is concerned with shaping and sizing of the fuselage, from where the civil aircraft configuration exercise begins. Related information ascertains seating arrangement, comfort level, and cabin width to accommodate passenger loading so that the longest in an aircraft family does not exceed the fineness ratio on the order of 13. The appropriate front and aft-end closure choices are then made. When the fuselage shell is established, the next task is to configure the interior for passenger and crew requirements. The flight – crew space in the forward closure (i. e., cockpit) and the pilot vision polar are then established. Inside the cabin, the crew and passenger requirements are approached simultaneously as integral requirements (e. g., seating, toilets, and galleys).
2. Wing Group. This is the most important component of the aircraft. The plan – form shape must be established and then sized for operational-field and flight – performance requirements. Options for high-lift devices are described in Section 3.12. Other smaller components (e. g., winglets) also are considered (see Section 3.21) but not all aircraft incorporate winglets.
3. Empennage Group. Choice, size, and placement result from the aircraft’s CG position and wing size. This book adheres to the conventional H-tail and V-tail configuration.
4. Nacelle Group. This topic is addressed in Chapter 10; only an outline for the shaping choice is provided herein.
These four groups of aircraft components provide the preliminary shaping of candidate aircraft configurations. After the wing-sizing and engine-matching exercises, the choice must be narrowed to one final configuration that offers the best compromise for the family variants to cover a wide market. The undercarriage is addressed separately in Chapter 7.
Iterations are required to position the empennage and undercarriage with respect to the wing because the CG position initially is not known. Weights are estimated from a provisional positioning and then the positions are fine tuned through iterations. (In a classroom exercise, one iteration is sufficient.)