G tolerance revisited

Background: just bought an RV-8 and discovered that the combination of back surgery 18 months ago, abdominal surgery a year before that, and fluid on the lungs in the last year had decimated my G tolerance.

Update: Had an unfilled prescription for more physical therapy for my back, so (as somebody suggested) I started that regime. No surprise, my core strength was pretty puny, and the therapist had a whole bunch of not very macho exercises that I could do, even with the limitations of my back. There's been a bunch of progress, and 3Gs seemed doable on a few maneuvers.

So I tried a loop at 4Gs. The maneuver itself was kind of okay, but I had minimal situational awareness during the maneuver, and that's probably not surprising. The SA was nowhere near what it was when I used to fly a Decathlon and check all the parameters all the way around (three decades ago...)

Some abdominal muscles registered surprise at the 4G exertion, and again, that's probably not a surprise. But there was what felt like skeletal discomfort, and that makes me think that post-surgery at age 64, I may have to declare a personal limit of 3Gs.

So what are the entry speeds and techniques for 3G maneuvers in an RV-8? (170 HP, c/s prop, no inverted systems.) All things considered, I'm not willing to go experiment and see what works and what doesn't.

The maneuvers I'd like to do (ha!) are point rolls, super slow rolls, rolling 360s, and tumbling maneuvers, but those aren't RV maneuvers (but they're all less than 3G maneuvers, plus and minus). I've seen positive G four point rolls in a Pitts, but I have no idea how to do those.

Comments? Suggestions? And I think that reality suggests that I be very conservative in my risk management...

Thanks!

Ed

I'm no expert, but my 1st thought is, have you ever botched a maneuver? (I have; see 1st statement.)

Not being able to tolerate 'normal' acro G loads would make me very cautious about doing acro without a check pilot until I'd up'd my tolerance.

FWIW...

Mild Acro

My opinion - You don't need to do overhead maneuvers at 4 g's in an RV. I initially thought so (I'm a former Navy light attack guy with a gazillion 4-g nuke delivery idiot loops to my credit) and explored that part of the envelope in the latter stages of Phase 1.

-8A with a 180 HP non-inverted Aerosport IO 360 and I can do 3 G overheads all day if I pay attention to entry and recovery speeds. 2 1/2 g loops are possible, but need more care. 2 G barrel rolls also easily done.

I practice a lot of slow flight / stalls / spin entries so I know how the plane feels at slow speed over the top if I screw up the entry. I also try really hard not to horse the nose around at slow speed. The old "if it's going to depart let go and wind your watch" has always worked for me in an RV.

Ed_Wischmeyer said:

The maneuver itself was kind of okay, but I had minimal situational awareness during the maneuver.

So what are the entry speeds and techniques for 3G maneuvers in an RV-8?

All things considered, I'm not willing to go experiment and see what works and what doesn't.

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Ed, I must be blunt. From your comments it seems it would not be a bad idea to get some basic refresher aerobatic training. Beginning aerobatic pilots with little experience and confidence are always the ones that seem to be very concerned about entry aerobatic speeds. Why would you be unwilling to "see what works"? There's no such thing as a magic airspeed or technique for doing 3G aerobatics in an RV-8. From cruise flight, pull 3G and add full power up. I guarantee you the nose will come around in some sort of looping fashion. Making it look pretty is another matter. Have you had any spin training...or are you current and proficient with them?

Ed_Wischmeyer said:

The maneuvers I'd like to do (ha!) are point rolls, super slow rolls, rolling 360s, and tumbling maneuvers, but those aren't RV maneuvers (but they're all less than 3G maneuvers, plus and minus). I've seen positive G four point rolls in a Pitts, but I have no idea how to do those.

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Super slow rolls and rolling 360s require inverted systems, and I would strongly recommend against messing with tumbles in an RV.

And regarding G tolerance, it will improve just by way of regular exposure. I promise.

Yes, I know...

