Hobby Dyno!!

[bigdave]

Well I guess that is what you could call it.

I just wanted to show a new test fixture I just designed and built.
I wanted something to allow me to test the power output of different motor, gearbox, and prop combinations. I had a nice cable tie container some old end caps K&S tubing, and a SS 4MM prop shaft collecting dust. So I put them to good use.
I have adapters for different sized output shafts. It works very well but I want to put some baffles in the water to try and keep down the vortex from forming.
I am using an Astro Flight watt meter to get my current and wattage measurements.
In these photos I was testing a new motor/gearbox combo with a 5 blade 55MM prop. Which is a very high load to test with.
You can see in the one photo what a 1 amp draw with 8 watts of power looks like. I think this will be a very efficient power unit.
I could not get a max figure as at about 7 amps it would start to cavitate really bad.
Hence the need for the baffles.
With a smaller 1 ¾” 3 bladed prop I could get a max of 4.5 amps at 32 watts. This only took a few hours to build and should be a handy tool. BD

[anonymous]

Very nice BD! Going to

Very nice BD! Going to change your name to (Big) David Taylor.
When do you start on the tow tank??

[Larry Kuntz]

Very nice BD. I bet

Very nice BD. I bet it makes a great milk shake too.

[Rogue Sub]

Do you think that the

Do you think that the prop wash dead ending at the bottom is effecting the power consomption because the prop is trying to compress the water down instead of a stead feed of incoming water as it moves forward in the water. Perhaps a circular design more like a wind tunnel. Or am I just being nit picky

[bigdave]

I think a good scimitar

I think a good scimitar prop would make a good shake.
I am sure there is a good fudge factor in the actual readings that the system would have in the sub.
But this does give me a good indication from motor to motor as a comparison.
Or just throw in some fruit and make a smoothie!! BD.

[redboat219]

Do you think that the

Do you think that the prop wash dead ending at the bottom is effecting the power consomption because the prop is trying to compress the water down instead of a stead feed of incoming water as it moves forward in the water. Perhaps a circular design more like a wind tunnel. Or am I just being nit picky

How bout putting in a smaller diameter tube to guide the water...Or you could just clamp the whole set-up on the edge of your bathtub.

[bigdave]

Actually the vessel of choice

Actually the vessel of choice was the laundry tub.
It is much easier to have it all at the work bench and not have to fumble around with trying to hold the fixture and the transmitter at the same time.
I will try some different ideas and see which works better. It is only a problem when you get the revs up or let it run for too long allowing the vortex to rear its ugly head. . BD.

[redboat219]

don't you need something like

don't you need something like a flow meter or mini turbine generator to measure the output of the motor/prop?

[bigdave]

It is not measuring the

It is not measuring the output in thrust if that is what you mean. The watt meter measures the power the motor is pulling from the battery.
The readout gives you the input voltage, watt output, amp draw, and amps used.
It is used most for selecting gear and prop combinations for a given motor, or to make sure your ESC can handle the power.
Plus what the expected run time could be from a battery. BD.

[boss subfixer]

BD
How's this for a dyno?

BD
How's this for a dyno? Just like a fast food restaurant, super sized!

[wlambing]

Donnie,

That's one helluva big

Donnie,

That's one helluva big epoxy remixerizer!!!!!!!!!!!!



B^)

[boss subfixer]

Whatever it takes Bill, whatever

Whatever it takes Bill, whatever it takes..

[bigdave]

Hey Don!!
That dyno of yours

Hey Don!!
That dyno of yours will never work buddy!!
Because someone has stolen the Modulator!!!!!

[fgroza]

Hey Dave,
Any of you guys

Hey Dave,
Any of you guys from Rochester work for Light'ng mixers? They would have what you need!!!
Frank

[bigdave]

Hi Frank,
I use to

Hi Frank,
I use to work just down the street from them at one time. We used their mixers in our large emulsion mixing kettles. That was back when people actually still used film!! BD.