kbalage

Yet another speed record breaker - BuWizz powered car over 40 km/h (with instructions)

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First of all please watch the teaser video from last week :)

 

 

A couple of months ago everyone and their grandma tried to build an RC car going faster than 40 km/h. Although I don't have a properly working old Technic RC unit with the remote (somehow I have only faulty ones), I have the necessary amount of buggy motors and 2 BuWizz units, so I had to give this a try :) The build is not 100% pure Lego (although BuWizz is built to be used with Lego), but it still has the fun factor and of course the challenge :) The whole process turned out to be much-much longer than I expected, but at the end it was a success!

 


I spent several weeks creating, improving and testing the car. The basic idea was to use 2 BuWizz units, 4 buggy motors and 4 Technic motorcycle wheels and to add only the minimal amount of components to remain light and fast. It had to be solid enough to survive all the crashes during the tests and record breaking attempts.

I had dozens of tests at various locations until I found a proper track and the final configuration of the car was created. During this time a lot of parts had to be replaced as the axles were bent after a couple of runs, you can see the examples in the video.

The car does not have a conventional steering to reduce weight. For the speed runs only small adjustments are needed, so the direction of the car is controlled by the speed difference of the wheels - there are two control sliders on the phone for each side of the vehicle.

The faster output of the buggy motors is used, the gear ratio is 3:1. I tested several combinations to drive the wheels, the most successful one turned out to be the usage of 36t and 12t beveled gears.

The speed was measured with the on-board GPS unit. The car was controlled mostly with my phone, but for the fastest run I was using an iPad (longer range). Even like this at full power the car ran out of range very quickly. 

I think it would be possible to go even faster with this car, but that would require a completely flat surface and a chase vehicle to ensure the controller stays in range. Maybe another time ;)

Edited by kbalage

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Very nice! 

Maybe get a phoneholder for a bike to stay in range.

since its powered by 2 buwizz and has no steering it is kind of in a league of its own, but i do think the rc units can compete, taking out the steering and making it 4WD will give them better results as well, i might try after my current racer reaches 40km/h.

Fun stuff, keep it up!

 

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You cannot call it fastest "something" LEGO as it uses 3rd party item, so claim is no longer valid. It is like throwing your MOC out the of the plane and claiming it broke sound barrier. 

I like the structure of the model to be fair.

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Thanks guys! I was so close so many times to 40 km/h but finally made it :) I think it was more about the road quality sometimes then the car itself.

@Marxpek I tried it on a bike, but I could not accelerate quickly enough before the end of the road, and the touch controls were still hard to handle :) Maybe if BuWizz adds gamepad support someday..

@zux I choose the title "Fastest Lego Technic car powered by BuWizz" for a reason, as far as I know there was no faster BuWizz-powered Lego car yet. I did not say it's 100% Lego, otherwise I'd call itt "OMG THIS IS THE SUPERFASTEST LEGO CAR EVER !!4!!4!!!" or something like that :) Using a 3rd party battery desinged and built especially for Lego is not really the same as throwing out the MOC of the plane and calling it a success.

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Reading your title it looks like "Fastest Lego Technic car powered by BuWizz". That's how I read it first which confused me a bit. Stating something like "Fastest Buwizz powered creation made of LEGO Technic" without emphasis on "LEGO" would be honest and sound much clearer.

Sorry for being this picky, but this happens when people state they are best at something, as facts needs to be checked :) Did you get the same speed by running in opposite direction?

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8 minutes ago, kbalage said:

I tried it on a bike, but I could not accelerate quickly enough before the end of the road, and the touch controls were still hard to handle :) Maybe if BuWizz adds gamepad support someday..

I have the same problem, I set up the car, take about 50m distance with the bike and get it up to 30 km/h and then start accelerating the car when it is about 15 meters ahead of me. bit tricky but it works for me (only drove over it once...) but i do have the advantage of real controllers... 

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@zux I see your point, but please give me the freedom of naming my videos and deciding on the sequence of words :) As I did not do the run in the opposite direction within 60 minutes I know I don't qualify to claim a Guiness World record (wouldn't be the "fastest Lego Technic car" anyway), but I can live with that... Joking aside, I had multiple runs with a speed between 39-40 km/h but this was the quickest as the car was running dead straight when it went out of remote range so it managed to go far enough to reach this speed.

@Marxpek - That's a good strategy for the RC unit, unfortunately if I go out of range with the bluetooth control it is not that simple to re-establish the connection. I'm following your attempts and hope you'll make it with a 100% pure Lego creation for everyone's satisfaction ;)

 

Edited by kbalage
typo

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I don't mind how the words are formulated, Buwizz seems affordable and dedicated enough for Lego applications to consider the result as respectable. :thumbup:

Liked the videos, I really appretiate that You create storylines and some concept for presentation, much more entertaining. Thanks for that! :classic:

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Awesome! I would have never attempted so destructive. 

