RC-Monster Forums - Speed Calculator

RC-Monster Forums (https://www.rc-monster.com/forum/index.php)

- Brushless (https://www.rc-monster.com/forum/forumdisplay.php?f=12)

- - Speed Calculator (https://www.rc-monster.com/forum/showthread.php?t=2259)

More updates:

- Fixed display bug for transmission data in Data Tables page.
- Added Axial AX-10 Crawler differential and transmission ratios, and spur gear sizes.
- Added differential ratios for HPI MT2 and HPI Wheely King.

Great! One of these days I ought to click that Paypal link.

Question - I noticed that if one does not use the preselected spurs, the calculators have no way of recognizing which pitch you are using, therefore, the calculations must assume a basic pitch. Is it mod1?

Thanks.

Actually, the pitch is not needed at all in the calculations, they are just there for informational purposes. The calculations simply use the tooth count...

Before I get any PM's: Yeah, I know the site is down. 1and1.com is apparently having some issues (even their main site isn't working). If you "need" the calc, it looks like you should have downloaded the zip archive, eh? :wink:

NVM, they seem to have rectified their problem. Carry on...

Quote:

Originally Posted by Gee (Post 211179)

Brian,

A suggestion for your already excellent web page. Don't know if you have time or think it would be worth the effort but never hurts to ask......

Maybe add an option to say your parameter solver or speed calculator that would pump out a table of what the est speed would be for say 10 different size pinions in increments of 1.

Don't know if I saying it correctly.

For example you would put all the info in for your RC on the est speed calc. Then instead of needing to go back and changing the pinion size from 10, 11, 12, etc. to see the different speed you would get. You could hit a button and it could display a table or something with the different speed you'd get for say a 10T - 20T pinion. It be cool then to go back and change the spur gear and see what the table would put out using the same pinions. Even on the reverse side say it would pump out the size pinion for estimated speeds of 30, 35, 45, 50, etc.

What do you think?

+1:yes:

Just out of curiousity Brian, why do you have the B4/T4 transmission ratio under the differential gear ratio and not under the transmission gear ratio section?

I don't know. A mistake perhaps? :oops:

FYI: I took a look at adding a popup table to list speeds with different pinons, or spurs, whatever, and decided against it. Just adds a level of complexity I don't really want to deal with. More like tedium than complexity. :smile:

What I DO want to add is an alert of some kind which will tell the user if they are geared too high. There is a point in gearing where the motor is not spinning fast enough per mph for smooth low speed/take-off operation (around 1mph). Looking back, it seems I set my vehicles up for around 1000+ rpm per mph and everything runs fine. I'd like to know if there is a good rule of thumb regarding this, but would also depend on motor size of course.

On a similar vein, GriffinRU had provided some input on this topic a while back with regards to the minimum motor rpm needed for adequate back-EMF pulses from the motor. The idea was dropped because my simple mind could not grasp what he was talking about, but I think it would be worthwhile to have this kind of data available.

I posted the following in another thread. If it IS accurate, and would be of use, I can add it to the calc:

Quote:

Originally Posted by Me

BTW: I don't think speed scales like the size does. From what I gather from this page, the formula for finding scale speed is:

1:1 speed = SQRT(scale) X scale_model_speed

So, if your 8th scale RC does 60mph, that scales up to SQRT(8) X 60 = 169.2mph.
Similarly, if your 10th scale RC does 90mph, that scales up to 284mph.

If someone can verify this, I can add this to the speed calc. :smile:

Just want to make sure the formula is accurate...

While I'm at it, no one has any information about the following?

Quote:

Originally Posted by Me again

What I DO want to add is an alert of some kind which will tell the user if they are geared too high. There is a point in gearing where the motor is not spinning fast enough per mph for smooth low speed/take-off operation (around 1mph). Looking back, it seems I set my vehicles up for around 1000+ rpm per mph and everything runs fine. I'd like to know if there is a good rule of thumb regarding this, but would also depend on motor size of course.

On a similar vein, GriffinRU had provided some input on this topic a while back with regards to the minimum motor rpm needed for adequate back-EMF pulses from the motor. The idea was dropped because my simple mind could not grasp what he was talking about, but I think it would be worthwhile to have this kind of data available.

Is there any way you could put info on 4wd elec trucks (zx-5,xxx4 etc...)
Thanks, I love this program!

Well, I would need the info you want entered. Read this (specifically the topic "How do I submit data for a transmission or differential?"). I hate dissecting parts lists and exploded diagrams for the needed values, so if you can provide the data, I will be more than happy to add it...

http://rcgearing.com/

Here is another potentialy helpful gearing site. :)

Hi Brian
I really love your calculator :yipi:

My E-Maxx has a top speed around 28 Mph with 2 Kyosho 550 motors
(Same as a 1750kv rating)

Would a MMM v3 2200kv be too much for my old Maxx ? (35 Mph)

Quote:

Originally Posted by SnoopMaxx (Post 232976)

Hi Brian
I really love your calculator :yipi:

My E-Maxx has a top speed around 28 Mph with 2 Kyosho 550 motors
(Same as a 1750kv rating)

Would a MMM v3 2200kv be too much for my old Maxx ? (35 Mph)

depends on what batts you run, and what you have done to the drive train..