Blood Pressure and g-Loading

RVSM

Member
Hello Flight Surgeons:

I have a question related to aerobatic flying.

What (if any) relationship is there to high-blood pressure (or, elevated blood pressure) and the high g-loading experienced when doing aerobatic flying? As anything been empirically documented on this and what's the going theory/philosophy for people with higher blood pressure who do aerobatics - should they abstain?

My concern (obviously) is that elevated blood pressure could lead to lower g-tolerance and easier black/red out situations in-flight. It is my uneducated guess and I'm looking for studied information on the subject, if such studies exist.

I don't have either high blood pressure, or diabetes. However, I do have a family history of high blood pressure and diabetes at the second and third previous generations. Thanks.
 
Thanks for the reply.

Might you know whether or not there have ever been any studies (official, or unofficial) of the same, that revealed "no evidence" and/or no correlation?
 
I'm not a physiologist or a doc, but have done plenty of training on the subject (to include the centerfuge and annual refresher briefs on the subject). They say that there is somewhat of a correlation between shorter stalkier guys having a higher resting G tolerance than lankier folks. Folks that don't overdo cardio do a little better. In theory, a guy with blood pressure on the high side of the "healthy" range will naturally have a higher resting G tolerance than a guy with very low blood pressure. That all being said, this is splitting hairs. When I did the centerfuge back in the day, all 6 of the guys I did it with had nearly identical resting G tolerances (around 4.5).....and we were all different in physical stature and presumably other physical attributes. The things that matter are 1) how recently and how often you expose your body to g-loading, and 2) things like hydration, good diet, exercise, etc. Personally, I very regularly (as in on a daily basis) see 7+ G's, and spend plenty of time above 4-5 G's. I'm a skinny guy with low blood pressure, but I am very adapted right now. When I go several weeks without doing it, the tolerance drops noticeably. If I'm dehydrated/tired/etc, it is also noticeable. I'm going to say that your health is a little less important than how often you do it, and how well rested and hydrated your body is at the time.

* When I say resting G tolerance, I mean the amount of G-loading your body can take without experiencing the effects of greyout/ tunnel vision, etc.
 
Back in the day, the guys who had the best G tolerance in my squadron were typically the short, chubby smokers who had high blood pressure and could barely pass the PT test.

For the OP, not something I would be concerned with, especially given the amounts/durations of G that you will likely experience in civilian aerobatics.
 
I'm not a physiologist or a doc, but have done plenty of training on the subject (to include the centerfuge and annual refresher briefs on the subject). They say that there is somewhat of a correlation between shorter stalkier guys having a higher resting G tolerance than lankier folks. Folks that don't overdo cardio do a little better. In theory, a guy with blood pressure on the high side of the "healthy" range will naturally have a higher resting G tolerance than a guy with very low blood pressure. That all being said, this is splitting hairs. When I did the centerfuge back in the day, all 6 of the guys I did it with had nearly identical resting G tolerances (around 4.5).....and we were all different in physical stature and presumably other physical attributes. The things that matter are 1) how recently and how often you expose your body to g-loading, and 2) things like hydration, good diet, exercise, etc. Personally, I very regularly (as in on a daily basis) see 7+ G's, and spend plenty of time above 4-5 G's. I'm a skinny guy with low blood pressure, but I am very adapted right now. When I go several weeks without doing it, the tolerance drops noticeably. If I'm dehydrated/tired/etc, it is also noticeable. I'm going to say that your health is a little less important than how often you do it, and how well rested and hydrated your body is at the time.

* When I say resting G tolerance, I mean the amount of G-loading your body can take without experiencing the effects of greyout/ tunnel vision, etc.


That's a very interesting post, thanks for the feedback.

I'm more on the eh'em stocky side of the equation. I ran track and played football mostly in my earlier years, but stayed in the weight room on a fairly decent basis. I stopped lifting weights seriously when I stopped playing ball - there was simply no reason to continue lifting weights on such a regimented basis anymore (5 days a week). Work over the years, has also stolen a tremendous amount of time away from maintaining a more regimented running routine, but I still manage in the range of 3-5 miles a week. I have not had a physical check-up in ages and I am a poor example of routine follow-ups at the Doctor - mostly because every time I went, they always said I was the model of health. You keep hearing that enough and you stop going to the Doctor for routine physicals.

I have no idea what my g-tolerance might be. Too bad there is no local centrifuge managed by a "certified" organization where stuff like that could be evaluated. The only way to know for sure, is to go up and pull some g's with an aerobatic pilot. I've heard of aerobatic performance competition pilots talk about the need to build-up their tolerance after taking some time off - like after coming back to competition from the off-season. So, your point about ramping up the loads does seem to make sense.

