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G load with Pitch Rate

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G load with Pitch Rate

Old 10th Feb 2021, 11:29
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G load with Pitch Rate

G’day All,

From my ancient memory I believe you can compute the G-load at any instant, as long as you know the TAS and pitch rate.

Probably isn’t that simple, so would someone please be kind enough to give an example with the actual parameters, numbers and units.

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Old 10th Feb 2021, 18:08
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I'd assume you'd (at least) also need bank angle...
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Old 10th Feb 2021, 19:50
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Just `google` aviation calculations`...several websites....
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Old 10th Feb 2021, 20:14
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Maybe turn rate is better than pitch rate for sustained gee, but the rate plus TAS should give
good gees for short time frame.

The roll and pitch angles can get more accuracy, but all that does is account for the one gee from mother Earth.

a good rule of thumb equation I have used gives surprisingly good numbers for air combat maneuvers as God's gee is not as big a player at obscene bank and pitch angles

gee= v^2/turn radius and you get radius by using tas/rate

Edwards and Pax grads can contribute.

Last edited by gums; 10th Feb 2021 at 23:13. Reason: added bazonga
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Old 10th Feb 2021, 22:57
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Originally Posted by CantRemember View Post
you can compute the G-load at any instant, as long as you know the TAS and pitch rate.
What'd be the G load when breaking into a high speed stall? Or any stall for that matter. Pitch increasing, AoA through the limits and, ... G?
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Old 10th Feb 2021, 23:10
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This should get you going: https://www.jhuapl.edu/Content/techd...01-Bythrow.pdf
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Old 11th Feb 2021, 01:27
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Thanks, Pilk, a great read about flying.

@ Detent.....

You can stall or "depart" at many speeds depending on your ride. Right? So I guess that is what you are getting at.

Biggest lesson I learned was use of aileron at high AoA could have a bad outcome due to adverse yaw or other gremlins. Also learned that wing rock and hard burble was not a good thing.

I always helped my students get to the stall/departure boundary in a disciplined manner so they could "feel" things. Some never could, and others flew like Yeager, heh heh.
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Old 11th Feb 2021, 02:36
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Just saying that if G could be determined directly from TAS and pitch rate, it would need to be solely dependent on those two variables. Rubbish.

g = 1/cos(bank) ? (in a level turn)
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Old 11th Feb 2021, 02:42
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Try this:

Aircraft Turn Information Calculator

Computes a range of turn statistics - including g rate - using entry speed, stall speed, and bank angle.
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Old 11th Feb 2021, 13:18
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Originally Posted by FlightDetent View Post
Just saying that if G could be determined directly from TAS and pitch rate, it would need to be solely dependent on those two variables. Rubbish.
In fact those two parameters are neither necessary nor sufficient.
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Old 11th Feb 2021, 13:30
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Thanks All, in the background was a questionable rule of thumb given to me some years ago about a suggested pitch rate that would stop people and carts getting airborne in a nose high upset recovery. With TAS as a parameter, there can’t be a one size fits all answer at all levels. I heard the guidance again on a UPRT video and this promoted me revisiting it.
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Old 11th Feb 2021, 16:39
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Mucho thanks, Pearly!!! I tried the calculator using F-16 and F-35 demo maneuver numbers and the numbers agree very closely to my approximation numbers. Because the bank angle is extreme, you will get a warning from the program. Pay no attention, just enter the numbers.

Gums' equation is gee=vee^2/radius and entry is at 360 ktas and 9 gees. The calculater entry should use the 360ktas and 83.7 deg angle of bank. Use 130 kts for stall just to make the calculator work. Walla! you get almost the same radius and gee. So close I think I screwed up, but I have run that simple equation versus tech order performance charts and had about same results.

For airliners you prolly have to use normal bank angle correction for God's gee, but I covered that already, and the famous "egg" that describes a constant gee loop will make the point. Your radius on the top is less than at the bottom due to God's extra gee toward the Earth. This was easy to demo in the Viper 'cause you could trim the sucker for 3.5 gee. Then get to maybe 400 knots wings level and let go, sit back, and watch as it did the loop. Got to see the limiter in action over the top, but confirmed several aspects of flight dynamics and the flight control system.

Last edited by gums; 11th Feb 2021 at 16:42. Reason: added number
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Old 11th Feb 2021, 19:14
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Originally Posted by CantRemember View Post
Thanks All, in the background was a questionable rule of thumb given to me some years ago about a suggested pitch rate that would stop people and carts getting airborne in a nose high upset recovery.
Thanks for clarifying that you are not looking at a scenario involving bank, only pitch.
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Old 11th Feb 2021, 20:27
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Dave

My frame of reference is up/down/left/right/forward/backward when sitting in the front seat ( hopefully the only seat, heh heh).

Go to the calculator that Pearl posted. Sure, at benign bank and pitch angles you might get a tenth of a gee delta versus my equation, an remember that I use rate as derived to get radius and in a zero gee frame of refernce . It's what you feel in the seat and what your gee meter reads in this discussion, huh? It is also what your wings are contributing in the "z" axis.

I think our thread starter was looking to my view - what you feel and what does the gee meter read?
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Old 15th Feb 2021, 21:56
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I'm unfamiliar with an easy way to work this out

Assuming there is 0 deg AoB / Sideslip, load factor will depend on: velocity (in both x and z body axis directions), acceleration (in both x and z body axis directions) and pitch rate (q). If the reference point (i.e. the location of the cart) does not coincide the CoG, pitch acceleration (q dot) will also play a part.

A level banked turn is quite straight forward. This scenario is a little more complex.
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Old 15th Feb 2021, 22:59
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Good stuff to tink about. Reynolds....

All of the body rates are in play, and then we take out God's gee. That's what the eventual flight path will produce with respect to mother Earth.

The thing is, what does the gee meter read, the way I read the original question. Correct?

Lotta difference between the gee on you depending on frame of reference ( not going into relativity theory and speed of light and....).

All the inputs Reynolds mentions are in play, but what you read on the gee meter and feel in the pitch axis is primarily a function of speed along one axis and rate along another that you are presented with sitting in row 0, seat A. A level turn at normal bank angles in a big plane or even a C150 will not give you many gee. Go to 60 deg of bank and you will get the two gees that the equations tellya. Keep banking to keep level and you get the number I got using that URL calculator for turn performance. If you devolve all the angles and coordinate frames, you will get to basic pitch rate corrected for angle of bank and pitch attitude WRT Earth ref system. Until you get down to 30 or 40 degrees of bank with pitch less than +/- of 20 deg or so, then I'll use my rule of thumb.

Best I recall, what you and the plane "feel" is the gees that you should pay attention to in order to keep from ripping the wings off, huh?
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Old 16th Feb 2021, 15:49
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Over on the "military" forum a discussion about turn rates and such.
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