[WIP] 40+ km/h racer - need your help!

[TechnicSummse]

1 hour ago, mocbuild101 said:

I have been doing some other stuff, I have done a few more tests - but they have all been less than 30km/h - so I didn't bother posting them...

I think I may have to try a trike design, with two wheels on the front, and only one wheel on the back.

But I'm still determined to beat your (2 motor) 34.8km/h record! - I haven't given up yet!

2 wheels in the front and just 1 on the back wont bring better results. Maybe it could help, if you can make a more stable construction, or reduce the rolling-resistance like that. But 3 wheels=3 wheels... and if you use just one driven wheel, you will loose some grip. But i also thaught about this :D

 

[mocbuild101]

8 hours ago, TechnicSummse said:

2 wheels in the front and just 1 on the back wont bring better results. Maybe it could help, if you can make a more stable construction, or reduce the rolling-resistance like that. But 3 wheels=3 wheels... and if you use just one driven wheel, you will loose some grip. But i also thaught about this :D

 

You do have a point there, but... there's no reason why I can't try it!

One of the reasons why I decided to try this setup, is because I could use bigger front wheels (less rolling resistance and axle friction) without gaining weight.

Edited July 14, 2017 by mocbuild101

[TechnicSummse]

I wasted another 7€ :(

I thaught i could try some other wheels... but sadly with the absolute same results, as you can see in the video at the bottom. All those older small and relativly big wheels seem to have way to soft rubber.

Any suggestion for other wheels? How soft are those? :

 

 

 

 

Until now...it seems this is the one and only: 

 

 

Edited July 15, 2017 by TechnicSummse

[mocbuild101]

2 hours ago, TechnicSummse said:

How soft are these? :

They are the same as the other wheels you tested (that use the same rim).

One thing I realised, you are doing the tests without putting the wheels on a surface - which you could simulate it by putting another (free spinning) wheel against it - and you will find that the tire won't come off the rim anymore.

[TechnicSummse]

1 hour ago, mocbuild101 said:

They are the same as the other wheels you tested (that use the same rim).

One thing I realised, you are doing the tests without putting the wheels on a surface - which you could simulate it by putting another (free spinning) wheel against it

 

I did that ;)

1 hour ago, mocbuild101 said:

- and you will find that the tire won't come off the rim anymore.

nope... it still blows of like a ballon, and you can look between rim and tire at the opposite side of the free-running "placeholder"-wheel.

And again.. all test are done with just 2400 rpm... i would need 2700 for 40 kph with the motorcycle wheel, and even a lot more with the futuristic wheels

[mocbuild101]

17 minutes ago, TechnicSummse said:

I did that ;) it still blows of like a ballon, and you can look between rim and tire at the opposite side of the free-running "placeholder"-wheel.

And again.. all test are done with just 2400 rpm... i would need 2700 for 40 kph with the motorcycle wheel, and even a lot more with the futuristic wheels

Oh... that's not what I got with my tests  - and I think I got it up to about 2500rpm. (but then again, that's only going by the maths of the gear ratio)

But you are right about needing a higher gear ratio for the smaller wheels, so maybe we do only have the one type of wheel...

[TechnicSummse]

I was redesigning evrything to a completely new model again in the last few days. It took me about ~10h of building time to finish this.

What's new?

 

- Until now, a not testet new gearing -> 2,25:1 (36:16) at the high output

      (this is the closest possible ratio (2,3333 would be perfect), wich should arithmeticaly lead to the same motor-rpm(1000) at 40 kph, then it was at my 34,8 kph record racer)

- just 2 half-beam bearings at the rear-axle

- kind of (adjustable) suspension (can be adjusted to be softer or harder, by adding or removing pins between the beams / hardest setting in the video)

- extra flat design

- center of gravity right before the rear axle

- weight: 1042g (without speed computer... will be ~1065 with it)

 

 

I will do some testruns later this day.

Here a few pictures and a video of the "suspension"

 

[mocbuild101]

I would put some tiny wheels on the outermost buggy motors - because if they touch the ground at 35-40km/h... those pin holes will be destroyed!!!

[Marxpek]

@TechnicSummse Looking good! maybe a bit wide.

I have not had a lot of time on the forum lately, but i have been doing some development, i'll try to post some today.

Looking forward to your results! (weather remains bad here..)

 

[TechnicSummse]

7 minutes ago, Marxpek said:

@TechnicSummse Looking good!

Thank you :)

Quote

maybe a bit wide.

Yes... maybe. I thaught the same... maybe i gonna build it 2 studs smaller soon. But for now, i will test it like it is... and see, how stable it runs.

Quote

I have not had a lot of time on the forum lately, but i have been doing some development, i'll try to post some today.

