Gyroscopic Precession

[propjob]

Those Gnome rotary-powered WW1 fighters also moved 90 degrees from whichever way the stick was pushed or pulled because of the gyroscopic effect of the rotating cylinders.

Art

[mgh]

Those Gnome rotary-powered WW1 fighters also moved 90 degrees from whichever way the stick was pushed or pulled because of the gyroscopic effect of the rotating cylinders.

Art

They didn't.

[NikeHerk67]

Hey Flight Simmers!

It has been a long, long time since I took high school level Physics. I am currently studying for a pilot's license and really want to make sure that I understand how gyroscopic instruments work. !

An interesting discussion........

I saw this question asked in a Physics discussion forum back in 2005 and all the answers were incorrect.
"The question was "how does a gyroscope start precessing in the first place?" http://www.physicsforums.com/archive...p/t-75134.html

So when the toy gyroscope is made to spin, exactly what really does cause it to start precessing in the first place?

The answer is simple, and to understand it will answer the question.

First of all, if gravity itself was the only force (torque) being placed on the gyroscope it just simply would not start to wobble until it slowed down and simply fell over, which has nothing to do with gyroscopic precessing.

The fact that the earth is spinning at approximately 1000MPH and rotates 360 degrees every 24 hours places a torque on the gyroscope's axis by changing its orientation in space, which has nothing to do with its verticle orientation to gravity when you set it down.

The same is true with the gyrocompass. For instance, a gyrocompass is oriented to true or magnetic north, whichever is preferred. In the early, mechanical only, gyrocompasses they had the problem of what is known a gyroscopic drift. The gyrocompass wants to maintain its orientation, but the rotation of the earth is playing on it as well. Gyroscopic precessing is an ever so slight a torque, but a force to be reckoned with none the less, as they say.

Perhaps this will help you understand.

[mgh]

Not surprisingly gyroscopes simply follow he basic laws of physics.

1 A perfect gyroscope with no friction or losses will remain pointing in the same direction in [b]inertial[b] space until some external effect acts on it. The earth however moves in inertial space so the gyroscope will change its heading relative to earth over time. Many science museums have a Foucoult Pendulum to demonstrate this a effect. A long pendulum is set swinging along a fixed line set in the floor As time passes the line the line pendulum swings on rotates in relation to the initial line. In fact the pendulum's still swing in the intital direction but the earth has rotated areound it.

2 The relationship between precession and torque is determined by the law of conservation of momentum. Basically, this requires that if a gyroscope is spinning at an angular velocity, wx, about the x-axis and the moment of inertia of the gyroscope about that axis is I then the the relationship between the applied torque about the y-axis, Ty, and the angular velocity of precession about the z-axis, wz, is given by:

Ty= I. wx.wz

where the 3 axes are at right angles (orthogonal).

[rockinrobin]

Like I said, go to a toy store and by one...(or do the math!)

[mgh]

The maths is quite simple as shown in the attached sketch, remembering that:

1 - angular momentum is a vector quantity and has magnitude and direction and,

2 - torque equals time rate of change of angular momentum

[NikeHerk67]

Hey Flight Simmers!

It has been a long, long time since I took high school level Physics. I am currently studying for a pilot's license and really want to make sure that I understand how gyroscopic instruments work.!

Since you're studying for your license and want to understand how the aircraft instruments work, here's some real good reading material, as well.

http://en.wikipedia.org/wiki/Heading_indicator

Also, scroll down to References and read:

"How Aircraft Instruments Work." Popular Science, March 1944, pp. 119, bottom half of page.
Very well illustrated for its time.

Also read about what can go wrong.........pilot error.......
NASA NASA Callback: Heading for Trouble, NASA Callback Safety Bulletin website, December 2005, No. 305. Retrieved August 29, 2010

My understanding:

If I apply a force (G) to turn the instrumental 90 degrees to the left along pivot point F, based on the laws of precession, the rotor will also turn 90 degrees along C-D to the left. So now the rotor will be parallel to the applied force and spinning "flat faced".

Correct/Incorrect?

I'd say incorrect: When you say you're tuning the instrument, yes you're turning the "housing of the instrument, but the gyros remain stable.

The reason gyros are used in any application are to offer stability. As you pitch, yaw, and roll the aircraft, the instruments take samples and the gyros keep the readings steady i.e. the compass, bank indicator, and the attitude indicator or "artificial horizon."

If you want to test your CFI's age, call the attitude indicator the "artificial horizon."
Back in the early 70's, when I first took a flying lesson, if I asked what my "attitude indicator" was, my CFI would have thought I was talking about the way I was behaving.

[Aarinu]

The same can be done on a bike. When a bike is in motion its wheels become like gyros.When you desire to turn on a bike you just lean into the direction you desire to go and the wheel and bike will turn in that direction.

Motorcycles are a good way to understand this. Motorcycles above 15 mph are actually steered backwards or counter steered. To go right, push right, turn left, push left. Look up countersteering on youtube

[mgh]

Motorcycles are a good way to understand this. Motorcycles above 15 mph are actually steered backwards or counter steered. To go right, push right, turn left, push left. Look up countersteering on youtube

How did I manage to ride and race motor bikes without knowing that?