Fighter Canopy Question

BeRich

BeRich

Very Special Agent
On the canopies of some of the newer fighters, there's a black outline above the pilots head. I can't find any pictures of this, but does anyone know what it's for?
 
BeRich said:
On the canopies of some of the newer fighters, there's a black outline above the pilots head. I can't find any pictures of this, but does anyone know what it's for?
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For some birds, it's the detonation cord for blowing the canopy apart prior to ejecting. AV-8 Harriers have this, among others.
 

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It is called Mild Detonating Cord (MDC), and it is basically a thermal charge coated in lead, used to shatter the plexiglass. In the T-45, it tended to spray molten lead all over folks during the ejection sequence......not good. From what I heard, they used the same cord from the Harrier, and it was extremely overpowered in the Hawk/Goshawk application. Either way, I much prefer jets with a canopy that seperates rather than shatters.
 
///AMG said:
It is called Mild Detonating Cord (MDC), and it is basically a thermal charge coated in lead, used to shatter the plexiglass. In the T-45, it tended to spray molten lead all over folks during the ejection sequence......not good. From what I heard, they used the same cord from the Harrier, and it was extremely overpowered in the Hawk/Goshawk application. Either way, I much prefer jets with a canopy that seperates rather than shatters.
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Taken to the extreme, while on this subject, is the Kamov Ka-50/52 Hokum. The helo has an ejection seat just like a fighter. When the pilot pulls the handles, the entire co-axial rotor system is jettisoned from the helicopter by explosive charges, followed by the canopy, followed by the seat.
 

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MikeD said:
Taken to the extreme, while on this subject, is the Kamov Ka-50/52 Hokum. The helo has an ejection seat just like a fighter. When the pilot pulls the handles, the entire co-axial rotor system is jettisoned from the helicopter by explosive charges, followed by the canopy, followed by the seat.
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very cool
 
///AMG said:
From what I heard, they used the same cord from the Harrier, and it was extremely overpowered in the Hawk/Goshawk application. Either way, I much prefer jets with a canopy that seperates rather than shatters.
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The AV-8 had to have the detcord canopy because the pilot might have to eject from a hover and/or slow airspeed.


Don't understand why the Hawk/Goshawk used it though?


Many seats have a "canopy breaker" on top to shatter the canopy if it doesn't come off.
 
USMCmech said:
The AV-8 had to have the detcord canopy because the pilot might have to eject from a hover and/or slow airspeed.


Don't understand why the Hawk/Goshawk used it though?


Many seats have a "canopy breaker" on top to shatter the canopy if it doesn't come off.
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Goshawk/Hawk canopy is hinged on the the right side and manually operated, so there wasn't really the option of blowing it in a traditional fashion....probably weight savings measures there I'd guess. Both types of seats we use in the Hornet (SJU7 older block and NACES for newer) have canopy breakers.
 
MikeD said:
Exactly. At least in the manly A-6 Intruder, you ejected through the canopy with no det cord. :)
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Don't know about the A-6, but there is still a "bail out" procedure in the PCL for the Prowler. Something about an inverted zoom climb, jettisoning the canopy, and dropping out.....not sure how you get to take the parachute with you on that one, but I guess there must be a way :eek:
 
///AMG said:
Goshawk/Hawk canopy is hinged on the the right side and manually operated, so there wasn't really the option of blowing it in a traditional fashion...
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The F-104 and U-2 have side-hinged canopies, and they jettison "in a traditional fashion".
 
///AMG said:
Goshawk/Hawk canopy is hinged on the the right side and manually operated, so there wasn't really the option of blowing it in a traditional fashion.
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Which would be a curious statement to anyone who has flown in a MiG-15UTI... which has a manually operated side swing canopy and which very much has a pyrotechnically lofted canopy. The pyros slam the canopy handle back and delatch the hinge and then blow two pistons up vertically about 6 inches, kicking the canopy straight up.

MDC is a time-saving technique. I operate a BAC Jet Provost for URT training, and interestingly enough there are two varients of the canopy system on that particular airframe: A canopy jettisoning and lofting version, and an updated version with MDC-Shattered canopies. There is about a 0.5 second advantage in ejection timing with the MDC canopy. Might not sound like a lot, but.... well.... it can be.


Milo

.
 
What's missing in the discussion is that these design decisions (of how the ejection sequence will function) are likely more based on aerodynamic behavior of the canopies during jettison than simply how they open during normal operation.

If the canopy will not separate cleanly from the cockpit area, either intruding into the pilot's 'bubble' or striking the aircraft as it departs, then engineers have to come up with another answer.
 
MikeD said:
Taken to the extreme, while on this subject, is the Kamov Ka-50/52 Hokum. The helo has an ejection seat just like a fighter. When the pilot pulls the handles, the entire co-axial rotor system is jettisoned from the helicopter by explosive charges, followed by the canopy, followed by the seat.
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I'd be curious to know how effective that actually is compared to one of traditional nature. Seems like one might get sliced and diced pretty quick even with the separation of the rotors
 
challenger said:
I'd be curious to know how effective that actually is compared to one of traditional nature. Seems like one might get sliced and diced pretty quick even with the separation of the rotors
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It depends. I imagine there is a speed envelope in order to allow the separated rotor system to clear the airframe before the seat fires. Doubt its much use in a hover. Being a helo, it can still autorotate fine, the ejection seat being for extreme structural damage or a situation where entering the auto isn't viable, again with limitations.
 
HuggyU2 said:
The F-104 and U-2 have side-hinged canopies, and they jettison "in a traditional fashion".
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Fun fact: The prototype of the F-104 fire the ejection seat DOWN... through the floor. They figured that was safer than up, as the T-tail might bifurcate the pilot during the ejection sequence.

This lead to a minimum ejection height limitation, as ejecting too close the ground had predictable results. Late on, this was decided to be a bit silly, and production commenced with a more standard upward firing seat.
 
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