Would be nice to see some news again ;)

Quote

Looking forward to your results! (weather remains bad here..)

Same here... it was raining the whole day.. but now the sun is shining, streets are close to dry... i can start soon :D

 

18 minutes ago, mocbuild101 said:

I would put some tiny wheels on the outermost buggy motors - because if they touch the ground at 35-40km/h... those pin holes will be destroyed!!!

I will do this if i build it 2 studs smaller. At the moment it seems to be pretty stable.

 

Edited July 16, 2017 by TechnicSummse

[TechnicSummse]

Back from testing... with really really sad results :(

i kind of killed my RC-unit... the battery-cover is broken, and the only way i could drive in the future, is taping the batteries to the RC-unit :/

The only good thing is... it seemed to be verry fast... i saw a 17,xxkph  on the speed computer (wich is ~39 kph because i attached it directly to the motor-output, which is geared up 2,25 to the wheel), but after the crash... not sure if there was a free spinng wheel while the crash... so i have to do some runs again... but not today... i'm just damn frustrated now:(

 

Here a few pictures...

 

This.... damn thing... 

led to this....

 

[Marxpek]

O man.. this sucks.. i  recall me writing this as one of the most likely things to break first, sad to see it happened to you man... maybe you can glue a tiny piece of wood in place for the tabs?

 

[mocbuild101]

Ouch!!! That's a very bad crash!

You can get a new battery cover here: (if you need it)

https://www.bricklink.com/v2/catalog/catalogitem.page?P=43457&name=Electric, RC Race Buggy Battery / Receiver Unit Battery Cover (for 6272c01)&category=[Electric]

But is there anything else broken? - it looks like there should be...

[TechnicSummse]

3 hours ago, mocbuild101 said:

Ouch!!! That's a very bad crash!

I had a few of such crashes... but until now the RC-stuff was ok allways... just broken beams/connectors/gears

3 hours ago, mocbuild101 said:

You can get a new battery cover here: (if you need it)

https://www.bricklink.com/v2/catalog/catalogitem.page?P=43457&name=Electric, RC Race Buggy Battery / Receiver Unit Battery Cover (for 6272c01)&category=[Electric]

Lots for sale -> 0 

3 hours ago, mocbuild101 said:

But is there anything else broken? - it looks like there should be...

It seems everything else is ok. If i have some time... i'll rebuild this evening.

I will try to build 2 studs smaller ... and the battery-box at the end of the car. I think with this model, i am really on the right way to 40+

[TechnicSummse]

I had a pause on this the last month. First i was building some other stuff, and last 3 weeks i was at vacation :)

But now i will start working on this again.

Some news to this... new "parts" arrived:

 

 

So i finally own a second RC-unit  .

I also baught 2 additional 94.2 Motorcycle tires, so i can try a big frontwheel-setup now.

 

A lot of things to do now... i can compare now 3 motors beeing powered from 1 RC-unit vs 2 rc-units. Also i can compare my current frontwheel vs the motorcycle-wheel. I will also compare the weight of the RC-unit vs battery-box+ micromotor+ 9v-switch. This will bring some new facts wich will help me to find the right way to the 40kph with 4 motors.

 

Another thing is.... i own 6 buggy-motors now... you can guess what... i defenetly will build a 6 motor-version in the future ;) But this will take a while... i wont start on this as long as i did not reach the 40 kph with 4 motors.

 

Tomorrow i will start building again, and also post some new pictures then.

 

[TechnicRCRacer]

Awesome! Glad you're continuing this!

2 hours ago, TechnicSummse said:

micromotor

How did you find a working one? All the ones I buy all are turned to dust. 

[TechnicSummse]

6 hours ago, TechnicRCRacer said:

Awesome! Glad you're continuing this!

How did you find a working one? All the ones I buy all are turned to dust. 

Hmm... i had 3, and all worked fine.

I baught 3 incomplete 8082 Universal-Building sets for 22-28€ each. At the end i had 2 complete sets... the leftover parts+ one complete set i sold again, and 1 set i kept.

2 of the 3 Motors were glued allready, but i didndt care about that, since it doesnt matter for regular use.

You can buy working micromotors on Bricklink for ~15€.

Edited August 19, 2017 by TechnicSummse

[mocbuild101]

8 hours ago, TechnicSummse said:

So i finally own a second RC-unit  .

That's something I don't need for my record (but I'd still like to get another one) - because I'm only using 2 motors

8 hours ago, TechnicSummse said:

I also baught 2 additional 94.2 Motorcycle tires, so i can try a big frontwheel-setup now.

That I would like to try, but I only have 2 of those wheels at the moment...

8 hours ago, TechnicSummse said:

Tomorrow i will start building again, and also post some new pictures then.

