# Military Jet Canopy...



## dtvonly (Apr 20, 2010)

Hi. Just curious...I have seen many modern jet fighter canopies with some sort of wire frame at the (inside) top of the canopy. See AV-8 Harrier or T-45 canopy. What is this wire frame for? Thanks.


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## FLYBOYJ (Apr 20, 2010)

dtvonly said:


> Hi. Just curious...I have seen many modern jet fighter canopies with some sort of wire frame at the (inside) top of the canopy. See AV-8 Harrier or T-45 canopy. What is this wire frame for? Thanks.



I pulled up a few pictures and don't see this. Post a picture of what you're talking about and we can give you an answer.


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## marshall (Apr 20, 2010)

Those are explosives to blow up the canopy when ejecting.


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## Airframes (Apr 20, 2010)

Yep.
It's MDC, Miniature Detonating Cord, which is a thinner version of the 'cord' used for detonating explosives, burning at between 15,000 and 18, 000 metres per second. When 'blanked', that is, kept as a circuit or with 'stops' set into it, it will explode instantly along it's length. In this form, normal Det Cord can be used as a cutting charge, for instance to drop a tree. In the MDc's set into the canopy, the instantanteous explosion shatters the canopy, allowing the ejector seat to pass through.
This is used on those aircraft types where the canopy can not be jettisoned safely as part of the ejection sequence, and is initiated by the first stage of pulling the firing handle on the seat. It tends to be employed more on military aircraft employed in the low level role, or on carrier ops, where the slight delay of a jettisoning canopy would be crucial in the event of ejection.


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## A4K (Apr 23, 2010)

Great info Terry!


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## T Bolt (Apr 23, 2010)

Sounds kind of scary something like that going off right above your head, but I guess if you’re going down in flames you’d pull the handle and be glad it was there[-o<


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## Glider (Apr 23, 2010)

You can always try punching through an intact canopy!!


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## Airframes (Apr 23, 2010)

Glenn, it wouldn't really be noticed, as it happens in around 0.025 of a second, followed immediately by the 'bang' of the seat. You'd be more concerned about the spinal compression I reckon!
Glider, that was tried, with 'axe blade' extensions on the top of the seat (as per Buccanneer), and although it worked, it did compound compression injuries, nence the introduction of MDC's.


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## A4K (Apr 23, 2010)

My post was edited, as I wrote that our Strikemasters had them. Tried to find pics, and none in the photos did! Started to question my own memory and sanity, as I'd SEEN them with them fitted, when found a brief comment on Google about how they were originally fitted, but later requested to be removed from RNZAF Blunty's...can't open the page though, so don't know the reason...

MDC (and the trusty Martin-Baker Mk(NZ)PB4 ejector seat) did save a kiwi pilot's life on one occasion - he struck powerlines flying low and solo in a 'Blunty' (Strikemaster). MDC went off, seat banged, and 1 second later the aircraft struck a hill... In his words: "I saw the nose (of the aircraft) crumple in front of me!"


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## Airframes (Apr 23, 2010)

Bl**dy hell! I bet he had to have a change of underwear! Good old MB, they've saved a fair number of lives over the years. Yheir web-site is quite interesting to look at, especially if you need pics of the seats, and which aircraft they were used in.
I can't quite remeber, but I don't think our Jet Provost 5's (basically the Strikemaster) had MDC's either.


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## A4K (Apr 24, 2010)

Cheers for the heads up Terry! That will come in handy for various RNZAF projects!

Not sure about the JP 5's myself, but of all photos I've seen so far, none seem to have it. Will check up on that.


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## Dilbert (Jul 30, 2010)

I'm not sure about modern aircraft but on the older birds of my day we had wires used as radio antennae on the underside of canopies. You can see them on the T-28, the rear section of the two part canopy. These aircraft had no ejection seats, we just went over the side (the pilot in the rear, usually an instructor but could be a student in instrument phase of training, was lucky to miss the horizontal stabs in the rear).


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## vikingBerserker (Jul 30, 2010)

Wow, I learned something new today.


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