Douglas A-4M - JATO Firing Delay, Distance Two MK; Mod 2; 5 KS-4500 JATO Bottles

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NA VAIR 01-40 AVI\I- l
Sectiun XI
Part 2
JATO FIRING DELAY , MINIMUM TAKEOFF
DISTANCE - TWO MK 7 MOD 2,
5KS - 4500 JATO BOTTLES
The minimum ground Tun distance and the total dis-
tance to clea r :l 50-foot obstlcJe may be realized by
'iring the JATO bottles so that burnout occurs at
1ft-off. Burnout at lift-off is recommended faT the
following re aso ns :
1. Bu r nout at lift-off produces the shor t est takeoff
distance.
2. A misfire can be detected early and the takeoff
can be aborted well before the refusal point.
The following trim settin gs are required for JATO
operation to :I\"oio excessive nose-hi!(h att it udes at
low gross weights due to noseup pitching moments
genera ted by possible ,JATO burning aIter lift-off.
Gross Weight Recommended Trim
(Pounds) (De~rees Noseu,e)
13.500
2
17.500
5
22.500
7
24.500 8
With the above recommended trim sett ings. the flight
u'im stick forc(> without , JA TO burning va r ies linearly
with g ross weight from approximately 12 pounds pu!l
at 16,000 pounds gross wei ght to 3 pounds pull at
24.500 pounds gross weight. This stick force is not
objectionable since a redu ction in angle-of - att3ck is
required to maintain airspeed 01' to continue
acceleration.
Il is recommended that th e firing point be esbblished
by distance markers alongside the Tunway. This
recommendation is made for the following reasons:
1. USing a time interval from brake release is
('onsidered to be too inaccurate.
2. Using a irspeed as a reference for JATO firing
would not be possible since, generally, JATO firing
occurs at a speed below the speed at which the ai r -
speed indic,lt.or begins to registe r .
Figure 11-10 shows the grou nd run dist a nce from
brake release to ignition of JA TO. Takeo ff speed,
ground run dist.tnce . and total hor izo n ta l dis tance to
SAMPLE JATO F IR ING DElAY
F~1-141
clea r a 50-foot obst:\cle a re presented in fib'Ure 11-11 .
Takeoff distances are based on half-flaps, military
tlu' usL and trim settings.
The takeoff ai rspeeds and distances are based on
JA TO fli ght test data of the I1100el A -4E aircraft.
Note the region in the altitude cOl'I'ection box wher e
1\IAXE\'l UM TA K EOFF WEIGHT MA Y BE EXCEEDED.
This re gion represents an area In which the minimum
acc eptable thrust-to ·weighl ratio may be encouniered.
resulting in ma r gin:ll climb out capabili tr. 0 1' the safe
tire limiti ng spee d at 175 knots ground speed may be
exc e eded. Since temper:l t ure and al titude are not
independent. the boundary lines in this box ar e shown
for extreme aHitude·temperature combinations. A
more detailed explanation of t he margin:tl regioll is
given undel' I\Iax imum T;lkeoff Weigh t The me t hod
of obtaining the .J ATO firing dist anc e. ,JATO takeoff
airspeed, JATO ground run distance, and total dis-
tance to clear a 50-foot obstacle is described in the
following examples.
SAMPLE PROBLEM
JATO Firing Delay
(Fo r figur t! 11 -10)
11-19