Autopilot recommendations?

Does anyone know of a single axis autopilot capable of disengaging the servo when the autopilot is not active?

I am building an RV4 and was planning to use a Digitrak single axis autopilot, however I am somewhat concerned about having residual servo drag on the ailerons and none on the elevator. I do mostly local flying, basic aeros and wish to retain the light harmonised feel of the 4. The autopilot installation is primarily for safety reasons and to reduce workload on the occasional cross country flight (hence single axis only).

Thanks in advance for any suggestions or recommendations.

Darren

Blowfly said:

Does anyone know of a single axis autopilot capable of disengaging the servo when the autopilot is not active?

I am building an RV4 and was planning to use a Digitrak single axis autopilot, however I am somewhat concerned about having residual servo drag on the ailerons and none on the elevator. I do mostly local flying, basic aeros and wish to retain the light harmonised feel of the 4. The autopilot installation is primarily for safety reasons and to reduce workload on the occasional cross country flight (hence single axis only).

Thanks in advance for any suggestions or recommendations.

Darren

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You won't find the TruTrak servo drag noticeable in flight, but if you want a system with a servo that has a clutch that completely disengages, you need to look at the Trio EZ-Pilot:

http://www.trioavionics.com/ez_pilot.htm

The fact that the EZ-Pilot is superbly supported by the manufacturer is an added bonus.

Sam Buchanan said:

You won't find the TruTrak servo drag noticeable in flight, but if you want a system with a servo that has a clutch that completely disengages, you need to look at the Trio EZ-Pilot:

http://www.trioavionics.com/ez_pilot.htm

The fact that the EZ-Pilot is superbly supported by the manufacturer is an added bonus.

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Thankyou for the Trio EZ-Pilot suggestion Sam.

The Trio does look very good and appears to have many features including the clutch arrangement. I do like the simplisity of the Digitrak however, and its 2 1/4" format will save some space on my panel. I'm sure you are right about the residual servo drag feeling much worse when the ailerons are unloaded on the ground. I'll give it a bit more thought. Thanks again for your input.

Darren

Flew my 6 for over a year with no AP. Now 30 hours or so with Trutrak servos (2 axis in my case). With the AP off, I can't tell the difference. Never even thought about it until seeing this post. Really, not an issue. I hear the Trio is good too. Good to have choices.

I've flown the same RV-8 with a TT autopilot and a clutched servo and later with a non-clutched servo. The difference was moderately apparent when parked in the hangar but not apparent in flight.

servo drag

In my 4 I have Tru Trak servos and Efis. I notice a slight drag when the AP is off and the servos have power. If I want a feel in the stick that is without the slight drag, I pull both the pitch and roll servo breakers. Without power to the servos the drag is very, very slight.

Does anyone know of a single axis autopilot capable of disengaging the servo when the

Go with the "Trio", You'll never know it's there! I just love mine, never a problem in 730 hrs of service.

Blowfly said:

Thankyou for the Trio EZ-Pilot suggestion Sam.

The Trio does look very good and appears to have many features including the clutch arrangement. I do like the simplisity of the Digitrak however, and its 2 1/4" format will save some space on my panel. I'm sure you are right about the residual servo drag feeling much worse when the ailerons are unloaded on the ground. I'll give it a bit more thought. Thanks again for your input.

Darren

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Not sure how you can get much simpler than pushing one button and the device is guiding your plane. That is all that is needed to activate the EZ-Pilot. But it also has a really complete feature set that allows you to do some cool stuff if you wish. I quickly got spoiled to the display which almost makes it unnecessary to even look at the GPS. But if you need the small format the DigiTrak will be a good option.

But I readily admit I'm biased, been flying Trio autopilots for nearly ten years, all the way from the earliest releases up to the Pro Pilot.

Just an FYI, but the Digitrak is no longer in production as of EXTREMELY recently. Parts supplies again. Fortunately this part is simply cosmetic (buttons of all things) so internal components are still readily available. We do have the Vizion 280 available as its replacement in the same 2 1/4" form factor. The Vizion series is currently in beta testing. We should have it ready to go within 4-6 weeks.

