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Home arrow Engineering arrow Small Unmanned Fixed-Wing Aircraft Design. A Practical Approach



This section encompasses not only the main lift-generating parts of a conventional aircraft but also the empennage surfaces such as horizontal and vertical tail surfaces. In other words, all these surfaces can essentially be classified as “wings” for the purposes of this section and the parameterization techniques outlined applied to all these parts of the aircraft.

Careful selection of wing geometry is of particular importance in ensuring that a good overall aircraft design is achieved. It is important that wing geometry is well parameterized in order to be able to make adequate modification to improve such things as cruise drag, stall characteristics, and so on.

For the purposes of this section, it is assumed that a wing section profile has been selected. This is often an early consideration for aircraft design taking into account the type of aircraft and mission being addressed. While it is desirable to develop parametric geometry models that allow section profiles to be modified, this takes considerably more effort in tools such as Solidworks. Therefore, here we assume that the level of parameterization for the wing surface is confined to

  • • span
  • • twist
  • • taper (root chord, tip chord) and
  • • sweep.

Further architectural sophistication can easily be achieved by having “multipanel” wings, where for each panel, all of the above variables can be defined separately. Indeed, for many light aircraft, the wing is a distinct multipanel configuration. Figure 17.22 is a photograph of the wing of a PA-28 aircraft showing the leading edge kink at the junction of the two essentially straight wing panels.

The wing parameterization technique outlined here cannot produce elliptical wing surfaces such as those employed on the Spitfire aircraft, but since such shapes are essentially used to control induced drag and this can be dealt with by suitable changes to camber or twist, this is of little concern - we tend to avoid elliptical wing shapes when using foam-cored wings.[1]

Multipanel wing of PA-28. Photo courtesy Bob Adams licenses/by-sa/2.0/ - no copyright is asserted by the inclusion of this image

Figure 17.22 Multipanel wing of PA-28. Photo courtesy Bob Adams licenses/by-sa/2.0/ - no copyright is asserted by the inclusion of this image.

  • [1] We did use an elliptical planform on the SULSA aircraft but mainly for aesthetic reasons rather than aerodynamicones; also, on that aircraft the entire wing was an SLS nylon printed structure.
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