Thanks for the concerns, but...
- I've taught basic aerobatics, although not recently
- I've done upright spins in a number of different planes and inverted spins in a Decathlon. I've also seen flat spins, rolling 360s, and shoulder rolls (basic tumbling maneuver).
- I know about not tumbling an RV, hence the "ha!" comment. Same for the other maneuvers. And I would not snap roll an RV, either.
- The reason for not wanting to try things on my own is that I'm not willing to risk a high G recovery from a botched maneuver with a back that might be painful under excessive G loads. I want to carefully expand my comfort zone, even though I would not exceed the airplane's limits.
- I've also published pilot reports on a number of aerobatic airplanes, including handling qualities while doing aerobatics, stick force gradients out to 6Gs, differing stall characteristics with increasing G load, and aileron forces with airspeed changes. Airplanes have ranged from a Europa to a (real) P-51 and a Thunder Mustang.
- But none of that is recent, hence my incremental, slow approach.

I think that the risk of me seriously botching a maneuver is quite low, and part of that risk mitigation was starting with high G turns where 1 G was never far away. That cautious approach is how I learned that my G tolerance was degraded.

But to put all this in perspective - the cautionary comments indicate that this board is a healthy community that looks out for the participants. This is a rare and wonderful attitude, and I commend and thank those who have written cautionary notes on my behalf. Experimental aviation needs a lot more of that.

Hi Ed,

To answer your original question - the bottom line for most all of my RV-8 "Gentleman's Aerobatics" is that if I start with 140 - 143 (kias), I can loop, roll and Cuban all day long and never exceed 3 G's.

Paul

G effects on DDD

Anyone have any comments/info/links to G effects on degenerative disk disease?

I'm looking hard for an 8. What kind of physical exercises or conditioning routine can a non acro pilot do on the ground to get ready for said G forces?

Geico266 said:

What kind of physical exercises or conditioning routine can a non acro pilot do on the ground to get ready for said G forces?

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I've done some spin training and only a little aerobatics, so I am far from an aerobatics expert.

I am, however, a physician with an interest in this subject.

The original post here raises questions about (1.) the importance of the level of fitness and also (2.) about spatial orientation.

I would think that the shoot-from-the-hip answer to your question ("What kind of exercises / conditioning") is that good old fashioned "get in shape" advice would be the most prudent initially. A stronger core -- the muscles that support the abdomen and spine -- is quite important, but overall improved cardiovascular health is also vital. In this regard, younger age is an advantage, as the diminished distensibility of the major blood vessels that occurs with the natural aging process is a disadvantage.

Assessing one's inner ear function (the vestibular system) is important, as vertigo can be a killer. In more extreme aerobatics, "G-induced vestibular dysfunction" (AKA "The Wobblies") can result, but that's probably not an issue with the limited aerobatics done in an RV. More likely, some vertigo and/or nausea may be more likely. Doing aerobatic maneuvers repeatedly (on a regular basis) seems to extinguish some of these unwanted effects.

There are MANY conditions that may contribute to spatial disorientation, including drug reactions, cardiovascular disease, various inner ear dysfunctions, cervical spine disease, various inflammatory or traumatic diseases, or even some allergic disease. By the way, the Navy says that some loss of spatial awareness is a contributor to more than 10% of their fatal aircraft accidents.

So, the easy first answer is that overall better physical conditioning is important, and spending 45 minutes or so per day in the gym and doing aerobic exercise is a good place to start.

Geico266 said:

I'm looking hard for an 8. What kind of physical exercises or conditioning routine can a non acro pilot do on the ground to get ready for said G forces?

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The above post contains great information. However...don't worry about it. If you came to an IAC contest, you might be surprised at how "out of shape" some of the guys look. In reality, for ~4G recreational RV acro, you really don't need to make any special effort to do exercises or get in shape unless you really have some sort of unusual physical issue. Among all my competition buddies, including those flying Unlimited, I'm not aware of any actual exercises or "conditioning" that they do just because they fly acro. The best G conditioning is developing tolerance from actual flying. Sean Tucker does exercises, but he's an old man and you're not him.