Originally Posted by Conrad
As most of the current 1/12th chassis makers are switching to inline battery setups, how much/what is the difference between those that have the cell centrally located and those that have the cell offset with electrics beside it. I'm purely talking about balance/handling here not the practicality of having more space for electronics.
Id be interested in hearing what differences people have found from a strictly weight-distribution point of view.
However, I think it is difficult to quantify exactly what the "inline battery" feature really does, considering that most of the "inline" chassis are longer and have a slightly wider front-end than their transverse layout brethren.
Originally Posted by racer x 1
pretty new to 1/12 and was wondering what effect does reactive caster have on the car? thanks
I thought we covered this a page or two ago, but maybe that was the AE 12R5 thread.
You need to understand how caster affects the dynamic camber curve of the front suspension. For most strut style suspensions, a greater caster angle will produce a greater camber gain during the suspensions compression arc. From what I understand, the reactive caster tends to increase the caster angle as the suspension compresses. So, at the beginning of the corner, at your turn-in point, you will have less caster... which translates into a very responsive car. As the suspension compresses through the middle of the corner, the caster angle increases... thereby reducing the positive camber of the outside tire, and allowing it a higher degree of grip.
So with reactive caster, you end up with a car that potentially has the "best of both worlds". Ie: Low caster angle at turn-in, which gives the car lots of turn-in steering and response... And high caster angle at corner exit, which gives the car more exit steering.
If you were to simply dial in your caster angle from a static point of view, ie: without any reactive caster, you would have to make more compromises. A lot of static caster can increase your steering at corner exit and increase your straight line stability... which may be favorable at your given track/circuit. But it may make the car a bit too lazy at turn-in/corner entry for your liking. This is a situation where reactive caster could be used beneficially.
However, nothing is as cut and dry anymore with brushless and lipo batteries. The Speed Merchant cars with the "new old school" front end(with no reactive caster) seem to be doing fantastic, especially in the slower stock classes.
Edit: It is also worth noting that with a standard front suspension, with no reactive caster, the camber angle changes as a function of caster angle, toe change(wheels being turned), Steering Axis Inclination, front roll center height, and suspension position(Z-height). With caster as a static quantity, the equation to find the resultant camber angle is complicated enough. With reactive caster, we are adding another 1st order differentiable variable to this equation, as the caster angle is now changing as a function of suspension position.
One would have to measure all the suspension pickup points and length of the control/lever arms and do a full kinematics analysis to determine the true camber curve. I would actually be very
interested in seeing the results of that study.