The effect of an engine failure on the remain- 
ing range and endurance is specific to the air- 
plane type and configuration. If an engine 
fails during optimum cruise of the turbojet 
airplane, the airplane must descend and experi- 
ence a loss of range. Since the turbojet air- 
plane is generally overpowered at (L/D),,, 
a loss of a powerplant will not cause a signi- 
ficant change in maximum endurance. If an 
engine fails during cruise of a reciprocating 
powered airplane, there will be a significant 
loss of range only if the maximum range condi- 
tion cannot be sustained with the remaining 
powerplants operating within the cruise power 
rating. If a power greater than the maximum 
cruise rating is necessary to sustain cruise, the 
specific fuel consumption increases and causes 
a reduction of range. Essentially the same 
relationship exists regarding maximum endur- 
ance of the reciprocating powered airplane. 
When critical conditions exist due to failure 
of a powerplant, the pilot must appreciate the 
reduced excess thrust and operate the airplane 
within specific limitations. If the engine-out 
performance of the airplane is marginal, the 
pilot must be aware of the very detrimental 
effect of steep turns.. Due to the increased load 
factor in a coordinated turn, there will be an 
increase in stall speed and-of greater import- 
ance to engine-out performance-an increase 
in induced drag. The following table illus- 
trates the effect of bank angle on stall speed 
and induced drag. 
TABLE 6.1 
Bank mglc, 6, dcgrccs Load factor 
0 0 
0.2 0.8 
0.7 3.1 
1.7 7.2 
3.2 13.3 
5.0 21.7 
7.5 33.3 
10.5 4% 0 
14.3 70.4 
IS. 9 loo. 0 
41.4 303.0 
NAVWEPS OD-BOT-80 
APPLICATION OF AERODYNAMICS 
TO SPECIFIC PROBLEMS OF FLYING 
The previous table of values illustrates the 
fact that coordinated turns with less than 15” 
of bank .cause no appreciable effect on stall 
speed or induced drag. However, note that 30” 
of bank will increase the induced drag by 33.3 
percent. Under critical conditions, such an in- 
crease in induced drag (and, hence, total drag) 
would be prohibitive causing the airplane to 
descend rather than climb. The second graph 
of figure 6.7 illustrates the case where the steep 
turn causes such a large increase in required 
thrust that a deficiency of thrust exists. When- 
ever engine failure produces critical perform- 
ance conditions it is wise to limit all turns to 
II0 of bank wherever possible. 
Another factor to consider in turning flight 
is the effect of sideslip. If the turn is not coor- 
dinated to hold sideslip to a minimum, addi- 
tional drag will be incurred due to the sideslip. 
The use of the flaps and landing gear can 
greatly affect the performance of the multi- 
engine airplane when a powerplant is inopera- 
tive. Since the extension of the landing gear 
and flaps increases the parasite drag, maximum 
performance of the airplane will be obtained 
with airplane in the clean configuration. In 
certain critical conditions, the extension of the 
landing gear and full flaps may create a defi- 
ciency of thrust at any speed and commit the 
airplane to descend. This condition is illus- 
trated by the second graph of figure 6.8. Thus, 
judicious use of the flaps and landing gear is 
necessary in the case of an engine failure. 
In the case of engine failure immediately 
after takeoff, it is important to maintain air- 
speed in excess of the minimum directional con- 
trol speed and accelerate to the best climb 
speed. After the engine failure, it will be fa- 
vorable to climb only as necenary to clear obstacles 
until the airplane reaches the best climb speed. Of 
course, the landing gear should be retracted as 
soon as the airplane is airborne to reduce para- 
site drag and, in the case of the propeller pow- 
ered airplane, it is imperative that the wind 
milling propeller be feathered. The flaps should 
be retracted only as rapidly as the increase in 
377