Speed Calculator

[captain harlock]

Mike is very good in making aluminum stuff, but I don't actually know if he can make me a 40T spur for the slippy's center diff?

[BrianG]

I'm sure it's possible. The only way to know for sure is to ask the man himself! :)

[BrianG]

Due to some reported inaccuracies in the top speeds of some setups, particularly over 40mph, I want to adjust all motor KV values to unloaded values and then have the program automatically enter the motor resistance in the appropriate place. Then, the user is free to enter appropriate amperage draw, thereby making the "loaded" KV more meaningful for their application.

I know I can use the Feigao chart to get the unloaded kv values for the BK Wanderers, but what about the Neus and LMTs? I assume all LMT motors (basic, basic XLs, 19xx, etc) list the loaded KV?

[BrianG]

OK, an updated version has been uploaded.

• All motor KV values were changed to unloaded wherever I could.
• The motor dropdown lists and the data page tell you if the KV is loaded or not.
• The top speed page automatically fills in the motor resistance for each motor where known.
• Added a "calculated KV" output on the top speed page which calculates the real loaded KV value providing the raw kv value is unloaded, and you enter the motor resistance and amperage draw.

Thanks go to GriffinRU for the Excel datasheets from his Motor Evaluation program, which is where I got the unloaded kv values and motor resistance for all the non-Wanderer motors.

As usual, link is in sig...

[MetalMan]

I found one slight problem. The Rustler/Stampede transmission shows a gear ratio of 1:1.

[BrianG]

Are you sure you don't mean the differential? I show a ratio of ~2.72:1 for the tranny, but a ratio of 1:1 for the diff (since there is no pinion and ring gear and the diff is really part of the tranny - much like the Jato).

[MetalMan]

Woops, my mistake :).

[BrianG]

LOL. It happens to the best of us. :)

How do you like the switch to unloaded kv values? Makes calculating loaded kv much easier. Also, there are still a bunch of unknown motor resistances. If you know where I can get the rest of the data, I'd really appreciate it. You can see which motors I'm missing in the data page...

[BrianG]

New version:

• Added a new page to calculate various Lithium battery charger figures and shows the max charge current and what the charger is limited by at various cell counts. Since most chargers require a 12vDC input, a power supply calculator is included to help the user pick the appropriately sized power supply.
  
• Added a charger information table to the "data" page.
  
• Added pre-defined spur gear drop-down list.

If anyone has the specs for more chargers handy, I will be happy to add them...

[gixxer]

brian your specs on the duratrax ice are backwards. it should be 4s and up to 8amps.

[BrianG]

LOL. ok, I can fix that. All the settings are in arrays, so it's fairly easy to mix something up. :)

[Dafni]

I was just thinking how great your little tool is, and what it became over the last couple months. Great, man. Thank you very much! It's one of the most clicked bookmarks on my desktop. I'll make sure to pass on any new numbers I come across.

It's growing so much, maybe you should put up a "NEWS" section on the start page!? :)

[Serum]

It is.. It is AWESOME Brian.

One powerfull tool indeed.

[BrianG]

Thanks guys! It HAS grown quite a bit from "v1", lol. I just keep adding things and adding things, and now it's almost a complete site in itself! I thought about creating a subdomain for it, but then I'd have to change the link.

The trouble is that it is getting to the point where it's almost getting too complex to use. The code for the help system is getting quite large - the array that holds the data has 76 entries! And the main code library alone is over 40k bytes! The original intent was to make a simple, inuitive tool that newbies could use, but now I wonder if it's too much?

As to adding a "news" page; I thought about it, but I'd rather people read about the news here and then navigate to it from here. The original intent was to supplement the RCM site, not to be so "stand-alone". If anything, I might simplify the release notes and put that on the home page.

Again, if anyone has more data (motors, transmissions, diffs, charger, etc) I would be more than happy to add it...

[riceman]

Brian - Thanks for keeping up the hard work on this. Very useful information all the way.