cause damage from excessive flight loads. The 
usual term given to the speed at point A is the 
“maneuver speed,” since consideration of 
subsonic aerodynamics wouId predict mini- 
mum usable turn radius to occur at this con- 
dition. The maneuver speed is a valuable 
reference point since an airplane operating 
below this point cannot produce a damaging 
positive flight load. Any combination of 
maneuver and gust cannot create damage due 
to excess airload when the airplane is below 
the maneuver speed. 
The maneuver speed can be computed from 
the following equation: 
where 
VP= maneuver speed 
V,= stall speed 
n limit = limit load factor 
Of course, the stall speed and limit load factor 
must be appropriate for the airplane gross 
weight. One notable fact is that this speed, 
once properly computed, remains a constant 
value if no significant change takes place in 
the spanwise weight distribution. The ma- 
neuver speed of the subject aircraft of figure 
5.4. would be 
v,= loo&3 
= 274 knots 
EFFECT OF HIGH SPEED FLIGHT 
Many different factors may be of structural 
importance in high speed flight. Any one or 
combination of these factors may be encount- 
ered if the airplane is operated beyond the 
limit (or redline) airspeed. 
At speeds beyond the limit speed the air- 
plane may encounter a critical gust. This is 
especially true of a high aspect ratio airplane 
with a low limit load factor. Of course, this 
NAVWEPS 00-801-80 
OPERATING STRENGTH LIMITATIONS 
is also an important consideration for an air- 
plane with a high limit load factor if the gust 
should be superimposed 00 a maneuver. Since 
the gust Ioad factor increment varies directly 
with airspeed and gust intensity, high airspeeds 
must be avoided in turbulent conditions. 
When it is impossible to avoid turbulent 
conditions and the airplane must be subject to 
gusts, the flight condition must be properly 
controlled to minimize the effect of turbulence. 
If possible, the airplane airspeed and power 
should be adjusted prior to entry into turbu- 
lence to provide a stabilized attitude. Ob- 
viously, penetration of turbulence should not 
be accomplished at an excess airspeed because 
of possible structural damage. On the other 
hand, an excessively low speed should not be 
chosen to penetrate turbulence for the gusts 
may cause stalling of the aircraft and difficulty 
of control. To select a proper penetration 
airspeed the speed should not be excessively 
high or ‘low-the two extremes must be 
tempered. The “maneuver” speed is an im- 
portant reference point since it is the highest 
speed that can be taken to alleviate stall due 
to gust and the lowest speed at which limit 
load factor can be develoPed aerodynamically. 
The optimum penetration speed occurs at or 
very near the maneuver speed. 
Aileron rever& is a phenomenon particular 
to high speed flight. When in flight at very 
high dynamic pressures, the wing torsional 
deflections which occur with aileron deflection 
are considerable and cause noticeable change 
in aileron effectiveness. The deflection of an 
aileron on a rigid wing creates a change in lift 
and produces a rolling moment. In addition 
the deflection of the control surface creates a 
twisting moment on the wing. When the 
actual elastic wing is subject to this condition 
at high dynamic pressures, the twisting mo- 
ment produces measurable twisting deforma- 
tions which affect the rolling performance of 
the aircraft. Figure 5.5 illustrates this process 
and the effect of airspeed on aileron effective- 
ness. At some high dynamic pressure, the 
339