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Building a dyno question


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#1 Brian Ambrose

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Posted 31 May 2017 - 02:52 PM

Would a four-blade fan blade that s about 2 inches tall, be enough drag on the motor to be useful if I was using a photo tach on the fan blade?

I'm looking to build some sort of a dyno, so I don't have to have the motor in a chassis.




#2 gotboostedvr6

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Posted 31 May 2017 - 02:58 PM

4" x 2.5" is the best prop to start with
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#3 swodem

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Posted 31 May 2017 - 05:56 PM

Personally I wouldn't use a prop screw. It loads up the bearings/bushings with a high level of thrust not designed for.

I would use a weight.

#4 Brian Ambrose

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Posted 31 May 2017 - 07:06 PM

That makes since, however wouldn't an angled gear do the same thing... making thrust?

#5 gotboostedvr6

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Posted 31 May 2017 - 07:46 PM

Never gave me trouble. Gotta oil liberally.
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#6 swodem

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Posted 30 July 2017 - 08:25 PM

That makes since, however wouldn't an angled gear do the same thing... making thrust?


No, it just improves mesh.

#7 Bazzie

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Posted 02 August 2017 - 07:06 PM

Drive a larger prop/fan through gears, that way you can avoid the thrust and change motor loading as required.

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#8 CoastalAngler1

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Posted 02 August 2017 - 07:11 PM

Does someone have a slot car motor dyno that can post a picture? Video?

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#9 bbr

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Posted 02 August 2017 - 08:03 PM

i think a dyno is good info if the motor tested was a precision-made motor.

With Retro motors, the on-track heat cycling determines the quality of a motor. Until it is run on track you don't know what you have.
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#10 crazyphysicsteacher

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Posted 03 August 2017 - 07:37 AM

Try the Simple Dyno website. 

The site has a program that can be used to build a dyno from.  ry using a 2 mm shaft gear to mount the small magnet the program requires. 

Any dyno really lets you make comparisons on it. So your system will work for you but will be really hard to compare to other results. I say keep going, there is merit to having a way to compare motors. 
I suggest using a system that lets you screw in the motor like you do in a chassis. 

Then use a belt drive system, like Pro Track or Parma make for rentals, to load a second wheel that spins to read the data. It will be more complex but will allow you to load the motor bushings how they will be used.

The important part of this is to be able to program in a voltage increase and rate of increase to measure voltage versus RPM change to compare how each test motor accelerates.
 
Let us know how it turns out.

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#11 Brian Ambrose

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Posted 03 August 2017 - 07:56 AM

Not looking to build a dyno any longer.

4FDB49EA-1CF2-4BEA-B5B6-38E71D1CA966.jpg

#12 MSwiss

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Posted 03 August 2017 - 08:29 AM

Have you had success with it?

IOW, has it identified the motor that is fastest on the track?

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#13 Brian Ambrose

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Posted 03 August 2017 - 08:51 AM

I last night was the first time I've used it. Also going to be getting/building a chassis dyno.

#14 tonyp

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Posted 03 August 2017 - 09:04 AM

I've never had a 'bad on the dyno' motor run good on the track. Same with my chassis dyno, if it's good, it's good on the track. Saves a lot of thrashing on race morning.
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#15 Noose

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Posted 03 August 2017 - 09:33 AM

Once you have readings from the Trinity dyno and if you have a rolling dyno, you can correlate the readings to performance on the various tracks for sure. With the five tracks we have here in our series, I know the hi amp ones run better at certain tracks than do the low amp ones.
 
The rolling dyno results have proven very reliable for a given motor in a given car.

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#16 Shooter7mustang

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Posted 03 August 2017 - 10:51 AM

Is the Trinity still available ?


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#17 tonyp

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Posted 03 August 2017 - 04:07 PM

No, haven't been for years, but we sold a ton for brushed RC motors. Since RC went brushless they are no longer usable, so there has to be a couple of thousand out there.


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#18 bbr

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Posted 03 August 2017 - 07:35 PM

http://www.ebay.com/...F6KRmb-o5DQmMjQ

 

I made this work with slot car motors


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#19 bbr

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Posted 03 August 2017 - 08:55 PM

made an adapter to position the slot motor, will post a picture when I get home tonight.

 
what I really want is a fantom like dyno.
this company make this, I think it can be modified to work with slot motors
01-01-0001-MD1-00.232_grande.png
 _20170804_002244.JPG
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#20 dalek

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Posted 06 August 2017 - 01:57 PM

Even though Brian went a different route, I'm posting what I built.  The rig lets me compare motors to each other.

 

It's still a work in progress, but it looks like I'll eventually test each motor with two props.  A prop that causes about a 3.5 amp draw at 6 volts and a smaller prop that causes about a 3.5 amp draw at 12 volts.

 

1110 copy.jpg

 

1111 copy.jpg

 

1118 copy.jpg

 

1122 copy.jpg

 

1125 copy.jpg

 

1128 copy.jpg

 


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#21 Brian Ambrose

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Posted 06 August 2017 - 02:59 PM

Very interesting Dale.

#22 gotboostedvr6

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Posted 06 August 2017 - 05:51 PM

Are you using eagle tree?
Freedom is never more than one generation away from extinction. We didn't pass it to our children in the bloodstream. It must be fought for, protected, and handed on for them to do the same, or one day we will spend our sunset years telling our children and our children's children what it was once like in the United States where men were free. - Ronald Regan #40 (1911 - 2004)

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#23 dalek

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Posted 07 August 2017 - 07:14 AM

Are you using eagle tree?

 

I didn't know what eagle tree was so I searched for it.
 
 
I assume you are wondering if I use one of their sensors, such as airspeed or what not.
 
What you see in the pictures is all that I use.  
 
The tachometer tells me when one motor is more powerful than another.

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#24 gotboostedvr6

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Posted 07 August 2017 - 07:32 AM

Does the tachometer use a optical sensor?
Freedom is never more than one generation away from extinction. We didn't pass it to our children in the bloodstream. It must be fought for, protected, and handed on for them to do the same, or one day we will spend our sunset years telling our children and our children's children what it was once like in the United States where men were free. - Ronald Regan #40 (1911 - 2004)

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#25 gotboostedvr6

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Posted 07 August 2017 - 07:34 AM

Edit. I see the sensor in the pic :)
Freedom is never more than one generation away from extinction. We didn't pass it to our children in the bloodstream. It must be fought for, protected, and handed on for them to do the same, or one day we will spend our sunset years telling our children and our children's children what it was once like in the United States where men were free. - Ronald Regan #40 (1911 - 2004)

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