G Force

[link4]

How much have you guys taken? Any had a grey/blackout during a manouvre?

Being a Trainee Civil pilot my tiny weak li'l a/c has and can only give me 4G before it decides to throw a tantrum :)

[Ewan Whosearmy]

Most pointy-nose guys have experienced grey-out, and some have even G-LOCed and lived to tell the tale. How many Gs you pull depends on aiframe limits as well as on ones G-tolerance and physical conditioning. For most fighter guys you're looking at airframe limits from 6-9Gs (depends on the jet in question, obviously), the higher of which is sustainable for quite some time if you're well-hydrated, doing your anti-G straining manouver in time and properly, and are physically conditioned to it.

Personally, I fly fast jets only about 6 times each year and just never have the currency to sustain serious Gs for any given time; 7-8Gs for more than 15-20 seconds is enough to bring on the onset grey-out for me! The big difference in my relatively-inexperienced opionion is that *sustained* Gs are more of an issue than quick spikes...

I am sure some of the fill-time fighter jockeys can add more information and stories!

[Runaway Gun]

'Quick Spikes' can put you to sleep just as easy as any other, especially if they catch you by surprise.

And if you have just been at negative G, you will suffer even worse when resuming hard positive G.
eg. Pull from 1G to 4G is a 3G increase. Start at Minus1G to Positive4G and you have an extra 2G increase before you even start. Did Coldplay release "Sudden Rush of blood FROM the head"?

[brickhistory]

Believe most 4th and 5th generation fighters can pull and hold 9+g for substantial periods of time. The limiting factor is the soft, squishy servo in the cockpit. Weight training/g currency/experience are all crucial to pulling heavy forces and operate effectively. A short, squatty body type can also help, but obviously there are exceptions - tall pilots who can pull with the best of them.

This is a, hopefully, funny piece I did about a fighter ride while serving as, has been so eloquently described on another thread, P.O.S 'scope-dope.' The max I experienced here was a wuss-ish 5.5.

