[WIP] trying to break 40km/h with only Lego "2 new designs, -steering advice needed"

[Marxpek]

The grey ones i had are from a 42036 set i bought myself. So those are fairly new.

[TechnicSummse]

43 minutes ago, Marxpek said:

The grey ones i had are from a 42036 set i bought myself. So those are fairly new.

Are you sure, that it is not just the wear, what differs them? You made many runs with yours allready... and the one you baught was probably not a single time driven by a motor, or used outdoors?

[Marxpek]

1 hour ago, TechnicSummse said:

Are you sure, that it is not just the wear, what differs them? You made many runs with yours allready... and the one you baught was probably not a single time driven by a motor, or used outdoors?

100% certain. The grey ones always where grey and non shiny and it clearly is no wear but a different type of rubber. The grey ones are also the newest. The 42036 set is the last set made that uses these tires. So the softer grey is the new version i guess.

[Marxpek]

Soo.. it has been a while, but with better and longer days on the horizon my racing blood starts boiling again!

I currently have 2 new designs:

The one above is ready to go, it is a minor variation to my racer from last summer that made 39,4km/h, this one is better balanced and has a slot for the speed computer.

The one beneath is still a WIP, its intention is to break the "only Lego"  40 km/h and beat the buwizz record! I am still working on the motor configuration, but this will be my most powerful creation yet.

More power, more problems... and i am hoping to get some suggestions on steering this, since this has always been the biggest issue with this.

Steering with the front wheel will be hard since it is motorized now, it could be done but it would be very bulky/heavy and most likely unstable.

I will show you first what i came up with to start with.

when steering with the controller, the small wheels will cause drag either left or right, hopefully making small adjustments in direction. (maybe i will put the wheels further out for more effect)

I also thought about 3 other options:

- use skid steering with a electrical swith on either side, controller by the servo on the rc unit, might be heavy and lots of wires needed

- use skid steering using 2 rc controllers, set either side's rc unit on another channel, might be hard when driving on my bike.. but maybe its power will need less runway.. so no bike..

- brake the rear wheels, either left or right, directly with the servo on the rc unit, effective and light but bad for the motors and rubbing parts.

I am really hoping someone has other ideas about high speed steering (better sayd: minor adjustments on a straight runway), or give other insights, before i put these parts at risk, of course any other suggestion or input is also welcomed.

 

 

[TechnicSummse]

Nice to see you back :D

I was thinking about reactivating my work on this also in the next weeks :)

 

My eyes are looking right?... you have 10 Motors and 5 RC-Units now? ... holy shit :D

Well i have to say, i also collected some... i have 11 Motors and 3 (or 4, one is electrically damaged) RC Units now.

 

But in the last months i was building on a 6x6 truck with 3 rc-units and 6 motors... so i have to deal with the lack of rc-units... 

 

Now lets come to the project... 3 RC-units, 8 Motors? Looks like you want to try my 3 motors per rc-unit-idea? Or will you add a 4th rc-unit?

To the steering...  i think braking the rear wheels should work ok... best to do this at the rims, to save the tires.

Another idea... what about using a turntable to mount the frontwheel on? ... using the servo-output to rotate the turntable with the wheel, completeley including motors? You could center the turntable with springs on the left and right side, connected back to the chassis.

Third idea... an air rudder?

 

 

 

 

 

Edited February 25, 2018 by TechnicSummse

[pagicence]

I can only tell you this: MARGINAL GAIN! That's the golden rule in formula 1. No matter how much the part is small or how low the weight is, if it's unnecessary get rid of it. A few like that and it ads up.

If you need speed; I saw people do some crazy stuff with BuWizz. from what I see you are trying to get 40km/h on the street. Try the basketball court in the gym, or something similar with less resistance. Or just change the gearing.

As for steering, I think this dude figure it out. He is using axles from 42000 set. Here is a youtube video. He's car is going straight.

[letsbuild]

3 hours ago, pagicence said:

I can only tell you this: MARGINAL GAIN! That's the golden rule in formula 1. No matter how much the part is small or how low the weight is, if it's unnecessary get rid of it. A few like that and it ads up.

If you need speed; I saw people do some crazy stuff with BuWizz. from what I see you are trying to get 40km/h on the street. Try the basketball court in the gym, or something similar with less resistance. Or just change the gearing.

As for steering, I think this dude figure it out. He is using axles from 42000 set. Here is a youtube video. He's car is going straight.

Now, you started off well, but in that second paragraph, well, that's where you go wrong. First, look at the title. It says " trying to break 40km/h with only Lego." Buwizz is not lego. If he wanted to use Buwizz, it would be a lot easier to reach 40km/h.

[mocbuild101]

6 hours ago, TechnicSummse said:

Nice to see you back :D

I was thinking about reactivating my work on this also in the next weeks :)

So was I... (though I'm only trying to get over 35km/h with a single RC unit )

On 2/24/2018 at 6:34 AM, Marxpek said:

I also thought about 3 other options:

Any type of steering that uses drag, braking, or slowing motors won't be very good if you're trying to get the most speed you can.

