G LOC i wonder does often happen to fighter pilot

[Pawelk198604]

I looked once interview with some old Polish decorated pilot veteran who fight in Battle of Britain

The pilot told how the Brits Polish pilots initially treated extremely patronizing, then saw that they were much better than british pilots.

Those pilot said that he had very wimpy body and sometime he pass out when he doing sharp turn to down the Messerschmidt.

He said that during WWII was very little research about about G force overload.

[CaptainKipard]

Modern aircraft gimbals are designed with motors that rotate the axes in a way that gimbal lock is not possible.

[Pawelk198604]

Modern aircraft gimbals are designed with motors that rotate the axes in a way that gimbal lock is not possible.

No it's not what meant G-LOC as in Loss Of Consciousness by g-force

[Razor235]

Not often. The flight suits pilots wear can pressurize the legs and abdomen to force blood into the brain. There is also a special "G-straining maneuver" the pilots are trained to do for higher Gs. You rapidly tense your abdominal muscles to force blood into the brain. To try and complete it, imagine that you are on the toilet with really bad constipation.

The military is also developing aircraft with more reclined seating positions, to prevent blood pooling in the feet.

Here's a video of the maneuver.

[Seret]

These days high-g is just part of their day job, anybody flying any kind of fast jet pulls serious g every day. They do develop higher tolerance than normal people, and they're aware of their limits and how far they can push it.

Going all the way to full g-loc is bad flying. At low level and high speed it pretty much means crashing, and in a dog fight it'll mean the other guy kills you.

[Kryten]

There's also the issue that enough g-force to knock out a trained pilot with a flight suit is enough g-force to severely damage a plane.

[Seret]

There is that. The aircraft have g counters, which is the main reason the g reading is on the HUD. Grounding an aircraft due to pulling like Rambo won't impress your boss or win you a lot of friends among the groundies.

It's not actually the flight suit BTW. The g suit is a separate garment worn over the top. It's basically a pair of trousers.

[78stonewobble]

Don't some planes, these days, via their flight computers, have artificial limits on how hard they can maneuver g wise?

[Nibb31]

Yes, fly-by-wire sets up all sorts of limits to prevent the aircraft from exceeding the airframe's flight envelope.

[Seret]

Don't some planes, these days, via their flight computers, have artificial limits on how hard they can maneuver g wise?

Yes, but that doesn't mean that it's always ok to take the aircraft right up to the limit. In my experience it's not unusual to have a lower limit imposed for operational or technical reasons. Continually thrashing the airframe will shorten its life, and could actually be dangerous on an airframe heading towards it's end of life phase.

[rtxoff]

I guess in fly by wire planes there is some kind of combat mode button which enables the plane to fly up to its limits or even exceed them by a percentage. Normally the plane restricts the pilots into pushing the plane into these limits.

[78stonewobble]

Yes, but that doesn't mean that it's always ok to take the aircraft right up to the limit. In my experience it's not unusual to have a lower limit imposed for operational or technical reasons. Continually thrashing the airframe will shorten its life, and could actually be dangerous on an airframe heading towards it's end of life phase.

True, but here I just meant in reference to G-lock for the pilots.

That the most maneuverable moderne fighters, might have software blocks to prevent too violent maneuvers, though presumably those are for, as you say, the airframe.

[Seret]

I guess in fly by wire planes there is some kind of combat mode button which enables the plane to fly up to its limits or even exceed them by a percentage. Normally the plane restricts the pilots into pushing the plane into these limits.

Well, I've never encountered any type with such a thing. The pilot is just supposed to make sure they fly within the limits.

[Meecrob]

I agree with Seret. There is a fundamental difference between the end use of civil and military fly-by-wire applications. Keep in mind that fly-by-wire does not mean Envelope Protection. Envelope Protection requires fly-by-wire- however.

[rpayne88]

Don't some planes, these days, via their flight computers, have artificial limits on how hard they can maneuver g wise?

Until the pilot throws a switch to override them.

(Usually on military fighter aircraft. e.g. F/A-18, F-15, F-16, F-22, ect. Not your average run of the mill civilian aerobatic plane though.)

[78stonewobble]

Well, I've never sat in a fighter cockpit, so I don't know.

Do have a former fighter mechanic in the family, but there are limits to how much detail we go into work. In any case he only has experience with F-16 A/B's, block 10-15.

I just imagined that even newer fighters or new versions of old ones, had some sort of, as rpayne88, called it "Envelope Protection", to protect the craft from potentially tearing itself apart, especially with ie. various weapons and drop tank loads on the wings.

[Meecrob]

As far as I know, no modern fighter aircraft have Envelope Protection. Fighter pilots are trained to squeeze every last drop of performance out of their aircraft with the training to know where the limits are. Commercial aircraft aren't evading enemy missiles so you don't need it to pull 9 Gs. This is where Envelope Protection comes in. In a commercial aircraft, if you are pulling 9 Gs, something is seriously wrong and the computer can prevent a pilot from entering such a condition inadvertantly. A fighter aircraft on the other hand SHOULD be pulling 9Gs IF it is required. They design them to be tougher than the humans flying them in case they need to be punished to bring a pilot home in one piece. This is also why commercial aircraft have service lives of 75000-100000 hours while fighter aircraft have service lives of ~5000 hours. Overall, I have not seen any form of Envelope Protection for fighter pilots built into the Fly-By-wire/Autopilot systems. Envelope Protection is accomplished by training the pilot to recognize the situation and react accordingly. Just because a computer CAN do it, doesn't mean a computer DOES do it. With a missile on my tail, I don't want some computer limiting me to 9 Gs when I need 9.2 to not get shot out of the sky.

Edited September 23, 2014 by Meecrob

[goldenpeach]

Modern aircraft gimbals are designed with motors that rotate the axes in a way that gimbal lock is not possible.

What is gimbal lock?

[Guest]

http://en.wikipedia.org/wiki/Gimbal_lock

[Seret]

Modern aircraft don't get gimbal lock because they use ring laser gyros.

[Rickenbacker]

I don't think G-LOC happens often to fighter pilots, simply because they're trained to recognize the onset of it, and avoid it. Greyout, and even blackout, probably happen a lot, but any pilot knows to back off the G:s when his vision starts to degrade.

[WestAir]

As an aside, there are commercial airliners that allow you to disable FBW protections. Mainly airbus - I don't know if Boeing has that option with their FBW aircraft.