Careful What you Wish For

Pinned by the crushing G-force, I could only move my eyeballs as the black crosses of the Luftwaffe fighter flicked by overhead. Powerless, I waited for the end.
The preceding wasn’t an event that happened in the flak-filled skies of Europe 60 years ago, but over the stark, sunbaked desert of New Mexico of ten years past. The end wasn’t the pounding of machine gun and cannon fire into my cockpit but the worst airplane ride my stomach had ever experienced.
Glasses at an early age prevented me from ever becoming a fighter pilot but I had gotten on the periphery of the action as a ground control intercept (GCI) officer in the Air Force. I attended hundreds of fighter mission briefing/debriefings bringing the advantages of an extra set of electronic eyeballs to the fight.
As the Chief of Training, I convinced the powers that be in my wing that I and my fellow controllers could do a better job if we could fly in the backseat of the fighters and fighter-trainers that lined the Holloman Air Force Base flight line.
Remarkably, my bosses went for the idea. In very short order, I completed the prerequisites: altitude chamber training, ejection seat procedures, and getting kitted out with flight gear. My aircraft would be the AT-38B fighter lead-in trainer. A souped up version of the venerable supersonic trainer, the AT version had a centerline station for carrying practice bombs or a gun pod. Other than that, it was pretty stock. In fact, neither the T or AT version had any sort of radar. My mount has been likened to a supersonic P-51.
The morning of the big day arrived and everything went as briefed. The mission was going to be us as “blue air” against “red air” - two Luftwaffe F-4 Phantoms. The Luftwaffe had a large training component at Holloman to train their new pilots in the brutish F-4. In New Mexico, they enjoyed more than 200 cloud-free days of flying weather per year versus the crowded, often weathered-in European environment.
We stepped, cranked engines, taxied, and launched as per the brief. I was in heaven as the flight took off and joined in close formation. Looking at our wingman, I could see his “Darth Vader-ish” helmet and oxygen mask. I knew that I was looking the same. Maybe that is part of the appeal of flying fighters.
After each flight went to their respective corners of the airspace, we went through our g-awareness turns, configured the switches for air-to-air and then it’s “FIGHT’S ON!”
Sitting at my radar scope on the ground the action seems to take several minutes before fighters get into visual range. Actually riding in the jet and the forty-mile separation closed in seconds. Before I knew it, my controller on the ground called “merged” which meant on his scope the separate radar blips had merged into one blob.
From experience, my pilot knew that the call often lagged by several seconds to the reality in the air. Sure enough, a quick look over his left shoulder and he glimpsed the gray F-4s flashing past overhead.
A mighty tug and pull on the stick in pursuit and my world in the back seat contracted. Being tall and skinny as well as not used to pulling “g’s,” I grayed out. I could hear everything, but until my pilot unloaded the jet, I wasn’t going to see anything.
After some swirling around in the sky, none of which could I reconstruct if I tried, we knocked it off and reset. Both flights turned for their points to set up for the next fight.
Regaining my vision, my stomach let me know that it was NOT happy at being there. I unclipped the side of my mask, loosened my shoulder harness and reached for the Mark 1 barf bag, successfully.
Thinking I had several more minutes to recover before the next engagement, I was totally unprepared for the “merged” call. The same pull and climbing turn as the last fight except this time the g’s forced my chest on my lap. The filled bag plummeted to the cockpit floor and spilled, I couldn’t rise up, and I didn’t think it could get any worse.
I was wrong. Since I was pinned forward, my head was actually in the way of the stick. My pilot, engrossed in the air combat, didn’t know of my predicament and I sure wasn’t going to tell him. Instead, realizing he wasn’t getting the full aft movement of the stick that he should have, he kept trying to brute force it back. My uncovered face repeatedly prevented that from happening.
After about the third smack in the face from the stick, I was reduced to praying for the gas gauge to sink to “bingo.” It couldn’t happen fast enough for me.
Finally at the end of the mission, we landed and opened the canopies. Luckily for me, the wind carried away most of the stench of my now stinking rear cockpit. I shakily climbed down the ladder. The jet’s crew chief was waiting for me with rags and cleaner. Since it was my mess, I got to clean it up.
I went home to a cool, dark room and thought long and hard about any more wishes.

[Soiled Glove]

I think that you'll find that it is the onset of g force that is more of a worry - a slow onset rate can be countered with the correct straining manoeuvres and 'kit' - a rapid onset, especially one where you are taken by surprise can lead to 'g-loc' at significantly lower g levels. Modern aircraft can snatch onset rates of >10g/sec. Although there are many options available for countering the g forces - counter pressure garments/pressure breathing/physical fitness etc - most 'g-loc' occurs with little/no warning whereas 'grey out' is more telegraphed to the pilot.

Trust me, you never want to g-loc!

[Mmmmnice]

Only 'loc-ed out' once - tandem seat - went to sleep during a max rate poss (only 5.5 ish). Very disturbing coming round (shaking and confused - no change then) not sure if one is the only person in the a/c! Fortunately the ranting breaking through from the back seat "..sleep through my demo blah blah.." reassured me - home for T and medals!
If you need to pull G to turn you're flying the wrong type of flying machine?
Go rotary

[Colonal Mustard]

Sorry, thought you were posting about the all male four piece group who were on some tele programme (G -4) i think they are called:\

[maxburner]

Typhoon will sustain 9 all day long - or at least until the fuel runs out. THAT is hard work. Brief pulls of 3 or 4 G are no problem at all once you are used to it. In between , ie from 4 up to 9, is where most peoples individual tolerance lays. Fighter types are usually comforatble at 7 or so, albeit with the right kit and the right anti-G straining manoeuvre. It's my experience that 8 or 9 G hurts! I never liked negative G very much. G-LOC is a massive problem. The individual may only black out for a second, but is unproductive for maybe 30 seconds when the G comes off. These days my mahogany bomber is at a stable 1G. I'd rather be flying!

