micro_Amps

[micro_Amps]

Quote:

guess what im saying is if you have your 5mm bit wheel spinning at 20,000 rpm, which is spinning a 10mm wheel. the 10mm wheel will not be doing 20,000 rpm. the exact rpm of the 10mm wheel would be…. (circumference of 5mm wheel is roughly 15.7mm, and of a 10mm wheel is roughly 31.4) so for every 2 rpm of the 5mm wheel you will get 1 rpm on the 10mm spindle.

Spanky you are spot on here. But if you have a cycle computer calibrated to read the SPEED (not rpm) of the 10mm spindle, you would still be accurate in your speed measurement of the 10mm spindle which is the same as the road speed.

This is getting a little confusing, it is difficult to talk of rpm, speed, (and power and torque) and not overlap lines of thought.
I appologise if I am unable to convey things with more clarity, I wish I could. I wish I could SHOW you exactly what I mean. I think part of the problem we have here is that delayed, written explanations dont have the ‘to and fro’ of real conversations.
I know we are both on the same track spanky, just a little unclear. We could go on for ages on this kind of thing, and I wont…..
But,
Let me try once more on Namunas rpm readings……
The readings are correct, I assure you. So long as the frequency (Hz) found at the rear wheel disc is multiplied by the gearing ratio on the bit then the readings are accurate.
Forget about the “speed”, we are talking rpms only here, and rpms is independant of speed. Speed is a relative term, rpm is not.
The size of the wheel with the slot in it is irrelevent. The slot will still come around once per revolution regardless of the size of the wheel. This frequency x the gearing ratio = motor rpm. Simple!!
Namuna you are correct, I bet my left one on it. If you do the readings with a different size slotted wheel, you will get the same results from the same motors.
Now I suppose I have made that as clear as mud.

Quote:

consider many different interchangeable rollers to change the gearing bit by bit

Jamie, I am way ahead of you on this one mate. I hope to be able to vary the load from zero (high speed) to standstill (or very low speed). That should accomodate all bits, single, duals, triples, and frankensteins. As ph2t has already mentioned, there is a reduction gearbox under there that will handle any speed.

Quote:

have also heard that RCmod is getting some new motors in sometime in the next few days.

Spanky if you hear they have them, can you email or PM me, I would love to get my hands on some of those.

:)uA

[micro_Amps]

One of a kind is right .
I wonder if it comes with an ejecter seat switch too.
:)uA

[micro_Amps]

Quote:

but you need some sort of stop for the bit. Saves you holding it. Do the different tyre compounds make a difference???

Jord, there will be a stop to hold the bit in place….I am imagining a 3 sided sponge foam lined arrangement to keep the bit from moving.
I had only just finished stage 1 of this project when I took the photo, so it was not made yet.
Yes tyres do make a difference to the speed. The softer stickier (pink or purple) tyres form the BCG coloured tyres set grip the best and give the best results. With other tyres you need to push down just a little to get good traction.

Quote:

Spanky brought up a good point, which now makes me believe I need to look at my resutlts (I did Power/RPM tests at: http://tinyrc.com/forums/showthread.php?s=&threadid=10662).

Namuna, your work is accurate. The diameter of the wheel being measured does not effect the amount of pulses being produced, the rpm does. It will still measure one pulse per revolution regardless of the diameter of the wheel. A 5mm wheel spinning at 20,000 rpm is spinning at the same rate as a 20mm wheel spinning at 20,000 rpm. The surface speed at the outside edge may be faster but thats not what you were measuring, it was the rpm, and your method is accurate, well done.
When car manufacturers quote various formulas for correcting measured speed with different tyre sizes, they are measuring the speed thru the driven wheel being measured, whos diameter will change with every different tyre. A dyno is different.
A dyno (as in this situation) measures the speed ‘of the road’ instead. I know it sounds silly, but the dyno measures the speed at the outside edge of the tyre, the road surface. On a dyno, changing the tyre diameter WILL change the speed measured, but wont change the accuracy of the dyno measurement. Its kinda confusing, but dont compare it to a speedo in a car, its not the same.

The discrepencies in rpm at the higher speed motors is to be expected. You will probably find an error tolerence in production. They are not a highly precise motor. Perhaps if you lube the shaft ends with a little silicon or teflon oil, you may find the revs come up a little. I have found this is the case on the dyno/speedo.

