Head rush/Blackout??!!

[05c4r]

Hi, i aim to be a pilot in the RAF or RN when i have done my A-levels and Degree but recently went on holiday to florida and went on some of the worlds best rollercoasters! Thats the good bit The worrying bit is that sometimes whilst riding the rollercoasters all of the blood would rush to my head and although i was fully conscious sometimes my sight would begin to blackout.

This also happened to a few of the other people i was with, does this mean that i would not be able to be a pilot? Or was it just from being really relaxed after queuing for ages from being exposed to a fair amount of G-force?

Any help would be appreciated?


Thanks

[samuraimatt]

This doesn't sound good. I would go and see a doctor if I were you.

[Pontius Navigator]

05c4R,

Don't worry. At the time you were just a relaxed, thrill-seeking, holiday maker. When you are trained to fly in aircraft with a high-g capability you will have the proper kit, you will expect the g, you will be taught how to get g-fit and you will be trained to strain.

[05c4r]

Thanks for your replys, I just did some research and it looks like it was slight G-LOC and according to wikipedia a normal untrained person can actually pass out at 4 to 6 G and the rollercoaster it happened on reached 5 G. Also at the time my fitness was pretty poor so it looks like it was must have just been normal?

Does this sound correct or am i completely wrong here?

Thanks

[BEagle]

Any untrained person exposed to 5G would probably 'grey out' as you describe. That's not the same as G-LOC which is a much nastier thing altogether and happens after the high-G exposure, not during it.

I certainly 'greyed out' at the age of 15 on an exciting ride. In the coal-hole of a Sea Vixen at the Farnbrough Airshow during a simulated attack. I remember thinking that it was like looking through a net curtain at the world outside.

God knows what nanny-state rules that would break today!

Don't worry - and get as fit as you can before you join. They seem to like that these days....

[lightningmate]

05c4r

Unprotected, relaxed +Gz tolerance measured on a man-carrying centrifuge can be as low as +3.5Gz. Mine certainly is/was when I was involved in such things. Most people are not relaxed, either on a centrifuge or a ride, so any vision loss for most people is likely to occur at higher +Gz levels, ie +4-5Gz.

I think you quite safe to assume your response was normal.

lm

[maxburner]

..............besides, after training you will have acquired God-like qualities not enjoyed by mere mortals. Now, where did I leave my invisibility cloak ..........

These days, after driving a desk for a while, I'd black out climbing into my G pants. Don't worry, sit back and enjoy the ride.

[RETDPI]

As Lightningmate has pointed out, a healthy young person greys, then blacks out out around 3-3.5g. Incidentally in a centrifuge with g gradually being increased following the loss of colour perception and encroaching tunnel vision, one can actually be fully conscious with a total vision loss before actual loss of consciousness occurs.
A higher g tolerance in a young person could actually be a very bad sign since one's tolerance is partly dictated by the elasticity of the blood vessels. Thus we older individuals often have a higher g tolerance as arteries harden with increasing age.

[6Z3]

Did you remember to grunt?
During my attempt at the 'Recovery from the Vertical' exercise on the JP many many years ago when BEagle was a stude, I carried out the recovery iaw the instruction except that I continued to pull, through the horizon straight back to the vertical, whereupon my instructor took control. What happened? I'd blacked out pulling no more than 4G, why? Well there were probably a number of reasons, three of which were:
Heavy weekend
No breakfast
Didn't remember to grunt

Try grunting next time

[threeputt]

05c4r

In addition, G tolerance is governed by the distance the brain is away from the larger of the major blood pumping organs of the body! With most people of your age this distance is quite large (and unless corrected can lead to blindness and hairy palms!). In taller people, the heart has to work far harder, under G forces, to get the blood to the brain.
I was a nav on GR1's and, at 6'4''/193cms, was taller than average.
My personal grey/black out limit seemed to be about 4-4.5, dependant on the pilot telling me when he was going to pull some G's, so that I was prepared and could strain against it. I remember one trip at Chivenor, during my Hawk training course, flying with Tom Leckey-Thompson as baggage in his boot during a staff 4v1, when I spent the entire 45 mins unconcious! He took off, loaded up the G's and that was it, 3P asleep in the boot.
I concur with the coments about fitness, I wasn't, I smoked like a bonfire and drank far too much to be as fit as I should have been at that period of my life (it got worse later in Germany).

You will be fine, trust me.

3P

[teeteringhead]

BEags

I certainly 'greyed out' at the age of 15 on an exciting ride.

... I'm sure the appropriate (well, appropriately puerile) response is: "fnarr fnarr"

[Snow Dog]

05c4r

Have no worries. The sensation is entirely different when it is you pulling the 'g's. If, and hopefully when (despite all these threads - it's fantastic here), you get in, all the training ticks along so that you hardly remember the exact point you became a g-monster.

I would take reassurance from the fact you didn't suffer motion sickness!

Dog

[05c4r]

Hi, thanks so much for all of your responses! Im glad it is a natural reaction; my main concern was that what if a persons G force tolerence is something that you are born with and you cannot increase, which i can now rest assured is not the case.

Once again thanks alot for all of your replys!

[[email protected]]

I trust you have now learned that the greying out/ blacking out is the blood rushing away from your head not towards it

[OCCWMF]

When the tutor first came in (no g limit) I did a solo max poss rate turn and lost all vision going through 2000' at 6.8g. Logic said that if I relaxed I would get my sight back at about 200' in a steep dive (I'm not that bright) so I held the g and rolled off some bank. Waiting for the engine note to change to signify a climb was then a slightly uncomfortable time. Got all sight back climbing through 1500' and vowed that I would never try to beat other peoples challenges again - only set them.

Vitamin g is essential for healthy pilots.

[Ex F111]

Are you big and fat and ate too many burgers and super-sized fries on the holiday??

A 'Slightly' stocky build is actually an advantage to G tolerance, but a body with the size 99,000 may not!

[05c4r]

No i wasn't fat at all; just had'nt done much excersise for quite a while.

[chevvron]

Had a ride in a 2-seat Hunter once with no G suit; as we pulled though a loop, I greyed out at 5.5g.