PHAK outdated Gyro Precession Explanation
Posted by Crustytoeskin@reddit | flying | View on Reddit | 16 comments
The book talks of turning a bicycle.
Gyroscope precession has very little impact on the turn.
They turn because you countersteer and cause the wheel to fall into the turn.
You then have a balance between centripetal force and gravity.
My understanding is precession has a little to do with yawing the wheel from counter steer towards to direction of the turn, but this is a very small percentage of the forces that cause the turn.
Goop290@reddit
Next they will say a bike doesnt balance due to rigidity in space but angular momentum..
Getting to nitty gritty. The phak is made for all people in all walks of life. Its simplified.
Crustytoeskin@reddit (OP)
The phak isn't simplified, it's wrong. That's my point.
It's not terminal. It can be saved
JSTootell@reddit
I took the MSF course to learn how to fly.
Crustytoeskin@reddit (OP)
Did they explain how a bike turns like a attitude indicator? 😁
pilotjlr@reddit
Lots of stuff in there are either outdated or oversimplified to the point of being wrong. Another example is how lift is created. Another example is a whole lot of the aeromedical chapter. It can be really funny if you discuss that with a doctor who’s read that chapter. I’m told a lot of it is 1950’s information.
Crustytoeskin@reddit (OP)
What's incorrect about how lift is created? If I recall, it discusses both newtons 3rd and Bernoullis. Which I believe to be how lift is created.
I did find the section on arms, moments and datums misleading. They explain as if the datum line on on the CG.
At least as far as I've read.
rkba260@reddit
Then you should read more, because neither one is accurate.
See NASA website for 'flow turning'.
WhiteoutDota@reddit
The PHAK is not wrong, just highly simplified. Flow turning is just an application of newtons 3rd law
Crustytoeskin@reddit (OP)
And Bernoullis from my quick googling
Due-Letterhead6372@reddit
Let me introduce you to my friends Navier and Stokes
pilotjlr@reddit
It’s not wrong, just oversimplified. Wikipedia has a good explanation once you get past the “simplified” section: https://en.wikipedia.org/wiki/Lift_(force)
It’s not necessarily a bad thing. When asked about lift in a checkride, we just say “newton’s third” and “Bernoulli”, and then the examiner nods and moves on.
joku249@reddit
The PHAK, especially the aerodynamics chapter, is so incredibly oversimplified, its often just straight up wrong. I go insane every time I read "centrifugal force."
flightist@reddit
People probably ought not to be using the PHAK to learn to ride a bike.
Crustytoeskin@reddit (OP)
Or to explain how one turns.
FlyingDog14@reddit
Don’t worry about it, answer questions in this industry the way the books say. Cooperate to graduate.
rFlyingTower@reddit
This is a copy of the original post body for posterity:
The book talks of turning a bicycle.
Gyroscope precession has very little impact on the turn.
They turn because you countersteer and cause the wheel to fall into the turn.
You then have a balance between centripetal force and gravity.
My understanding is precession has a little to do with yawing the wheel from counter steer towards to direction of the turn, but this is a very small percentage of the forces that cause the turn.
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