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 Post subject: Blackout G's are real
PostPosted: Fri Sep 16, 2016 9:21 am 
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Antisocial General
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Location: MLC, Lyran Alliance.
F-16 pilot blacked out from a high-G roll. Yikes.

http://www.cnn.com/videos/politics/2016 ... t-orig.cnn

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PostPosted: Fri Sep 16, 2016 7:17 pm 
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Test Pilot
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Location: That flattop, up the well, overhead …
:o Don't they test pilots for that kind'a thing ahead of time?

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PostPosted: Fri Sep 16, 2016 7:50 pm 
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Supreme Mugwump
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Joined: Wed Dec 06, 2006 3:42 pm
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every man has his limits.
the reasons why someone crosses the limit are many, this is what comes to my mind:
-failure of anti-G clothing
-an inexperienced pilot pulls to many Gs(they would know there limit, but not at wich exact manouvre they cross that line)
-some malfunction ads to the Gs
-pilot is slightly ill, wich lowers his G-tolerance
-reflexive action, for example when an obstacle seems to suddenly appear.


I guess there are some experts here?

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PostPosted: Mon Sep 19, 2016 2:45 am 
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Loki
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high gees are never something to sneeze at.

Even if you KNOW you can do them...one should still be careful.

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PostPosted: Thu Oct 20, 2016 5:02 am 
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Major General
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Quote:
I guess there are some experts here?
Hi guys, miss me? I know, I know... with every shot so far...

Having been a Viper driver in a former life (good gravy, it is basically half a lifetime ago now!) maybe I can give some details on G-LOC that can give a better picture of how hard it is to say just what probably happened. There are no easy answers on this as there's a myriad of contributing factors that can arise.

G-LOC -- G-Force induced Loss of Consciousness -- is indeed not only real, it's a sneaky bastard. It can bitch slap you across the face and you can't do a thing about it, or it can sneak up on you slowly unawares until it shoves a dagger between your ribs from behind... where you can't do a damned thing about it... or anything in-between.

I've experienced it six times, four times under controlled conditions in training, twice more I'd rather not discuss. EVERY time was different...

The overall "progression" used in texts about it -- greyout (loss of colour vision), tunnel vision, blackout, and passing out (actual loss of consciousness) glosses over a slew of fine details and the fact that they don't necessarily have to happen in that order... or at the same speed every time even under the same G-Loading.

There are a host of other effects such as hypoxia induced narcosis. Typically your heart and lungs are racing a mile a minute because 1) it's a thrill, and 2) trying to keep the old noggin running. You mix in a little bit of narcosis and it's like mainlining heroin. To say your judgement becomes impaired is a bit of an understatement. This can even occur during sustained turns long before grey-out becomes noticeable. While the eye is EXTREMELY sensitive to low oxygen levels in the blood, sustained long term the brain can start to malfunction first, and if it does you won't even notice even as far along as when your view of the world narrows.

To combat this your flightsuit inflates to try and push blood back up to your head by squeezing it out of your extremities. This can actually be dangerous long term since, well... IT'S SQUEEZING THE BLOOD OUT OF YOUR EXTREMITIES IN A LOW OXYGEN CONDITION.

There's nothing like stripping off your flight suit to find your feet bluish black, and looking like you went five rounds with Iron Mike in his prime the next day all-over. It's a grueling experience and in combat situations it HAS resulted in the need for amputations. You don't hear that discussed a whole lot. Still, amputation beats augering-in.

When the pressure is released it has to be done slowly too -- the suit doesn't just go "pooft" all at once like a BP cuff. Clotting becomes a concern since it becomes like a overdone pressure bandage. Some early pressure suits did result in test pilots dying of aneurysms and it's STILL not unheard of to have fighter pilots just keel over from a clot getting lodged in the brain or heart. You won't hear that talked about a whole lot either.

Another thing is the oxygen mask. In high G situations the amount of oxygen being pumped in increases to try and keep the lights on upstairs. This only works so much because there are limits to how much oxygen the blood can carry. This also has the risk that when the G forces stop, you've now got over-oxygenated blood circulating at regular rates.

The Viper made a lot of simple ergonomic changes to make the pilot less reliant on such things. Simple changes too -- the seat is reclined roughly fifteen degrees more than most other fighters. This somewhat more comfy relaxed position puts you more "flat" to the direction of G-forces in a high-G pitch based turn, reducing the stress on the heart to keep the blood going properly to ALL parts of the body.

A further simple ergonomic aid is that not only is it a HOTAS configuration (hands on throttle and stick) it's a side-stick. This means you don't have to waste energy supporting your arm to hold onto the controls. This can let you squeeze just a few more G's and a little bit longer in the turn, giving you an advantage even over planes as if not more maneuverable than you.

