The Good Pain of Pulling Gs
Of all the facets of my flying missions and adventures, as I get along in life a bit, I think I most miss the feeling of pulling Gs.
The movie Top Gun Maverick did a pretty good job of showing the challenges and thrills of fighter operations. I enjoyed the heck out of the movie. The movie made viewers aware of “pulling gs” which occur when you aggressively maneuver in a fighter jet.
A “G” is the force of gravity. We go through life every day at one G. Each G when maneuvering an aircraft equals added force equal to another gravity. So, a pilot who weighs 200 lbs pulling a 3-G turn would have to function while experiencing the equivalent of weighing 600 lbs.
To aggressively turn an aircraft, you must “pull Gs.” There is much to cover about what pulling Gs means when flying high-performance aircraft.
Before the F-16 joined the Air Force in the late 1970s, fighter aircraft had G-limits in the 7.0 to 7.5 range. The F-16 was the first jet with a 9.0 G-limit. More on that, a little further on. The OV-10 had a limit of 6.5 Gs. The G-limit is how many you can pull without causing structural damage to the aircraft.
As fighter pilots, we wore a g-suit to help cope with high-g maneuvering. The g-suit was like a pair of chaps with bladders in the legs and waist. The suit plugged into a valve in the cockpit, and, when you pulled Gs, the suit would be pressurized with air.
The physical effect of pulling Gs is that the forces push the blood in your body to the lowest extremities. I like to say that pulling Gs makes your blood go from your brain to your ass. It doesn’t take a lot of Gs, maybe 4 to 5, for an untrained person to pass out. This is called g-induced loss of consciousness, or GLOC.
If the Gs are immediately reduced, it can take 60 seconds or longer to regain consciousness. If you are flying in a single-seat fighter traveling at up to 1,000 feet per second, you can see why experiencing a GLOC would be unacceptable.
To counter the effects of high Gs, I (like all pilots) strain against the G-suit and tighten my chest and diaphragm with a Valsalva maneuver. This maneuver is like a grunt from deep in your abdomen, but not holding your breath.
With practice and experience, a fighter pilot can operate under the high g-loads of modern jets. In the OV-10, we didn’t wear G-suits and had no problem with the 6.5 G limit. When I flew the F-16, it would start to get painful at about 7.5 Gs. It was not significant pain, but I used it as an indicator that I didn’t have much more G capability available to turn harder.
Narrowing of vision was another effect of high-g maneuvering. We called it tunnel vision. As the Gs increase, your field of vision gets smaller and smaller. Keep pulling and your vision could go down to a spot of light and then nothing. We called this a grayout. It was also a big sign to back off on the Gs. No one still alive knows the margin between a gray-out and GLOC.
This post turned into quite the ramble. In an upcoming post, I will discuss how G-forces are used when maneuvering. Lots of good mathy stuff. But it’s fun math. Of all the facets of my flying missions and adventures, as I get along in life a bit, I think I most miss the feeling of pulling Gs.
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We less fortunate have diluted G forces- as babies, most of us enjoyed the toss-and catch, and I suspect the ones that loved the‘flying’ sensation the most are driven to buy Corvettes or 911s. Pat Bedard wrote about our desire to feel those lovely G- forces.
I give you a lot of credit Tim it takes guts to this. I would have to wear a diaper LOL.