Speed Calculator - Page 12 - RC-Monster Forums

Serum · 11.07.2006, 03:30 PM

Yeah Brain..

Serum · 11.07.2006, 03:34 PM

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..

BrianG · 06:57 PM

Quote:

Originally Posted by Serum

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.

Serum · 11.08.2006, 02:46 AM

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.

BrianG · 01:37 PM

Quote:

Originally Posted by Serum

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. :)

coolhandcountry · 11.08.2006, 03:25 PM

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

BrianG · 11.08.2006, 03:29 PM

Quote:

Originally Posted by coolhandcountry

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:

BrianG · 11.08.2006, 11:45 PM

Fixed the Savage output ratio...

BrianG · 11.14.2006, 11:38 PM

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).

MetalMan · 11.15.2006, 02:17 AM

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!

BrianG · 11.15.2006, 02:28 AM

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.

Dafni · 11.15.2006, 03:41 AM

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

Nick · 11.15.2006, 05:05 AM

That's a really good feature! Nice work.

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

Dafni · 11.15.2006, 08:41 AM

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

BrianG · 11.15.2006, 10:40 AM

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).