Sure wish there was an "AP101 Buyers Guide." I'm at the point of deciding to install an AP in my -4, and while I'll probably be going AFS or Dynon, I've looked over the Trutrak, EZ and Pro on Trio, and AP pages of AFS and Dynon and it's all a bit confusing. Just when I thought I decided what servo's to purchase, I found out that manufacture doesn't sell one of the two mounts needed for a -4. I'd like to do the 'add-on' servo's for the AFS or Dynon since the controls are integrated and eliminates another panel mount device, as well as removes some weight, but maybe I'm overlooking some advantages to having a stand-alone controller?

Master Designs said:

Sure wish there was an "AP101 Buyers Guide." I'm at the point of deciding to install an AP in my -4, and while I'll probably be going AFS or Dynon, I've looked over the Trutrak, EZ and Pro on Trio, and AP pages of AFS and Dynon and it's all a bit confusing. Just when I thought I decided what servo's to purchase, I found out that manufacture doesn't sell one of the two mounts needed for a -4. I'd like to do the 'add-on' servo's for the AFS or Dynon since the controls are integrated and eliminates another panel mount device, as well as removes some weight, but maybe I'm overlooking some advantages to having a stand-alone controller?

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We kinda, sorta do have an AP101 Buyers Guide. It is located in the VAF archives but it does require a bit of digging sometimes. But I think about all the questions have been asked and answered at some point. Toss your questions into the Search engine and see what pops out.....or ask us again.

Servo mounts are usually not very difficult to construct but see where you have purchased an RV-4 so this might be more intimidating than it would be for a builder. By the way, you may legally install the autopilot yourself but if you feel you need assistance, get an experienced RV builder to help.

Stand-alone vs integrated----really comes down to mission profile and personal comfort levels. Many IFR pilots want a device independent of the flight instruments, other IFR pilots want it integrated for ease of use. Really isn't a safety issue for VFR, just your preference.

Enjoy your new RV-4!

Master Designs said:

maybe I'm overlooking some advantages to having a stand-alone controller?

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If you are flying in IMC and your EFIS dies/malfunctions (risk is pretty low), what will your autopilot do?

A stand-alone head can keep you on course and wings level to give you think time to determine what are the next appropriate actions you need to take. The last thing you want to do at this point is to have to hand fly, troubleshoot, coordinate, communicate, keep the spouse calm, etc. Anything that can assist to minimize workload in this emergency situation is goodness.

I am not familar with the various failure modes of the integrated APs. I'm sure that Dynon or GRT would be more than happy to educated a perspective buyer.

If you are only going to fly VFR, it's probably not a big deal. I prefer to be more risk adverse in IMC.

bob

Smaller panel size TT vs larger Trio: I've flown behind both. If you can fit it, I like the Trio. Its larger size allows for more buttons and lights, less multiplexing of button functions. I think it's easier to use. This is important for me because I normally control it from the GRT efis. But if the efis dies I want to be able to use the autopilot in stand-alone fashion, and I want it to be as straight forward as possible, given the stress of having had the efis quit. This applies in IMC. As Bob said, if you only fly vfr and you have an efis, then that company's autopilot will be hard to beat cost wise. Of course you give up the redundancy, but vfr who cares?

Gotta ask yourself, why....

Blowfly said:

Does anyone know of a single axis autopilot capable of disengaging the servo when the autopilot is not active?

I am building an RV4 and was planning to use a Digitrak single axis autopilot, however I am somewhat concerned about having residual servo drag on the ailerons and none on the elevator. I do mostly local flying, basic aeros and wish to retain the light harmonised feel of the 4. The autopilot installation is primarily for safety reasons and to reduce workload on the occasional cross country flight (hence single axis only).

Thanks in advance for any suggestions or recommendations.

Darren

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Darren, my answer? NONE.

In the 10 years and 1300 hours I flew my RV4 I never once wished I had an autopilot. I wished more that I had paid even closer detail to weight savings as the lighter it is, the better it flies. Personally, the added weight, complexity and not to mention expense just isn't worth it IMHO...Besides, the cost alone will buy quite a bit of 100LL.
And I quote from my RV4 builders manual "Strive to keep your RV4 light, clean and simple, you will enjoy it much more, keep in mind it was designed as a Sport-plane first and foremost."

