Page 31
ARTICLES
Overall view of the PP
-
TVM charge.
PP
-
TVM cross section.
Ejection system ensures:
- Emergency egress from the aircraft in any
order (1. front canopy, front pilot, 2. rear
canopy, rear pilot or vise versa)
- Ejection of one crew in flight
- Proper ejection sequence in both cockpits
while preventing simultaneous ejection from
both cockpits, simultaneous canopy jettison,
or any combination thereof.
Description of the Ejection Sequence
Once the pilot has decided that an emergency
egress from the aircraft is necessary, all that
needs to be done is to pull on the ejection
handles upwards to initiate the ejection
sequence All other system activities are fully
automatic and completely independent.
- This leads to an electromagnetic initiation
of the ejection sequence of the second pilot,
starting with canopy jettison.
- Initiation ignition of the URM-1 rocket engine,
- Securing shoulder straps
- Igniting the charges for canopy jettison
The seat will begin to move upwards along
its rails, and at the beginning of the ejection
sequence:
- The pilot’s legs are brought into the seat and
secured within the first 1,000mm,
- After 315mm, uncoupling of the ORK-9A
communication link via static cable ‘II’
(on the left side of the seat) and a switch
to the KP-27M oxygen system,
- After 800mm, the LUN 5820-8 (KAP-3P/39V)
dynamic pressure device valve is disengaged
and the LUN 5820-8 and LUN 5821-8 (AD-3/39)
firing seat releases are triggered via a static
‘I’ cable on the left and right seat sides,
- After 850mm, the electrical connection
between the aircraft and the seat is severed
via cable ‘Iia’ on the right side of the seat.
After between 0.25 and 0.45 seconds after
the severed connection, the second seat
and canopy are armed.
After the seats clear the aircraft:
- At the 1500mm point, with the use of cable ‘III’
located on the right side of the seat,
the URM-1 rocket booster is initiated.
- At 1680mm, the telescopic system has done
its job and the URM-1 is responsible for
continued acceleration of the seat.
- At 2800mm, the stabilizer chute is deployed
via cable ‘IV’ on the left side of the seat,
- The seat stabilizing chute is deployed by
the jettisoning of a weight and the seat with
the pilot are slowed.
- Following the expiration of the set time delay
of the LUN 5820-8 and LUN 5821-8 ‘releasers’
of the ejection seat unlock the torso and
shoulder restraint locks as well as the foot
restraint locks,
Seat Release Sequence
- The ejection handles are released,
- The pilot, emergency pack and parachute
are separated from the seat,
- After 600mm, the automatic parachute
release LUN 5932-8 (AD-
3P/39) and the combined parachute release
LUN 5931-8 (KAP-3P/39V) activate,
- The PL-70I parachute is opened by the
LUN 5932-8 automatic release, and the
stabilization parachute is pulled out,
- The LUN 5931-8 release unlocks the PL-70I
parachute canopy bag retaining lock
and withdraws the bag from the canopy
of the PL-70I parachute and fills it with air,
- The decent of the pilot with the main chute.
Chute Release Sequence:
The emergency system also allows for the
jettisoning of the cockpit canopies without
a subsequent seat ejection.
To activate it, it is necessary to flip the lever
of the emergency canopy jettison
(on the ground, secured by locking device
No. 1), located on the right side of the cockpit.
Finally, the pyromechanism of the canopy(ies)
will work and the seats will be unlocked.
Total number and location of explosive
charges in the rescue system of the
L-39
- Two PK-7T units (or PP
-
TVM) associated
with the telescopic component of the system,
- Four VMP-2M units for the chute deployment
system’
- Two 120-4-2785 (or VVPR) associated
with the shoulder restraint system
- Two URM-1 rocket boosters,
- Two PK-3M-1 (or PP
-
POP) associated
with the canopy jettison system.
Note: The original charges were of Russian
or Soviet origin. Over time, they were repla
-
ced by products of domestic Czechoslovak
(Czech) oigin, manufactured by Explosia a.s. in
Semtín (types shown in parentheses).
Speed
(km/h)
Release LUN 5820-8
Time (s)
Release LUN 5821-8
Time (s)
v≤450 0,4 1,5
v>450 Blocked 1,5
Altitude (m) releaseLUN 5931-8
Time (s)/Altitude (m)
ReleaseLUN 5932-8
Time (s)
H≤4000 1,5 0,5
H>4000 After deceding to 4000 0,5
INFO Eduard
31
May 2024