[Tarnished]

It is indeed the onset rate that'll get you and has killed more than a few guys over the years. As Max says Typhoon (and others) can sustain 9g all day long and yes it does hurt. Did a lot of centrifuge testing of various standards of the Typhoon kit and helmet combinations. Without a doubt the protection offered by the equipment is excellent if a little strange getting used to the pressure breathing. But the point should be made why turn and pull lots of g when you can hoof off and ASRAAM using the helmet? It is going to change everything.

[chevvron]

On a Hunter ride with no g-suit (me not the p.i.c!) we pulled through a loop at 4.5g and I 'greyed out'; guess I was about 75% conscious. It was a bit like a general anaesthetic taking effect; eyesight started to go from the periphery inwards until none at all for a split second, then my 'driver' (Terry Adcock) started to ease off the pressure and eyesight instantly returned.
It was all right for Terry, he HAD got a g-suit, but I found it very instructive, giving me a greater insight of a phenomenon I'd only read about. I'd already had a flight in a Hawk with a g-suit, so I knew what was happening.
Terry had previously pulled the tailplane off a Buccaneer pulling 9g plus to avoid a German police helicopter!

[callsign Metman]

Do I get a medal for 2G in a Bae146??

62 degree AOB in orbits in case you were wondering!

CM

[Bob Viking]

Had a couple of back seats with the reds. Not allowed to wear g-pants in the back to avoid the controls. +7 and -3 in the same trip. Luckily they were very good at telling me when the G was coming so I could strain!
Hope this doesn't come across as a boast. It isn't meant to!
BV:ok:

[BEagle]

As a confirmed jockstrapophobe and member of Athletics Anonymous (feel like exercise, phone a mate to talk you out of it), I found no great snags coping with TWU Hawk flying at the age of 30. No 'working out' (whatever that is) or other froms of ritual self-abuse, just a good anti 'g' suit and a bit of grunting.... It had been the same 5 years earlier on the G-nat, where we used to do those pull-to-5, squeeze-to-6 medium level turning trips...:eek:

But back when I did the Hunter TWU in 1976, our 'turning trousers' (I understand that digi-yoof now term them 'speed jeans') were pressurised from storage bottles. This was fine until you were doing a range recovery at Pembrey when the puff ran out - suddenly no anti 'g' and things did indeed go grey. Or as my chum Ozzy (he of Jamaican descent) was wont to say "I nearly blacked out completely!"

I think we used up to 7.2G in the early days of the Hawk, but might be wrong. Th chaps doing the CFS course did an 8G experience, but it was probably a bit like the supersonic trip - just to show it could do it.

I do wonder why the TypHoon should need to stick its nose up its own bum at 9G though.....

[Tarnished]

Because it can Beages old chap, because it can!

Its all part of the total care package offered free of charge when you buy the jet.

Unstable platform, high thrust to weight, energy management is the new skill to be learned. You can pull/push all you want, bleed energy or not, regain energy like you wouldn't believe, all included in the price:)

[maxburner]

Tarnished,

Stop it old chap. You are bringing tears to my eyes. Now, where did I put that pencil sharpener. Oh yes, it's behind the stapler. Ahhh:sad:

Max

[BEagle]

It's probably also pretty handy to be able to pull like a good 'un if one porks up an aerobatic display in Gloucestershire and nearly smears several tens of millions of pounds worth of aeroplane plus oneself along the ground directly in front of the VIP marquees.....

Saw that - very nearly fatal.......

[PPRuNe Pop]

I thought T had given a very lucid description of that BEag's. Pity we can't use the search yet but I for one felt, as others did, that it wasn't 'quite' as bad as we thought. Or did I get that wrong? I am doing extra time on the BB at the minute!!! :{

[BEagle]

I was just climbing onto the wing of my aeroplane to lead our little formation back home to the Covert Oxonian Aerodrome when I saw the TypHoon start accelerating earthwards in its descent. The attitude pitched nose up, the afterburners were certainly lit.....but it kept descending, getting lower and lower until it missed the ground by barely 30 ft, I would estimate...