V/R
Smokey

smokyray said:

Darren, my answer? NONE.

In the 10 years and 1300 hours I flew my RV4 I never once wished I had an autopilot. I wished more that I had paid even closer detail to weight savings as the lighter it is, the better it flies. Personally, the added weight, complexity and not to mention expense just isn't worth it IMHO...Besides, the cost alone will buy quite a bit of 100LL.
And I quote from my RV4 builders manual "Strive to keep your RV4 light, clean and simple, you will enjoy it much more, keep in mind it was designed as a Sport-plane first and foremost."

V/R
Smokey

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Thank you all for the very useful advice and suggestions. Having access to such a well informed and generous network of pilots and builders is absolutely invaluable.....!

Cheers,

Darren

Mk-2Kne autopilot



- Steven
800+ RV3 hours
(four more last Sunday!)

FWIW. I had a two axis AP ITruTrak) in a Thorp, and found that I used the Altitude hold all the time, almost every flight, but rarely used the directional part (which controlled the ailerons and was tied into the panel mounted GPS). I was always deviating from the path shown on the GPS for one reason or another. So, IMHO if you only want one axis and want to simplify your flying, get the Alt hold rather than the directional. But I only fly VFR too...

Darren,
I'm in a similar boat as you. My annual is in Oct and it's time for me to install an autopilot when I've got everything apart. Here's my input after months of research; Your mileage may vary....
- 1st question: to EFIS or not to EFIS. If you've been planning on going glass panel, the incremental cost of adding autopilot servos to the Garmin or Dynon makes lots of sense. I don't have the time or money for glass, so I'm adding a stand-alone autopilot.
- VFR or IFR?: Costs have really been dropping on stand-alone autopilots; probably to compete with the EFIS add-ons. You can get a full-featured 2-axis for not much more than what a single axis cost 3 years ago.
..IFR- I plan on making my 6A an instrument platform, so I think the Trio Pro Pilot is probably the best Bang for your Buck on the market right now. $2800 for something that's very user friendly as a stand-alone display w/ altitude pre-select, climb/descent, backup battery. A $500 upgrade gives you GPS steering & vertical guidance. TruTrak has some great offerings, but... the sorcerer was out of my price range and the DigiFlight IIVSVG's future is bleak and is $4,600 vs the $3,300 for Pro Pilot. I've been waiting on the Gemini AP 780/880s to come out, but it's been years and not sure what the price point will be yet. And then time to work the bugs out... The Gemini's have huge potential.
...VFR-(single axis) I don't think you'll be able to beat the Trio EZ-pilot at $1650. Clutched servo, good interface, and can follow GPS as well as just level wings. (two axis). The TruTrak ADI PilotII would probably been the way I'd go if it had vertical steering. I like the idea of a backup attitude indicator, but just not enough features for me to put it in the IFR category. If you're just VFR and already have a AI, could be simple swap and maybe even save some weight.

So:
- Trio EZ-Pilot single-axis for $165
-- Trio Pro Pilot two-axis for $2800
---TruTrak ADI Pilot II two-axis & attitude indicator $3800.

After trips to the Outer Banks, Key West, and Austin Tx from ATL in the last year, an autopilot is going to make those 5-hour trips much more enjoyable for me!

Let me step back in and help unmuddy a couple things.

1) Our servos do have a little bit of residual torque. The residual is virtually imperceptible. However, there is no need to cut power to them to eliminate that. If residual torque increases when power is applied to the autopilot controller, there is most likely a wiring issue causing excessive residual torque.

2) The Digiflight II VSGV price is $3300. This doesn't include the hardware kits, but they are $75 each. It will be replaced with the Vizion 385 once the Vizion is out of beta testing and will cost the same.

I hope this helps!

Thanks Lucas for clarifying that residual torque on the Digitrak servo should be the same whether power is applied to the controller or not. I will certainly consider the single axis Vizion when it is released and also the more capable (albeit larger format) Trio EZ-Pilot. Thanks again to all of those above who have provided a wealth of information regarding the various autopilot systems and their particular features.

Cheers, Darren