Not a problem;

(going fron the wheels to the motor)

Diff is 43/13
outputshaft 30/31 (gear on the outputshaft is larger (31) than the 'drivegear' (30)
1st gear 44/18
2nd gear 41/21
3rd gear 38/24

OK, new version. Added overlap of motors for a slightly wider selection of motors, added a section for adding other ratios (thanks to the Savage for having another ratio in the tranny :031:), and added the three-speed Savage ratios.

Speed Calculator

Did mean to make it complicated brian. I just wanted you to have a complete
calculator. But you did do a nice job.

That's OK. I think it passed complicated a while ago...

We only put the pressure on you cause we know you can handle it. :018:

Yeah Brain..

Why didn't you added the extra gears in selecting the 3 speed settings? It's just a part of the ratio, which is fixed.

The stock savage also uses extra gears.... a 29/32... just implement them in the first line..

Yeah, I could have done that, but there are two reasons why I didn't:

1: The "engine" requires a set of two tooth counts to get a ratio. To allow for another set would involve more than one ratio (and more tooth counts). I could have fudged it by putting in a dummy tooth count to still use two teeth to equal the final ratio, but that wouldn't be as accurate. Plus, the dropdown list shows the tooth counts and it would have been technically incorrect, not to mention confusing to a user who happens to know the ratio. I wanted the highest precision possible. Incidentally, this is why I don't do any rounding until the very end.

2: The addition of another ratio section can be used if the user has some other ratio not inlcuded in the normal tranny, diff, spur/pinion setups. So far, it is really only used for the saveage, but there may be other setups in the future.

In the end, it was simpler and more accurate to implement it this way even though it was more work.

more accurate?

Accuracy has got anything to do with it? it's just an extra number that's added. It's not that your calculator is looking at gears resistance.

OK, I didn't really want to get into it, but here goes:

All the ratios for the transmissions and diffs have two values; input tooth count and output tooth count. I don't have provisions for adding other tooth counts for one entry because then the code to handle this wouldn't be the same for the rest of the "normal" ratios. Anyway, dividing the two tooth counts values results in a (usually) long decimal number. This precision is kept until the displayed result. If I just fudge in a number for the Savage to maintain a two tooth count scheme, I will be introducing some variance. Granted, it's not much, but it's there.

For example, the savage first gear tooth counts are 44 and 18, which is a 2.44444 (repeats 4) :1 ratio. The savage output ratio tooth counts are 31 and 30, which is a 1.03333 (repeats 3) :1 ratio. Now, to keep my two-number scheme, I would have to multiply these two values to get a "virtual" ratio count, which would be 2.5259 (repeats 259). That would them turn the 18T gear into a 17.4195 (and so on) tooth gear. This doesn't even make sense; how can you have less than half a tooth?? But that's what I would have to do to account for both ratios with one set of tooth counts. Even then, it's not accurate since the numbers repeat, not even mentioning any rounding errors. Once you take this already inaccurate number and use it with the other ratios and formulas, the result can be off by a substantial margin.

Ugg. So, in the end, creating another ratio section was more accurate and makes sense.

Edit By the way, when I said "engine" on the last post, I meant the code engine, not the BL motor. That probably caused some confusion. :)

I thought the savage had a 31 drive and 30 driven gear for the out put.

Actually, yes, now that I read Serum's first post, I see that now. Grrr. Looks like another revision will be uploaded tonight! :007: :007:

Fixed the Savage output ratio...

Added new feature, "Random Parameter Solver". It simply lets you leave one parameter blank and it will calculate the missing value. Good for "what if" scenarios...

The link as usual: Speed Calculator

Direct link to new section: Random Parameter Solver

Feedback welcome (especially any noticed bugs).

You just made the perfect addition IMO. Before I was using a RC Gearing program I have, since I can just mess around with the pinion size to get the speed I was looking for. Now, I can just enter the speed and it will tell me what pinion to use - EXCELLENT!

Cool, glad you liked it. :)

Is the interface confusing at all? I tried to implement something a little different, but I wasn't sure if it would confuse anyone. The hardest part of this one was transposing the main equation to find the different values based on the known values available. Ugg.

Brian, would be nice if you could add that Mugen Diff ratio we once talked about. I sent you a PM to confirm the ratio some time ago.

Thank you
DAF

That's a really good feature! Nice work.

