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

[Marxpek]

Once again there is a speed limit to break! This time the aim is 40 km/h and this time i am not alone!

After i broke the 35 km/h limit, the record seems in trouble with @TechnicSummse on the horizon! He too is trying to break the 40km/h with Lego and is getting some serious results, until this day i have not broken his (unpublished record) of 38.4km/h, go check out what he does, good fun!

I always tried to make my racers look somewhat good, I also tried to build them so they can survive a crash, that's all out of the window now, lightweight, low roll-resistance, all the proven concepts i will have to use here. 

This is fully untested, except for the steering unit, this has functioned fine on a 30km/h+ testdrive, but on my old setup with the wheel in the back.

The steering setup resembles a shopping cart wheel setup, with the pivot point way in front of the wheel so it wants to go straight by itself, but it allows for accurate and low drag corrections. I might try to reduce its weight a bit more.

sorry for the weird setting in the pictures, ill make better ones later on when it's final..

Now i am waiting for the right moment to do some test runs, the lack of time and the rain on days when i do have time, can be somewhat frustrating for me since i am eager to test this.

I have a good feeling about this, but of course i would be glad to take suggestions and consider them.

What are your predictions on it's speed? Place your bet before the test runs! ;D

 

 

 

Edited February 23, 2018 by Marxpek

[TechnicRCRacer]

Wow, too much RC I bet around 38 ish. 

[BrickbyBrickTechnic]

Interesting setup! Can't wait to see if it breaks the record. 

[mocbuild101]

Looks good!

I don't know if you posted this somewhere else, but what is the GPS device you are using? - it's really small!

[Marxpek]

1 hour ago, mocbuild101 said:

I don't know if you posted this somewhere else, but what is the GPS device you are using? - it's really small!

It is a Brighton 100 cycling computer.

http://corp.brytonsport.com/products/rider100?lang=eng

[TechnicSummse]

Looks really nice so far :)

But with the wheels beeing close together you will need support wheels. Otherwhise you will scratch your outer buggy-motors on the ground ( or the RC-unit). 

I see you are using thin beams as bearing now also ;)

What i dont understand here, is your steering...? Can you make some close up pictures there?

 

But i guess this can be 38+ or even ore? :D

 

[mocbuild101]

2 hours ago, Marxpek said:

It is a Brighton 100 cycling computer.

http://corp.brytonsport.com/products/rider100?lang=eng

Oh, $80 is too expensive for me... (I looked it up on ebay)

But... today I realized I do have GPS , in my sports watch! I'm not sure if it's 100% accurate or not, but I think it might be...

Will do some tests tomorrow...

[PorkyMonster]

Just wondering... how do you guys judge whether the car has reached its top speed?

I mean, at low speed you can probably tell that it is still accelerating... but at 200m and already quite fast, what if it can still go even faster further down? Trial and error? Or do you set a fixed max distance just for the sake of comparing?

I was playing around using L motors and realised that 10m (in door) is far far far from enough...

[Marxpek]

2 hours ago, TechnicSummse said:

But with the wheels beeing close together you will need support wheels. Otherwhise you will scratch your outer buggy-motors on the ground ( or the RC-unit). 

I see you are using thin beams as bearing now also ;)

What i dont understand here, is your steering...? Can you make some close up pictures there?

I have added some tiny wheels on the buggy motors pinholes after taking pictures, i still need a similar solution for the front, but it really wants to stay on its wheels when driving and even when steering, this steering setup does not tilt the car like i assume your does a bit?, but yes, i will use these wheels to save the units from getting banged up too much, but they rarely touch the ground (indoors)

small video on the workings of my steering:

That should explain it better than words. 

I think you could use a better front wheel in your racer (this one "36.8 x 14 ZR" is much more "racy") than your offset thread front wheel, however mine will have to spin faster then yours at the same speed since it is smaller, maybe causing more friction, but it will have less roll-resistance, tests will have to show , but for now its raining cats and dogs here... summer in The Netherlands is great ;D

 

36 minutes ago, mocbuild101 said:

But... today I realized I do have GPS , in my sports watch! I'm not sure if it's 100% accurate or not, but I think it might be...