Likewise on early -16's the stick didn't move, and even on new ones it only moves because they put it on a rubber grommet to let it flex, but that movement is NOT how it registers your inputs. The whole thing is made from multiple strain guages that measure how hard you are pushing, NOT the stick's position. In this way it reacts hundreds if not thousands of times faster than a conventional stick becuase the FORCE to move the stick can be read BEFORE it even has a chance to be moved! In that way unlike any other aircraft it feels like an extension of yourself -- and can in fact be a bit TOO MUCH integration. Remember, on the -16 you're not flying the aircraft, the computer is -- instantly turning what you input into the best possible control scenario to do it... instead of left and right being tied to your ailerons and ONLY the ailerons, it could move the rudder too, mix in some elevator to overcome some AoA drift... just as up and down not simply moving the elevators, the computer could deploy the flaperons, adjust the ailerons symmetrically... and do so a thousand times faster than your muscles can move... but nearly as fast as the impulse from your brain tells that muscle to move the stick; again often before that stick even has time to move in response to the pressure!

But... if these were such great advances, why don't any new fighters use them? Well, there's a problem with this. That extra little edge actually led to the fact that the warning signs of grey-out and tunnel vision took longer to set in DESPITE the declining oxygen count. This is because while the blood is certainly getting around better, it's still slowly pooling in places and the amount of oxygen is decreasing. The heart and lungs are now working less hard than they would without these aids, but still having to work harder meaning it's actually consuming more oxygen that could be going someplace else -- like the head! This slower decline of oxygen and longer time before the effects become apparent can result in the functionality upstairs having gone so far south, Andmundson waved "Hi" to you on the way by!

Also the higher tolerances and faster reactions lets you hit that max-G loading faster and stay there longer -- it creates an illusion of safety and control whilst the pilot just digs themselves a bigger hole to fall into. As one of the instructors at Eglin kept telling me "Don't create problems you don't have!". The Viper quite often made it WAY too easy to do that.

The blackout part is also horribly glossed over as that can mean MANY things apart from just "loss of vision" as you can LITERALLY blackout. A literal blackout is this fun period where you appear awake, conscious, responsive to others -- and so completely out of your gord that you will have ZERO recollection of passing events later. You hit this point, even if you don't pass out, you can lose anywhere from a minute to a half hour after it sets in! You ever imbibed so much that you clearly were awake all night, but you don't remember how you got home or who that girl is in bed with you? Yeah, that. It's actually worse when you don't remember landing or being taken to the infirmary after zipping around transonic at angels 30.

In many ways, this precarious line between the brain going "screw you guys, I'm going home" and "I'm ok, no, really" is one of the few times the subconscious gets to do the driving. Monsters from the Id indeed.

... and let me tell you, that fella deep in the recesses of the animal brain? Not the sharpest of knives or the brightest of bulbs. That old antenna doesn't get every station. One brick short of having any bricks. One couplet short of a sonnet. One flower short of an arrangement. Few screams short of an orgasm. Mind like a steel sieve. Inflate to one standard atmosphere stamped next to the ear... Hell, we even had one specifically for it: Short on oxygen one time too many!

Which is not exactly the best choice to have at the stick doing several hundred knots at a few angels in altitude in a high stress environment.

.. and that sustained compromise of oxygen to the brain I mentioned? That can trigger these types of blackout BEFORE you ever even come CLOSE to the tunnel vision or being aware you can't see! All you need to do is being a sustained turn for too long.

Really in a knife fight turning and burning, the sustained turn is really your bread and butter too. The most dangerous thing to your health can be the only difference between getting your ass shot off or shooting the other guy's ass off. All of the fancy manuevers and tricks are based around one simple concept, staying at the speed at which you have the smallest turn radius. You'll hear talk about "oh it can out-turn us as it can do a 10g turn!" -- yeah, at what speed?

Comparison we were given in training - A 10G turn at Mach 3 means you have the turn radius of the USS IOWA at 30 nautical. At 10G turn at 16mph gives you the turn radius of a quarter. Not entirely accurate and is a gross oversimplification, but the analogy gives you the idea of scale.

F-16C can reach 10 G's -- but that's NOT it's "fastest turn" by a long-shot since it has to be supersonic to do it! The optimum speed for a turn on an aircraft is called "corner velocity". For the F-16 that's 450 knots (a hair under 520mph) at 9g's. It can't actually pull more G's at that speed because there's not enough air going over the wings to turn faster, but at the same time if it was going faster that turn radius gets bigger meaning more and more G's are needed to even hold the same arc.

Almost all of your combat doctrine and tactics revolve around trying to maintain that speed WITHOUT losing distance from the enemy or closing too quickly. The former separation can put you out of weapons parameters, the latter can run you up against the risk of "overshooting" the target giving them the opportunity to turn the tables. Sometimes you just flat out have to give up on maintaining that speed for a brief period just to "stay in parameters"

... in that way, it all comes down to one of a pilots most important mantras -- Energy is life. All air combat is about the application of energy. The Sarge in ME2 had it right, and it's not just in space that Newton is the deadliest SOB.

If you'll remember high school science there are two major types of energy: kinetic and potential. Kinetic is easy -- velocity is quite obviously kinetic energy... you also have DRAG as a form of kinetic energy, being the one you have to fight the most. The harder you turn, the more you maneuver, greater the drag making you dig deeper into your energy reserve.