Great! But I won't be starting again until after TC12 - but I guess that's not so bad, because there isn't competition for using only 2 motors

[TechnicSummse]

1 minute ago, mocbuild101 said:

Great! But I won't be starting again until after TC12 - but I guess that's not so bad, because there isn't competition for using only 2 motors

I am thinking about breaking my old record there... maybe i can get a 35,xx -36 kph? :D

At the end i think its way more boring to build a 6 motor car, then a 2 motor-car. I think there wont be many people wich could join the 6 motor-competition.

And as it seems, we could have some more competion soon with @rkkm and @jam8280.

I would love to see a few tries from "new" people with different thinkings :)

[mocbuild101]

6 hours ago, TechnicSummse said:

And as it seems, we could have some more competion soon with @rkkm and @jam8280.

Oh yeah, I forgot about them... But I do agree it would be good to see some new designs - although I don't think it would qualify as competition if they use SBricks. (non-Lego)

Edited August 19, 2017 by mocbuild101

[rkkm]

Meh, im not really in record breakers, i have build ones trycycle with rc unit with steering and no gearing and it went 25kmh, i think that i will start competition with fastest racers, so prepare :P

But i have got an idea in doing record that could kick all of your megablocks if my calculations are not wrong, but it would require some more parts etc. 

For now im looking forward to build a small racer, 2 rc motors, sbrick, small batbox, servo - this will be fun car - easy to ride, with disc brakes or clutch which would change output using to power wheels from slow to fast and fast to slow, so stay tuned :P Also i plan to build a racer with 1 rc unit and 3 motors to test some combinations with gears and racer with 4 motors and 2 rc units, but i will have to wait for new batteries cause with normal alkaine ones, weight is too much, about 500g both rc units, if i use 2 rc units with my batteries voltage will increase by 2v and weight will decrease by more than 200g, and i will also try combination similar to what i want to try in a record breaker but for now im doing some tests, for example i have done pivot wheel, by using 68mm tire and putting in it 62.4 mm tire so the steering got pivot cause wheel hub is perfectly in centre of wheel and it require less torque to drive when stteered so only pros! It is a bit wip cause i dont got for now money or wheels from set 8448 and their wheel hubs, it would cost me 25E and rest of money i have spent on sbrick, second prototype of mine is making steering with pivot, with positive caster angle ( 30 degree ) and with ackermans geometry, i dont know if it is but for now in my thinking its best option of possible steering :)

[ThatOneBuilder]

This could beat a car in acceleration with some more R&D! Best of luck to you and wish you many more RC units , haha!

[TechnicSummse]

I have some news again 

 

At the beginning the really good news...i found some superglue, and the lost plastic-noses (they were inside the rc-unit).

And it seems to be pretty stable again.

 

Yesterday i built a simple testbench to compare my buggymotors under load. The load can be adjusted with the rubberband.

I testet all 6 motors and found 1 motor wich was really worse then the other 5. While 5 motors were in the ~1100 rpm-range (+- 10 rpm), the 6th motor did only 1020-1040 rpm. This is 7% less power... means, i wont use this motor for my 4 motor-car anymore.

 

 

This evening i started to build again. First i will try to build a usefull steering with the 94,2 motorcycle front wheel.

At first i wanted basicly copy the steering system wich @Marxpek used at his latest build. But then i decided to keep the idea of my known setup and change it to be able to house the big wheel.

Below a few pictures of the first try... i defenetly will rework this, but its a start :)

 

 

 

Finally a picture wich i HAD to take, while those motors were laying on the ground... it just does look so good :D

[TechnicSummse]

I completed the car again :)

As i mentioned earlier, i compared the rc-unit vs PF-battery-box (+9v switch+micromotor+wires). The rc-unit is 100g heavier then the PF-box. This, and the fact, that i testet the PF-box under load... (at ~1000 rpm) running 2 minutes without activating the protection, resulted in using the PF-box again for my newest try.

 

I changed a few things compared to my last car, but mostly things wich you cannot really see. Especially the axle-bearing and the reinforced rear-part of the car. At the same time, i was able to make more room for the wheels, wich results in a 1stud broader rear-axle, for more driving-stability

The frontwheel is now also a 94.2 motorcycle wheel. 

At the end i ended with a really heavy 1150g . But i think the reworked rear-part and the new wheel could still bring some improvement.

What i like most is the really soft "suspension" this time. I would say ~70-80% of the cars weight is sprung-suspendet now, as you can see in the video below:

If evrything goes fine, i will do some testdriving later this evening.

 

Edited August 26, 2017 by TechnicSummse

[nicjasno]

This is not very good for high speed runs on very uneven surfaces.