cvairwerks
Staff Sergeant
I work with both legacy and current systems.
Low speed canopies are much harder to deal with for a couple of reasons. They are much lighter weight and that comes with some structural issues. Light weight means light structure, which translates to significant flexing. You need a lower but longer impulse to make it leave the cockpit and do so cleanly. The alternative is pyro cutting, but again that has to be tied to the seat and have a secondary initiation system. Punching thu lighter canopy glass has big problems as the thin material flexes and then fractures in unpredictible patterns. Going thu a 1/4" thick canopy has a much higher possibility of producing sharpnel injuries over the current systems. It also requries a bigger and heavier seat, as it now needs to be able to break the canopy and shield the pilot while exiting the resultant opening. Simply releasing the canopy doesn't mean that it will separate or do so cleanly. Most manual canopy removals have airspeed limitations, or they simply don't work. The SF-260 is a good example. Unless you are within a certain speed window, the canopy will not come off the fuselage due to airflow. Below that window, one has to manually push it up to get airflow under it before it will separate. One other thing with the -260... pull the handle and you had better be prepared to jump, as the canopy is going to remove the vertical fin and rudder when it goes....
On disconnects...when the seat fires, it need to automatically sever or break any electrical or pneumatic attachments between the pilot and the aircraft and upon the man-seat separation sequence, any of them between the pilot and the seat. A standard U-174/U 4 conductor plug requires more than a few pounds of force to unplug. That force can be enough in an ejection that it pulls the pilots' head partially out of alignment during the sequence and results in some trauma to the neck. Being in the correct position is one reason that seats are quite complicated. Out of position will result in serious or fatal injuries 100% of the time. Even with all the seat does to minimize this, virtually every pilot that has ejected ends up with some neck or back trauma.
Standardization is great, but doesn't really keep the consumables problem in check. There are over 10,000 ACES 2 seats that have been produced and are in the inventory of 26 contries, but the pyro production to support those seats is gone or almost gone.
BTW... current standard for the time between ejection initiation and the pilot being on the parachute is 1.6 seconds for zero/zero.
Crew escape is a pretty specialized pack of engineering covering the range of human physiology to aerodyamics to explosive dynamics.
Low speed canopies are much harder to deal with for a couple of reasons. They are much lighter weight and that comes with some structural issues. Light weight means light structure, which translates to significant flexing. You need a lower but longer impulse to make it leave the cockpit and do so cleanly. The alternative is pyro cutting, but again that has to be tied to the seat and have a secondary initiation system. Punching thu lighter canopy glass has big problems as the thin material flexes and then fractures in unpredictible patterns. Going thu a 1/4" thick canopy has a much higher possibility of producing sharpnel injuries over the current systems. It also requries a bigger and heavier seat, as it now needs to be able to break the canopy and shield the pilot while exiting the resultant opening. Simply releasing the canopy doesn't mean that it will separate or do so cleanly. Most manual canopy removals have airspeed limitations, or they simply don't work. The SF-260 is a good example. Unless you are within a certain speed window, the canopy will not come off the fuselage due to airflow. Below that window, one has to manually push it up to get airflow under it before it will separate. One other thing with the -260... pull the handle and you had better be prepared to jump, as the canopy is going to remove the vertical fin and rudder when it goes....
On disconnects...when the seat fires, it need to automatically sever or break any electrical or pneumatic attachments between the pilot and the aircraft and upon the man-seat separation sequence, any of them between the pilot and the seat. A standard U-174/U 4 conductor plug requires more than a few pounds of force to unplug. That force can be enough in an ejection that it pulls the pilots' head partially out of alignment during the sequence and results in some trauma to the neck. Being in the correct position is one reason that seats are quite complicated. Out of position will result in serious or fatal injuries 100% of the time. Even with all the seat does to minimize this, virtually every pilot that has ejected ends up with some neck or back trauma.
Standardization is great, but doesn't really keep the consumables problem in check. There are over 10,000 ACES 2 seats that have been produced and are in the inventory of 26 contries, but the pyro production to support those seats is gone or almost gone.
BTW... current standard for the time between ejection initiation and the pilot being on the parachute is 1.6 seconds for zero/zero.
Crew escape is a pretty specialized pack of engineering covering the range of human physiology to aerodyamics to explosive dynamics.
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