I would suggest steering the front wheel (motors and all), via a large turntable or something, as that won't add any unnecessary drag.

 

Edit: I see @TechnicSummse beat me to that idea...

Edited February 26, 2018 by mocbuild101

[sirslayer]

I've ssen this youtube video from niciasno and his thoughts about using Lego's suspension. I think his videos series are very helpful!! 

 

 

[TechnicSummse]

7 hours ago, pagicence said:

I can only tell you this: MARGINAL GAIN! That's the golden rule in formula 1. No matter how much the part is small or how low the weight is, if it's unnecessary get rid of it. A few like that and it ads up.

He is doing this kind of Stuff for about 1 year now... he really know the basics ;)

7 hours ago, pagicence said:

If you need speed; I saw people do some crazy stuff with BuWizz. from what I see you are trying to get 40km/h on the street. Try the basketball court in the gym, or something similar with less resistance. Or just change the gearing.

The gearing is optimized for the motors power, to have no wasted torque at the maximum speed... will mean, if he gears higher, the car will be slower, because of the lack of torque... and if he gears down, the car will be slower, because of the lack of rpm...

7 hours ago, pagicence said:

As for steering, I think this dude figure it out. He is using axles from 42000 set. Here is a youtube video. He's car is going straight.

2 Things here... 

1. this car uses 2 frontwheels= to much rolling resistance...

2. this steering mechanism will work for his so called "high speed" wich is below 20 kph... we are talking about 40 kph... its pretty much different ;)

 

3 hours ago, sirslayer said:

I've ssen this youtube video from niciasno and his thoughts about using Lego's suspension. I think his videos series are very helpful!! 

We had the discussion about suspension allready 1 year ago :D

At the end... we all decidet, to not use any suspesnio... the negative things on it dominate the positive ones in our purpose.

3 hours ago, mocbuild101 said:

So was I... (though I'm only trying to get over 35km/h with a single RC unit )

Nice to hear :)

[letsbuild]

15 hours ago, mocbuild101 said:

I would suggest steering the front wheel (motors and all), via a large turntable or something, as that won't add any unnecessary drag.

A turntable would be a good idea, if you could, it would be helpful to put it on backwards (reverse tricycle style). This would make it easier for the car to return to center.

[Marxpek]

good to see the competition is still strong aswell! 

This will be the year 40 will be broken by Lego alone, im sure. (and lets take the buwizz record aswell, that is my new aim at least)

20 hours ago, TechnicSummse said:

My eyes are looking right?... you have 10 Motors and 5 RC-Units now? ... holy shit :D

these and some spares ;) both will be up and running

20 hours ago, TechnicSummse said:

Now lets come to the project... 3 RC-units, 8 Motors? Looks like you want to try my 3 motors per rc-unit-idea?

yes too all, since you managed to use it for that long, it got me convinced, and i can burn through 3 spare units if i have to... did you ever burn one up with 3 motors?

i am just hoping the radio interferrence is doable with 3 units, (tests showed significant more random input, but my experience is that the controllers will override it, mostly..)

20 hours ago, TechnicSummse said:

Another idea... what about using a turntable to mount the frontwheel on? ... using the servo-output to rotate the turntable with the wheel, completeley including motors? You could center the turntable with springs on the left and right side, connected back to the chassis.

i tried this, the turntables are not ment to be loaded vertically, i see them get separated on a bump at 30km/h+, so i ditched the idea... there was also a big amount of play in the steering and the turntable itself, and they don't mount to the rc unit nicely without ruining ground clearance.

Putting the turntable in front horizontally (similar to my steering in my 4 motor racer). is an option but very bulky or unstable, and ground clearance becomes a mess.

 

13 hours ago, mocbuild101 said:

Any type of steering that uses drag, braking, or slowing motors won't be very good if you're trying to get the most speed you can

very true but steering is always paired with drag. And in a straight record run i won't have to steer at all. my steering setup is not really for steering, more for damage control, maybe 1 or 2 corrections, if else i reset the run.

@pagicence thanks for the input and idea's but like technicsummse already mentioned, we have been at it for a while now, maybe read up on our threads, some nice info here and there :)

 

I have just one big question for all:

Does (electrical) 3 wheeled skid steering even work? and when the 3rd front wheel is powered? .the 2 controllers option is the best weight wise, but im doubtful wether it will work or not.

 

[Permo]

Wow ! quite the challenge you took on there....

How is this powered ? Lego batterybox ?

[TechnicSummse]

@Marxpek

Did you try an air-rudder, like airboats steer for example?

 

To answer your question... no.. i did not burn any rc unit with the 3 motor-setup. The burned one i have... i baught like it was for 1€ on ebay... sadly the seller could not tell me, how it was destroyed... i was verry curious about that.

 

One thing you should keep in mind with your latest design is a problem i came across:

If you use seperatet axles (seperately driven rearwheels), you wont have a staright run at all, since there are (in our case) huge differences in motor speeds. Especially, if you power them from different power sources.

