The 3DRCForums -Discuss Anything Thread-

[AKfreak]

Your missing the point. Forget about the weight, and forget about the rotation around the string once the wheel is perpendicular to the floor because I'm not talking about the "torque chasing the angular momentum" here (gyroscopic propulsion).... the wheel would spin flat and horizontal to the floor if there were no angular momentum.

So when the wheel hangs from the string and is horizontal to the floor, consider the wheel the propeller on a plane facing straight down to the ground. As the wheel rotation speed increases, the angular momentum wants to force the wheel axle 90 degrees from the string so that the axle is parallel to the floor and perpendicular to the string. So if the plane is still facing down to the ground, the precession wants to move the rotating disk of the prop 90 degrees, which translates to left yaw.

The thing you are missing is the first frames of the video where the wheel is hanging from the sting and not rotating. The difference between that position, and perpendicular position of the rotating wheel, is supported by angular momentum. In an airplane, this force yaws the plane to the left more and more as the speed of the rotating propeller increases. This is one of the other reasons why, in a hover, and with no increases AoA, when you goose the throttle, the plane jerks to the left.

I'll find another video to explain this further.

[video=youtube_share;NeXIV-wMVUk]http://youtu.be/NeXIV-wMVUk[/video]

 

[aronph]

My bad. It's gettin all physicisty uppinHEEYAH!

 

[Bbcorvette18]

Ok, let me ask another way. What happens when Funny Cars drag race? At the beginning of the race, the wheel accelerate at incredible speeds. If precession were acting upon them, then why doesn't the car veer way off course as the wheels spin and slip over the asphalt? SHouldn't the back end of the car slide to the left or right? Or does the fact that you have two wheels at either end of the axle cancel out the precession?

If so, then what about a motorcycle? When you pop the clutch on a Bike, should the spinning wheel slip over the ground and cause the tail to swing to the right?

Uh they all do slide to the left or right depending on many factors like driver or rider input.

 

[3dbandit]

Ok, let me ask another way. What happens when Funny Cars drag race? At the beginning of the race, the wheel accelerate at incredible speeds. If precession were acting upon them, then why doesn't the car veer way off course as the wheels spin and slip over the asphalt? SHouldn't the back end of the car slide to the left or right? Or does the fact that you have two wheels at either end of the axle cancel out the precession?

If so, then what about a motorcycle? When you pop the clutch on a Bike, should the spinning wheel slip over the ground and cause the tail to swing to the right?

I think your asking why the car doesn't slide to the left, breaking free from the road, when accelerating . If so then read here:

On these vehicles there is a noticeable effect of torque, but the high coefficient of friction with rubber tires and the mass of vehicle prevents lateral slipping. A commonly accepted coefficient of static friction for tires against dry asphalt is 0.72. since there is no previous lateral movement, static friction should still apply even though the wheels are rolling forward. If a drag car weighs apx 1100 kg. With G=9.8m/s^2, N(normal force)= 10780newtons. Ff(static force of friction)= N*C. Ff= 7761 meaning it would take over 7761 newtons of continuous force to get the rear tires to slip sideways. That's over 70% of the force exerted by the ground against the tires due to gravity. I would be very surprised to see that much force generated through rotational momentum prior to launch. A funny car puts out apx 9800N/m of longitudinal torque at the wheels; the lateral force from rotational momentum should be far less.


[MENTION=95]Aeroplayin[/MENTION] did I get my math right and in correct context on this. I'm still kinda new to physics...

 

[Aeroplayin]

Looks right to me, but what do I know about hockey?

And if anyone wants to convert force in Newtons to Kg or lbs, just multiply by 0.10197 to get Kilograms and then multiply Kg by about 2.2 to get pounds, so 7761 N = 1745 pounds of force. And Newton-meters should really be written as N-m as to not be confused with Newtons per meter.

 

[3dmike]

GO DUCKS!!! Had a great day yesterday with some friends! Went to my first Ducks football game! I've never been much of a football fan (ya I know I know) , was always more into cars, motorcycles etc. It was fun and the tailgate pregame party, had some crazy good food.

 

[Decal Dennis]

Door skin graphics, picture overlay

Which one do you guys like, top or bottom pic? I'm kinda torn between both of them

 

[gyro]

Door skin graphics, picture overlay

Which one do you guys like, top or bottom pic? I'm kinda torn between both of them

Bottom

 

[Ohio AV8TOR]

I'm not going to help un tear you as I like the top. I think the background image looks better on both doors.

 

[Decal Dennis]

Thanks for the help, texted the pic to my customer and he wants both, that way he can change out the rear panel for a different look occasionally.

He hasn't notice one of the details in there yet lol