[MOC] [WIP] Small RWD Drifting

[NoEXIST]

Hello everybody! I like to build small models for indoor playing, and wanting to make models fast for a limited area indicates drift. 

As you know, drifting in Lego is quite a specific thing. I seen a lot of models called "Drifting Model" with Rear-Wheel Drive, but all of them only can do some donuts. 

With All-Wheel Drive model, everything is easier and it works, but it isn't as interesting as bringing something new. 

Recently I came across a rather interesting chassis on Instagram in which a servo motor wasn't used and nothing controlled the steering wheels. 

This was the reason to do something similar. 

 

I started by making something similar with 2L motors and Buwizz

Now about the features:

- control by separate gas dasge on the rear wheels 

- castor angle 

- displacement of the wheel mount relative to the steering hub pivot point 

- reverse Ackermann angle 

Next improvements will be: 

- adding 2 more L motors 

- adding tilting suspension on the front axle for increased traction 

As a conclusion, I want to show a short video that showing what this chassis config can do:

I will glad to hear your thoughts about this:)

Edited July 20, 2021 by NoEXIST

[Jurss]

Interesting. You also already learned how to drift arount table leg.

[NoEXIST]

2 minutes ago, Jurss said:

Interesting. You also already learned how to drift arount table leg.

This is also possible on All-Wheel Drive, but on this scale there is a problem with the steering angle.

[Gray Gear]

This is very interesting to me. So the steering is completely free and just follows the motion of the car?

I might have to experiment with this some time...

[NoEXIST]

17 minutes ago, Gray Gear said:

This is very interesting to me. So the steering is completely free and just follows the motion of the car?

I might have to experiment with this some time...

Yes, the steering system is free and the rack is 11,5 stud long in the case of the wide chassis version

[amorti]

Looks good! Remarkably well controlled.

I think hanging two more motors out the back will upset the balance. Try drifting in an early Porsche...

How purist are you? CaDA Pro L motors deliver significantly more speed and torque than Lego L motors, and they're pretty cheap.

https://www.custombricks.de/motors-cables-sbrick/cada-power-functions-l-motor.html

Edited July 17, 2021 by amorti

[NoEXIST]

1 hour ago, amorti said:

Looks good! Remarkably well controlled.

I think hanging two more motors out the back will upset the balance. Try drifting in an early Porsche...

How purist are you? CaDA Pro L motors deliver significantly more speed and torque than Lego L motors, and they're pretty cheap.

https://www.custombricks.de/motors-cables-sbrick/cada-power-functions-l-motor.html

Thank you! On the first render, the entire weight of the chassis is in the wheelbase, but tests have shown that it is better to take the weight out of the rear axle. 

Usually tests of such specific things show that they do not work logically

Or am I drawing the wrong conclusions:)

 

At the expense of Chinese motors, I try to do without them, the main non-lego part is the Buwizz

[2GodBDGlory]

Very interesting!

[Hrafn]

I wonder what would happen if you also had powered steering?  Or a motor that could lock the steering angle on command?

I wouldn't have expected this kind of behavior without active steering - it reminds me a bit of the way a bicycle can self steer to correct wobbles if it is moving fast enough.

[sebulba56]

A fantastic concept which now deserves a nice bodywork. How about something that looks like a tuned BMW or a Supra ?

[NoEXIST]

On 7/18/2021 at 2:14 AM, Hrafn said:

I wonder what would happen if you also had powered steering?  Or a motor that could lock the steering angle on command?

I wouldn't have expected this kind of behavior without active steering - it reminds me a bit of the way a bicycle can self steer to correct wobbles if it is moving fast enough.

If we talk about a steering system with a servo, then we need to understand that the Lego servo isn't accurate and fast enough. Also a gyroscopic stabilizer would be required for control.

The idea with a motor that lock the wheels in one position is interesting, but it isn't required here because wheels themselves hold in the desired position until I change it myself. 

I know one person who is trying to apply all of this to a 1:10 scale drift. 

It uses:

- 3 RC Buggy Motors 

- 2 Chinese GeekServos 

- RC 3S LiPo 

- Gyro stabilizer 

- and other custom components 

 

I think my version looks simpler:)

 

P.S. if you are interested there is that guy

https://www.instagram.com/hacheroku/

 

Edited July 20, 2021 by NoEXIST

[NoEXIST]

On 7/18/2021 at 12:53 PM, sebulba56 said:

A fantastic concept which now deserves a nice bodywork. How about something that looks like a tuned BMW or a Supra ?

