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  #1  
Old 08-21-2013, 05:21 PM
Chino Tom's Avatar
Chino Tom Chino Tom is offline
 
Join Date: Jun 2005
Location: Chino, CA
Posts: 641
Default RV-12 Autopilot

For those of you who installed the autopilot in the RV-12 and are
flying. How well does it perform holding a heading, tracking a GPS
course and holding altitude? Especially interested while in light
turbulance. Are you happy with it's performance?
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Chino, CA
RV-8A,180/CS/Carb, AFS 4500 EFIS/EMS
RV-6, sold, 820 hrs of fun.
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  #2  
Old 08-21-2013, 08:52 PM
RFSchaller RFSchaller is offline
 
Join Date: Oct 2010
Location: Phoenix, AZ
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I have the D180 and AP74. It's fantastic. In smooth air it will hold altitude within 10 feet if tuned properly. I'm very glad I installed it.
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  #3  
Old 08-21-2013, 09:02 PM
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rv3flier rv3flier is offline
 
Join Date: Apr 2008
Location: La Center WA
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If the turbulence is very light, the autopilot seems to work quite well. However, in light to moderate turbulence I prefer to hand fly it. I haven't tried adjusting the autopilot sensitivity settings since I bought it with just over 80 hours. In more than very light turbulence, it's a bit jerky. So perhaps the sensitivity needs to be reduced a bit more.

I flew it back from south of OKC to the PNW when the winds along my route were quite high -- up to over 30 kts with resulting turbulence in mountainous areas. I've found that the RV-12 trims out nicely though and is easy to hand fly. The autopilot does come in handy while handling charts or changing settings on the GPS or IFly720.

I hope that others will chime in who've had more experience with the system.
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  #4  
Old 08-22-2013, 02:52 PM
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Chino Tom Chino Tom is offline
 
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Quote:
Originally Posted by rv3flier View Post
I hope that others will chime in who've had more experience with the system.
I was hoping that would be the case too.
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Chino, CA
RV-8A,180/CS/Carb, AFS 4500 EFIS/EMS
RV-6, sold, 820 hrs of fun.
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  #5  
Old 08-22-2013, 08:49 PM
jersey jersey is offline
 
Join Date: May 2010
Location: Wharton, Texas
Posts: 121
Default Do it again

I also have a D180 with an AP74 and glad I have it. I found that in a moderate to heavy chop it's better to hand fly unless your looking through sectionals adjusting frequencies etc. Other wise it holds to GPS tracking and altitude with amazing precision. Worth the effort to install and money. I do notice that at low power setting (less than 90 knots) it tends to hunt for altitude some, in which case I just trim for altitude and use the tracking / heading modes. Sure is nice when your above the clouds listening to blue grass gospel though.


Gary Eldridge karm
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  #6  
Old 08-23-2013, 05:00 AM
BigJohn BigJohn is offline
 
Join Date: Nov 2008
Location: Gloversville, NY
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I've been using my D-180/AP74 for over two years now. It works great (except for the infamous NAVSRC dropout), but it did require some tweaking of the settings in setup.
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  #7  
Old 08-23-2013, 06:50 PM
NASA515 NASA515 is offline
 
Join Date: Nov 2011
Location: Hansville, Washington
Posts: 536
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Until about 10 days ago, my experience was not good. I have the Skyview system. The airplane could hold heading, but in altitude hold, it would phugoid dramatically and uncontrollably. It would overshoot selected headings and airspeeds, although I could live with that.

I had hardware problems and went through two SV main systems and three ADAHRS. I also have a problem with the "bouncy" Vans ADAHRS mounting - and have a temporary fix awaiting a permanent Vans stiffening package. ADAHRS vibration causes big problems with the Autopilot.

I had trouble hand-trimming the airplane for level flight - it did "OK", but needed constant tweaking which on a cross-country flight became quite tiring. Every teensy-tiny jab at the stab trim button would cause an overshoot of the "sweet spot."

I decided to fix that and in several iterations, slowed down the stab trim motor using the Vans Control Box adjusting screw. After my last adjustment, I had REALLY slowed down the trim motor - almost double the starting speed. BUT - I can now trim for good hands off level flight. I am happy there - but might slow the trim motor down even a tad more.

