TruTrak pitch hunting solution

I've been trying to get the settings correct for my TruTrak 2 axis digiflight system. With the auto pilot engaged and selecting a heading on the autopilot head, the plane banks correctly, starts turning and then starts bobbing up and down in pitch, which diverges until I turn it off.

I experimented with different settings in torque, sensitivity and static lag. I then thought to try it with my alternate static source open (to cockpit). It became rock solid in the turn.

I called Tru Trak and explained all this and the first thing they asked was if my static source was on the pitot tube. Why, yes it was! They then stated that they felt that kind should be outlawed and while they may have worked with the old steam gauges with bellows, modern stuff was far too sensitive and that there were actually pressure pulses beneath the wing causing the pitch excursions in the auto pilot. They recommended using the standard Vans location and ports.

Between this and the major fussing I had to do to get my airspeed to read correctly with the current static source on the pitot tube, I'm finally ready to concede defeat and put the static source where Vans says to.

Education and Recreation!

Jeremy Constant
RV7A 100hrs

I have a static on the pitot tube also. Works great for airspeed. But since the Tru Trak pilot source was in back............I did add the Van's static system. The Tru Trak doesn't hunt or bob.

L.Adamson --- RV6A

I just vented mine to the cabin and the hunting problems went away. If I open or close the cabin vents I will get a slight pitch up an then return to normal.

Try turning on 'Half Step'. This fixed an issue I had that sounds very similar to what you are experiencing.

Gerald Clabots said:

I just vented mine to the cabin and the hunting problems went away. If I open or close the cabin vents I will get a slight pitch up an then return to normal.

Click to expand...

A friend went to Osh this year with another mutual friend in the right seat. As "entertainment" the right seater kept opening and closing the vent on his side to "adjust" the altitude while in altitude hold It apparently became quite annoying

Jeremy

jjconstant said:

Between this and the major fussing I had to do to get my airspeed to read correctly with the current static source on the pitot tube, I'm finally ready to concede defeat and put the static source where Vans says to.

Click to expand...

"Ahhh grasshopper, you are finally begining to see the light....."

Smart man, that Van!

jjconstant said:

A friend went to Osh this year with another mutual friend in the right seat. As "entertainment" the right seater kept opening and closing the vent on his side to "adjust" the altitude while in altitude hold It apparently became quite annoying

Jeremy

Click to expand...

You rekon he would have got the message if he had been left at a fuel stop? Continued flight of the non-instructor in the right seat is always optional.

Gerald Clabots said:

I just vented mine to the cabin and the hunting problems went away. If I open or close the cabin vents I will get a slight pitch up an then return to normal.

Click to expand...

Ditto: Also, Tuppergal got my (pitch) attention by pulling the cabin heat full-on during a night flight Rosie