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The aircraft has plenty of items (area) for the wind to strike including wing, wires, struts, pilot, carriage, engine, wheels, tubes, fuel tanks, etc. Parasitic drag can be reduced by streamlining the items. Round tubes can be streamlined reducing the drag to one-third, and cowlings can be used to streamline the pilot and the carriage completely, but not without the additional expense and additional weight of the streamlining. Streamlining does make a noticeable difference in the speed and gas mileage of the WSC, especially for the faster aircraft. [Figure 2-16] 

With the large speed range of WSC aircraft, weight, complexity, amount and expense of streamlining, and resultant drag reduction are determined by the specific mission for the aircraft and the manufacturers’ make and model. [Figure 2-17] 

Total drag is the combination of parasite and induced drag. 

To help explain the force of drag, the mathematical equation D = C$_{D}$ x q x  S is used. The formula for drag is the same as the formula for lift, except the C$_{D}$ is used instead of the C$_{L}$. In this equation, drag (D) is the product of the coeffi cient of drag (C$_{D}$), dynamic pressure ( q ) determined by the velocity squared times the air density factor, and surface area (S) of the carriage and wing. The overall drag coefficient is the ratio of drag pressure to dynamic pressure. 

Induced and parasitic drag have opposite effects as AOA decreases and speed increases. Note the total drag in Figure 2-18 . It is high at the slowest air speeds at high angles of attack near the stall, decreases to the lowest at the most efficient airspeed, and then progressively increases as the speed increases. The WSC wing can fly with a large range of airspeeds. 

Generally, the most efficient speed is at the lowest total drag providing the best rate of climb, glide ratio, and cruise economy. However, slower speeds provide higher angles of climb, and faster speeds provide quicker transportation. [Figure 2-18] 

Total drag = parasitic drag + induced drag 

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