I'm quite a ways away from doing any solo aerobatics, but I do need to start thinking about things and preparing as much as I can for them before I get there. The basic health stuff like eating right, staying hydrated, etc., all make sense as well. However, on the surface, it initially seemed to me that having higher blood-pressure, would be a problem on the "Red-Out" side of the equation, as opposed to the "Gray-Out" side. I had not thought about it the way you explained it.

I've also read that Women, have a naturally higher tolerance for g-loading than do Men, and that it had something to do with their overall physique and their height to weight ratios.

Thanks!
 
Back in the day, the guys who had the best G tolerance in my squadron were typically the short, chubby smokers who had high blood pressure and could barely pass the PT test.

For the OP, not something I would be concerned with, especially given the amounts/durations of G that you will likely experience in civilian aerobatics.


I was hoping to be able to operate something with a bit more sustainability down the road. There are a variety of L-39's out there now, and there are some viable options for the T-38 and the F-5B. From what I understand, there are a few AlphJet possibilities as well. Actually, there are a lot of "old" jet warbirds out there and available, or that will come available at some point. But, I'm a more "modern" jet warbird kind of guy.

Having said that, the vintage category of warbirds is awful difficult not to like as well, with the Hawker Sea Fury and the P-51D, rounding out my list of the best and most desirable. The problem with buying any aircraft is getting up to speed on the physical status of the aircraft, its true history as opposed to the one the seller wants to tell you about and the psychological trust factor that the airframe is truly sound and ready for several years of more service. This especially applies to the warbirds. For me, the trust factor is the biggest thing of all. Can I trust the seller, airframe, engine and can I trust the price is right. Seems like a lot of homework.

I just love Aviation. There's so much to explore!
 
If you are talking about training category jets, I wouldn't worry a whole lot about G's. Yeah you can snap on probably a decent load in any of those jets, but they are going to bleed down relatively quickly unless you are doing something with a lot of "god's G" (aka gravity) helping you out like some real fast nose low pull outs. They just don't have the thrust to weight ratios to sustain big amounts of G for a long period of time. I've never flown an F-5, but I have fought them plenty, and while nimble and hard to see, they can't do a level 9 G break turn all day long like an Eagle/Viper/other combat jet. Little lightweight exhibition airplanes with real powerful recip engines are going to more than likely work you out a lot more.

Also, the recency of your experience is pretty big. Your body adapts quickly to repeated exposure, but it also loses this pretty quick too. I'd say that if I go more than 4-5 days out of the cockpit, I notice a fairly significant loss of tolerance like greying a little and having to strain a lot during the 4-6G "G-WARM" we do at the start of every flight, where I normally don't even notice anything aside from having to tense up my legs a little during the 6G peak pull if I'm current.
 
Most warbird owners take it very easy on the G, for a number of reasons.

Yeah I was referring more towards some of the crazy little non warbird airplanes flying the airshow/demo circuit. But I can imagine that those warbirds are probably about as long in the tooth as many of the guys flying them :)
 
Yeah I was referring more towards some of the crazy little non warbird airplanes flying the airshow/demo circuit. But I can imagine that those warbirds are probably about as long in the tooth as many of the guys flying them :)

Well, the real issues are:

- Many owners don't know exactly what the airplanes have been through during their operational history, nor the metallurgical condition of all the key components (especially an issue with North American products, where there are known historical problems with intergranular corrosion on vital airframe parts, like the longerons). Let's not forget that these aircraft were originally built during a war emergency and weren't exactly expected to still be yanking-and-banking 60+ years later. The workers did not build for long-term protection of internal components. A fatal T-6 crash several years ago was the result of both corroded structural parts and an operational history of improper aerobatic flight (as in, over Gs and asymmetric over Gs that weren't given due maintenance attention) -- the wing came off in flight.

- At the prices these aircraft are worth today, their relative rarity, and their historical significance, the financial cost of breaking something (including the airplane itself) just isn't worth it. If you want to go G your lips off, there are much safer and less expensive ways to do it than in a Mustang or a P-38.
 
Go buy a used MiG-21... I see those things around for relatively cheap. Good luck on the gas and engine overhauls though. I remember hearing somewhere that the engine on the MiG-21 was built to be used for a short period and then just thrown out and replaced. Relatively cheap operating costs from a national budget standpoint.
 
Back
Top