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

[TechnicSummse]

1 hour ago, TechnicSummse said:

A 37,3 kph-run was the best result today. But im really really sure, it could be faster on a longer track. It seems at the end i will also need a GPS-devce to get a usefull speed-graph.

Gearing: -> ???? Who can guess it? (you have to think a bit outside of the box ) -> The one who guesses it first, gets a cookie 

-> If you can guess it, please post it in a spoiler ;)

18 minutes ago, Marxpek said:

yeah just noticed that was not an option.. must be 24:12 then?

No.... its a gearing not used by anyone of us so far... you must think outside the box :D

 

Edited July 6, 2017 by TechnicSummse

[Marxpek]

don't tell me you used a turntable...

[TechnicSummse]

2 minutes ago, Marxpek said:

don't tell me you used a turntable...

now you are thinking in the right direction :D

But no... its not a turntable... but i also thaught about that :P

[Marxpek]

Hmmm you are using a tire in stead of a gear?

[TechnicSummse]

10 minutes ago, Marxpek said:

Hmmm you are using a tire in stead of a gear?

I also thaught about a rubber-band once... but no.. rubber-band would slip to much, and a tire would produce to much friction... 

It has teeth ;)

 

If no one can find it, i will reveal the gearing tomorrow at ~13 o clock 

Edited July 6, 2017 by TechnicSummse

[offroadcreations]

Did you use

Spoiler

An older style differential somehow?

 

[TechnicSummse]

4 minutes ago, Offroadcreat1ons said:

Did you use

  Reveal hidden contents

An older style differential somehow?

 

100 points...you will get the cookie :D

Its a 28:8 gearing. I will post some pictures tomorrow

[offroadcreations]

56 minutes ago, TechnicSummse said:

100 points...you will get the cookie :D

Awesome!

56 minutes ago, TechnicSummse said:

Its a 28:8 gearing. I will post some pictures tomorrow

I'll be eagerly waiting to see how you integrated it.

[Aventador2004]

1 hour ago, TechnicSummse said:

100 points...you will get the cookie :D

Never delete history, enjoy your internet site cookie @Offroadcreat1ons 

[PorkyMonster]

5 hours ago, TechnicSummse said:

A 37,3 kph-run was the best result today. But im really really sure, it could be faster on a longer track. It seems at the end i will also need a GPS-devce to get a usefull speed-graph.

This is pretty much the same design then my 38,7kph-car, but with some improvements on stability and a totally new gearing.

Total weight including speed computer -> 1046g

That's great! Now here's another idea - since traction is not an issue, how about adding some "wings" along both sides to provide some air lift that'll increase along with speed? Can use those flatter ones, like:

  and  and end up with 

This will lighten the entire car and reduce rolling resistance, while not adding much to air resistance. Who knows, the car might actually "take off" .

[mocbuild101]

2 hours ago, PorkyMonster said:

That's great! Now here's another idea - since traction is not an issue, how about adding some "wings" along both sides to provide some air lift that'll increase along with speed? Can use those flatter ones, like:

This will lighten the entire car and reduce rolling resistance, while not adding much to air resistance.

That wouldn't work... those panels would only create enough lift to lift themselves (at most) at the speeds we are going at.

So really all it would be doing is adding weight (slower acceleration) and air resistance (slightly slower top speed).

 

2 hours ago, PorkyMonster said:

Who knows, the car might actually "take off" .

Doesn't everyone know that flying Lego is impossible?!

[TechnicRCRacer]

@mocbuild101Meh, it wouldn't add too much weight. Who knows, trial and error is a good way to go!

Edited July 7, 2017 by TechnicRCRacer

[mocbuild101]

Just now, TechnicRCRacer said:

Who knows, trial and error is a good way to go!

Well yes, it wouldn't hurt to give it a go... we seem to be trying everything else!

[Marxpek]

@TechnicSummse ahw im a bit disapointed by your riddle.. a differential is far from a out of the box solution. And what makes you think i did not try that? I have ?

