Home Engineering Small Unmanned Fixed-Wing Aircraft Design. A Practical Approach
Based on these hand sketches, exact “master sketches” can now be created. First, all significant dimensions need to be captured in a set of of 2D fully dimensioned CAD sketches: typically a side elevation, plan view, and front elevation. These sketches need to be constructed at the top level of the assembly hierarchy and not associated with any particular part.
Illustrated in Figure 17.13 is the fully dimensioned exact CAD plan view sketch being created on the imported hand sketch, which is used as an initial template.
The two master sketches for the UAV assembly are shown in Figure 17.14. Note that all the features within these exact sketches are fully dimensioned and therefore fully defined. In
Figure 17.11 Plan and side view hand sketches.
Figure 17.12 Hand sketch scaled and positioned orthogonally in Solidworks.
Figure 17.13 Exact, dimensioned sketch being created on hand-sketch outline.
Solidworks, the sketch changes from blue to black to signify that it is fully defined: in other words, unambiguous and fixed in space.
Within these sketches, it is important that meaningful names are given to each dimension to make the assembly and associated design table more comprehensible. As parts are defined or brought into the assembly, the key dimensions need to be connected with the master sketch to “synchronize” the whole assembly and conform to the “Systems Engineering” interface definitions.
Figure 17.14 The “master” driving sketches in the assembly.
Figure 17.15 Design table for example UAV.
Having identified all the key master geometry parameters in high-level sketches belonging to the assembly, it is very easy to create a design table (spreadsheet), which can then be linked to other spreadsheets that contain design calculations. An extract of the design table for the example UAV is shown in Figure 17.15.
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