That is a good idea! check if the gps is available in 1 second mode on high accuracy, (normally it is measured around every 4 seconds, not giving very accurate results on relative short runs like we do, but try it anyway if there is no 1 second mode)

27 minutes ago, PorkyMonster said:

 

Just wondering... how do you guys judge whether the car has reached its top speed?

I mean, at low speed you can probably tell that it is still accelerating... but at 200m and already quite fast, what if it can still go even faster further down? Trial and error? Or do you set a fixed max distance just for the sake of comparing?

 

The buggy motors have quite a distinct sound, and you can hear when they are on their top, although its kind of hard to hear when cycling at 35 km/h..

So mostly: trial and error for me, just get the best run you can and check the results afterwards, if i can (most runs end in crashing into the grassy border of my track) i will race the entire length of my track, just to be sure, but also when you have done as much tests as I/we have, you will get the feeling for it, you can "see" the speed and I can feel how hard i have to pedal for it to keep up.

Most of the time it took about 150m for me, perfectly showing on the gps data, that is very helpful to me. My last double rc unit racer needed 170m to go over 35 km/h but that one was heavy so needed a long track. Getting a good run is always tricky, any small bump or dirt on the road can cause a severe crash at 25km/h+ and there always is human error, cycling fast and controlling the racers can be a bit tricky, you kind of cannot instantly brake on the bicycle since your hands are on the controller..

[TechnicSummse]

1 hour ago, Marxpek said:

That should explain it better than words. 

Ah, now i see, how your steering works... its different then mine. But this is also a nice and clever idea. What i dont linke there... it is way to stable and heavy.

I designed my frontpart, to be verry loose. When crashing, the axles can be pushed back, and the beams will bend outwards. You can call it something like a crumple zone. Like this, the RC-unit is protectet.

I think if you crash with this steering setup, all the crashing energy will go staright to the first RC-unit(s pinholes)

1 hour ago, Marxpek said:

I think you could use a better front wheel in your racer (this one "36.8 x 14 ZR" is much more "racy") than your offset thread front wheel, however mine will have to spin faster then yours at the same speed since it is smaller, maybe causing more friction, but it will have less roll-resistance, tests will have to show , but for now its raining cats and dogs here... summer in The Netherlands is great ;D

I love this wheel :O

I think i need to buy one of those :D

Well at the end i didnt buy any special parts for this project yet. I just used the best what i could find in my partlist.

I got the rearwheels for free when i baught some mixed parts, and i decided to like them more then the Claas Xerion-wheel.

Long time, i was using this one as frontwheel: http://rebrickable.com/parts/55978/tyre-37-x-22-zr/ from the getaway racer-set 42046

But it was worse then the one i am using now. My actual frontwheel is smaller and has one big plus... it has a pinhole, and not an axlehole... meaning it can freely spinning at the axle, AND the axle can spin in its bearing-points...it spins soooo good :D

If we could race indoors, i would use this one: http://rebrickable.com/parts/2815/technic-wedge-belt-wheel-tire/. That would be the best possible wheel at all

 

Edited June 28, 2017 by TechnicSummse

[mocbuild101]

4 hours ago, Marxpek said:

That is a good idea! check if the gps is available in 1 second mode on high accuracy, (normally it is measured around every 4 seconds, not giving very accurate results on relative short runs like we do, but try it anyway if there is no 1 second mode)

It doesn't have any modes, it's kind-of just: turn on -> use -> view data

But I think would be reading every 4 seconds (or about that) - because refresh of the speed on screen is slow, but I should be able counter that by going at top speed for longer...

[Marxpek]

2 hours ago, TechnicSummse said:

it is way to stable and heavy

I don't see how being stable is a bad thing, maybe you mean rigid/stiff? I agree that is a bit on the heavy side but like i stated before, i will try to reduce the weight a bit more, but as you might have noticed, i have an (automated) habit of bracing everything, i can/will reduce the weight in the rear bracing as well.