Thank you! It will be quite problematic to make cars with short rear bumper. I think about something like Nissan Stagea 

Edited July 20, 2021 by NoEXIST

[2GodBDGlory]

I suppose the reverse Ackermann is an essential feature?

[NoEXIST]

57 minutes ago, 2GodBDGlory said:

I suppose the reverse Ackermann is an essential feature?

From my experience, I want to say that yes, with the correct Ackerman or without him at all it was worse

[Hrafn]

I wonder if it would work as well with braked differential steering as discussed here:

The utility of anti-ackermann is an interesting finding.

[Ullum Zurt]

Is it just me is someone else able to see the images in this thread?

[Gray Gear]

@Ullum Zurt I can see the images just fine

[NoEXIST]

9 hours ago, Hrafn said:

I wonder if it would work as well with braked differential steering as discussed here:



The utility of anti-ackermann is an interesting finding.

An interesting mechanism, theoretically it can work, but this implies a large number of gears that carry power losses

3 hours ago, Ullum Zurt said:

Is it just me is someone else able to see the images in this thread?

I will try to update the post later. I hope I won't ruin anything

 

[Ullum Zurt]

3 hours ago, NoEXIST said:

I will try to update the post later. I hope I won't ruin anything

Thank you! What exactly did you do? There are a bunch of photos in many other threads I also can't see. With some details, I can inform the other posters what to update.

On 7/17/2021 at 10:56 PM, Gray Gear said:

So the steering is completely free and just follows the motion of the car?

If my understanding of this is correct, the castor angle allows the steering to alternate between the extremes based on how the bodyweight of the chassis shifts. If that is the case, how exactly do you shift the bodyweight of the chassis? And does this mean that once it starts steering, it cannot go straight without stopping?

[NoEXIST]

22 minutes ago, Ullum Zurt said:

Thank you! What exactly did you do? There are a bunch of photos in many other threads I also can't see. With some details, I can inform the other posters what to update.

If my understanding of this is correct, the castor angle allows the steering to alternate between the extremes based on how the bodyweight of the chassis shifts. If that is the case, how exactly do you shift the bodyweight of the chassis? And does this mean that once it starts steering, it cannot go straight without stopping?

I changed links to photos (previously they were just from messengers, now from bricksafe)

Not sure if everyone will have exactly the same problem

[Ullum Zurt]

7 minutes ago, NoEXIST said:

I changed links to photos (previously they were just from messengers, now from bricksafe)

Not sure if everyone will have exactly the same problem

I'm not sure why I'm (seemingly) the only one with this problem, but thank you.

[NoEXIST]

48 minutes ago, Ullum Zurt said:

Thank you! What exactly did you do? There are a bunch of photos in many other threads I also can't see. With some details, I can inform the other posters what to update.

If my understanding of this is correct, the castor angle allows the steering to alternate between the extremes based on how the bodyweight of the chassis shifts. If that is the case, how exactly do you shift the bodyweight of the chassis? And does this mean that once it starts steering, it cannot go straight without stopping?

In fact, during drift, the wheels change their position not only to the extreme, but also to slightly turned.

Just as easily they can be returned to the center position.

 

Edited July 20, 2021 by NoEXIST

[Hrafn]

Have you experimented with weight distribution to see how it affects the responsiveness of the steering to changes in rear wheel speed?  It looks pretty much optimized now.

[NoEXIST]

4 minutes ago, Hrafn said:

Have you experimented with weight distribution to see how it affects the responsiveness of the steering to changes in rear wheel speed?  It looks pretty much optimized now.

At the moment, the best option was with a buwizz installed behind the rear axle.

In the video demonstrating the steering system, the earlier version of the chassis, where I thought about the interior, in the end I think it will not

[Mechbuilds]

On 7/17/2021 at 11:12 PM, NoEXIST said:

Thank you! On the first render, the entire weight of the chassis is in the wheelbase, but tests have shown that it is better to take the weight out of the rear axle. 

Usually tests of such specific things show that they do not work logically

Or am I drawing the wrong conclusions:)

 

At the expense of Chinese motors, I try to do without them, the main non-lego part is the Buwizz

Actually it's quite logical.. You want the rear tyres to loose grip in order to drift. So you need to take weight out of the rear axle so the tyres have less grip. 

Very interesting method of making a drift chassis. Instead of using the normal servo steering system, you've basically used a tank steering system. 
Looks like it's working quite well! 

Will you release instructions on the chassis?