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2 or 3 axis autopilot?

How many autopilot axis?

  • Pitch and roll only

    Votes: 100 84.7%

  • Pitch, roll, and yaw

    Votes: 12 10.2%

  • I don’t need no stinkin autopilot

    Votes: 6 5.1%
  • Total voters
    118
  • Poll closed .
I

inktomi

Active Member
Sponsor
Hi,

I’ve seen a couple threads mentioning yaw stability without feet on the rudder peddles in turbulent air. I’m pretty tall, and so in general my feet are always on the pedals regardless, but I’m curious - I’m going to install an autopilot and basic IFR capabilities (for marine layer, not hard IFR) and I’m wondering if it would make sense to install a servo for yaw along with pitch and roll.

The YD button is there on the autopilot head either way… might be nice for it to do something?

What do you all collectively think?
 
I am the (so far) sole vote for no AP. My -8 has an AP, as did my previous 172, but for VFR I have never felt any need to use it; I do love to fly hands-on. And the plane is stable enough to stay on course and hold altitude within checkride standards for longer than enough to do whatever both hands might be needed for.

For IFR, it’s a plus. For VFR I say save the cost, weight and potential maintenance. The less tech, the fewer opportunities to say “what’s it doing this time?”
 
FL Flier said:
I am the (so far) sole vote for no AP. My -8 has an AP, as did my previous 172, but for VFR I have never felt any need to use it; I do love to fly hands-on. And the plane is stable enough to stay on course and hold altitude within checkride standards for longer than enough to do whatever both hands might be needed for.
For IFR, it’s a plus. For VFR I say save the cost, weight and potential maintenance. The less tech, the fewer opportunities to say “what’s it doing this time?”
Click to expand...

That's interesting. I too am the "sole vote" for "no A/P"! Does that tell you something about polls?
 
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I'd be interested to see how you would go about installing a yaw servo in an RV. Unless the 8 is different than my 7 they don't have a closed loop rudder system so a servo with a capstan and bridle cable won't work.

Not saying that you couldn't make it work, but it seems like a major project and the juice might not be worth the squeeze.
 
I did not have an auto pilot for first 12 years and 800 hours of flying. Finally put one in and then after only a few hours I removed the servos as I did not like the feeling of the controls. Decided last year to reconnect up the servos and happy I did. Very helpful on longer cross countries especially in mild turbulence.

I really don’t think there is a need for yaw.

Desert Rat said:
I'd be interested to see how you would go about installing a yaw servo in an RV. Unless the 8 is different than my 7 they don't have a closed loop rudder system so a servo with a capstan and bridle cable won't work.

Not saying that you couldn't make it work, but it seems like a major project and the juice might not be worth the squeeze.
Click to expand...

I was thinking the same about a yaw servo. Need a new scheme for driving the rudder.
 
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Desert Rat said:
I'd be interested to see how you would go about installing a yaw servo in an RV. Unless the 8 is different than my 7 they don't have a closed loop rudder system so a servo with a capstan and bridle cable won't work.

Not saying that you couldn't make it work, but it seems like a major project and the juice might not be worth the squeeze.
Click to expand...

Ahh, interesting! This is great info. On the RV-10, people install the servo for yaw (and there's even a kit for it), and I recently switched to the -8 so I was thinking about what plans of mine would change. Using the GSA 28, it looks like they only make kits for roll and pitch - so this might be a moot point unless I want to get into one-off territory (I don't).

On the rental DA40s I fly, I generally only use the autopilot when flying IFR, or maybe on longer cross countries to relax a little after hand flying for an hour or two. I would plan on the same in the RV-8.

Thank you!
 
jrs14855 said:
Dynon offers servos with cables. Attach the cables to the rudder cables in the tailcone.
Click to expand...

So does Garmin. My point was that it would require significant effort to figure out how to make it work on an open loop system. Garmin already has it kitted for the 10, but not for anything else, so you'd have to roll your own solution unless you're saying dynon already has a solution?
 
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And the 14

Desert Rat said:
So does Garmin. My point was that it would require significant effort to figure out how to make it work on an open loop system. Garmin already has it kitted for the 10, but not for anything else, so you'd have to roll your own solution unless you're saying dynon already has a solution?
Click to expand...

Vans also has it kitted for the 14. The following is my opinion only but I can definitely tell the difference yaw off and on especially in climb out and obviously on the rudder pedals then. I’ve not changed my current settings (yaw gain and centering torque) but plan to experiment more soon. My wife can tell almost immediately if off. The servo acts almost immediately to side loads and it can be tested on the ground. Push on the vertical stab and the rudder immediately corrects in the opposite direction. Currently the yaw damper correct about a half a ball and need to apply much less rudder force for the 10 mins to get to altitude. Also saves adding tabs and whatever else we put on the rudder to correct for ball centering. I really like the yaw servo and money well spent.
 
dmattmul said:
Currently the yaw damper correct about a half a ball . . . . . . . . . . . saves adding tabs and whatever else we put on the rudder to correct for ball centering. I really like the yaw servo and money well spent.
Click to expand...