And congrats on breaking a record I guess?

EDIT: one question: do you only use iMovie to edit your films?

Edited by BrickbyBrickTechnic

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2 hours ago, kbalage said:

@zux I see your point, but please give me the freedom of naming my videos and deciding on the sequence of words :) As I did not do the run in the opposite direction within 60 minutes I know I don't qualify to claim a Guiness World record (wouldn't be the "fastest Lego Technic car" anyway), but I can live with that... Joking aside, I had multiple runs with a speed between 39-40 km/h but this was the quickest as the car was running dead straight when it went out of remote range so it managed to go far enough to reach this speed.

Heh, Guiness records :) My concern regarding test run in opposite direction is the fact max speed is usually a resultant of both runs, making sure you are not running the test downhill. Thus the reference to the plane I did few posts above. 

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41 km/h... wow, really unbelievable! The 3200 rpm on wheels is a feat on its own - I'm surprised that centrifugal forces are not pulling the tire out of the rim. 

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It's amazing, every time you build something, it's even more powerful!

I had a feeling that the BuWizz was going to be the first over 40km/h, and it not really much of a surprise, considering how much power it has in fast mode...

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Thanks again folks!

@Davidz90 - If it was unloaded the wheel was spinning well over 4000 RPM, the Lego speed meter could not measure the exact value.

@mocbuild101 - I'm sure I won't make something this fast in the near future, I spent way too much time with this project :) I'm sticking to the "small & relatively fast" formula, although I could not resist to start to build @agrof's amazing class 1 buggy and try to implement some of my ideas :)

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Hey @kbalage,

i was not here at EB for about 1 week, thats why i did not see your topic here ;)

You have a few nice ideas in your setup... especially the skid-steering, wich allows you to save the weight of a servo/steering-unit/rack and so on...

As @zux wrote, i guess most people (on YT) think your car is 100% Lego... but still i like it, i like how it works, and how it acts.

 

Can you tell me something about the weight?

If you are in the same weight-range as we are with the rc-unit(s)... i think your gearing is to high for highst possible speed. I had a 40+ Run with 2,25:1 (36:16)... Marxpek uses 2,5:1 (40:16)... i think 3:1 at the fast output ist a bit to much and even slows you down.

Another point where you loose a lot of speed is your output pinhole-friction... as you can see easy on your part-wear... you could use just half beams for the axles... and max. 2 half beam-pin-holes per axle... otherwhise you create tons of friction wich slows you dow.

 

Even if i am evious because i would love to have such a fast car (i do not own a single buwizz, but mainly because i'm a pursit), i would still love to see, how fast this could really go with some optimizing :)

 

But i have to say 1 thing... i really LOVE how you did your video :)

Edited by TechnicSummse

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@TechnicSummse About the weight, the car without the GPS and the 2 BuWizz units is around ~700g, one Buwizz unit is 70g, GPS unit with holder is 65g, so altogether it was around 900g. 


I tested the car with several gearing ratios, this seemed to work the best - 36t & 12t beveled gears. Half beams did not seem to be strong enough to survive the crashes :) I'm sure the structure could be improved further, my main goal I set for myself was to go over 40 km/h, so that was all for me. I have no intention to compete with anyone, I was simply curious if I can reach the same speed range like the cars you made :) Theoretically it could go much faster, the 3200 RPM I measured on the test pad would mean ~56 km/h, but I'd need absolute ideal circumstances to reach that. 

The main problem with BuWizz is the limitation of the BT range and the stability of the connection, at this speed it can go out of range in 1-2 seconds and once the connection is lost it's not that easy to re-establish it. Additionally, once it goes out of range sometimes  it still spins the wheels at full power so that's one of the reason I had to create a "survivor" type of car, there were tons of crashes.

I don't think there's a major difference between the capabilities of our vehicles so I don't think you should be envious. Purism is always subjective, for a Power Functions purist your vehicle also uses obsolete parts so there always will be made-up standards where ones fits and the other does not :) At the end of the day these are funny technical challenges we create for ourselves so I don't think we should take these too serious.

I'm glad you like the video, for me the subject of the video is only one part, the presentation is also equally important. Trying to improve myself constantly at this as well :)

 

Edited by kbalage

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@MattL600 Thanks, the animation was a nice and new challenge, never done this before. I tried first to stick to the 15-20 fps recommended by the experienced brickfilm creators, but it really needs practice and experience to create motion with that many steps. Finally I created the animation with only 10 fps, but I think the result is still ok. It took a couple of hours to create all the shots, I used mostly my phone for that with a dedicated stop motion app.

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That is an amazing accomplishment! I really don't care what you call it, it is great! I am amazed that the Technic elements held together,  how much better it would work on a very smooth surface.

Andy D

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