NAWEPS OO-BOT-BO  BASIC AERODYNAMICS  takeoff distance may occur.  Also, the initial  climb performance may be marginal at an  excessively  low airspeed.  There are modern  configurations of airplanes of very low aspect  ratio (plus sweepback) which-if  over-  rotated during a high altitude, high gross  weight takeoff-cannot fly out of ground  effect.  With the more conventional airplane  configuration, an excess  angle of attack pro-  duces a well defined stall.  However, the  modern airplane configuration at an excessive  angle of attack has no sharply defined stall  but developes an excessive  amount of induced  drag.  To be sure that it will not go unsaid,  an excessively  low angle of attack on takeoff  creates its own problems-excess takeoff  speed and distance and critical tire loads.  very high speed flight does not favor the use of  high aspect  ratio planforms.  Low aspect ratio  planforms have structural advantages and  allow the use of thin, low drag sections  for high  speed flight.  The aerodynamics of transonic  and supersonic  flight also favor short span, low  aspect ratio surfaces. Thus, the modern con-  figuration of airplane designed for high speed  flight will have a low aspect ratio planform  with characteristic  aspect  ratios of two to four.  The most important impression that should  result is that the typical modern configuration  will have high angles of attack for maximum  lift and very prodigious drag due to lift at low  flight speeds. This fact is of importance to  theNaval Aviator because  the majority of pilot-  caused accidents occur during this regime of  flight-during  takeoff, approach, and landing.  Induced drag predominates in these regimes of  flight.  (2) During appra& where the pilot must  exercise proper technique to control the  flight path.  “Attitude  plus power equals  performance.” The modern high speed  con-  figuration at low speeds  will have low lift-  drag ratios due to the high induced drag 1  and can require relatively high power set-  tings during the power approach. If the  pilot interprets that his airplane is below  the desired glide path, his first reaction rnu~t  trot be to just ease the nose up.  An increase  in angle of attack without an increase in  power will lower the airspeed and greatly  increase the induced drag.  Such a reaction  could create a high rate of descent and lead  to very undesirable consequences. The an-  gle of attack indicator coupled with the  mirror landing system provides reference  to  the pilot and emphasizes that during the  steady approach  “angle  of attack is the  primary control of airspeed and power is the  primary control of rate of climb or descent.”  Steep turns during approach at low airspeed  are always undesirable in any type of air-  plane because  of the increased  stall speed  and  induced drag.  Steep turns at low airspeeds  in a low aspect ratio airplane can create  extremely high induced drag and can incur  dangerous sink rates.  The modern configuration of high speed air-  plane usually has a low aspect ratio planform  with high wing loading.  When wing sweep-  back is coupled with low aspect  ratio, the wing  lift curve has distinct curvature and is very flat  at high angles of attack, i.e., at high CL, C, in-  creases  very slowly with an increase in 01.  In  addition, the drag curve shows extremely rapid  rise at high lift coefficients  since the drag due  to lift is so very large.  These effects produce  flying qualities which are distinctly different  from a more “conventional”  high aspect ratio  airplane configuration.  Some of the most important ramifications of  the modern high speed configuration are:  (1) During takeoff  where the airplane must  not be over-rotated to an excessive  angle of  attack.  Any given airplane will have some  fixed angle of attack (and CJ which produces  the best takeoff performance and this angle  of attack will not vary with weight, density  altitude, or temperature.  An excessive  angle  of attack produces additional induced drag  and may have an undesirable effect on takeoff  performance. Takeoff acceleration may be  seriously reduced and a large increase in  Revised January 1965  73 