Flap Sensor

Time: 4 Hours

One nice feature of the VP-X is the flap control. With a position sensor, a smal device the translates the actual position of the flaps into a digital signal, you can take advantage of several features. The first is exact control of the flap motor either up or down with a single switch movement. The second is intermediate flap steps. Once the sensor is set up you can define the value of the flaps full up and flaps full extended. With those two numbers you can use any value in between to have intermediate flap stops. First up is to instal a sensor, I’m using a Ray Allen POS-12 that I got from Aircraft Spruce. There are no plans for how to attach this sensor but a few builders have documented how they did their install. The sensor is just a small potentiometer that has a rod that slides in and out for a total travel of 1.2 inches. The idea is to attach this sensor to the side bulkhead below the flap motor. Then attach the rod end to the flap push tune so that when the rod moves up and down as the flaps do it would either extend or retract the sensor rod. I went to a local hobby shop to get a few parts, clevis’s and threaded rod, that I used to bridge the sensor to the adel clamp I put on the flap push tube. I mounted the sensor to a scrap piece of sheet and put in an approximate 30° bend in the top end to give the sensor a straight shot to the flap tube when I clamped it to the bulkhead. 

It ended up working really well after I made a few adjustments. The idea was to have the sensor rod extend almost completely and retract almost completely. Once I had that adjusted I drilled the bulkhead for a screw to attach it. I hooked up my laptop to the VP-X and brought up the flap settings. The sensor was showing up perfect and just indicates a number between 0-255. That’s the digital number of where the flaps are. The up position was showing 0 so I set the VP-X at 1 to allow the motor to shut off. The number with the flaps full down was 233 so I set that for the flaps full setting. So now when I click the flap switch down on my grip the flaps run to full down and then the motor stops. The same happens with a single click up which brings the flaps full up. The VP-X also allows for two intermediat flap stops. So with the flaps full up or 0° I used my digital level to zero out for 0°. I adjusted the flaps down till the level read 10° down and looked at the sensor number. I plugged that number into the first flap stop. I repeated this process for 20° down flaps for the second flap stop. So now the VP-X goes to 10° flaps with the first click down on the flap switch. Click it again and you get 20° and once more for full flaps down at 40°. One click up and the they retract fully. I will be able to use the sensor data to create a flap indication on the Dynon screen as well later down the road. Turned out to. E a cool feature of the VP-X for just a little extra work. 

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