Dave has done a good job at explaining the use of the balance meter in adjusting the IVO prop.
As to the particulars, the meter I used can be found in the Mouser electronics catalog here:
and the part number is 391-0105.
There are actually two meters that would work.
One has a scale with numbers (PN 391-0115)and the other one just has a magnitude indication either side of zero.
I chose the latter because I wanted to mount it vertically rather than horizontally and the numbers would have been sideways and don't really indicate true values anyway.
For the shunt resistor I chose a Vishay/Dale LVR wirewound 5 watt power resistor with a value of 0.015ohm 1%. The part number in the Mouser catalog is 71-LVR5-0.015 and can be found here:
This value was calculated to provide full scale deflection of the meter in either direction
prior to popping the breaker.
The shunt resistor is placed in series with one of the wires that goes to the pitch change motor and the meter is connected across the resistor.
Remember, as IVO recommends, do not change the length of the wiring that powers the prop pitch change motor as the wire length effects the current at which the breaker will pop.
I've included a photo that shows the engine/prop management section of my instrument panel. The prop section is in the upper left corner. The meter is on the left, the circuit breaker is in the center and the toggle switch is to the right of the circuit breaker.
With my right hand resting on the throttle it is easy to change the prop pitch with a flick of my thumb while watching the meter for movement.
This circuit is a nice addition for the IVO prop as it gives some feedback to the pilot of what is happening when the prop is being adjusted.
If you toggle the prop change switch and the meter does not deflect you will know that the prop is not moving. As the prop gets closer to its end of travel so does the meter. If the meter pegs immediately then you know you are at the end of travel.
I always thought that IVO's solution of popping a circuit breaker was not a good way to determine that you are at the limit.
Please keep in mind that this circuit addition is not sanctioned or approved by IVO and as such if you decide to include it in your aircraft design you are doing so at your own risk.
Jim
--- On Sun, 10/18/09, Dave <david.staten@gmail.com> wrote:
From: Dave <david.staten@gmail.com>
Subject: [FlyRotary] Re: IVO Question (was) Static rpm
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Date: Sunday, October 18, 2009, 10:54 PM
25 or 30 amp bi directional ammeter mounted with appropriate shunt IN LINE/Series with prop circuit. The circuit breaker pops at 20 on the IVO. The current varies with the amount of resistance on the prop adjustment motor. Mid range pitch draws very little current so it will be towards the middle of the scale. Large deflections from midrange pitch will cause large indications on the ammeter.
This is an instantaneous reading that is seen only when the prop circuit is being energized. Bi directional is used so that you can roughly gauge how much the prop is from mid range towards the limits as you both coarsen and fine the blade pitch.
Someone on here years ago posted the right shunt to use, and I bought it.. but that email is on another machine. Good luck with the archive search.
Dave
stephen haas wrote:
> Interesting concept... Tell me more please sir.
>
>
> --- On *Sun,
10/18/09, James Maher /<
delta11xd@att.net>/* wrote:
>
>
> From: James Maher <
delta11xd@att.net>
> Subject: [FlyRotary] Re: IVO Question (was) Static rpm
> To: "Rotary motors in aircraft" <
flyrotary@lancaironline.net>
> Date: Sunday, October 18, 2009, 12:31 PM
>
>
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