Douglas A-4M - PART 2 TAKEOFF; TAKEOFF CHARTS; OPERATIONAL TAKEOFF DISTANCE

NAVAIR 01-40AVM-l
Section Xl
Part 2
PART 2
TAKEOFF
TAKEOFF CHARTS
The takeoff charts present takeo ff distan ce, maximum
takeoff weight. JA TO firing delay, and JA TO takeoff
distance. The charts encompass suc h varia bles as
takeoff weIght, equivalent ai rspeed, amb ient runw ay
temperature, runw ay pressure alt itude , headwind,
and runway g radient H all flaps and MILI TA R'i
thrust are recommended f or all takeoffs.
Variables, which are not co nsidered in the charts,
that will influence the accele r ation of the ai r c ralt
during ground run are pilo t b raking to m ai nt ain di-
rection al cont r ol; ru nway surface co ndit ions whi ch
constitute a [o wer or higher value for the rolling
coefficient of friction ($.I); external sto r e loadings on
the wing st.'ltions which protrude forward or n ea r th e
leading edge of the wing and influen ce the flow Held
of
ai r over the wing, reducing lift and increasing re-
quired takeoff speeds; and rough or bum py runways
which inf l uence the taxi attitude of the air c ralt , in-
troducin g aerodynamic braking during the ground run.
Of th ese va r iables, pilot braking, whi ch Is a fun ction
of pilot technique, probably has the gr eatest Influence
on acce le rati on-reta rdati on and will increase the
ground run sign if icantly.
OPERATIONAL T AKEOFF DISTANCE
Operational takeoff dist an ce, total distance to clea r
a
50-foot obstacle, without JA TO a ssist. and re com-
mended takeoff sp eeds are shown in figure 11 -8.
R TakeoH dis tan ces are based on haU ftaps. MILITARY
/j thrust, and 8 degrees aircraft noseup trim.
The takeoff airspeeds and dista.nces are based on
NATC
flight test data of the Model A-4E ai rcraft.
Note the region in the altitude co rrecti on box where
MAXIMUM TAK EOFF WEIGHT f\. ·IA Y BE EX CEEDED.
This region represents an ar ea in which the minimum
acceptable thrust- to-weight ratio may be e ncountered.
resulting in marginal climbo ut capability, or the sale
tire limit speed of 175 knots g round speed may be ex-
ceeded. Since temperature and alt itud e ar e not in-
dependent . the boundary tines in this bo x are shown
for extreme altitude-temperatu r e comb inati ons. A
more detailed explanation of the ma r ginal region is
given under maximum takeofI weight. The method of
obtaining the ground run distance. tot al dist a nce to
clear a 50- foot obstacle, takeoff airspeed, and the
line speed chec k are des cri bed in the following
example .
Not e
II o ll erat ional conditions require takeoffs
for which computed takeoff distance places
the ai rcralt in the region labeled TAKEOFF
IS MARGINAL on the chart . lift-off speed
sh ould be inc r eased app r oxi mately 5 to 10
knots. not to exceed tire limiting speed.
Th is w ill result in increased r ates of clim b.
Runway length
and location of abort gear
must be considered in planning this type oI
takeoff.
SAMPLE P ROBLEM
Ta ke off Di stan ce - O per ati onal
(For figure 11- 8)
(A)
Takeoff weight .. 20.000Ib
(8) Takeoff airspeed
146 KIAS
(e) Ambient runway air
tempe r ature ..
(0) Runway pressure :liUtude
2000
ft
(E) H ea dwind. 10 kn
(F) Runway
gradient -2 percent
(G)
G round run distance
2450 ft
(HI Total distance to clear
50-foOl obstacle
3600 ft
LINE SPEED C HECK
A line sp eed check is a simple procedure for deter-
min ing th at aircraft acceleration during takeoH run !
is normal. If aircraft acceleration is not normal,
the line speed check is sufficien tl y early to allow
normal braking to stop the aircraft on the runway.
The
pllot selec ts a suitable and r ecognizable known
distance down the runway f rom the point that takeoff
run commenc es (such as runway distance marker.
runwa y intersection, etc.). The normal takeoff dis-
tance cha rt is used by entering the chart at the sel ec -
ted dist a nce and workin g in reverse through the chart.
11-17