40 replies to this topic

[Tampabay racer]

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.

[gotboostedvr6]

4" x 2.5" is the best prop to start with

[swodem]

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.

[Tampabay racer]

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

[gotboostedvr6]

Never gave me trouble. Gotta oil liberally.

[swodem]

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

No, it just improves mesh.

[Bazzie]

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

[CoastalAngler1]

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

[bbr]

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.

[crazyphysicsteacher]

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.

[Tampabay racer]

Not looking to build a dyno any longer.

[MSwiss]

Have you had success with it?

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

[Tampabay racer]

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

[tonyp]

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.

[Noose]

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.

[Shooter7mustang]

Is the Trinity still available ?

[tonyp]

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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[bbr]

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

 

I made this work with slot car motors

[bbr]

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

 

[dalek]

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.

 

 

 

 

 

 

 

[Tampabay racer]

Very interesting Dale.

[gotboostedvr6]

Are you using eagle tree?

[dalek]

Are you using eagle tree?

 

I didn't know what eagle tree was so I searched for it.

 

Among the results was:  http://www.eagletree...s.com/index.php

 

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.

[gotboostedvr6]

Does the tachometer use a optical sensor?

[gotboostedvr6]

Edit. I see the sensor in the pic