Jump to content

TruTrac Digiflight II VS porpoise


NC Bill

Recommended Posts

My autopilot seems to hunt for altitude hold about +/- 50' in both TRACK & GPS mode.

 

Problem is airspeed can vary +/- 15 kts during the excursions.

 

TruTrac support suggested some setup changes which didn't resolve the issue.

 

Has anyone had any similar experience.

Link to comment
Share on other sites

Hi Bill,

 

Hopefully someone here that has good working TruTrak setting numbers will get their numbers off their control unit and post them here for you. Have you done all the up dates to the Dynon's and the control unit? You should be at 5.4 version and you have to up date an HS34 separate from the D100 and D120.

Link to comment
Share on other sites

Roger -

 

I've got dual Skyviews installed and upgraded to v3.1.

 

696 is v4.40.

 

TruTrac is at v2.2 but Tech Support suggested that upgrading to v2.4 by them is unlikely to effect change. They did suggest increasing ACTIVITY & STATIC LAG settings , neither of which helped.

Link to comment
Share on other sites

My AP has same problem but plus or minus 500 feet vert, then it will randomly just make a 25 degree turn always to the right? Gotta love TT. I'm going to pull the head and send it back. It's 5 yrs old and never has worked right.

Link to comment
Share on other sites

My AP has same problem but plus or minus 500 feet vert, then it will randomly just make a 25 degree turn always to the right? Gotta love TT. I'm going to pull the head and send it back. It's 5 yrs old and never has worked right.

 

Mike, what type of instruments do you have in your plane? Garmim glass, steam, "other"? Just trying to figure out why your TT works so poorly. Have you sent your A/P into TT previously or have you been putting up with it for 5 years? My experience with TT tells me that they will provide correct encoded altitude input at the shop and repair it so that the unit correctly responds correctly. Once they do this, if you find that the A/P still will not hold altitude in your plane, you will want to find out where a problem is with your altitude encoder or with the equipment that provides data to your A/P. Or, perhaps there's a problem with the data cable?

Link to comment
Share on other sites

I was able to get my IIVS flying nicely by modifying the settings from factory also. I'll post them if you want. Sometimes, when cruising just over the inversion layer, you can get into smooth updrafts and downdrafts and I would get the same +/-15 kt excursions. Repeated night and early morning flying has proven that it will fly level and straight. Sometimes you have to stick fly.

Link to comment
Share on other sites

I'll post them if you want.

 

I'd be grateful if you would post yours.

 

Interesting to compare with Dick's.

 

BTW Dick, I am using yours and on one short test flight there were no excursions noted. I have a 3 hr next week and that'll be the REAL test ;) Thanks again for the spreadsheet.

Link to comment
Share on other sites

Bill and Opticsguy, I'm glad to hear that my data helped. Always good to have more data points for comparison so please post your TT settings that work for you so forum members can compare. Since our TT A/P steers using aileron and not rudder, I note that there is sometimes a fairly active "up/down" of the wings that occurs when the A/P works to keep the plane on track during gusty days. Not a perfect system but short of spending big bucks for a A/P system that uses both the aileron and rudder for automatic coordinated steering, I'm very pleased with the way it works.

Link to comment
Share on other sites

I had some really smooth air yesterday between Fredericksburg and Denton, TX. I was able to experiment with the parameters. I did not like the static lag being anything other than zero. If I was flying in some sort of thermal environment I might want this at a higher number, but I usually stick fly when it's that bumpy.

 

With vertical activity at 4 and micro-activity at 2, in smooth air the plane would pitch up and down slightly every few seconds. Clearly, this combination has a resonance close to the aerodynamic stability parameters.

 

I now have Vertical activity at 2, static lag at 0, and microactivity at 1. I really like this result.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...