SlotForum banner
61 - 74 of 74 Posts

·
Registered
Joined
·
976 Posts
If anyone wants to do a little research there's a British 1/32 slot racer that built his car's with flywheels and won or come a place in the constructors championship, I think it was BSCRA. anyway worth a look at the way it's built. Maybe some of you aspiring builders may wont to try and see if you can reproduce a winner at your club. 🤔
John.
 

·
Bob Chapman
Joined
·
7,085 Posts
Discussion Starter · #64 ·
I'd love to see that John.
Its that kind of ingenuity that pushes this hobby.
Thanks for bringing it up.
Ill see if I can find something on it.
Cheers
Bob
 

·
Slot King
Joined
·
3,705 Posts
The best way to understand it fully is to read up on Euler' equations.and do the maths.
I used the lecture notes and textbooks from my student days, sorry I don't know where or if it's to be found on the internet.
As an answer this is of the chocolate teapot variety, are we saying that although we have the explanation, we are not going to share it with fellow forum members?
Anyway for those wondering, this is what precession looks like in simple terms. And of course you can see straight away that this is not the case for our spinning motor shaft, because it is held firmly at both ends and therefore cannot wobble as shown in the drawing.
Font Circle Electric blue Diagram Signage


The analogy with a hand held bicycle wheel is extremely dubious. The wheel diametre is many times the width of the axle, it will always try to wobble.
Repeat the experiment with an axle 4 metres long and rigidly fixed at both end and the results will be vastly different.

Agreed, there are plenty of examples of that in hard body racing although powerful motors by hard body standards are not all that powerful compared to the quickest motors in BSCRA type cars.
However the fact remains BSCRA F1 class (inline) cars are undriveable with the more powerful motors that work very well in BSCRA sports class (anglewinder) car
Are you speaking from personal experience?
Here is an armature from an in line BSCRA type car, it is probably the wildest wind I have in my collection of around 120 rewound motors, I can assure you the car is perfectly drivable (although the NSR tyres do struggle to handle the power :)).
Wood Hearth Gas Brick Bumper



I am not at all convinced that precession has an actual real life negative impact on handling of in line cars, the explanations given so far just do not add up.
Further, real life experience of driving in liners doesn't show a tendency for cars to turn better one way than the other which presumably would be the case if precession worked a significant factor.
Looking at the fastest lap time at SSRC (my local club) there isn't a great deal of difference between in line and sidewinders, and what there is can be explained by the very different rules of the 2 classes.


Joel

PS: Tony, if you go to Skyline, let me know and I'll join you.
 

·
Premium Member
Joined
·
2,438 Posts
I never mentioned precession. That is a different phenomenon as toe illustration shows.
The bike wheel analogy is meant as an experiment you can try at home where you can feel for yourself the forces described. They are described in books as the left and right handed rules or something similar because by using your thumb,index, and middle fingers as three axes at right angles, you can workout the direction of the resultant force given the direction of rotation on the other two axes.
The flywheel F1 car had been described before in the pages of this forum. It reproduces the sidewinder effect using a flywheel instead of the armature. I think it would work even better with one of today’s roller clutches fitted so that the flywheel didn’t have to keep being accelerated and decelerated.
 

·
Premium Member
Joined
·
2,438 Posts
Further to previous precession is a rather obscure result of the forces mentioned. The resultant force from the spin of the gyro and it’s rotation about the base is the one that holds it up.
 

·
Registered
Joined
·
3,669 Posts
Are you speaking from personal experience?
Yes I am talking from experience of racing modern BSCRA cars and the very different experience of NSR tyres on hardbody cars.
What speaks much louder than anything I can say is the experience of the BSCRA national champions over the last few decades using more powerful motors in the BSCRA sports class (where nobody uses inlines) than in the BSCRA F1 class. (where the rules require everybody to use inlines) As I've already explained in post 56, there are quite a few differences between the classes apart from motor orientation.
I've not noticed a difference in handling between the left and right hand corners with BSCRA F1 cars. Maybe they do corner slight quicker one way than the other. There are inevitable small differences in track conditions, camber, bumpiness etc.which any half decent driver more or less automatically adapts to anyway so I guess they deal with the inevitable changes due to gyro couples the same way. Maybe the top drivers can detect a difference, but I'm sure they are more bothered about things they can change to go faster rather than the inline configuration the rules say they must have.
In my experience, BSCRA cars only work properly with the right tyres and track conditions. Using them outside their normal operating window means the don't handle properly.
As has already been pointed out in post 65 Slot Racing History gives a more direct comparison of the gyro effect in BSCRA F1 where the gyro car was better in corners than a conventional F1 - extra “gyroscopic grip” as the builder put it. Sure that was over 30 years ago, the cars have changed quite a bit since then.......but the laws of physics are still the same.
 

·
Registered
Joined
·
3,669 Posts
The analogy with a hand held bicycle wheel is extremely dubious. The wheel diametre is many times the width of the axle, it will always try to wobble.
Repeat the experiment with an axle 4 metres long and rigidly fixed at both end and the results will be vastly different.
GP has already responded to that point, I'll just add-
The laws of physics apply to all rotating bodies, be they slot car armatures, bicycle wheels, wheels on 4 metre long axles or anything else.
Even those who can get their heads round the maths can find a practical demonstration useful.
A bicycle wheel demonstration produces forces that are easy to feel with the wheel rotating at a convenient speed.
The gyrosopic action due to a slot car armature rotating behave in exactly the same way, but the magnitude will be different. Those who can get their heads round the maths calculate the exact numbers..
 

·
Kevs Racing Bits
Joined
·
4,811 Posts
The problem with gyroscopic action in our motors is they're constantly changing speeds, some time pushing, some time being pushed...good luck with the maths :ROFLMAO:
 

·
Premium Member
Joined
·
2,438 Posts
Kevan, the gyroscopic action does not depend on whether the motor is under power or braking. At the same revs the action will be the same.

Re in-lines, the effect will be to lift or depress the front and rear axles depending on the direction of the bend. I can imagine that this would be very hard to detect by a driver over and above the other much larger causes of the same effect such as braking or accelerating torque on the rear axle and weight transfer.
 

·
Bob Chapman
Joined
·
7,085 Posts
Discussion Starter · #74 ·
There are certainly many factors of causation. I think from what I have read here that the resultant action would be to apply the actions or choices which have less effect on the handling factor. This could be very different in individual car setups. Chassis rigidity, pod rigidity , body float , pod float,
Any suspension , and tightness of the mounting screws . For optimum configuration there are a lot of variables to deal with rotational forces . Technology transfer to our hobby is way behind when it comes to stability of platform. We have come a very long way from gyroscopic guidance and stability systems to the current electronic versions used in 1:1 and RC model aircraft.
Since slot cars run on a single plane unlike aircraft , I can only see weight distribution as a viable option.
I dont mean static, but active weight distribution. I wonder who will invent it first ?
Cheers
Bob
 
61 - 74 of 74 Posts
Top