Hi,
I discovered this link when conversing in a different thread, and thought it had value of a general nature when trying to understand effects of G forces, so I am posting it here. Very informative, and entertaining too!
Enjoy,
Rick
Typical contest flight in the Pitts S1S or S2B was 6G. When I started flying the Sukhoi I very quickly started pulling as much as plus 11 and negative 8.5. Because of the differences in the seats, 6 G's in the Pitts always seemed harder for me than 10 in the Sukhoi. A 10 G 90 degree corner is over so fast in the Sukhoi you hardly notice it.
Damon as always has some very concise information, I would only add that I think being tired and hungry is a big factor. I really run out of energy when my blood sugar is low. For contests I always had a good supply of high energy snacks.
Try a 1V1 with a Raptor....
V/R
Smokey
PS: You haven't lived until you have someone trying to kill you...
Try a 1V1 with a Raptor....
V/R
Smokey
PS: You haven't lived until you have someone trying to kill you...
Here's a weird one:
- 6-9 Gs in a centrifuge sucks. I mean, everyone single one of those Gs just plain hurts. Doable, but an all-around miserable and nauseating experience.
- 6-9 Gs in the aircraft is a workout, but strangely enough it's an entirely different endeavor. That's because by the time you've worked up to the G over a few weeks and become sufficiently familiar with the muscle memory and the physical tasks (proper breathing, G-straining maneuver, etc), it is far easier to take into stride. Pulling Gs becomes a secondary task, like balancing on a bike, allowing you to concentrate on the primary task (killing the bandit, flying formation, etc).
Fighter pilots and WSOs run into trouble when the G-strain tasks become so second nature that they over-prioritize other tasks at the expense of the G-strain's required effort: The quality of their G strain backs off and they don't get/keep enough oxygen-rich blood to the brain. WSOs sometimes G-LOC because they can't always anticipate the pilot's high-G pull: They're immediately behind the G in the strain and can't push the blood back up to their brain (remember that when carrying a passenger in the RV-4, 6, 7, or 8). Some of you hit on other key aspects like hydration, nutrition, fatigue.
Pulling Gs is like shooting a nice firearm: It makes for absolutely thrilling sport, but you cannot just pick it up and pull the trigger...you MUST know how to do it first. Searching through "centrifuge training" on YouTube will give you an idea of the sort of effort required to pull just 6 Gs. (Warning: Viewing YouTube videos on centrifuge training does not constitute valid computer-based training ).
There are a few of us here in the VAF that work this issue quite often: I'm the Air Combat Command Director of Safety, and Paul Gardetto and Bruce Edwards are physiologists/flight surgeons here at the ACC Surgeon General. Feel free to ask us about Gs, pilot physiology, and their applications to aviation safety if you have a question...that?s what we do.
Try a 1V1 with a Raptor....
V/R
Smokey
PS: You haven't lived until you have someone trying to kill you...
Okay, Scroll,
I'll take you up on that offer.
I punched my ticket on the centrifuge ride when I was 45 or so. Probably not the smartest thing to do but I wanted it and it was required for where I was headed.
I don't recall seeing any data on age vs G-tolerance and when the risk of X amount of Gs becomes prohibitive, individual tolerance not withstanding., i.e pull on the aorta, etc.
Any comments?
Dave A.
6A build
This might be slightly off topic but..
The article was interesting, and it got me thinking about what sort of impact G forces our RV's are built to. If you took the "outdated military standard" of 18G's, and used a 200lb pilot, could the standard vans restraint system hold up? In other words, can the seat belt mounts take a 3600 lb load? What about a 10K lb load (50G's)?
I would guess the belts and cables could, but what about the aluminum it is all mounted to?
I am not an engineer, so I would find it amazing that such a light structure would hold such a heavy load. Imagine a large SUV hanging from your seat belt!
Folks,
Beers on me for the way-delayed response. Bugsy, FM, and I have been scattered to the 4 corners, juggling chainsaws, etc...pick your metaphor.
OK, I owe answers.
Damon--Negative Gs:
Most recent research confirms that negative Gs still suck. They're just painful, and the pain level is the limiting pilot on the pilot (unless you reach the airframe negative-G limit first). There are no effective G-strain maneuvers to mitigate the effect.
However, there is one new finding that high-performance pilots should pay attention, particularly in the sport pilot aerobatics area: The push-pull effect on the resting G tolerance window.
Every pilot has a resting G tolerance. That means if you slowly increase the G (say, 1/10 of a G per second, or one full G increase over 10 seconds) and DO NOT employ a G strain maneuver, the body will compensate with higher blood pressure and increased delivery to the brain. At some point, the body can't quite meet the demand and the pilot must strain. That's the resting G tolerance. In my last centrifuge spin, my resting G tolerance was about 5 Gs. Thus, my resting G tolerance window is 5 - 0 Gs, or a 5 G window.
The problem: That window slides left if we push negative Gs. So if I push to -2 Gs, my resting G window's top end is now at +3 Gs (-2 +5 = +3 Gs). If the pilot plans to execute a push-pull type maneuver transitioning quickly between negative to positive Gs, he must be prepared to execute a G strain at a lower positive G than he's/she's normally accustomed to. Otherwise, he's in danger of GLoC at a lower G than normal.
Dave--Older Pilots and Gs:
No new research here, but the existing research is still sound. As we age...er, season, our normal G tolerance decreases. Many factors impact this for good and bad: fitness, hydration, cardio vascular health, and particularly our frequency of exposure to Gs. We can keep our resting G tolerance up through good living, but we really have to anticipate G onset because the 'seasoning' body's ability to react to Gs decreases with age. The top-end G tolerance also decreases, and there's only so much a good G strain can do to combat GLOC in any pilot but particularly
Did I answer your questions? Again, sorry for the late reply.
Hey, very cool, thanks for checking on it!
I noticed I had more trouble on the push pull type of maneuvers if I held negative G, even as little as -1 negative G, for a longer period of time, say 6 or 7 seconds, and then pulled 4 or more positive G quickly thereafter. A maneuver like a square loop.
On something like an outside snap an a downline, with a pull out, you might hit 4 or 5 negative G in the snap, followed within about 2 to 3 seconds seconds a +6 or +7 G pull. That seemed to be easier to deal with than my first scenario. The snap hurts though, good to know research confirms they suck!
What I would really be interested in would be any further research into "the wobblies" (g induced vestibular dysfunction). There were several theories floating around back in the nineties about why negative G would cause this, and what the causes were, but I don't think there was ever anything definitive. Since we sport aerobatic types are the only ones dumb enough to do this negative stuff regularly, I guess it's not worth the time and money to investigate too thoroughly, and I understand that, but I was curious if there had been anything since what we knew in the nineties about it.
Thanks again,
Damon
I can't find anything new in the USAF research, because you're right: Military pilots don't spend much time on the negative side of the G meter. Dr Mueller's paper (published in the 2002 Ear-Nose-Throat Journal) seems to be the latest article to appear in web searches:
http://mvl.mit.edu/JClub/Spr03/MullerPaper.pdf
Thank you for that link, that was very interesting, I had not read that one. Again, no single cause was identified, but the general routine mentioned in the report for trying to prevent GIVD is pretty much what I remember. I suspect I know the pilot mentioned in the study pretty well, he has had that problem since I met him in 1993. He is a very aggressive pilot, started flying in Advanced almost immediately, and has had problems with the wobblies from day one.
It would be interesting to hear if you guys ever do go back and try some experiments in negative G in the centrifuge. The biggest problem with that of course is I guess a professional pilot could be risking his or her career if the symptoms do not subside!
Thanks again for taking the time on this!