Project #3. Two motors, Three wheels, Six grand!

[Capo_au]

Very true.

While on the topic of basic physics principles I should also bring up something else that bugs me. Traction is not proportional to tire size. If two tiers of different tread widths are placed on the same (perfectly flat) surface with the same weight placed on them (including tier weight) they will produce the same traction. Traction is dependent on weight and on the friction coefficient of the rubber. This is a mistake I see made ofter by seasoned experts in their field.

For anyone who is involved with cars this is very counter intuitive, but have a read of this for more info.

This is something you can prove to your self at home if you really want to cement the concept. Take a flat surface, like a chopping board and place a book on it, spine down so that the book is vertical. Tilt the board until the book slides off. Now if you lay the book flat on the same surface and you have just increased its surface area 10 fold (think wider tier) yet upon tipping the board the book will still slide off at the same angle of tilt. For the same weight book on the same surface the traction is the same regardless of surface area (think tier footprint). This works great when explaining the problem to kids.

Anyway, if you really wanted to maximum acceleration of out the trike it would mean shifting the weight towards the back wheel. This may make it handle like a pig but with out wheel spin the straight line performance could be mind bending.

Alternatively, you could always get creative with a spoiler.

Then you really would get some looks :lol:

-Capo

 

[recumpence]

There is also a limit on how much adhesion a given surface area can achieve no matter how much weight is added to that surface.

I understand the issue of pressure per square inch equating to the conclusion that a wider tire does not add traction. That is true to a point. However, a wider tire normally adds traction in most real world circumstances. I have, howver, seen a reduction in traction with added tire width on certain surfaces. On dry pavement, though, the typical 2 inch wide tires just do not want to accept 20hp. To that end, a wider tire helps remendously. Wider tires do not always help, though. It all depends on the tire, the surface, how much weight is present, and even weather and environmental considerations.

Matt

 

[Capo_au]

Yep, like most things its only applicable up to a point in the real world. Unless your lucky enough to be cruising around on a polished concrete floor, a wider tire will no doubt help.

But short of modifying the frame, is it possible to put a wider tier on this particular trike?

 

[gunthn]

You may also want to consider a bumper or some sort of cattle pusher like a train or line up a really good orthopedist. :wink: I am assuming that will exceed the speed of highway traffic!

Kawasaki once had a slogan: Power to the ground.

It was related to suspension. A wheel that bounces and spins does not deliver power. Without suspension I would imagine the same is true of etrikes. Tires and suspension are far more critical than power in off road racing. I could easily leave a 300 two stroke ktm behind on a yamaha 250 4 stroke with a trials radial tire. Less than half the power but power that pushes machine forward not the wheel across the ground. Control is the key.

 

[Arlo1]

Thats funny just past half way I think you can hear one of the kids say "Dads crazy" too funny.

 

[Miles]

NB: Matt's video and comments on it merged into this thread above: http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=11422&p=209686#p209686

 

[methods]

Given this thread will probably spur some folks to build similar high power trikes I feel the need to spam with this very important note:


Trike riders - please be aware that running a hall throttle can be very dangerous.
It is recommended that you run a Magura or thumb type throttle.

Hard riding + hall throttle could = uncontrollable trike

Sorry for the "Public Service Announcement" - not usually my style - but I feel strongly about this.

-methods

 

[recumpence]

Good call Methy!

I use the Magura cut to helf length with a half grip.

I also always have my battery connectors where I can reach them.

Safety first. Thanks for posting!

Matt