Quote:

I presume you need the voltage and current readings so you can calculate wattage?? I dont really think that it is accurate enough.

Jamie, yes you are correct, I will be using wattage as the measure of the power output of the BCG motors. It is actually more acurate that way because……
A high revving motor producing a high voltage will probably produce a low current and therefore a medium wattage output,
A lower revving motor will produce a lower voltage but may be able to produce a higher current output, thus a higher wattage output, therefore it is the STRONGER motor of the two. This is primarily what I want to prove amonst all the different (OEM) motors.
There are 3 things to be considered
#1 is speed (rpms)
#2 is output power produced
#3 is output torque produced.
All of these things are different, they are related but they are different. It is easy to cross over between them when talking about motor power and speed and stuff like that.
I still have a long way to go before perfecting the power output part of this dyno but I am getting there.

Im going to stop rambling now.

:)uA

Edited by – micro_Amps on 30 April 2003 20:22:23

[micro_Amps]

Quote:

This stuff is addictive.

Kevsta, kiss your bank balance and your social life goodbye.
I have, I know I’m not the only one, and I’ve only been into these things for 6 months !!

:DuA

[micro_Amps]

It is a bit delicate. The steering gears are tiny. The max. speed is 5.6km/h so it can move but I wouldnt slam it into a wall too often.
Also you cant get parts if anything goes wrong.
So it gets driven with kid gloves….
:)uA

[micro_Amps]

Quote:

but the question is the same, do I need a bike computer with variable wheel radius setting or can I use a simpler (and cheaper) unit ?

Efarel, the cycle computer I used, it is able to be set to ANY wheel circumference from 5mm to 4000mm. It is very versatile.
That makes it usable for just about any speed measuring project so long as you know the circumference of the wheel being measured.

Jamie, we are thinking along the same lines, but I have no accurate idea what kind of power these cars will put out. Depends on the output voltage too, not just the current.
Keep one thing in mind tho, you need to start readings with ZERO load, if you are using constantly meshed gears with a permag motor you will never be able to remove the load.
The motor being used as a generator will probably be a ‘wound field’ motor specifically for this application.
I’m still working on it……

And yes I am also thinking of dyno comps, distance comps etc, etc
It may open up a new dimension for these little cars.

:)uA

[micro_Amps]

Quote:

Perhaps you can re-tune the 27Mhz car to it’s controller and also re-tune the 57Mhz car to it’s controller.

That would be where I start. Try extending the aerials and retuning the Rx vari-inductor. Hopefully that will make the cars a little more selective in which signal they respond too.
:)uA

[micro_Amps]

Yeh, but it is only a matter of time before we get schematics for those too. I hope.
:)uA

[micro_Amps]

Dunno :question:
Dunno :question:
Dunno :question: (into a brick ! :shock:) 🙁
and Dunno :question:
But all will be revealed when it arrives.
I am expecting it this week. 😀

:)uA

Hey trackmaster, how do you charge it and what is the speed like.
Give us a rundown.

Edited by – micro_Amps on 27 April 2003 19:05:40

[micro_Amps]

I am planning to have a modified DC motor, running as a generator, driven by the bit runnng on the dyno. The strength of the bit motor will determine the output of the generator, which will be measured (voltage and current).
Just ideas ticking over…..
:)uA

[micro_Amps]

Do we have any 60 year olds, Hmmmmm, cmon fess up.:smiley2:

[micro_Amps]

Have a look around at various sites for mods, maybe a longer aerial would get you better range. If you are keen then removing the cripple cap will get even more range, and if your feeling confident a dual cell mod and a 3.0 or 3.8 motor will really get you movin ……
They aren’t real flash straight out of the box, but once you become familiar with what you can do to them to improve them, you’ll be hooked, trust me.
:)uA

P.S. My first bit was an S2000 Compact too, but that was a long time and many bits ago.

Edited by – micro_Amps on 27 April 2003 18:39:39

[micro_Amps]

Have a look around at various sites for mods, maybe a longer aerial would get you better range. If you are keen then removing the cripple cap will get even more range, and if your feeling confident a dual cell mod and a 3.0 or 3.8 motor will really get you movin’……
They aren’t real flash straight out of the box, but once you become familiar with what you can do to them to improve them, you’ll be hooked, trust me.
:)uA

P.S. My first bit was an S2000 Compact too, but that was a long time and many bits ago.

