Forum: F-35 Design & Construction

asiatrails wrote:

Ok is this opinion or something backed up by facts? As far as I know, there have been no sucessful underwater ejections without the use of det. cords.

Nobody ever tested ejection seats under water, although it was used once on an US Navy A-7 Corsair II on 10th of June 1969 during night carquals on USS Constellation, Lt. Russ Pearson had hook malfunction and rolled of the deck, after submerged, he had to eject through the canopy. In A-7 the canopy is not propelled like in F-16 or F-22, therefore after initiating ejection sequence, outside pressure forced it to stay in place, and the seat with pilot had to smash through the plexiglas - which wasn't very healthy. Although pilot lived to tell the tale.

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I think we will have to disagree on this, detonation cord is not a nice to have feature in a zero-zero ejection situation; it can mean the difference between survival and a failed ejection.

asiatrails wrote:

I think we will have to disagree on this, detonation cord is not a nice to have feature in a zero-zero ejection situation; it can mean the difference between survival and a failed ejection.

Care to explain your conviction? There is no way the canopy can stop the rocket powered seat from smashing right through. The seat's heat rest WILL impact the canopy first not the helmet. The seat will punch through and the pilot will be egressed. The only question is whether he'll get a few cuts and bruises.

Looking for some input on this one. I was under the impression that only the STOVL variant had detcord in the canopy. Do all 3 variants have exploding canopies?

All 3.

No sense designing two different types of ejection systems, especially as the A and C would have to be heavier and more complex with typical canopy jettison system - even more than the F-16, as the '35 open into the "wrong" way and the air flow is not helping it when in forward flight. Just take a look at the MiG-21 canopy design evolution.

The det-cord is the simplest and lightest way to do this.

Although there is also a third way, but not really fun one. The Pilatus PC-7, have an Martin Baker Mk.15 seats, that have in them... some sort of a cannon, that shoots a projectile through the canopy - shattering it. Less dangerous materials on one plane, but that's not very elegant solution.

Sundowner wrote:

asiatrails wrote:

Ok is this opinion or something backed up by facts? As far as I know, there have been no sucessful underwater ejections without the use of det. cords.

Nobody ever tested ejection seats under water, although it was used once on an US Navy A-7 Corsair II on 10th of June 1969 during night carquals on USS Constellation, Lt. Russ Pearson had hook malfunction and rolled of the deck, after submerged, he had to eject through the canopy. In A-7 the canopy is not propelled like in F-16 or F-22, therefore after initiating ejection sequence, outside pressure forced it to stay in place, and the seat with pilot had to smash through the plexiglas - which wasn't very healthy. Although pilot lived to tell the tale.

Great job, Sundowner - I was just about to post about this exact same incident! For anyone not familiar, check this out: http://www.ejectionsite.com/eunderh2o.htm

Mike

Dwightlooi said:

Quote:

BTW, one thing which I think should be noted is that the detonator cords in the plexiglass merely a nice to have feature to reduce the likelihood of injury during ejection. If they should fail, the seat will punch through the glass anyway and the pilot will be successfully removed from the cockpit to a parachute landing. This is true of systems where the canopy is jettisoned too. The seat can and WILL smash straight through the transparency if it has to.

Ahh...No.

In numerous situations the det cord is not just nice to have but a requirement for a successful ejection, the hovering harrier is a great example. The canopy is not going to get out of the way fast enough during a hover before the pilot would most likely hit it. Dwight, I don't know the when the last time you were rocket propelled through plexiglass but I'm not a volunteer, even if you only had a few cuts and bruises.
Next, a lot of the newer cockpits are not like the old ones. Some older seats had canopy breaker's affixed to the top of the seat (T-38's, as an example) to go through the canopy but not the F-16 (no provisions for a through the canopy ejection).

The F-16 is an example of a canopy that will not let the seat eject through it. Oh it might crack it and possibly stick in it but its not going to make it through the canopy with out significanly reducing a pilots seating height by over 18 inches. If the seat did make it out (very, very doubtful) it would probably only go part way and scrape the pilot off on the jagged poly carbonate that was not designed for through the canopy ejection. Not something I want to find out about.

The F-16 WILL NOT, repeat WILL NOT eject through the canopy. If the Canopy doesn't go, the pilot has the rest of his life to figure out how to land the plane or get the canopy off through other means.

On the positive side, it's also pretty well nearly impossible for something on the outside, like a bird, to get in.

However, I have seen the results of a low altitude high speed bird-strike where the waves created on the canopy at impact smashed the HUD combining glass and put a big crack in the top of the pilot's helmet. Shocked

regards, OL

StratoJet wrote:

Didn't know that. Thanks.

Maybe a little research back into why the NAVY doesn't like loosing control of an aircraft when all of a sudden canopy and seat all H--- break loose.

This is a NAVY requirement to punch through the glass the risk to a pilot is some but blow the canopy and make the airplane dive, buck, sway or what! you just might ingest the pilot into the engine or maybe swat him one with the tail, stab or who knows what. This is one area our engineering hasn't been able to model all the unknowns when you jettison the Can.

Forum: F-35 Design & Construction

F-35 canopy - Why does it open from the rear