2 hours ago, TechnicSummse said:

I think if you crash with this steering setup, all the crashing energy will go staright to the first RC-unit(s pinholes)

I hardly ever crash into solid objects since i only drive on tracks with grass next to them (my new untested track has the same, it's one of my demands on a track, no curbs for sure)

And if i do crash into something solid, my guts tell me the 15L liftarm, the pins or the 5.5L axle will snap before the rc unit pinholes gives way, the real danger is driving over it with my bike when control is lost... that would be bad.. 

i tried the 37x22 in this setup as well, but they are too wide after a bit of scouting in my collection of wheels i found these to be perfect for this cause,

I have considered using the http://rebrickable.com/parts/2815/technic-wedge-belt-wheel-tire/ but think it will break under the stress (maybe not on a perfect track), these pulley wheels aren't that strong, i broke a few using them as extra axle connectors on the motorcycle tire and they break easily under high stress.

2 hours ago, TechnicSummse said:

it has a pinhole, and not an axlehole... meaning it can freely spinning at the axle

I also tried the wheel you are using now, its is ok but you can hear the resistance of the thread when you roll it on a hard surface, and i am not convinced having 2 bearing points in the front wheel is better than 1, you are adding an extra frictionpoint, to the system and There is some sideways motion on 2 points as well, causing more friction.

I guess having 1 point with a faster spinning axle gives less resistance than having 2 point with less speed on the axles, but that is just my gut feeling, no tests were done...

Just now, mocbuild101 said:

but I should be able counter that by going at top speed for longer..

That would fix it indeed, but that will not make it any easier for you.

Did you do any comparison with another gps device? or something else maybe?

[mocbuild101]

2 minutes ago, Marxpek said:

Did you do any comparison with another gps device? or something else maybe?

No, except for the video option.

[Marxpek]

 

Just now, mocbuild101 said:

No, except for the video option

And that mindstorm setup idea you had? is that viable? i like that idea since you do not have to add anything to the car (no weight from the gps device, and no friction from the speed computer)

[mocbuild101]

Just now, Marxpek said:

And that mindstorm setup idea you had? is that viable? i like that idea since you do not have to add anything to the car (no weight from the gps device, and no friction from the speed computer)

Yeah, I've got that - but the problem is: I can't use the GPS inside, and I can't use the Mindstorms setup outside.

[Marxpek]

Just now, mocbuild101 said:

and I can't use the Mindstorms setup outside.

I never saw this set in action and know very little about it, it needs a pc or a wall outlet? really no way to take it outside? or is that about the light sensor? maybe a laserpen can overcome that (if that does not destroy the sensor..?) it would be so cool to do the accurate measuring with Lego as well..

[mocbuild101]

Just now, Marxpek said:

I never saw this set in action and know very little about it, it needs a pc or a wall outlet? really no way to take it outside? or is that about the light sensor? maybe a laserpen can overcome that (if that does not destroy the sensor..?) it would be so cool to do the accurate measuring with Lego as well..

The light sensor won't be able to detect the light of the torch, but yes lasers would be better - but I don't have any at the moment.

I hope to be able to make it work better outside (and inside too!)...

[Marxpek]

Just now, mocbuild101 said:

I hope to be able to make it work better outside (and inside too!)...

You are testing the setup already? if so, what are the problems? and are the result you get somewhat consistent?

And.. will your speedracer project stay hidden? you mentioned in your drift racer topic you are working on it ;D

[nerdsforprez]

aren't there front wheel combinations that would offer less resistance?  I know that is a very nit-picky observation.... but if you are really splitting hairs between who is the fastest with limited other factors  it may help.  What about the front wheels like these.....

 

 

[mocbuild101]

12 hours ago, Marxpek said:

You are testing the setup already? if so, what are the problems? and are the result you get somewhat consistent?

And.. will your speedracer project stay hidden? you mentioned in your drift racer topic you are working on it ;D

I'm mainly only having problems with using a torch... I need to get lasers!

Well... yes - at least until I get above 35km/h. (although 40km/h+ is my goal!)

But I won't be doing any testing today - it's raining! (yeah, not doing it inside anymore)

Edited June 29, 2017 by mocbuild101

[TechnicSummse]

3 hours ago, nerdsforprez said:

aren't there front wheel combinations that would offer less resistance?  I know that is a very nit-picky observation.... but if you are really splitting hairs between who is the fastest with limited other factors  it may help.  What about the front wheels like these.....

We talked allready about htis one:

But @Marxpek is afraid they will break to fast. And i know from similar small wheel wich i testet... that running them on a regular street doesnt work.