I hope you understand what i want to point out here.

 

Edit:

The rudder i meant like this for example:

Edited February 26, 2018 by TechnicSummse

[sirslayer]

@marxpek do you need to do a 3 wheel design? a 4 wheel design might go faster since the third front wheel could be the issue . is it higher speeds you are reaching? how stable is your design at its tops speed? maybe over voltage your motors to 12 volts or higher to get higher rpms can do the trick..  if its a pure design then you need to lose weight 

Edited February 26, 2018 by sirslayer

[Marxpek]

3 minutes ago, TechnicSummse said:

If you use seperatet axles (seperately driven rearwheels), you wont have a staright run at all, since there are (in our case) huge differences in motor speeds. Especially, if you power them from different power sources.

I hope you understand what i want to point out here.

i considered this, to prevent this, or partially even it out, i was planning to crosswire the motors and maybe use a frictionpin version of a limited slip diff between the rear axle, of course this only works with drag steering. not with electrical steering (in wich i have little faith but will most likely try)

7 minutes ago, TechnicSummse said:

Did you try an air-rudder, like airboats steer for exam

i have little faith in air rudders, it is just another way of causing drag, and my guess is it would need quitte a big surface and thus be bulky, so no i have not tried it and i doubt i will, i say: convince me!

 

34 minutes ago, Permo said:

How is this powered ? Lego batterybox ?

hey perma welcome to EB and the thread, im using rc units here, if you read the thread you can find out more ;)

[Marxpek]

17 minutes ago, sirslayer said:

a 4 wheel design might go faster since the third front wheel could be the issue . is it higher speeds you are reaching? how stable is your design at its tops speed? maybe over voltage your motors to 12 volts or higher to get higher rpms can do the trick..  if its a pure design then you need to lose weight 

 4 wheels give more rollresistance and weight more, however with the motorized front it might be different, i'll see into it. The 4 motor finished design rides pretty straight, but it does not like big bumps.. the other is unfinished

I think it will be pretty hard to run the motors at 12 volt with a Lego solution.. ive seen a 18v version wich was pretty complex/dangerous but all Lego..

Edited February 26, 2018 by Marxpek

[kbalage]

17 hours ago, letsbuild said:

If he wanted to use Buwizz, it would be a lot easier to reach 40km/h.

I can tell you about that part how "easy" is to reach 40 km/h with BuWizz  

But to stay on topic - as you have tons of motors and RC units now, why not to go simple and try a similar config like my BuWizz record breaker. You'll need to have more power as the RC units are heavy as mud, but something like a 4 wheel setup, 4 RC units, 8 motors, no any moving parts from steering, just steered with the speed difference of the motors on the two sides.

[TechnicSummse]

10 minutes ago, kbalage said:

I can tell you about that part how "easy" is to reach 40 km/h with BuWizz  

But to stay on topic - as you have tons of motors and RC units now, why not to go simple and try a similar config like my BuWizz record breaker. You'll need to have more power as the RC units are heavy as mud, but something like a 4 wheel setup, 4 RC units, 8 motors, no any moving parts from steering, just steered with the speed difference of the motors on the two sides.

This would need 2 remotes on 2 different channels... and 2 rc-units on channel 1 and another 2 rc units on channel 2... 

Theoretically this could be ok... but it would be pretty hard to handle with 2 of the rc-remotes controlling at the same time... they are really bulky

Edited February 26, 2018 by TechnicSummse

[kbalage]

@TechnicSummse I agree it wouldn't be easy but certainly not impossible. I had to do the same with a touchscreen and two virtual sliders.

[Marxpek]

 

19 minutes ago, kbalage said:

I can tell you about that part how "easy" is to reach 40 km/h with BuWizz  

But to stay on topic - as you have tons of motors and RC units now, why not to go simple and try a similar config like my BuWizz record breaker. You'll need to have more power as the RC units are heavy as mud, but something like a 4 wheel setup, 4 RC units, 8 motors, no any moving parts from steering, just steered with the speed difference of the motors on the two sides.

The buwizz has great advantages over the rc unit, weight and voltage makes it a clear winner and with the same amount of rc motors and a similar design a buwizz will always win, but making anything out of Lego controllable (and control it) at that speed is an accomplishment and by no means easy.. time for me to get some buwizz...

After testing i will adapt the design as always, maybe 4 wheels, but i will not add a extra rc unit for the same amount of motors.. 

21 minutes ago, TechnicSummse said:

This would need 2 remotes on 2 different channels... and 2 rc-units on channel 1 and another 2 rc units on channel 2... 

Theoretically this could be ok... but it would be pretty hard to handle with 2 of the rc-remotes controlling at the same time... they are really bulky

It also is exactly what i suggested as my best option if 3 wheeled skid steering works, using 2 controllers, but not looking forward to work 2 controllers while riding a bike at 35km/h, but.. whatever it takes..

 

@TechnicSummse since you invested in rc parts now, did you also invest in a gps device? ;D