[TechnicSummse]

1 hour ago, Marxpek said:

@TechnicSummse ahw im a bit disapointed by your riddle.. a differential is far from a out of the box solution. And what makes you think i did not try that? I have ?

I did not use it as a differential, i used it as a gear, by blocking the 12t bevel gears in the differentials with just 1 axle going completely through the differential between 2 motors.

Like that i have a 28t-gear, to provide me another gearing range, wich i usually could not use. Or is there any other 28t-gear? 

 

But the first run directly killed me a 12t bevel gear, while breaking 

 

 

7 hours ago, Offroadcreat1ons said:

Awesome!

I'll be eagerly waiting to see how you integrated it.

Here the promised picture ;)

There are just two 8stud axles between the 4 motors.

Edited July 7, 2017 by TechnicSummse

[PorkyMonster]

2 hours ago, mocbuild101 said:

That wouldn't work... those panels would only create enough lift to lift themselves (at most) at the speeds we are going at.

So really all it would be doing is adding weight (slower acceleration) and air resistance (slightly slower top speed).

2 hours ago, TechnicRCRacer said:

Meh, it wouldn't add too much weight. Who knows, trial and error is a good way to go!

Speed is quite interesting at that scale... Assuming the model is 1:10 scale, does it mean its speed should actually be multiplied by 10? Some websites claim that instead of that, we should just multiply with sq root 10... in any case, the "real" speed would then become either 373 or 118 kph... in either case, it'll be fast enough for such "wings" to have some effects. Also, air should be denser lower down... 

 

[Marxpek]

I tried the exact same thing with the differential... did not like it. Since it made the construction too wide. And the gear itself  can start to wobble. These ancient gears arent realky solid..

[TechnicSummse]

3 hours ago, Marxpek said:

I tried the exact same thing with the differential... did not like it. Since it made the construction too wide. And the gear itself  can start to wobble. These ancient gears arent realky solid..

Well... as you can see, it gives some nice result... and i liked the idea, because it is something new. Maybe not the best... but it was worth a try :)

To the construction... this is 5 studs wide between the motor pinholes... it fits perfectly to the RC-units pinholes in one line. Construction could not be easyer then this :D

By the way.. you are right... the gears are not as solid as others... but i killed allready a few older 24 teeth gears on my testruns.  so what? :D

Im pretty sure, i will test a turntable at one day...but at the moment i only own one newer style turntable, so i will try some other gearings :)

[Marxpek]

16 minutes ago, TechnicSummse said:

and i liked the idea, because it is something new. Maybe not the best... but it was worth a try :)

I tried it for the exact same reason, but i never tested it since i found them too wobbly:

16 minutes ago, TechnicSummse said:

the gears are not as solid as others... but i killed allready a few older 24 teeth gears on my testruns.  so what? :D

Well i decided to not test them because i do not own a lot of these diffs and these are the only ones that work well on a 90 degree angle and a linear mesh, so i wanted to save these diffs, but i must admit i never suspected this result.

I have some of these turntables z56 lying around, i already started with the idea before i mentioned it in this topic, (that's why i sayd: don't tell me.. i was doing the same at that very moment ;D) but the gear will become at least 3 studs wide and i will need a rebuild for that.

Did you get the 36t gears? im a bit let down by the results with the 36-12 gearing.. my old 40-16 seems better.

Btw do you think we should use the slow output at all? effectively we are using a extra set of (loaded) gears in the system.

[mocbuild101]

8 hours ago, TechnicSummse said:

Here the promised picture ;)

There are just two 8stud axles between the 4 motors.

Is the 8z gear offset at all?

 

7 hours ago, PorkyMonster said:

Speed is quite interesting at that scale... Assuming the model is 1:10 scale, does it mean its speed should actually be multiplied by 10? Some websites claim that instead of that, we should just multiply with sq root 10... in any case, the "real" speed would then become either 373 or 118 kph... in either case, it'll be fast enough for such "wings" to have some effects. Also, air should be denser lower down... 