This would be a really nice wheel, if you had an indoor place wich is ~150m...

 

 

 

2 hours ago, mocbuild101 said:

I'm mainly only having problems with using a torch... I need to get lasers!

Well... yes - at least until I get above 35km/h. (although 40km/h+ is my goal!)

But I won't be doing any testing today - it's raining! (yeah, not doing it inside anymore)

But dont waste more time for your meassuring-system then for your car... i would love to see some results here soon :D

Edited June 29, 2017 by TechnicSummse

[Marxpek]

 

After doing a bit more weight and profile reduction, I managed to do 1 test run but soon after decided to stop trying, everything was still wet from the rain and when the racer ended up in the grass, the racer was all wet and muddy, so it needs cleaning and a better day first to fully test it.

The acceleration surprised me a bit, so it went out of range from my controller faster then i had anticipated, losing control and power and going uphill, it still managed to go well over 35 (i'll keep the actual speeds a bit of a surprise), it is a bit hard to extrapolate the speed from the gps curve since it was a uphill ride, but there is power left for sure, At least i know my steering setup is working very good at 35km+.

The steering works just as i had imagined and is causing very little drag on corrections while not pushing the car into a roll-over on relative sharp steering.

P.s this is not my new track, just a decent piece of asphalt in a park near me, but this park has some up- and downhill parts so it is not really useable for me, but i wanted to do some quick tests nearby, since rain is always just around the corner here.

I'll keep you informed.

6 hours ago, nerdsforprez said:

aren't there front wheel combinations that would offer less resistance?  I know that is a very nit-picky observation.... but if you are really splitting hairs between who is the fastest with limited other factors  it may help.  What about the front wheels like these.....

Is this the large old pulley wheel with a tire on it? or the smaller pulley wheel we discussed earlier in this thread? I think both would be to weak for this, but it is a good idea of course, the more narrow and the lighter the better, but we have to keep track of real world situations, like bumps or crashes or steering errors, I also have a feeling it would be very easy to loose the tire on this wheel.

[nerdsforprez]

40 minutes ago, Marxpek said:

 

 

 

Is this the large old pulley wheel with a tire on it? or the smaller pulley wheel we discussed earlier in this thread? I think both would be to weak for this, but it is a good idea of course, the more narrow and the lighter the better, but we have to keep track of real world situations, like bumps or crashes or steering errors, I also have a feeling it would be very easy to loose the tire on this wheel.

Yes - it is the pulley.  Admittedly, I am unsure where the tire is from.  I think it is a large rubber band on the pulley.  The large blue rubber band I know fits as well. 

I hear your concerns of the strength, but they are rather strong given their appearance.  Just like the overall theme of what you are doing here though..... you will never really know unless you give it a try....

[mocbuild101]

7 hours ago, TechnicSummse said:

But dont waste more time for your meassuring-system then for your car... i would love to see some results here soon :D

I not, I only spent half a day testing that - and then I remembered the GPS in my watch.

I have been building, and my first car (2 buggy motors) has a theoretical speed of about 47km/h , but I'm still waiting for some good weather to test it...

4 hours ago, Marxpek said:

it still managed to go well over 35 (i'll keep the actual speeds a bit of a surprise)

But not yet over 40km/h, right?

3 hours ago, nerdsforprez said:

I am unsure where the tire is from

I know that there are 2 in the "Klutz crazy action contraptions" book.

[Marxpek]

1 hour ago, mocbuild101 said:

But not yet over 40km/h, right?

not yet indeed, but i have not been able to go all out with this racer yet.

1 hour ago, mocbuild101 said:

I know that there are 2 in the "Klutz crazy action contraptions" book.

is it a Lego tire? i could not find any that fit this pulley wheel.

1 hour ago, mocbuild101 said:

I have been building, and my first car (2 buggy motors) has a theoretical speed of about 47km/h , but I'm still waiting for some good weather to test it..

It feels a little low to me, my current theoretical speed is 75,46 km/h,  @TechnicSummse racer that did 38km/h+ has a theoretical 66km/h and my first steering record with 2 motors had a theoretical speed of 57,13 km/h,  but it is very hard to say what works best, at least yours will have no problem accelerating, but my guess is you can gear it up further!