Vendetta Final Proposal Part 2 - Cal Poly

management system could then be used to enhance cruise performance by pumping fuel in a way which results in neutral
or marginal static stability. Canting the horizontals in a V-tail configuration was investigated in an attempt to shape the
empennage in a stealthy manner. The effective area of the vertical and horizontal are functions of the square of the
cosine of the cant angle. These effects are reflected in Figure 10.1.
Figure 10.1 - Horizontal Area Required for Static Stability with Cant Angle
It can be seen from the plot that as cant angle increases, total planform area of the horizontal must increase to
maintain the nominally desired static stability of 5%. Five percent was chosen because at this stage in the sizing it was
uncertain what the dynamic characteristics of the aircraft would be. Attempting to maintain a minimally statically stable
aircraft eases the job of control system design. Angles up to 30° were looked at because it would be unwise from an
RCS point of view to approach a 90° angle created by larger cants near 45°. Beyond 45° the trend would be the same;
however the horizontal would drive the area instead of the vertical.
This plot shows that only 118 ft 2 of horizontal area is required to maintain the desired static margin. This is far
off from the historical class I method and by initial inspection appears small. The area required maintaining static
stability is not the driving factor in the size of the horizontal. Control power required to rotate the aircraft, dynamic
considerations, and high angle-of-attack recovery will most likely drive this size.
A similar study was conducted on the vertical stabilizer to see what area would required for varying cant angles to
maintain 0.001 (1/degree) lateral weathercock stability. This is illustrated in Figure 10.2.
49