motors, ratios and weights

[piterx]

hey guys....i think this is something everyone of you thinks about whenever you have to build the transmission of your mocs:

what ratio should i use?

it's obviusly something that deals with the final weight of your model....that you usually don't know at the transmission stage

so i was wondering if it worths making a schedule in this topic like the one below, to know wich one is the maximum weight, with an X ratio that can be moved by a Y motor....obviously without stressing the motor

i think it's gonna be useful to set our models better

i will start adding something based on my personal experience and it would be awesome if you do the same :)

once we get some datas to put in the schedule, i'll make a nice version of it with a jpg

if you wanna partecipate to this thing be sure to specify the usage of your test ^^

Edited July 16, 2013 by piterx

[The Ghost Racer]

What do you mean extreme?

[Sariel]

I don't think you can make it reliable. There are dozens of factors you're not taking into account: the size of wheels, the type of the tires, the complexity of the drivetrain, the exact type of surface you're driving on... All these things affect how a motor performs in a model. Even brand of the batteries and the temperature they're operating in matters. There's a reason why determining a ratio is so difficult - it depends on a dozen of variables, not just ratio and load.

In the meantime, you should probably get familiar with this: http://www.philohome.com/motors/motorcomp.htm

Edited July 16, 2013 by Sariel

[piterx]

yeah i know what you mean sariel....but if you want to take into account all the N factors that can occur, it gets just too complicated....and it would become something for mechanical engineers (wich i'm not lol)

i was thinking to something more generic....like an ideal ratio for an ideal weight based on experiences

something that can help you determine, more or less, how much load you can add to your model and what to expect from it

What do you mean extreme?

some extreme usage such as crawling or power pulling

probably the best solution would be building a test chassis, with a place to add weight on it, and test every motor on the same vehicle to see the differences :)

Edited July 16, 2013 by piterx

[Doc_Brown]

I think this is a great idea! Here's my contribution, dunno what my hot rod will weigh as of yet. I will update this! :)

MOTOR RATIO WEIGHT INDOOR OFFROAD EXTREME

Nxt 3:1 1350g x x x

Large 3rd party tires, 1.9" 108mm.

Edited July 16, 2013 by Doc_Brown

[piterx]

yeah that's exactly what i was talking about doc :)

something based on experience that gives an idea!

the only thing is that if you're using two motors you should divide the weight by two

so it will be

1 nxt motor 3:1 675g x x x

[Doc_Brown]

Arrhh true true, or (2 x NXT) hehe

Yeh just add tire size to the the mix, and that should give anyone a good "base" to work from.

[piterx]

;) ok i think that's a good idea

i'll make a schedule in jpg as the one above just messed up -.-

[legomuppet9]

Yep I think you need to add size of tyres too, as well as the weight and ratio and number of motors. Makes it a bit more accurate without making it overly complicated Even though to get it very accurate you would need to take into account everything that Sariel mentioned

[piterx]

ok added wheels :)

i think once i'll have more data to add i will just make different sheets for each motor and i will sort them for weight

cmon guys share your ratios and weights

Edited July 16, 2013 by piterx

[The Ghost Racer]

some extreme usage such as crawling or power pulling

Last year I build a rock crawler drived by an XL Motor and was perfectly.

https://www.youtube....h?v=9WHZXjnTWKI Sorry for the video quality but I only have this to show you, I had to take it apart to realize the Tatra and I have no pictures of it ..

Look at how much power concentrated in a single vehicle made ​​by zblj https://www.youtube....d&v=6D2RpWdwG00

Edited July 16, 2013 by The Ghost Racer

[Jeka Jackson]

Hi)

Jeep wrangler

2XL, 56 wheels (94,8 tires), 1-st gear 8:24, 20:28, 8:24, 2-nd gear 12:20, 20:28, 8:24, weight 2,3 kg, x , x , x

[piterx]

thank you jeka ^^

i will add the 1st gear only dividing the weight by two

1 xl 1.150g and help me for the ratio please :P

i suck so much in maths o.o....shame on me

[Jeka Jackson]

~ 1:6,7 (if I'm right)

[The Ghost Racer]

Tatra T813 4x4 Trial Truck

3XL Motors (2 for drive, 1 for sterring), Unimog wheelws and tires, final gear ratio about 9:1, weight: 2kg, X X X

Edited July 16, 2013 by The Ghost Racer

[piterx]

great guys ;) i will add them in some hours