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Dynon vs Tru Trak

jthocker

jthocker

Well Known Member
Finally got a chance to fly my RV8 next to it's twin and compare autopilot performance.

My RV8 s/n 82689 and my friends RV8 s/n 82688 were built as twins last year and are identical except for mine has a Dynon autopilot and Larry Wolf has a TruTrak ADI II.

Flying side by side and 200 feet apart, we both selected "direct to" KRID,then selected "NAV" and "Alt Hold". We were at 3500 ft. and in smooth air.

For 10 minutes we flew in formation on autopilot without converging or diverging. Occasionally Larry's plane appeared to be sometimes slightly above the horizon and sometimes slightly below the horizon. Checking the Dynon altitude showed it locked into the little yellow alt. bug.
I'm guessing we both were oscillating within the 10 ft. resolutions of our Dynon altimeters.

It appears to me that Dynon "oscillation" issues might be due to loose shear screws, as, at least for me, fixing that, has made my autopilot equal to or better than the Tru Trak. When I say better, I'm referring to features and bang for the buck, not performance.:D
 
Jon:

I plan on following the Dynon service instruction for tightening the sheer screw tomorrow and will fly it Sunday. Hope you're right. :)
 
Working fine

Jon,
Thanks. I'll keep an eye out for it. For now my AP is working great, but it only has about 6 hours on it.
 
But how about turning on to a heading, intercepting a radial, etc?

The other issue is that if your EFIS falls over so will your autopilot. Your friend will be able to engage his TruTrak and figure out what has gone wrong. You will have to formate on him all the way down.

Pete
 
Pete
Thats an excellent point. Larry's mission, in his plane, is the ability to go IFR.
That's why his plane is equipped with the ADI II and an SL30.
Our thinking was, total electrical failure---he has Dynon and 496 with backup batteries. EFIS failure--- turn on the autopilot and link it to the 496.
The ADI II "nav mode" will fly the final approach segment from the 496 data base, even an ILS very well, albeit you're on the hook for the vertical "nav".
As for comparing heading and radial intercepts, it's hard because the ADI II flys GPS ground track or GPS nav. There is no ability to select heading on the ADI II, unless you lose the GPS signal, then I think the ADI II reverts to heading mode.

The mission for my airplane is VFR. So all my eggs are in one basket with the Dynon, 496, SL40, Dynon unheated pitot. Of course I'm seriously thinking about upgrading now, because I would have been the 5th airplane in the "Moon over RV's" pic.:(
 
The other issue is that if your EFIS falls over so will your autopilot.
Click to expand...

So what!!!

Gee you might actually have to hand fly it for a change.... you know how you were once trained to do!:eek:

And if you are in IMC you would of course have a second EFIS or Vac driven AH......not that you have to, but you would.

Some of you guys worry about some stuff far too much!

DB:cool:
 
49clipper

So far, my ADI II does not hold alitude or heading very well at all. No gps input to it yet, so I am hoping that is the reason. I thought it should hold altitude without the gps input, but maybe not. It wanders up and down based on how the trim is set. Very disapointed thus far. Heading is a constant turn the left. By setting the correction, I can roll level but then it seems to yaw quite a bit. Is this normal with a trutrack w/o gps input?
 
The TruTrak is made to operate with a GPS. You can't calibrate it with one installed and connected to it. Until you have it installed properly you can not expect it to work as it is suppose to. I have installed a few of these pilots and they all work flawlessly.
 
I'm surprised, Jim........

....since mine flew great right out of the box, with no additional "tweaking" in flight needed. The second flight was in really lumpy air and it hunted a little but it was not unacceptable. Yours may need some inflight adjustment as some sometimes do. Are all your pitot-static lines leak free?

Regards,
 
Pierre,
Are you flying the ADI pilot II ?
Just installed my servo mounting brackets and the pitch servo.
As the Stein harness is not shielded I assume routing next to the battery cable is permisable with no ill effects.
 
49clipper said:
So far, my ADI II does not hold alitude or heading very well at all. No gps input to it yet, so I am hoping that is the reason. I thought it should hold altitude without the gps input, but maybe not. It wanders up and down based on how the trim is set. Very disapointed thus far. Heading is a constant turn the left. By setting the correction, I can roll level but then it seems to yaw quite a bit. Is this normal with a trutrack w/o gps input?
Click to expand...

The ADI Pilot should be used with a GPS as it does not have a magnetometer. The Bank Angle backup mode is just that, a backup mode only.

Also, be sure this is powered up on the ground while stationary, not after you take off. The gyros go through a centering procedure during the power up sequence.

You may need to adjust your vertical activity setting. Make sure your torque settings are no lower than 10 (12 preferred). Lastly, you may need to increase the static lag setting if your static system is connected to several different instruments.

http://trutrakap.com/forum/index.php
 
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