SlotForum banner
1 - 2 of 2 Posts

· Russell Sheldon
Joined
·
2,846 Posts
Let's be honest, from a technical perspective, modern mass produced ready-to-run slot cars are hardly inspiring. In the main, poor handling is largely overcome by the simple addition of traction magnets. The motors are not particularly powerful and are toy-like, not suprisingly since they are gernerally designed to power battery operated toys and household appliances. Hence, the difference in handling between a sidewinder versus an inline configured 'ready-to-run' (r-t-r) production car is hardly noticeable. The difference in handling is however markedly different with Eurosport cars.

With modern "speed crazed moron" slot racing (1/32nd and 1/24th Eurosport), the reason for having a sidewinder or anglewinder motor installation is to optimise the gyroscopic effect that is caused by the rotation of the armature to aid handling. The gyroscopic force concerned is called precession, which is the reaction of a rotating mass at 90 degrees to the force applied.

With an inline chassis with a powerful motor, precession causes a weight transfer from one end of the car to the other, producing a tendency to de-slot when turning one way, and excessive tail slide when turning the other. With the motor sideways, the weight transfer is across the car, and with the armature turning in the opposite direction to the wheels (due to the gears) the weight transfer is always toward the inside of the corner, which keeps the car stable and reduces any tendency to tip.

A glance at modern 1/32nd and 1/24th Eurosport or Group chassis will show that the motor is installed at a slight angle to the rear axle, hence the term "anglewinder". The reason for this is purely to enable the use of smaller diameter rear tyres than can be used with a full sidewinder configuration. With the motor set at a slight angle, the anglewinder represents the best compromise between the conflicting requirements of theory and practicality.

So what has this to do with braking.....??


The effect of driving torque is clearly shown by the way that dragsters lift their front wheels off the ground when accelerating. The opposite torque effect - when decelerating - is not so obvious, but it is there in a big way; heavy pressure comes down on the front axle when braking.

It is this deceleration torque that is used by the top slot racers to help them to take corners fast. They leave their braking to a 'last moment' critical point. Bang goes the brakes dead short on the motor and the powerful reverse torque at once brings heavy pressure to bear on the front of the car. If your chassis is designed correctly, this pressure forces the guide to stay hard down in the slot. If you brake too early, and let the car coast into the bend, you lose this 'reverse torque' effect and the car will most likely flop out of the slot.

Worse still, if you brake even earlier and have to use a short burst of power just before the bend, the 'dragster-type torque effect' will tend to lift the front of the car and de-slotting is almost certain.

Given the lack of power of the r-t-r cars and magnets helping to keep it in the slot, the above is however probably totally irrelevant, but I thought I would post it anyway!
 

· Russell Sheldon
Joined
·
2,846 Posts
Hi Inte,

Sorry, I wasn't trying to be a wise guy...

Hopefully this article from Model Cars, October 1969, can explain it better:

'TORQUING' POINTS by R. W. Wootton

A slot car motor spinning at 100 revs per second is quite a powerful little gyroscope, and gyroscopes do some peculiar things, among them 'PRECESSION'.

Fig. 1 shows a spinning motor, rotating clockwise, mounted in an old tobacco tin. You will see that a brass strip (1) has been strapped around the motor to enable the two stub axles (2) and (3) to be soldered to it, in line with one another; and the ends of these stub axles pass through clearance holes in the tin.



With the tin lying on the table, try rotating it in a clockwise direction (clockwise if you look down on it). At once the endbell of the motor moves upward, and the can end downward. In fact, if you keep on rotating the tin, the motor as a whole will rotate on the stub axles in the direction shown by the arrow (4).

This rotation is known as gyroscopic precession, or simply precession. The moral is that a sidewinder will take both right and left hand track curvature well because precession helps to combat any (centrifugal) overturning tendency in either direction. It is particularly effective in sudden breakaway sliding when cornering.

But what about the inline? Here, precision simply tends only to transfer weight from the car's back axle to the front when going round a right-hand bend, and vice versa. It is of little or no assistance to the problem of road holding when cornering.

And what about the precession tendency of the back axle with its quite considerable weight of wheels and tyres? Although spinning much slower than the motor, it is, nevertheless, another significant gyro system which, however, unfortunately does not assist cornering but only aggravates it, as you can figure out from the tobacco tin experiment.
 
1 - 2 of 2 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top