That saves me some time :D.

I don't know what's going on, but the server where R/C Calculations is hosted is having problems. I called them earlier today and they said it would be only a few hours to fix, but it's been over 12 hours.

Anyone want to host a mirror? I can supply the files in a ZIP archive. Mike? :)

Looks like starluckrc is hosted by the same guys...

I have my whole site hosted through 1and1.com, which were quite reliable (up until now). Grr. But I suppose these things happen. Makes me wonder how hard it is to simply replace the bad component in the server? Even if that was a bad disk, I can upload everything again. I'd rather do that than wait this long. All I know is if the servers I am in charge of where I work were down this long, I'd be in the unemployment line!

Good thing you don't work there then. We may have some good deals for you
RCs. ;)

LOL CHC. :)

Anyway, the site seems to be back up (for now)...

Man!

I just calculated the speed of the 1940/9 in a 4wd 1/8 buggy with 6s lipos and 21T pinion with 44T spur and the speed was a bit overrated. I mean, its too good to be true. 88mph is too much!

It probably is too good to be true. Remember I didn't account for wind resistance or weight. Although, if you enter the motor resistance and approximate amperage draw, the kv will drop some giving you a more accurate reading.

So, it's hard to get such a speed in a 1/8 buggy, eh?

With 6s.. yes, with 8s, you might go over! :)

One of my friends was able to get his kyosho to the 80s, but he is a hardcore nitro guy. There is a possibility with six lipos, but maybe I need to go high in the number of teeth for the pinion.

Well Brian I was finally able to put your calculator to the test. I entered my setup on my Emaxx and it came back with 47 mph. It sure seemed faster than that though.

Well I got a GPS off ebay for a steal a couple weeks ago and I just took the setup out and tested the for real.

I'm pleased to report that in real life it came to 47.9mph. Thats darn close. Kinda freaky. One side note though... The test was done running in a grass field. On pavement i'm sure i could have squeezed another few mph out of it.

Just a quick testimonial to the accuracy of this tool you made. Nice job!


BTW: Of all the nitros that were out there bashing today, only 1 was able to register a 40mph run, and it was only 41.3mph and that was some guy beating his chest obout his $400 motor. Most were only running around 31-35mph.

Well, that's nice to know. :) Depending on the motor you are using, it could have been using loaded kv values, which may not be totally accurate if you are not loading the motor the same amount as done when they spec'd it. Or, maybe you had some tire balooning.

Ahhh, I love hearing those stories about the "slow" Nitros. They had their day, but with technology the way it is, electric will eventually take over for all but the hardcore Nitro guys who for some reason actually like the fumes (Bleh!).

We are here to RULE THE WORLD!!! HA HA HA HA HAAAA........

Hey, aren't you still using Nitro in your Losi 8 truggy? Hmmm? ;)

Are you trying to justify the 0.9mph inaccuracy. :005: This was a compliment.. Not a criticism. Man you are a perfectioninst. :rolleyes:


My setup. Emaxx w/ stock diffs and 2nd gear tranny, 5.8" Zombie-maxx tires (duct taped to reduce balooning), Lehner 1940/7 motor, BK12020 ESC, 5s TrueRC lipo (I assumed 3.5V/cell under load). 51T/16T gearing.