The Mambamax 7700 is fast on 30x 4.2v cells. :D

A nice addition to your "unit converter" would be a Farenheit to Celsius thing.

Dafni: I thought I added the Mugen diff... I'll have to check on that. Adding the unit conversion for temperature will be easy to do. I'll see if I can add those things tonight.

Nick; yeah, I'm sure it would be - up until it blows up. 288,750 rpm is just a tad high though, don't you think? ;) You defintely should have gotten a warning for that (let me know if you didn't).

I have come to a size comparsion. The 1920 is or has the same size rotor as a s can 540.
The L can is 35 x 19 mm rotor.
The xl can is a 50 x 19 mm rotor.
So the 1950 would or should be and xl. IMO
The 1930 and 1940 is another question.

Added Mugen diff and temperature converter (sorry I forgot about the diff Dafni).

CHC: So, you think a 1950 has the same torque as an XL motor of the same kv? I figured an XL was closer to a 1940. What I ended up doing is made a list of 4 motor sizes (S, L, XL, and XXL) for each motor can size (eg: 540) and equated each level with a vehicle weight range. Then, each motor falls into one of these levels so the program knows which motor(s) to choose based on weight. It seems to be pretty accurate judging by the common setups found here.

Well the lmt motors run a lot different. The 1950 is real close to xl. It may edge
it out by a knats butt in power. A 1930 will pull a emaxx around pretty easy.
The emaxx weighed in at 11 lb rtr. Shayne ran an emaxx with a 1920 as well.
I didn't have heat issues with motor either. Not sure about shayne.

When I do a speed calculation. Is weight in the equation with the calculator?

CHC:
So, are you saying the motor selector is not picking the correct motors for the application?

Nick:
The only calculator that factors in weight is the motor selector. I know it seems like there must be a lot of duplication of code on the max speed calc, motor selector, and solver page, but believe me, each one works quite differently because of the focus for each one.

For instance, on the solver, you wouldn't want to figure out how much ballooning you need to achieve a certain speed because you really don't want it. Likewise, you wouldn't want to calculate the motor kv needed based on vehicle weight. Weight affects motor size, not the motor kv value.

The motor selector was intended to help newbies with a starting point for which motor to pick based on other more easily selected parameters.

The motor selector and solver are intended more for initial planning. Use the solver to try a bunch of different scenarios. Then use the motor selector to get a range of motors to use. Finally, use the top speed calc to get an accurate speed rating which takes as many factors as possible.

Where is the motor selector calculator located at?

Accually no.
The lmt motors just seem more versatile in terms of vehicles.
The lmt motors well run cool when the feigaos are hot and ready to melt.
I got a lmt 1950 geared right tall and would never would have thought the 9xl would survive. Then again I tried it and it didn't make it as well. It got hot faster.
And hotter to.

CHC:
So, when you say "Actually no", do you mean "no, it's not right", or "no, the selector is not picking the correct motor"?

Nick:
Motor Selector

But, I just went to the site and there is an error loading the library code. I'll have to fix that when I get home tonight. I don't know why it wasn't updated, I FTP'd all the files up at once...

It was no to your question.

So, are you saying the motor selector is not picking the correct motors for the application?

I couldn't get the motor selector working.

That makes sense since nothing is working. All of the code that is common to all the various pages has been put into a seperate "library.js" file. This includes code to write the links to the top of the page, various code to build the parameter lists, etc. Without that, everything is broken.

Ok, I was able to setup FTP in IE and make the fix. Everything is working now. I had forgotten one little ' mark.

Can this be Stickied? I think Brian has put some real good work into this and it's really useful. For it to be a few pages back would be a waste, it deserves to be in a permanent position for frequent access/use.

Just a thought. :)

I agree :).

Wow! I feel honored, my own stickie! :o

I thought it had been deleted at first until I did a search and found it!

Well I know you put alot in to it brian. I feel you deserved it as well.
Congrats on a stickie.

Thanks CHC!

I added another page for BEC wiring and info. It even has diagrams. :) I figure the question gets asked enough to warrant its own page...

R/C Calculations

Brilliant Brian!

Great addition!!

Brian, RC Calculations is an awesome work. Congratulations!

Some spanish dudes are asking me to translate it.
Do you think is a good idea?

Thanks all!

I don't see why translating it should be a big deal. Although, the Google web translator would work well in a pinch...

Another small update to the BEC & Wiring page. Added fan hookup option and a couple other small things...