NAVWEPS OD-SOT-80 
APPLICATION OF AERODYNAMICS, 
TO SPECIFIC PROBLEMS OF FLYING 
airplane. Density altitude will determine 
the true airspeed at takeoff and can affect 
the takeoff acceleration by altering the 
powerplant thrust. The effect of tempeta- 
ture alone is important in the case of the 
turbine powered aircraft since inlet air tem- 
perature will affect powerplant thrust. Ic 
should be noted that a typical turbojet ait- 
plane may he approximately twice as sensi- 
tive to density altitude and five to ten times 
as sensitive to temperature as a representa- 
cive reciprocating engine powered airplane. 
(4) Specific humidity must be accounted 
for in the case of the reciprocating engine 
powered airplane. A high water vapor 
content in the air will cause a definite reduc- 
tion in takeoff power and takeoff acceler- 
ation. 
(5) The runluay condition will deserve con- 
sideration when the takeoff acceleration is 
basically low. The runway slope must be 
compared carefully with the surface winds 
because ordinary values of runway slope will 
usually favor choice of the runway with 
headwind and upslope rather than down- 
slope and tailwind. The surface condition 
of the runway has little bearing on takeoff 
distance as long as the runway is a hard 
surface. 
Each .of these factors must be accounted 
for and the takeoff distance properly com- 
puted for the existing conditions. Since 
obstacle clearance distance is generally a 
function of the same factors which affect 
takeoff distance, the obstacle clearance dis- 
tance is usually related as some proportion 
of the takeoff distance. Of course, the take- 
off and obstacle clearance distances related 
by the handbook data will be obtained by 
the techniques and procedures outlined in the 
handbook. 
TYPICAL ERRORS. The takeoff distance 
of an airplane should be computed for each 
takeoff. A most inexcusable error would be to 
attempt takeoff from a runway of insufficient 
length. Familiarity with the airplane hand- 
book performance data and proper accounting 
of weight, wind, altitude, temperature, etc., 
are necessary parts of flying. Conditions of 
high gross weight, high pressure altitude and 
temperature, and unfavorable winds create the 
extreme requirements of runway length, espe- 
cially for the turbine powered airplane. Under 
these conditions, use of the handbook data is 
mandatory and no guesswork can be tolerated. 
One typical.etror of takeoff technique is the 
premature or excess pitch rotation of the air- 
plane. Premzture or excm pitch rotation of the 
airplane may seriously reduce the takeoff accel- 
eration and increase the takeoff distance. In 
addition, when the airplane is placed at an 
excessive angle of attack during takeoff, the 
airplane may become airborne at too low a 
speed and the result may be a stall, lack of ade- 
quate control (especially in a crosswind), or 
poor initial climb performance. In fact. there 
are certain low aspect ratio configurations of 
airplanes which, at an excessive angle of ar- 
tack, will not fly out of ground effect. Thus, 
over-rotation of the airplane ,during takeoff 
may hinder takeoff acceleration or the.initial 
climb. It is quite typical for an airplane to be 
placed at an excess angle of attack and become 
airborne prematurely then settle back fo rhe 
runway. When the proper angle of attack is 
assumed, the airplane simply accelerates to the 
takeoff speed and becomes airborne wirh suf- 
ficient initial rate of climb. In this sense, the 
appropriate rotation and takeoff speeds or an 
angle of attack indicator must be used. 
If the airplane is subject to a sudden pull-up 
or Jteep tzzra after becoming airborne, rhe,resulr 
may be a stall, spin, or reduction in initial rate 
of climb. The increased angle of attack may 
exceed the critical angle of attack or the in- 
crease in induced drag may be quite large. For 
this reason, any clearing turns made immedi- 
ately after takeoff or deck launch must be slight