Heres the data output from you calculator:
<TABLE cellSpacing=0 cellPadding=2 border=1><TBODY><TR vAlign=top><TD noWrap>Differential Ratio: </TD><TD>2.8461538461538462</TD></TR><TR vAlign=top><TD noWrap>Transmission Ratio: </TD><TD>1.7222222222222223</TD></TR><TR vAlign=top><TD noWrap>Other Ratio: </TD><TD>1</TD></TR><TR vAlign=top><TD noWrap>Spur Tooth Count: </TD><TD>51</TD></TR><TR vAlign=top><TD noWrap>Pinion Tooth Count: </TD><TD>16</TD></TR><TR vAlign=top><TD noWrap>Total Voltage: </TD><TD>17.5</TD></TR><TR vAlign=top><TD noWrap>Motor KV: </TD><TD>2239</TD></TR><TR vAlign=top><TD noWrap>Tire Diameter (inches): </TD><TD>5.8</TD></TR><TR vAlign=top><TD noWrap>Tire Ballooning (inches): </TD><TD>0.25</TD></TR><TR vAlign=top><TD noWrap>Motor Current Draw: </TD><TD>0</TD></TR><TR vAlign=top><TD noWrap>Motor coil Ω: </TD><TD>0</TD></TR><TR vAlign=top><TD noWrap>Spur/Pinion Ratio: </TD><TD>3.19 : 1</TD></TR><TR vAlign=top><TD noWrap>Total Ratio: </TD><TD>15.6242 : 1</TD></TR><TR vAlign=top><TD noWrap>Tire Circumference (inches): </TD><TD>19.79 inches (502.72mm)</TD></TR><TR vAlign=top><TD noWrap>Total Motor Speed: </TD><TD>39182.5 RPM</TD></TR><TR vAlign=top><TD noWrap>Vehicle Speed: </TD><TD>47 MPH (75.5km/h)</TD></TR><TR vAlign=top><TD noWrap>Effective Speed Rate: </TD><TD>2.69mph/V (4.31kmh/V)</TD></TR></TBODY></TABLE>

Lol, yeah, I guess I am at times. :dft001: I didn't take it as criticism, just trying to explain the discrepancy. :)

Let's pile on Brian hee hee

It's OK, I have broad shoulders... But be careful though, now that I'm getting older, I may break something. :)

To stop the balooning, do you put the duct tape on the outside?

No, that would wear out wayyy too fast. You put it on the inside of the tire.

I'm getting new pro-line MT tires, should I do this? I get balooning now.

I thought that the MT tires had ribs on the inside to reduce ballooning. If you are using them now and get too much balloon, then duct tape should fix you up.

Thanks for the info, no I'm using the revo stock tires, I should get the MT tires tomorrow.

Guys, can you post a pic of a duct taped tires?

something like this;

<a href="http://picasaweb.google.com/buikpijn/MiniT/photo#5043206707253894562"><img src="http://lh5.google.com/image/buikpijn/Rf0Rx7q8XaI/AAAAAAAAAJA/LqMtgA9GST0/s144/CIMG1984.JPG" /></a>

Did you fix the insert to the tires internally with ducted tapes, or just the inside of the tires?

That's just the tire... turned inside-out and wrapped with tape. Then you flip it back and install with foam etc as normal...

Amen Glass.

Then, the idea is to fill up the gap between the tire and the insert, right?
I should try it very soon.

The MTR tires do have internal ribbing that should reduce ballooning, but in my experience, it doesn't help. The Bowtie MTRs on my Revo get almost as large as the Crime Fighter MTs do!

Well not really... the ides is that the tape won't stretch. So when the tire wants to stretch and balloon out... the tape can't. If the tape is stuck good enough to the trie, it will hold the tire at it's normal diameter.

Just like if the tape was on the outside.. you can see how that would stop the tire from ballooning.... same thing if it's on the inside, assuming it's sticky enough to stay stuck. :)

Stretchy tape wouldn't work... it must be a duct or strapping type...

I've heard gorilla tape works well as it is quite sticky. Just don't forget to clean the residue off the tire first.

Nice, nice, ver nice!..:)

GD, Brian, I announce both of you as Deputy Captains as of today.
Congratulations!:005:

Okay, a different question:

Is there a possibility that I can change the gears of the slipperential from 21:44 to something like 24:40 ?

I want to decrease the gear ratio to make it as low as possible. 2:2 ratio is quite high and I've noticed that the truck was somewhat undergeared.

I want to change the slipperential's own gears( of the center diff and topshaft) and not the spur or pinion.

To lower the ratio of the slipperential would require a different spur gear on the differential. To my knowledge, there are no other plastic spur gears that fit onto any center diffs that have fewer than 44 teeth, besides the one on the Revo that has 28 teeth (but that's a completely different diff).

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?

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

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?

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...

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