Table 2-1.--Sequencer Timings
Altitude (ft):
0-8K
8K-18K
18+
KEAS:
500-600
ALL
0-300
300-500
ALL
MODE:
1
2
3
4
5
1.
Gas pressure from seat initiator cartridges, delay cartridge, or
0.00
0.00
0.00
0.00
0.00
command sequencing system initiates catapult and thermal
batteries.
2.
Start switches close after 32 inches of seat travel.
0.18
0.18
0.18
0.18
0.18
3.
Sequencer supplies dual pulse to fire drogue deployment
0.22
0.22
0.22
0.22
0.22
catapult.
--
--
--
--
4.
Sequencer supplies dual pulse to fire drogue bridle release
0.32
cartridge and release drogue bridle.
5.
Sequencer supplies dual pulse to fire parachute deployment
0.45
1.10
1.30
2.90
4.80 +t
rocket.
--
6.
Sequencer supplies dual pulse to fire drogue bridle release
.125
1.45
3.05
4.95 +t
cartridge and release drogue bridle.
7.
Sequencer supplies dual pulse to fire barostatic release unit
0.65
1.30
1.50
3.10
5.00 +t
cartridge and release harness locks.
8.
Sequencer supplies dual pulse to fire barostatic release unit
0.66
1.31
1.51
3.11
5.01 +t
cartridge (backup).
NOTES TO TABLE 2-1
1.
All times are referenced to seat catapult initiation. To obtain times referenced to sequencer start
switches, subtract 0.18 second.
2.
Mode selection environmental sensing takes place between 0.245 second and 0.305 second
(8 microprocessor cycles).
3.
In mode 5 operation, altitude sensing recommences at 4.80 seconds, continuing until the seat falls to 18,000 ft. (t)=time
interval between 4.80 seconds and falling to 18,000 ft.
multipurpose initiators, actuating two pyrotechnic
when the start switches close. Mode selection is
cartridges. The gas generated by these two cartridges is
dependent on altitude and airspeed parameters.
piped around the seat to perform the following
SEQUENCER MODES
functions:
Initiate the underseat rocket motor
When the ejection seat is fired, two onboard
thermal batteries are immediately energized, supplying
Deploy the pitot tubes from the sides of the seat
usable electrical power to the sequencer after just 100
headbox
milliseconds, with the seat having traveled about 5
Close two electrical switches (sequencer start
inches up the ejection catapult. The sequencer
switches)
microprocessors then run through an initialization
routine and by 120 milliseconds the sequencer is ready
The sequencer responds to the closure of either
and waiting to perform.
start switch by changing to the ejection mode. The
switch starts an electronic clock and all subsequent
As the seat rises from the cockpit, two steel cables
events are timed from this point. In the absence of a
(approximately 42 inches) are pulled from the
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