MiG-21 Ejection Seat KM-1


The described pilot ejection system is the one of the MiG-21US (Type 68/69, NATO Mongol B/C). However, the KM-1 ejection seat is used in MiG-21PFM, M, MF. The MiG-21F, F-13, PF and some PFMs have the not so good SK seat which basically can't be used on the ground , on takeoff up to (about) 170m (550 ft) and on landig below 200m (600ft) depending upon speed and pitch angle. The MiG-21 BIS uses a slightly improved KM-1M which has a different leg restrain mechanism.

The KM-1 ejection seat can provide the crew a safe and efficient escape from the aircraft. The seat is propelled from the aircraft by an ejection gun which is assisted by a rocket motor. The seat system includes an automatic ejection sequencing system. The front canopy separates before the rear canopy followed by the pilot in the aft cockpit and the pilot in the front cockpit last in any case when the ejection is initiated by either pilot through the ejection handles. In Type 68 (MiG-21US) both canopies will be jettisoned if one of the emergency canopy jettison handles is pulled.
In Type 69 (MiG-21UM) the rear canopy can be jettisoned separately. However, both canopies jettison if initiated by the pilot in the front cockpit. If necessary, ejection can be accomplished at ground level between 75 knots and 280 knots. If faster than 280 knots, an altitude of 100 ft or higher should be observed. The ejection seat system also includes an emergency oxygen system and a survival kit in the seat pan.

EJECTION SEAT SEQUENCING

Once the Pilot pulls the ejection handle the canopy cartridge ignites and jettisons the canopy which removes the interlock block. Simultaneously with the canopy jettison, a second cartridge initiates shoulder harness tightening and arm protector extension. The removal of the interlock block fires the ejection gun if the pull is maintained. The seat starts to move, engaging the Speed/Time Computer (KPA-4, PPK-2), and separating the common connector after a movement of 1 inch. The telescopic rail and first stabilizing chute deployment is initiated with a 4 inch movement. After 16 inches, leg restrain is engaged, followed by rocket motor ignition after 32 inch. If below 280 KIAS the first stab.chute jettisons immediately, deploying second stab.-chute, arm protectors retraction, and engaging separation sequencer PPK-1.If faster then 280 KIAS, this will be accomplished after 0.1...1.6 s according to speed.  Seat - pilot separation is after 1.5 s if below 10000 ft with the regular set up. Deploy survival kit manually at an altitude of 3000...1000 ft AGL.

EJECTION SEAT ENVELOPE


...on takeoff roll v 70 KIAS Alt.= 0
...low level 70 v 275 KIAS Alt.= 0
from 275 to 635 KIAS minimum ALT.= 100 ft AGL
from 635 to 665 KIAS minimum Alt.=3000 ft AGL
...approach to land w/o leveling off Alt.= 180 ft AGL

Minimumm safe altitude for different dive angles (KIAS) Altitude (meters)



Speed / Dive Angle 0-30 -60-90
120 0300 645900
275 -150480 9901260
360 -720330 10501400
530 -1650-90 10501600