Edited by – micro_Amps on 27 April 2003 18:39:39

[micro_Amps]

Yeh it was good fun, we will do it again, and hope to see some extra faces there too, and do some racin’.
Seriously tho, take another look at the photos, who would want to hang out with a bunch of ugly mugs like that, 😯 hehehe :smiley2: .

Crom and Lazboy (and others?), you were missed, but we will pencil you in for next time.
There’s a lot to learn because everybody seems to be doing something different with their cars.
Even tho it was at a pub, we had the whole upstairs restaraunt to ourselves with the odd spectator taking interest.

Heres a better pic of the dual batt bit. This little rocket has been capable of over 17.7 Km/h in the past (on my running treadmill) it is the same chassis that is shown at 15km/h in the DYNO thread (in the techo section)
It has a range of 10m+ as well. Lots of fun, this is how they all should be.
:)uA

Edited by – micro_Amps on 27 April 2003 18:52:54

[micro_Amps]

That is actually the biggest difference I have noticed. My dual cell with a piano wire whip aerial has the longest range of all my bits.
I suppose I need to maesure it properly.
uA

[micro_Amps]

If I remember correctly, the sports version of the P76 was called the “Targa Florio” hehehe.
Sweeeeeeeeet……
:)uA

[micro_Amps]

The boosters are noisey when they are not on boost because the power is ‘pulsed’on low speed.
The sound will reduce as the gears wear in, try a TINY bit of oil on the gears and play around with changing motors.
You will find the best setup as you learn more.
Get your self a 3.8 motor and a 150 or 200 mAh battery for the car and it will rock!
Have fun
:)uA

[micro_Amps]

The link works if you open it to a fresh browser screen. Nice pic of your front springs.
Let me try something else.

Ok, this is an attempt insert that picture to this post by copying the URL in its ‘properties’.

Lets see if that worked.
uA

Nope that didnt work. Seems you can link to it, but not bring t into a forum. Oh well, it was worth a try

That worked that time, go figure, I guess it does work.
Was the URL wrong or something??

Edited by – micro_Amps on 25 April 2003 11:04:13

Edited by – micro_Amps on 25 April 2003 11:06:21

[micro_Amps]

I can assure you it is accurate, I have the equipment to be able to calibrate this kind of thing. Its what I do for my work.

The cars speed is correct, it has been faster in the past but is running a different motor now. It has a 3.8, 8.25 gears and 2.4v Nimh cells and goes like a rocket

I will be doing some comparison tests with different motors and batteries etc, but not for a while. I will be putting my spare time into developing the power measuring part of the dyno.
Stage 2 is to build and install a variable electric load that will load the rear wheels of the bits from zero load to lock up. Zero load is actually the hard part!
Stage 3 is to measure the output of the load in stage 2 driven by the rear wheels, probably in micro watts, only then will it be a true bit dyno.
Stage 4 is to work out the torque. I have ideas for all stages except this stage, maybe I will seek help from all of you when I get there.
But there is still a long way to go.

Spanky thanks for your comments, I appreciate healthy criticism, and also the good words of ther people too.

As I develop this further, I will post the results.

:)micro_Amps

Edited by – micro_Amps on 25 April 2003 16:00:06

[micro_Amps]

HeHeHe:smiley2:
Burning the midnight oil too I see.
🙂

[micro_Amps]

HeHeHe:smiley2:
Burning the midnight oil too I see.
🙂

[micro_Amps]

Thats great, thanks for the info, I’ll give this a try later on.

Unfortunately ph2t, the picture in your post didnt work.
You might want to try that again.
:)uA

Edited by – micro_Amps on 25 April 2003 09:08:23

[micro_Amps]

Good on you Kevsta and welcome too.
$41 thats pretty good, which model and frequency did you get.? and what is the range like?
I think we should all buy another at this price.

Hey ph2t they are only $41 at Kmart !!!!
:DuA

[micro_Amps]

Good on you Kevsta and welcome too.
$41 thats pretty good, which model and frequency did you get.? and what is the range like?
I think we should all buy another at this price.

Hey ph2t they are only $41 at Kmart !!!!
:DuA

[micro_Amps]

I also have one of these on order. It should be here in a couple more days. I enquired as to whether it is fully proportional controls, and was assured it is so I bought one.
I’ll do a reveiw when I have it in my eager little hands.
:)uA

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