text: in drag and there is a two-fold effect. A 50- 
  percent increase in weight produces an increase 
  of 83.8 percent in the power required to main- 
  tain a specific CL. This is the result of a 50- 
  percent increase in thrust required coupled with 
  a 22.5-percent increase in speed. The effect of a 
  weight change on thrust required, power re- 
  quired, and airspeed at specific angles of attack 
  and lift coefficients provides an important basis 
  for various techniques of cruise and endurance 
  conditions of flight. 
  
  an increase in f to account for the additional 
  changes in parasite drag which may vary with 
  C‘. 
  
  1 Figure 2.3 illustrates the effect on the curves 
  of thrust and power required of a change in the 
  equivalent parasite area,!, of the configuration. 
  Since parasite drag predominates in the region 
  of high flight speed, a change in f will produce 
  the greatest change in thrust and power re- 
  quired at high speed. Since parasite drag is 
  relatively small in the region of low speed 
  flight, a change in f will produce relatively 
  small changes in thrust and power required at 
  low speeds. The principal effect of a change in 
  equivalent parasite area of the configuration is 
  to change the parasite drag at any given air- 
  speed. 