General > General Technical Chat
WTF!!! (French Airforce FUBAR)
paulca:
One odd thing as well. In the event of ejection there are several sensitive systems with destruct mechanisms in them. Like the IFF gear and "Music" boxes (ECM and ECCM software). These cannot fall into enemy hands and usually have mechanisms to destroy them. Presumably these didn't go off either.
jogri:
The safety pins are just a mechanical stop to prevent you from pulling the ejection handle and the drogue chute from launching, they are just there to make sure nothing hits a primer (and some explosives detonate somewhere on the seat).
I don't see how those can cut off a pyrotechnic line without inducing a major risk of a malfunction: You can stop a shock line by decreasing its diameter or inserting some sort of blockage, but tinkering with the system responsible for getting the pilot out of a failing aircraft on a daily basis (each start/landing) seems like a really bad idea.
And i don't think that they use electronic locks for ejection seats as anything electronic can be jammed->you really don't want someone jamming your ejection seat.
They probably use something like C4 for the pyrotechnic lines so the chances of it going off on its own after the line has been severed are basically nonexistent but i wouldn't trust it if i was sitting on a armed ejection seat.
The radio equipment is probably scheduled to self-destruct after the pilot flying left the airplane as it is safer (the selfdestruct might damage other equipment or the plane) and because the pilot absolutely needs the IFF if his ejection seat malfunctions and he is stuck in his plane.
jmelson:
--- Quote from: jogri on April 15, 2020, 04:18:26 pm ---The safety pins are just a mechanical stop to prevent you from pulling the ejection handle and the drogue chute from launching, they are just there to make sure nothing hits a primer (and some explosives detonate somewhere on the seat).
--- End quote ---
The old systems were entirely mechanical/explosive/pneumatic, with no electrical components. Some newer systems may have limited electrical functions for sequencing and time delays, powered by a lithium battery totally separate from the aircraft electrical system. And, generally, there are safety pins that lock out the ejection handles so people don't fire the system with their shoes or elbows while getting in/out. These handles are in pretty exposed areas so that they can be pulled in high-G events. There are very limited overrides and lockouts other than the handle safety pins to minimize things that could disable the system when it is needed. There were some aircraft where a loss of the canopy could eject the crew, as the loss of the canopy at high speed could disable the pilot or indicate an accident that caused the pilot to be disabled.
Jon
paulca:
I only know sim aircraft, but the F18, A10, Harrier and F14 ALL have a "Seat Arm" lever, either where the armrest would be or on the side of the seat. In rafale cockpit photos you can see a flat yellow and black chevron's lever beside the pilots thigh. I think that's the same thing.
jmelson:
--- Quote from: jogri on April 15, 2020, 04:18:26 pm ---
They probably use something like C4 for the pyrotechnic lines so the chances of it going off on its own after the line has been severed are basically nonexistent but i wouldn't trust it if i was sitting on a armed ejection seat.
--- End quote ---
The pyrotechnic lines use hexanitrostilbene, I think. It is very heat resistant, and needs a strong initiator to start the shock wave.
Jon
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