Squee; I was thinking about doing that, but what effect would the truck type have? Depending on how people make their setups, materials used, cell-type, etc, weight can vary quite a bit for the same truck. Therefore, I would think weight alone would be more accurate since that's what the motor "sees" as the load.

Believe me, I'm not trying to shoot down your suggestion, I just need to able to do this programmatically and accurately.

Yea, I understand. Perhaps you could have a thing to were they can select whether its an onroad or offroad vehical? That could have alot to do with motor selection. Like a 380C vs. 540.

That sounds valid! Now, I gotta figure out exactly what/how much effect it will have and how to apply it in choosing the motor. Ugg, this is getting complex!

I know you can handle it brian. :018: I have faith in you. You can do it.

do you think you can add LIPO info into the battery section along with the cell voltage as well.....

Does these seem right? Seems close, just wondering what other people think.

Nice tool by the way!


http://img74.imageshack.us/img74/2522/yomh9.png

When I put 72t spur, it decreases the speed. Wouldn't higher gearing increase it?

sjcrss: What do you mean? There is a dropdown for the number of cells and another for the cell voltage which covers the various voltage ranges of both NiXX and LiPo.

Nick:
Thanks!

That theoretical speed looks about right for the values you entered, but I bet you got a warning for that RPM! 6s is a wee bit hot IMO, but if it works for you, then have fun. At that voltage and motor wind, current consumption must be quite high?

Also increasing the tooth count on the spur gear makes it geared lower so it won't go as fast, but have more power. Increasing the pinion is probably what you're thinking of.

I'm wondering if you should factor weight in it? I just put a Mamba 7700 in what would be my E-Maxx and it says 85mph. :P

I'll get a Venom speed meter and maybe feedback to see how accurate it is. Will be nice to know.

Nick: This is exactly why I'm going to factor weight in the motor selector calculator. Someone could even enter in the kv for a regular mamba system (which has a high kv) and the numbers on paper would look impressive even though real-world results would be disappointing to say the least! Too bad most motors don't specify the torque rating...

I started work on the new version last night. While I'm at it, I totally restructured the layout to have each seperate section in its own web page (using frames). There was just too many lines of code for easy editing. It's not close to ready yet, but for those wanting to see the progress, I will have the beta version uploaded here.

I figure the best way to handle the weight factor is to suggest the motor size by weight, and then the wind/kv by voltage used. I'm thinking of using this as a guidline for weight:

0-2 lbs = 380 can size (regular Mamba system?)
3-5 lbs = 540 "S" can size
6-9 lbs = 540 "L" can size
9-15 lbs = 540 "XL" size
13+ = 540 "XXL" can size or something like the 22xx LMT series.

How does this look?

ok..thanks...the new version is looking real good.....what programming format are you writing this in...just wondering cause Im taking programming classes at this time......

It's Javascript and HTML (DHTML).

I found a typo by the way, when I put 7XL motor and put it over RPM the Message says it's a 6XL. :)

Look forward to seeing it updated.

cool , thanks..

Thanks for the heads-up on the 6XL / 7XL thing. I'll check it out when I get home.

Yes, the page itself is simple HTML, but the code is done in Javascript. I have very little DHTML on there for simplicity. I think the only thing that could be considered DHTML is the help system. My main site, scriptasylum.com, is where I used to create all kinds of scripts, but I got out of it.

Very cool. I do alot of PHP myself, never tried anything more than basic Javascript although Ajax is making me want to.

Fixed in both the regular and beta versions... Actually, the recommended rpm displayed in the warning box was wrong as well. Was simply an issue with array indexing.

I'm working on the motor selector and have some questions. I need to group all the 540 can motors by S, L, XL, and XXL size.

Would the Lehner Basics be considered S size?
Would the Lehner Basics XL be considered L size?
Would both the LMT 1940 and 1950 be considered XL size? Or is the 1940 more L size and the 1950 XL size?

Argg! LMT has too many sizes! Better question:
Where do the following motors fall in the S, L, XL (and maybe XXL) size rating?
1920 S?
1930 L?
1940 XL?
1950 XXL?

OK, no one has responded to my questions, so I guess I'll have to make some assumptions.

