Forum: General

OK, that's more or less what I meant. If the seat fired 0.13 sec after canopy jettison in a 0/0 ejection then the seat would/could hit the canopy when it fired.

Shades of Topgun.... (the movie) Wink

In the recent article about the F-16D canopy jettison at Luke ( http://www.f-16.net/f-16_news_article966.html ) it was mentioned the canopy hit the vertical tail. Are the charges positioned and/or timed such that the canopy is given a rearward trajectory (in the absense of sufficient airspeed)

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habu2, the canopy jettison works by releasing the canopy (by severing the hooks as per prior post) and then firing two rockets located on the front of the canopy frame, one per side. The canopy rotates on its normal hinge point past the normal position and is released to fly free. In the case of a no wind ejection the rockets have enough force to push the canopy back out of the seat path. (The F/A-22 uses a single 'Y' shaped rocket. I have photos of the tests where they had mikes next to the manikin's head to see if the rocket blast would deafen a pilot. The manikin also had thermal sensors to make sure it wasn't exposed to excessive heat. One of the photos shows the net that caught the canopy from a 0-0 test some 50ft behind and above the cockpit. The systems are very similar, which is why I mention it.)

Kevin
The Ejection Site

ps to make something clear- if the seat is initiated by pulling the firing handle, the canopy jettisons and once it releases from the aircraft and is clear of the ejection path a lanyard attached to the canopy pulls a valve or initiator in the rear of the cockpit which sends hot gas back into the seat. This is what initiates the seat catapult. Thus the delay is based on when the canopy reaches the point where the lanyard reaches maximum extension.

OK that makes perfect sense - thanks Kevin!

I've seen the 62nd jet that punched the canopy(my squadron shares the hanger with the 62nd) Not as much damage as you would think. We had a D model A/C 83-1181 do the same thing three years ago (for the same reason too) however it was jettisoned in a hanger and came back down on the wing. Plane was down for months.

Quote:

We had a D model A/C 83-1181 do the same thing three years ago (for the same reason too)

Rampage, what was the reason? Can you say?

Great reading here about the technical side of ejections!

Has anyone thought about my question in the first reply? Why do the Thunderbirds perform the split-S at 2500 AGL and the manual says 5000 AGL minimum? Is the manual just one of those things that sits around collecting dust and noone uses it?

Thanks........

The canopy has 2 ten foot (approx) lanyards that have to reach their limit during jettison before the seat will fire up the rails, thats how the seat knows its safe to fire. Kevin is right...the higher airspeed rips it off quicker than just a 0/0 ejection. Its a 2 edged sword though because the higher speed the ejection the more dangerous it becomes, limb flailing can be a significant issue above 500 kts.

habu2 wrote:

Are the charges positioned and/or timed such that the canopy is given a rearward trajectory (in the absense of sufficient airspeed)

Yes they are designed to jettison the canopy onto the left wing (from pilots perspective), this is taught in egress fam in the USAF.

The "canopy will land on the left wing" info is being removed from the egress videos that the AF uses as there is no technical reason for that to be in there, the rockets drive the canopy straight back. I do my best in my egress classes to dispell information such as this.

Quote:

Why do the Thunderbirds perform the split-S at 2500 AGL and the manual says 5000 AGL minimum?

As the Thunderbirds are airshow performers, the crowd prefer their show to be close to the ground. Non-airshow rated military pilots are normally ordered to perform aerobatics at a much safer height (eg. Recover Not Below 3000ft AGL), as they don't specialise in that sort of thing.

OK I know this is speculation, but here goes. Somewhere (maybe here) I read/heard that one or more of the TBird jets were towed off to a hangar immediately prior to the start of the show, and then towed back. No proof that the towed jet(s) was actually flown in the show but I'm wondering....

Pre-show, solo pilot goes through all his cockpit checks, including setting baro for MO on the altimeter. Some other problem requires his jet to be towed to the hangar, where it is determined he needs to change to the backup jet. In the hurry and confusion, he jumps in the other jet and taxis back to meet the push for show start. Possible he didn't check/reset baro in the spare jet...

Again, this is pure speculation on my part but it would be a plausible (but not excusable) explanation.

Can anyone comment on the pre-show jet-in&out-of-hangar reports?

The control tower... can you spot the photographer??? Wink

Also, notice there is no other high ground in the area from which to take the photo.

Last edited by Lieven on Jan 29, 2004 - 09:29 AM; edited 1 time in total

For a picture of the canopy ejection, see also: <a href="http://www.f-16.net/f-16_forum_viewtopic-t-514.html">Thunderbird crash photo (head-on)</a>

That photo was taken by SSgt Bennie J. Davis III - Still Photographer, USAF

Habu2,

It probably was not a switch error that led him to misread his altitude. On the hud remote control panel there is a three way switch for the alt readout. Baro, Rdr, or Auto.

Even if the switch was in rdr or auto, it could not have led him to think he was higher than he was for two reasons.

When he checks his alt at the top before rolling over, if it was giving him agl info, then that number would be much lower than the tgt alt, thus it could not be misleading him to think he was higher than actual.
When he does a final alt check after rolling over, the rdr altimeter is not functioning as he is inverted.

Pretty cut and dry what happened.

On a second note, I'd like to say hello as I'm new to this forum. I currently fly the viper out at luke. Pretty good forum you all have got going here. Going through the posts its nice to see folks from maintainers to pilots contributing.

-JF

RDR is pretty useless when you are inverted at the top of the loop. Wink

There are pitch and roll limits on RDR mode. IIRC RDR only works below 500 ft AGL as well. Above that (if in AUTO) it switches to BARO.

Forum: General

T-Bird crash accident report released