ZipZaps Speed Calculator v1.0

rfnagel · #1 05-28-2003, 12:04 PM

I whipped up a quick utility in QBasic to calculate ZipZap speeds based on motor RPM and gear ratio -

Unzip to a directory on yer hard drive, and read the included ZAPSPEED.TXT file for useage instructions.

(Edit) New version, see post below...

rfnagel · #2 05-28-2003, 12:05 PM

Here's the included Readme...

(Edit) New version, see post below...

BabyKiller · #3 05-28-2003, 01:58 PM

hmm very un acurate it claims my 38000 rpm 3.43 gears go 18mph

sessiz10 · #4 05-28-2003, 03:06 PM

Quote:

Originally posted by BabyKiller
hmm very un acurate it claims my 38000 rpm 3.43 gears go 18mph

I haven't tried the program yet but I'm pretty sure the calculator gives you a - load rating. The car's wheels could spin this fast if they are free from any resistence or added burden like weight and friction.

*EDIT-
"What is this thing anyway?
--------------------------
This utility will calculate speeds for Radio Shack's ZipZaps micro remote
control cars. Note that there are many factors that come into play when
determining the TRUE top speed of ZipZap cars (such as friction, battery
condition, PC board version, laws of physics, etc...), and this utility should
only be used as a mathematical comparison."

From the read me in the .zip file

rfnagel · #5 05-28-2003, 03:26 PM

Ditto to what Sessiz10 posted... read the docs. The formula used (as mentioned in the docs) is as accurate as it gets LOL. The only margin of error would be my measuring the circumference of the tires.

FYI there would be no way to create a utility that would accurately measure speed (taking into account friction factors and such). The only way to do this would be a dynamo of some sort, or actual timed speed tests.

Nevertheless, it can give you a good idea of how various motor and gear ratio combinations will perform.

BabyKiller · #6 05-28-2003, 03:58 PM

good idea that like 14mph off damn

rfnagel · #7 05-28-2003, 05:19 PM

Quote:

Originally posted by BabyKiller
good idea that like 14mph off damn

Sorry bud, U lost me there....

flatlander_14 · #8 05-28-2003, 05:43 PM

thats a cool program and all, but what we really need is something that can factor in a second or third cell. or at least let voltage be in the equation. i would love that

i could test how accurate it really is when i get my speed trap and 1/4 mile set up.

rfnagel · #9 05-28-2003, 06:24 PM

That's a good idea -

Problem is, the formula is strictly a mechanical type of equation. Adding some form of voltage equations to the formula would be just as problematic and inaccurate as trying to factor in motor torque, friction, and such. This is why in it's current state it can only be used as a mathematical mechanical comparison.

Although... I have found that the calculated speeds of the utility are fairly close when using the stock RS store-bought stuff.

flatlander_14 · #10 05-28-2003, 06:33 PM

well if you get a volt meter and measure how many more times the voltage is than a single cell 1.2v car you can use those multipliers as a base estimate for speed increase. i dunno, just a suggestion

BabyKiller · #11 05-28-2003, 07:32 PM

um i ment the program says the car goes 18mph when it actually goes 4 so this is a toughy stay with me 18-14=4

flatlander_14 · #12 05-28-2003, 08:26 PM

babykiller, its accurate, your car just doesnt have the power to get up to that speed. there is no way in hell your motor will ever turn out its full 38000 rpms witha gear as tall as 3.43. there is a reason why the zipzap gears are between 8.25:1 and 12:1. it is accurate when you use realistic gear ratios. its like in videogames, if you gear a 500hp car to hit 200 in first gear, that doesnt mean it will ever get there any time soon. i did this in a game of mine and it took about 2-1/2 miles to reach top speed. lets just say it takes that long for your car to reach top speed with those gears, it would have to have *~50ft* of straight and smooth track to reach it. im not saying any of this is very realistic, but when you figure out the wheel's rpms, it is close to a real car's. for instance, a 38000 motor with 8.25:1 gears will prodice 4606 rpms at the wheel when there is no load. if it can bare to reach that, it will take quite a while. the 38000 with 3.43 gears would give the wheels 11078 rpms. i even hacked a car in a game of mine and it sucks with that many rpms. of course all of this is based on "tony logic" but the main point is that of course the program will be inaccurate if you use a gear like that.

#13 05-28-2003, 09:13 PM

The calculator calculates the highest potential speed.

So if you had waited enough then it could go the full 18mph but it doesn't becuse it can't reach its potential with the time you drove it. I'm not sure my Zip ever reached 6mph in my room due to my small play area but I'm pretty sure it did when racing it on my friends floor. Now a cool add-on would be a formula to show how long it'd take to get to that highest potential speed (HPS) in feet & time

rfnagel · #14 05-29-2003, 02:24 AM

@flatlander_14, this is exactly what I was trying to convey... BK's gear's are so tall that the motor will never have enough torque to get the wheels spinning at that speed on the ground.

As far as the voltage, that sounds like it would work, as long as it's safe to assume that double the voltage would equate to double the motor RPM. Sorry dumb question, the ZipZaps stock receiver battery is 1.2v? What are the common mod baterries that folks are using?

@BK, I have seen charts on the Net where folks have actually clocked their various store-bought ZZ setups. My utility seems fairly accurate when using the statndard RS stuff.

My PT cruiser with the purple 34,000 RPM motor and the red 8.25:1 gears does indeed reach a top real-world speed of about 6.7mph... hence the utility is 1) accurate, and 2) my ZZ seems to go faster than your modded one, compared to mine with no mods or third-party addons <G>.

Also, the other speeds that I've seen verified on the Net using the other motor and gear combinations seem to jibe with what my utility calculates.

Nevertheless, as flatlander_14 has posted (as well as what I've been trying to convey is, motor torque, as well as friction and other factors play a massive role in what the true real-world top speed would be.

Take for example a NASCAR geared for a superspeedway such as Daytona... it takes them three laps to get the car up to top speed LOL (~190 MPH or so). Taller gears would mathematically equate out to a much faster top speed, but the motor would never have the torque to get it there LOL.

@nouseforname101, that's a good idea as well -

Again though, were back to several unknown variables such as motor torque and such. Now if we had some form of manufacturer's torque specs on the motors, we'd have a basis for the equation -

BabyKiller · #15 05-29-2003, 05:59 AM

how the **** does your 3.4 8.25.1 gears reach that speed

and i have a duel cell that reachs that speed but damn thats as fast as ive got it to go its using a r-spec and 12:1 gears all the other gears take like 20feet to get faster than 12:1