What was technically impressive was that it was rock-steady and wings level throughout. Just far, far too low and one very lucky pilot indeed...

Saw something similar happen to a CF-18 at Abootsford many years ago - but this was even closer.

[Conan the Librarian]

I posted a 20 second clip of the Typhoon incident several weeks ago, (Which I cannot see using the new Pprune search function.) It was shot from a different angle and I defy anyone not to shake their head afterwards.

I will go back and look for it now, but if anyone wishes to see it -then a PM will have it whisking your way.


Conan

[Tarnished]

Thread Hijack Beags, not fair at all. There but for the grace of God etc etc. All aspects were well covered before. I suspect you and Uncle Roger from Flight International are related. I also thought it particularly unfair of him to drag the incident up again as a question in his Xmas quiz.

The thread is about how much G we've pulled, life time cumulative....... and centrifuge time counts.:eek:

Tarnished

[jumpseater]

So if all you chaps who have pulled G in an aircraft added your cumulative scores up, who would be the heaviest?:cool:

[Tarnished]

I'm pretty sure the winner (heaviest) guy would be Sqn Ldr Terry Adcock (Ret'd) who used to fly the RAF CAM (Centre for Aviation Medicine) Hawks for many years. Their Hawks were cleared to do these 9g Typhoon profiles where the g-suits and helemets were tried and tested with many different pilots with dear old Terry along for the ride as the safety captain. He must have hundreds if not thousands of 9g counts on his body.

in addition to the flying he also did a load of stuff on the 'fuge. On one particular run he was the victim of a 'runaway' when the thing went to 12 or 13 g IIRC for a short time before it was brought under control.

Mind you he did get an MBE for all his efforts, not sure its a fair exchange.

Tarnished

[PPRuNe Pop]

The gurus and techies are working hard to get the last 20 or so plugins sorted on the BB. A few days may be about right but Danny has gone down with the dreaded lurgy. Balls out all the time guys.

[Tim Mills]

Once long ago, between proper jobs, if the RAF and Exec Jet flying can be called proper jobs, I was lucky (foolhardy?) enough to do a year with an aerobatic team sponsored by a well known tobacco company, and led by my mate Manx Kelly. We flew two seater Pitts, whose G limits were the same right way up or upside down. I didn't mind the right way up bits, because I was used to it from blunt sharp pointed aeroplanes like the Meatbox, Vampire, and even the old Canberra on LABS practice. But one of the horrid manoeuvres we did was to pull up in a vic of three to the vertical, then push down into a bunt all the way round to the vertical again, when, huge sigh of relief, we would pull round for the second half of the loop.

I can't remember the max negative G we reached at the bottom of the bunt where of course we were going fastest, so most neg G, probably about -3 I should think, so equivalent to +4. But I know I didn't like it much! Quite apart from the ailerons working the wrong way when formating upside down; well they don't, but ones instict does, stick away from leader, you get closer!

I know some of the experts, like Manx himself and Neil Williams, were quite at home with negative G, but I never enjoyed it. Wouldn't have missed my year with them though!

[John Blakeley]

A few years ago, with lots of support from the USAF and the Luftwaffe, 3BM TV made a documentary called "Fighting the G Force" which was quite well received and has been sold to Air Forces around the world. It went out on C4 at the time but can also be seen occasionally on Discovery Wings - worth recording if it comes up.

I understand that as a result of some "not so smart procurement" by the DPA the RAF's new centrifuge at Henlow was not built as contracted for and is now on an indefinite hold thanks to lack of funds - the original having been wasted on a commercial failure. Presumably this is not good news in terms of training and selection of individuals with a high g tolerance. Is the old Farnborough centrifuge still running?