Using an active system, like an autopilot, to fix an out of trim issue is not a good idea. It is more expensive, more complicated, more maintenance, and more drag then adding a small wedge to the rudder.
 
In climb

plehrke said:
Using an active system, like an autopilot, to fix an out of trim issue is not a good idea. It is more expensive, more complicated, more maintenance, and more drag then adding a small wedge to the rudder.
Click to expand...

Most of us need to use rudder in a climb, yaw damper reduces that effort and the A/P does not need to be actively engaged for the yaw damper to perform its function.
 
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The OB put in an autopilot in my airplane on an ARINC429 module so I have four choices on any given flight...ALT/HDG hold, track from EFIS, track or approach from GPS navigator, or leave it disengaged. My airplane is pretty stable in the yaw axis, don't really feel the need for a yaw damper.

I use the autopilot maybe half the time. I like having the AP option a lot, and it certainly adds value to the airplane. Although I don't always use it, the lack of one would be been a big negative on my list of pros and cons when I was looking to buy.
 
I totally agree about the added value of having one installed in the case I want to sell the plane down the road. It seems like a two axis autopilot is probably the easiest path on the RV-8, though with some effort the yaw axis could maybe be added as well.

I don’t want to overcomplicate an already complicated project, so probably a two axis autopilot is what I’ll install. I’d rather not stray too far off the common path with something as critical as a flight control surface.
 
inktomi said:
I totally agree about the added value of having one installed in the case I want to sell the plane down the road. It seems like a two axis autopilot is probably the easiest path on the RV-8, though with some effort the yaw axis could maybe be added as well.

I don’t want to overcomplicate an already complicated project, so probably a two axis autopilot is what I’ll install. I’d rather not stray too far off the common path with something as critical as a flight control surface.
Click to expand...

Yaw dampers have been installed on RV-10s and -14s. Has anyone installed a yaw damper on an RV-8 yet? I haven't heard of anyone. I haven't felt the need for it in either my previous RV-8 nor my current RV-8 (~3300 hrs RV-8 time).

I do enjoy the two-axis SkyView autopilot in my current RV-8.
 
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I never thought my 7 needed a YD. It wouldn’t be horrendously complicated to do it but you wouldn’t have the benefit of a well thought out design with plenty of history like the 10/14. I personally think it’s overkill for a 2 seater.

I have one in the RV10 though and it’s remarkably effective. Ball glued to the center for the whole flight.
The difference between on and off is very noticeable in turbulence.
 
Well I for one loves having a two axis auto pilot.
Flown without one for a long time, But, when I redid my panel two years ago we put-er in the package and never regretted it.
Say your at 10,500 and nobody else around you can relax and let Mable fly the plane for awhile.
Love it Fixit
 
My wife has a Rans S7, a while back, that we installed a 2 axis auto pilot in. It did not work well in a turn with feet on the floor. However it worked quite well with feet on the peddles locking the rudder straight ahead. The fix was to place light springs ahead of the peddles that kept the rudder centered, permitting acceptable feet on the floor performance.
 
Fly one just to evaluate

mike newall said:
Keep your feet on the rudder pedals, with pressure ...........

No yaw damper required in any RV :D
Click to expand...

I was also skeptical about a yaw damper but PLEASE unless you have actually tried one how can you comment? (Either good or bad)

We are experimental builders and fliers. Why not actually experiment and evaluate, then comment?

I’m not putting anyone down (not intentionally) but the builders I’ve talked to most do not understand how yaw damper even works. It’s nothing like pitch and roll control. It functions without the A/P even activated. It compensates for any side loads applied by outside forces like wind gust to keep your fuselage perfectly in line. I’ve got many hours in a Bonanza and this would have resolved 99% of the tail wag this airframe possessed. In Florida, climbing in the afternoon we see lots of thermal activity and this smooths out these incredibly well. It reacts in mili-seconds to side load gusts. Ok, I’m off my soapbox. Do as you think you want/need.
 
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I have no idea about a yaw damper, I don't have one fitted and don't see the need, but ...
However, from the basic autopilot perspective I very, very much like having a 2-axis autopilot in my RV-6. I have flown without for several hundred hours and really like it (basic Garmin fed from G5 with GMC507, no GPS hooked up). I use it on most flights, there is no drag on the controls (unlike the Trutrak that I had in my last 6A).
It may depend where you fly and what kind of flying you do. I fly under some busy airspace, the autopilot helps me not to bust into the stuff above. Last weekend I flew back home from 500 miles away in 3 hours, the autopilot was in pretty much all the way. Really helpful.
My vote is defo for a 2-axis, I don't feel the need for a yaw damper.
 
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