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View Full Version : Autopilots: Navaid vs new generation


Vern
01-13-2005, 11:10 AM
Would some who have flown RV's with the Navaid and are now using one of the more modern single/dual axis autopilots care to comment on how the new ones compare? Comments appreciated,as I'm looking for a recommendation for my 6A. Thanks!

Sam Buchanan
01-13-2005, 11:29 AM
Vern, I have some comments posted on my site about my experiences with the Navaid and the EZ-Pilot:

http://home.hiwaay.net/~sbuc/journal/EZ_Pilot.htm

Bottom line, the new, digital units are far more capable than the Navaid. Yes, the Navaid can keep you on track, but the new designs do it much more reliably and offer many features lacking on the Navaid.

Sam Buchanan

rv7boy
01-13-2005, 11:39 AM
Vern,
If you have a Navaid already installed, then the previous reply is appropriate. But if you are considering a new installation, you should check out the thread entitled "auto pilot" in the RV-7/7A forum of this site. Martin Sutter's input is especially worth reading.
Don Hull

Sam Buchanan
01-13-2005, 01:29 PM
Well, I thought is was an appropriate reply for somebody considering a new installation,too. <grin>

Trio offers a new Navaid servo to builders who are installing from scratch. Even though the venerable Navaid servo is analog, it seems to have an excellent field history and has worked perfectly on my RV-6 for over 600 hours. TruTrak also has a version of their fine unit that will drive a Navaid servo for those who want to upgrade. Both the EZ-Pilot and DigiTrak are very capable units that operate much more precisely than the Navaid.

I am also a satisfied TruTrak customer since I fly their terrific AlTrak altitude hold. However, the EZ-Pilot as features that no other sub-$2000 autopilot can match. The user and installation manuals can be downloaded from the respective websites so additional research can be conducted.

The chief software/hardware guy at Trio, Chuck, has extensive background in military GPS missile guidance and I have found the Trio bunch to support their system very enthusiastically. The one time I called for info on the AlTrak resulted in good support as well.

We are fortunate to have access to some really cool technology for our planes, and no doubt even more impressive stuff is in the future.

Sam Buchanan

gmcjetpilot
01-13-2005, 05:33 PM
No debate that the new autopilots have more capability than the Navaid and are digital vs analog, but why do the digital autopilots need a GPS signal to keep the wings level?

The Navaid does NOT req a GPS signal to work. It has the classic small spinning mass, driven by an electric motor, to provide the "gyroscopic platform." The new Gen electronic platforms have some need to resolve their "attitude" by getting GPS ground track, as I understand it. :confused:

What if the GPS signal is lost? I realize these are VFR/experimental autopilots and gps is very reliable. What is the opinion of those in the know?

I know some EFIS do use GPS to resolve a solution to display attitude while other EFIS do not. I have a Navaid and wounder if the digital autopilots will improve so they can independently operate from the GPS.

Any comments, or insight? :o

Thanks G RV-4, RV-7

Sam Buchanan
01-13-2005, 07:43 PM
[QUOTE=gmcjetpilot]No debate that the new autopilots have more capability than the Navaid and are digital vs analog, but why do the digital autopilots need a GPS signal to keep the wings level?

The Navaid does NOT req a GPS signal to work. It has the classic small spinning mass, driven by an electric motor, to provide the "gyroscopic platform." The new Gen electronic platforms have some need to resolve their "attitude" by getting GPS ground track, as I understand it. :confused:

What if the GPS signal is lost? I realize these are VFR/experimental autopilots and gps is very reliable. What is the opinion of those in the know?

I know some EFIS do use GPS to resolve a solution to display attitude while other EFIS do not. I have a Navaid and wounder if the digital autopilots will improve so they can independently operate from the GPS.

Any comments, or insight? :o

=============================================

The digital autopilots have good performance for a reasonable period of time without GPS input. Your question is valid and is one I had great interest in when I first started foolin' around with solid state EFIS's and autopilots. When the DigiTrak first hit the market, I had an extended email discourse with one of TruTrak's engineers about this very matter. And one of the first tests I posed to my new EZ-Pilot was to force it to fly without GPS. The results of that test are here:

http://home.hiwaay.net/~sbuc/journal/EZ_Pilot.htm

Since that original test, the EZ-Pilot has been enhanced with new sensor orientation and new software to make the unit even more stable without GPS input. The unit should be able to keep the plane upright for quite an extended period of time, the exact amount I don't know. Even when the unit starts to satuarate, it won't go belly up, it just starts to slowly drift off course. The trim switch can be used to "educate" the platform and correct for the drift.

Yes, the Navaid doesn't require GPS. But providing GPS data to the new units allows them to have features that were never possible with the mechanical Navaid. I am comfortable with the digital devices because of the reliability of GPS and the satisfactory non-GPS performance they deliver.

The idea of depending on GPS for an EFIS's AHRS platform is more controversial. Those who go to the bank with GPS's reliability are ok with basing the AHRS on a system that needs GPS for full functionality. Personally, I would prefer the AHRS be autonomous, and no doubt this is the way of the future. Like the autopilots, many of the new, inexpensive (!?!) EFII will continue to function with loss of GPS, but not at full speed.

That is why there is still a place for backups!

Sam Buchanan (RV-6, Dynon, EZ-Pilot, AlTrak, uEncoder, AnyWhereMap, Lowrance and Garmin GPS's.......and a sectional!)

yellowrv1
01-23-2005, 06:30 PM
Vern, We have had the Trio EZ pilot for about a year now. It worked sporadically with the Lowrance AirMap 300, but works quite well now with the Garmin 296(Won't update unless something quits working !!!see GPS forum). All of our questions have been answered by the inventors..sic. Sorta like Vans was 12 years ago ! E-mail us if you want me to fly over from Thomaston and We'll let you monkey with it for a while. We have found it useful and relaible. We have had no experience with other units like Sam and Mike S. have. One good thing about the new EZ units is the built in slip indicator which is not on our early unit, but then a friend reminded me that's what my *** is for !


Rick Raines N329RP 6A