... and where is that reserve? Your potential energy: Altitude and fuel. Fuel kind of sucks, whilst increasing your thrust can help you stave off drag, climb, and go faster, it's a limited pool and once you use it, it's gone. You cannot magically turn slowing down back into fuel.

Altitude on the other hand you can freely trade with velocity. Sure there's a degree of loss, but it's usually an amicable arrangement. Going too slow? Enemy pulling away from you? Dive to trade altitude for speed. Going too fast and overshooting the target? Climb, trading speed for altitude.

The most basic combat maneuvers, such as Yo-Yo's depend on that trade. A Yo-Yo is simply where you climb (high yo-yo) or dive (low yo-yo) in a manner whereby the end of the maneuver you are going roughly the same speed you started at, but by climbing and diving in the turn you avoided a stall, lost speed without losing energy, or simply traveled farther at the same overall speed. It's a bit like the difference between an outside, inside, and apex turn in racing. Inside turn at a slower speed can result in the same amount of time through the turn as an outside one at a higher speed... which is why passing on the outside in a turn is such a stone cold ***** -- you have to be going a LOT faster than who you are passing to do it.

In air combat, you're not trying to pass, so when possible you turn on the outside to maintain a "superior" position on the other guy, but to do so you need to be able to turn with or faster than them so they can't "slip away". The tighter your max turn radius and closer you are to the speed needed for it, the better that control. Just as if you're on the recieving end, being able to out-turn your opponent can let you slip away, or trick them into blowing right past you.

... laughably this is why Maverick's bullshit "bang the breaks" stunt would be pure suicide in real air combat; he just sacrificed ALL his energy meaning the enemy could easily turn out of his firing parameters and he wouldn't have the juice to turn with them! A situation made worse by the fact he was allegedly up against more nimble aircraft and you can't take a fight up into the vertical (the fatcat's specialty given its ridiculous lift and wing-loading) if you don't have the airspeed or engines to climb! (and the TF-30 was a pathetically under-powered pile of trash).

But let's just say there's a reason the Navy's -16N's sat there gathering dust; broke the spirit of too many fatcat drivers when used as aggressors!

In a combat jet you have ALL sorts of dials, indicators, and information on the HUD telling you essentials about the state of the aircraft in regards to these things. It's more than just airspeed and velocity. You watch how many pounds of fuel you have left like a hawk. As you lose fuel you gain maneuverability due to being lighter, but your choices dwindle too as you approach bingo. (Time to go home). There's the AoA (angle of attack) indicator telling you the difference between where your nose is pointed and the actual direction you are travelling. In reality fighter aircraft move more like drift cars in maneuvers. You have slip on all axis and you have to watch that too... the higher your pitch-wise AoA, the higher your drag likely is so the more thrust you'll need to apply or more altitude you'll need to trade.

There's an endless parade of information assaulting you in flight parameters alone, and that's before you get into micromanaging the radar aperture and rate, handling comms, keeping an eye glued to your radar warning receiver for new threats...

It creates a condition called "information overload" and has been a major concern in fighters pretty much since they went electronic. It's why the two man scenario with one guy just watching the electrics became commonplace on front-line interceptors for a good while, and only as the tech side advanced did the idea of a one man interceptor become considered viable again.

Even so there were a LOT of worries about the -15 and -16 in that regard in the early days. New tech, unproven, and just one poor sod to handle it with no GiB to watch his keister. I can't imagine in the two and a half decades since I was last a stick jockey this scenario is any better. Sure the avionics probably blows what we had on roughly the same airframe out of the water the same way my i7 4770k beats the tar out of the 286 I had at the time -- but the stream of information on the "digital battlefield" has only increased.

So imagine that flood of information you HAVE to watch, and then toss G-forces and that they can compromise your judgement on top. It's a miracle you don't hear about things like this happening more often; and that's BEFORE we even talk about the possibility of mechanical failure. One instructor told my class it was the equivalent of balancing plates on your head whilst juggling three knives with your right hand, patting your belly with the other, running a marathon, all while some Army nurse is su... uhm... ok, I'll not finish that one.

I'm just glad to hear the AGCS is a reality instead of a blueprint now. The "Bitching Betty" might be annoying, but it's useless if you're not awake to do anything about its warnings!

Alright, I'll zip it -- rambling a bit and probably butting head with the post limit size. So... you folks miss me?

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It seems very queer that we invariably entrust the writing of our regulations for the next war to men totally devoid of anything but theoretical knowledge.[/i][/color][/size]


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PostPosted: Mon Oct 24, 2016 1:23 am 
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Loki
Loki

Joined: Sun Sep 16, 2001 8:00 pm
Posts: 11444
Location: Minnesnowta
nice post dude...:)

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Medron Pryde - The Great and Terrible :blah:
[img]http://faileas.greywolf.googlepages.com/WOTD.png[/img]
[url=http://www.pryderockindustries.com]P.R.I.[/url] - The home of BattleTech programs and files
"I'm gonna Tea Party like its 1776." - Medron Pryde
Who is John Galt?


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