Taco wrote:
---I guess I should have said can anyone explain the physics involved in why tongue weight is important.---
I'll give it a try.
It's not tongue weight which is a critical factor -- it is the tongue weight percentage.
Tongue weight percentage is a measure of the ratio of distance from TT's axles to TT's center of gravity divided by the distance from TT's axles to the ball coupler.
The ratio is important because it is one of the factors which determine how much
lateral force the TT might exert on the ball.
For given TT mass, polar moment of inertia, dimensions, and application of lateral force on the TT, there is an optimum value of tongue weight percentage which will minimize the lateral force which the TT imposes on the ball coupler.
When a right-directed lateral force is applied to a TT at a point behind the CG, two things happen:
1) the TT's CG begins to accelerate toward the right, and
2) the TT begins a counter-clockwise (when viewed from above) yaw acceleration about the CG.
The right-directed acceleration of the CG causes the ball coupler to tend to move to the right.
The CCW yaw acceleration of the TT about the CG causes the ball coupler to tend to move to the left.
With the optimum TW%, the right-directed acceleration of the coupler will be equal to the left-directed acceleration, and there will be little or no lateral force imposed on the ball.
So, the optimum tongue weight percentage is not controlled by TV rear axle loading considerations.
The optimum tongue weight percentage is controlled by TT yaw dynamics which determine how much lateral force is imposed on the ball.
Ron