Anyway, I did a little more work. It's not quite done yet as I still have to factor in the weight variable (tomorrow night's project) so it picks the motor can length (S, L, XL, XXL), but I think I have the layout done. So far, it picks the motor can type (540, 380, etc) from the weight entered and picks motors whose kv value are +/- 5% of the calculated value. Then the program divides the remaining motors by motor quality. Take a look and offer feedback. BETA VERSION.

BTW: The "hard coded" values in there are just to ease my testing. Those will be stripped in the final version. Just override as necessary.

yeah... I would agree with your assumption

The 1950 is like a xl. It has almost the same deminsions. The 1930 is little shorter than l the 1940 is little longer. I think the 1920 is about an s can.

Thanks. So, the 1920 is an "S", the 1930 is an "L", and the 1940/1950 are considered "XL"?

The only reason for this rating system is so that I can choose the appropriate motor for the weight of the vehicle. Heavier ones need more torque, which requires a longer can. I guess I could get away form the S, L, XL, thing and simply go with a number rating system.

The 1940 is kind of inbetween the l and xl. So you can kind of say either.

OK, the final version is up. R/C Calculations

Sweet tool! Very good job, Brian. Thank you.

DAF

Very good!

thanks brian...I like the final version....very easy to navigate thru

Thanks all!

I still am not too sure on the motor selector. See if this sounds right to you:

For choosing the motor size (300 vs 540 can, and then S, L, XL) I am using the truck weight:

If weight < 1.5lbs, use the smaller 300/380 size can. (regular Mamba).
If weight between 1.5 and 5 lbs, use an S size
If weight between 5 and 8 lbs, use an L size
If weight between 8 and 16 lbs, use an XL size
If weight between 12 and 25 lbs, use an XXL size (LMT 1950)

I have some weight overlap for the XL and XXL size, but I wonder if there should be some overlap with the others? I know a smaller motor may work on a heavier truck, but this is for an "ideal" setup.

Then, I use the calculated requried kv value to determine the applicable motors which have a kv that falls near that value.

I wonder if there's any way to figure out how many watt/lbs we need to go a certain speed?.. that would be Freakin' awesome..... I don't know if I'm sayin' it right, but you' know what I mean....

Yeah, the trouble is getting that spec from all the different motor manufacturers. This is more generic and gained from experience and reading these forums, but probably not as accurate.

Maybe I can have a word with Mr Lehner about this. When he's in the right mood, he's very helpful ;)

But the weight/size thing looks good, Brain. From my experience it makes sense.

That would be great! I want to make this tool as accurate and easy to use as possible. Boy, it sure has changed from version 1!

So, you don't think there should be some overlap for the other motors?

It reccomends me a 6XL for 6s on a 14lb truck. To do upto 60mph.

6XL on 6S should give you a High RPM Warning.

Overlap for motors, why not? With something like a good choice/better choice note?

Are friend Mr. Promod did some testing on watts per speed. It took about 2000 watts for an emaxx to hi 60 mph. That was with a 2240 and lehner xl motor.

Must of the smaller motors I've tested will pull great watts(even more than a large motor) but will not run the speed of a larger motor. So watts don't tell the whole story.
My 2240/10 on 6S pulled around 2200 watts to run 60 mph. The 2240/12 on 9S made 3300 watts. Never did a speed test with the 9s but would think it would run close to 70 mph if the truck would stay on the ground:027: .

Thank you,
Promod

Oops! I guess I forgot to implement warnings for the calculated values!

Barry, have you ever seen this graph of the lehner 1950?

http://lehner-motoren.com/motordaten...50-6HA.32V.xls

I noticed you got a 1st and 2nd gear to a savage.

What about the 1st 2nd and 3rd on a 3 speed savage?

I can add that. What's the 3rd gear ratio? Actually I need the tooth count, not the ratio. This allows me to maintain the highest precision possible.

In the 3-speed, does first and/or second gear change as well, or do they just add a third gear?

first is lower by 10%. 2nd is lower than 2 speed 2nd. 3rd is 10% higher. I am not sure on tooth count. I did know one time. Rene may have it handy.