BrianB wrote:
I am not an expert on ejection seat sequencing, not having been a rigger in the military, but once the parachute starts to leave the pack the opening sequence is the same for military and general aviation types. I think that the military seats like the ACES II seats flown in most American fighters do have a logic circuit that times the opening of the pack based on altitude and airspeed...... on the deck=fast deployment and high and fast=slower sequence. Randy Haskin, is that accurate?
In the ACES seat, the C-9 parachute is actually part of the seat -- it is packed right aft of the headrest and between the pitot tubes. As such, the seat can sense airspeed and altitude, and make smart decisions about when to open the chute based on reducing opening shock. If you bail out high, the seat simply keeps the pilot in the seat with a small drogue chute deployed and waits until you're at a lower altitude. At lower altitude, it deploys the drogue chute and waits until the seat slows a bit before deploying the main chute. In the case of Noodle above, even at the insane airspeed that he punched out at, the seat deployed the chute immediately and it was nearly ripped to shreds by the speed. Never the less it decelerated him enough at a low enough altitude that he plopped into the ocean at a survivable speed. He had far more injuries from his limbs flailing around at 675 knots than he did from the high speed opening shock.
There is actually no provision for a "manual" bailout in the ACES seat, since you're not actually wearing the chute.
In other seats -- such as the one in the T-38 -- a standard back chute is worn. Other than a barometer that gets pulled when the seatbelt pulls it, the seat has no vote in when the chute gets pulled. Either the pilot manually deploys it by pulling the D-handle, or the barometer automatically deploys it when you've fallen below 15K baro altitude.