Summary

A V-n diagram consists of flight speeds on the x-axis and corresponding load factor constraints on the y-axis. To ensure structural integrity and maneuverability during flight, the aircraft’s speed and load factor should remain in the area enclosed by the plotted lines in the V-n diagram, which represent various stages of flight and environmental factors such as gusts. The objective of this document is to develop a logical code outline to create a V-n diagram for this year’s competition aircraft.

all glory to Roskam

Needed Outputs

• V_S - +1g stall speed
• V_S_neg - negative stall speed
• V_C - cruise speed
• V_D - dive speed
• V_A - maneuver speed
• n_lim_pos - positive design limit load factor (plotted as horizontal line)
• n_lim_neg - negative design limit load factor (plotted as horizontal line)
• n_lim_V_C - cruise gust limit load factor (plotted as lines originating from +1g stall speed)
• n_lim_V_D - dive gust limit load factor (plotted as lines originating from +1g stall speed)

The Equations

n_lim_pos

Per the SAE rules of a MTOW of 55 lbs, this equation yields an n_lim_pos value of 4.5, so we will use the n_lim value of 3.8. Graph this as the horizontal line y = 3.8.