Then I turned my attention to the Autopilot. I was determined to fix that or die trying (that's just an expression!) I started with the default settings, then went with Mitch's East Coast Blue settings, then a couple of other guys' settings. Nothing worked. There are many inter-related parameters, and once you start messing with them, off you go into Never-Never Land. I know!

Dynon released an Autopilot Tuning Manual, so others must be having problems too. I read and re-read that manual until I knew it by heart. Then I was determined to "make it work."

I made two 3 hour long test flights up and down Hood Canal - following the steps - first the Airspeed selection adjustment, then the Roll and Pitch adjustments, slowly and incrementlly. It was VERY tedious. In the end, I didn't figure I had it right yet, but I flew a cross-country and it worked quite well.

[IMG][/IMG]

[IMG][/IMG]

Since then, I've made several more - here's a flight I made yesterday from Bremerton (KPWT) to Waterville, Washington (2S5) - climbing through the Seattle Class Bravo with a stream of Headings and Altitudes, then across the Cascades at 9500 ft. - ATC all the way. The Autopilot nailed and locked all the Courses and Altitudes just like a Boeing! I was very pleased.

[IMG][/IMG]

I like Autopilots because I like to look for other airplanes, read the charts, take a lot of pictures, take a drink of water, and especially keep those nice ATC controllers happy. Yesterday, the Autopilot really made the flight into a joy.

Bob Bogash
N737G
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  #8  
Old 08-23-2013, 09:12 PM
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Special Delivery Special Delivery is offline
 
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Bob,
Glad to hear you've resolved your autopilot issues. Would you please share your settings?
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Last edited by Special Delivery : 08-23-2013 at 09:22 PM.
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  #9  
Old 08-25-2013, 11:35 AM
NASA515 NASA515 is offline
 
Join Date: Nov 2011
Location: Hansville, Washington
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All torques at 100%

ROLL
Sensitivity explored 5-15 - Final=12
Gain explored 0-1.0 - Final=1.0

PITCH
Sensitivity explored 10-24 - Final=10
Gain explored 0.5-1.0 - Final= 1.0
Pull Rate explored 1.0-1.7 - Final 1.0
Alt Gain explored 0.1-2.5 - Final 0.5

Note that a lot of these are near the Defaults. My first experience with using the Defaults was very poor. With the new replacement unit(s) - the Defaults performed well. Reducing the ADAHRS vibration also likely helped. If Vans decides not to address this problem, then I will install a permanent fix of my own design.

Note also that the Pitch Channel has 12 adjustable parameters - 8 of them significant to controlling the airplane in pitch. Dynon's Tuning Manual only addresses about three of these. I have ignored or just played slightly with these other settings. It's not hard to see that they all inter-relate and can mess with both your head and your airplane. In Statistics, this would be a multi-variate Design of Experiments, with such a large number of variables (power and airspeed also play a part), that the number of experiments required to explore the complete envelope would be in the tens of thousands.

I decided to explore a wide envelope in the three main parameters - max to min - to see what the effect was, and then returned to the Defaults and incremented them in small steps. As mentioned, it could be the prior units were faulty.

When comparing my values with some of the others that were posted, I notice a wide variation. I don't know why. Maybe the Autopilot control boxes have some significant variability. Maybe the vibration sensed by the Dynon system varies significantly between airplanes. Maybe, a combination of airframe, engine, aerodynamic, and avionic variabilities combine to make each airplane set-up completely unique.

I mention this as a caveat so you don't think my settings are the Holy Grail. The other guys' settings didn't work for me, but worked for them. You can use mine as a starting point if you want, and see how it goes.

When all else fails, try going back to the Defaults, and using the Tuning Manual.

Bottom Line - I've been able to move the system from totally unusable in pitch to (currently) performing, not only acceptably, but very well. The system is functioning as Dynon describes it, as I was hoping it would, and I am happy.

Bob Bogash
N737G
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  #10  
Old 08-26-2013, 11:14 AM
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Chino Tom Chino Tom is offline
 
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Location: Chino, CA
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Thanks Bob for that detailed post. That is what I was interested in.

Regards,
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Tom Prokop
Chino, CA
RV-8A,180/CS/Carb, AFS 4500 EFIS/EMS
RV-6, sold, 820 hrs of fun.
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