text: inlet is that the optimum shape is variable with 
  inlet 
  In 
  flow direction and Mach number. 
  other words, to derive highest efficiency and 
  stability of operation, the geometry of the 
  inlet would be different at each Mach number 
  and angle of attack of flight. A typical super- 
  sonic military aircraft may experience large 
  variations in angle of attack, sideslip angle, 
  and flight Mach number during normal oper- 
  ation. These large variations in inlet 
  flow 
  important design 
  conditions create certain 
  considerations. 
  
  (4) In order to reduce interference drag 
  in transonic and supersonic flight, the gross 
  cross section of the aircraft may be “area 
  ruled” 
  to approach that of some optimum 
  high speed shape. 
  One of the most important qualities of high 
  speed configurations will be the low speed 
  flight characteristics. The low aspect ratio 
  swept wing planform has the characteristic 
  of high 
  flight speeds. 
  Steep turns, excessively low airspeeds, and 
  steep, power-off approaches can then produce 
  extremely high rates of descent during landing. 
  Sweepback and low aspect ratio can cause 
  severe deterioration ‘of handling qualities at 
  speeds below those recommended for takeoff 
  and landing. On the other hand, thin, swept 
  wings at high wing 
  loading will have rela- 
  landing speeds. Any excess of 
  tively high 
  this basically high airspeed can create an im- 
  possible requirement of brakes, tires, and arrest 
  ing gear. These characteristics require that 
  the pilot account for the variation of optimum 
  speeds with weight changes and adhere to the 
  procedures and techniques outlined 
  the 
  flight handbook. 
  
  (1) The inlet should provide the highest 
  practical efficiency. The ratio of recovered 
  total pressure to airstream total pressure is 
  an appropriate measure of this efficiency. 
  
  (2) The inlet should match the demands 
  
  of the powerplant for airflow. The airflow 
  captured by the inlet should match that 
  necessary for engine operation. 
  
  (3) Operation of the inlet at flight condi- 
  tions other than the design condition should 
  not cause a noticeable loss of efficiency or 
  excess drag. The operation of the 
  inlet 
  should be stable and not allow 
  conditions (an oscillation of shock location 
  possible during off-design operation). 