Chapter 7 provides details of the undercarriage (i. e., landing gear) design. There is little difference between civil and military aircraft design layouts in undercarriage positioning.
Undercarriage positioning is CG-dependent. At this design stage, the CG position is not established because aircraft component weights are not known. It is now evident that an iterative process is necessary. From experience, the undercarriage may be positioned after estimating the CG position and rotational tail clearances. Ensure that the aircraft does not tip in any direction for all possible weight distributions. (Tipping occurs in some homebuilt designs – especially the canards – when the pilot steps out of the aircraft.) This book addresses only the tricycle type – that is, a forward nose wheel followed by two main wheels behind the aftmost CG. The undercarriage position shown in Figure 6.13 is approximately 60% of the MAC. Readers should use the three views.