 

Just like water and gravity, air doesn't scale properly - you would need to go faster at a smaller scale.

 

2 hours ago, TechnicSummse said:

To the construction... this is 5 studs wide between the motor pinholes... it fits perfectly to the RC-units pinholes in one line. Construction could not be easyer then this :D

Isn't it great when things match up like that!

 

2 hours ago, Marxpek said:

Btw do you think we should use the slow output at all? effectively we are using a extra set of (loaded) gears in the system.

Well, to put it simply, no.

[TechnicSummse]

6 hours ago, Marxpek said:

Did you get the 36t gears? im a bit let down by the results with the 36-12 gearing.. my old 40-16 seems better.

Not yet... i am still w8ing for this order to arrive :(

Hmm sounds like my 40:12 testing... but i think i choosed the wrong offset here, and the 12t gear was just a little bit to close to the 40t gear. 36:12 should run smoothly. What was the problem there? Simply a bad speed-result?

Quote

Btw do you think we should use the slow output at all? effectively we are using a extra set of (loaded) gears in the system.

Quote

Well, to put it simply, no.

Well i thaught about that... and thats why i created such crazy constructions like "The Machine"

Im not quite sure if it makes a difference if the gear is loaded or not... it produces friction anyway. But i have the feeling, using the high-speed-output should be better.

At the end it is way easier (with 4 or more motors) to use the low output. As i told allready a few days ago, its hard to get evrything fit, when using the fast output. Its just too hard, to come out of the motorcase with the gearing. This would also be the reason, why i would use the 56t turntable...

Quote

Isn't it great when things match up like that!

Thats the biggest reason to use the low output... simple and matching design (in the 4 motor-case)

 

3 hours ago, mocbuild101 said:

Is the 8z gear offset at all?

yep.. its offset 1 stud... 28+8= 36 <-> 24+12= 36

-> its the same offset

Edited July 7, 2017 by TechnicSummse

[TechnicSummse]

Because of some new ideas... i ordered a few parts last week. Yesterday, they finally arrived.

Especially i was hoping for those:

I thaught, with the right gearing, they could bring some wonders...

Well.. maybe they could... if the rubber wouldnt be soooo soft. If you thaught about buying them for your speed-car... dont do it!!!

Here is a little video, wich shows, why you should not use those wheels at high speeds :(

 

This is just ~2300 rpm.... to reach 40 kph with those wheels they would need to rotate with ~2700 rpm.

The tire-ballooning is so heavy... after a few seconds, the tire jumps from the rim. As you can see, you can look between the tire and the rim... and see the cable :O

Edited July 13, 2017 by TechnicSummse

[mocbuild101]

2 hours ago, TechnicSummse said:

I thaught, with the right gearing, they could bring some wonders...

Well.. maybe they could... if the rubber wouldnt be soooo soft. If you thaught about buying them for your speed-car... dont do it!!!

Here is a little video, wich shows, why you should not use those wheels at high speeds :(

If only you had asked someone here, we could have told you how soft they are!

Oh well, I'm sure you will find a use for them .

Did you get some more gears too? - you mentioned that you were going to get some... 

[TechnicSummse]

4 hours ago, mocbuild101 said:

If only you had asked someone here, we could have told you how soft they are!

Oh well, I'm sure you will find a use for them .

Did you get some more gears too? - you mentioned that you were going to get some... 

I got a few 36t gears, 2 old differentials, to have some spare ones... 4 of those super soft motorcycle wheels, and a few of @Marxpek's glued frontwheel.

The glued wheel wich marxpek uses, is way to hard... this wont bring any good results... i will stay with my current frontwheel, this is way softer.

What about you? I havent seen any results for a long time.. its hard to get over 33, right? :D 

[mocbuild101]

9 hours ago, TechnicSummse said:

What about you? I havent seen any results for a long time.. its hard to get over 33, right? :D

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!