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jmbaute
12-04-2007, 03:11 PM
I've never had the luxury of flying a plane with an autopilot. My old Mooney has a 'wing leveler', which has never worked. On my recent flight from Atlanta to San Antonio, about 13 hours round trip, I sure thought a lot about how I'd have an autopilot in my RV. I find the info on the various manufacturer's web sites helpful, but I still have questions about what these things can do, particularly when it comes to instrument flying (the ink on my instrument ticket is still wet). So, I thought I'd throw out some general questions as to how these are used...I'm not looking for answers on what the best manufacturer is, mainly how an autopilot can help reduce fatigue and make for a safer flight, so, if you will indulge me:

1. I've heard that you should turn them off in turbulence and hand fly. True or False? Seems to me that the processor can react much faster to upsets than I could. I would also think that the servos would have some sort of clutch that would prevent control surface damage?

2. How well does the altitude hold function work when you are flying in & out of clouds? I find that hand flying it takes some work to stay where you're supposed to.

3. How are these things typically used when flying approaches? I assume (?) you could use it to track a localizer in to the runway. What do you do when it is time to descend? If you push the stick forward to start down at the FAF, will the device disengage, leaving you in 'manual pilot' mode for the rest of the approach? If so, is that really an issue?

4. Same question as above, but for a precision approach like an ILS, can a 2 axis device keep you on the glideslope or is that just fantasy on my part?

I'd also be interested to learn how most of you use them to make your flight safer/more enjoyable. Others out there with similar questions, please chime in, I'd like to learn as much as I can from those who know about these things, to help frame my future purchase of an autopilot.

scard
12-04-2007, 04:56 PM
my Reference is my TruTrak DFII VSGV with about 100hrs so far:

1. It does much better in turbulence than I do. I've never had to disconnect it when it gets bumpy.

2. Holds well within the instrument resolution :).

3. Can either fly a vertical profile, vertical speed, airspeed decent, or whatever you want.

4. Not fantasy at all. I get a real kick watching mine fly right down the ILS or WAAS GPS approach vertical profile.

It seems that a lot of people really scoff at the idea of an A/P in an RV, but they can scoff all they want. I really enjoy letting the computer do some of the work when things get busy. I use mine all the time.

videobobk
12-04-2007, 04:57 PM
Not an expert here, but I'll give it a shot.

1. You are right about the clutch. Usually the only time I get a "clutch slipping" warning is when I try to hand fly while the AP is on. I do believe my AP does better than I can hand fly. I haven't turned it off for turbulence yet.

2. As near as I can tell, my alt hold can't see any clouds. It just holds altitude, plus or minus about 20'. 'Course I don't know for sure, not having that instrument ticket yet.

3. Here is where different models may differ. With mine, I watch for the descent point (intercepting the GS) and dial in the descent rate it gives me, normally in the 400-500 fpm range. It just tracks right on in, normally with no further effort on my part.

4. Actually, all I am flying are GPS approaches, but from what little I have done, it has to be a BUNCH easier than chasing a needle. It is obvious you still have to scan and correct, but I have been able to do practice approaches with only the throttle and/or a reset of descent rate.

The RV (mine is a 9A) is an easy plane to fly, but there are times when a little help goes a long way. I wouldn't part with AP/alt hold. You may find that the "best" AP is whatever the respondent owns as it seems everyone is happy with their system. I have a Trio AP and Alt Hold II (added descent rate, etc.) I believe it was the best bang for the buck. YMMV.

Bob Kelly

tc1234c
12-04-2007, 05:30 PM
I agree with what Scott and Bob said. I have almost the same setup as Scott. I did several IFR flights through clouds. All but one using AP. The one without AP (returned for service) was tasking when I was in the cloud and had to do descending turns while chatting with approach. All three of us are flying 9A, an easier IFR platform than other RVs. With AP on, I have the time to check the chart, set the radio and monitoring the progress.

For my setup, the GRT EFIS has synthetic approach (SA). When doing GPS approach (mine is non-WAAS), EFIS can provide guidance to fly the plane down the SA glide slope. Of course no obstacle avoidance guaranteed.

LifeofReiley
12-04-2007, 05:35 PM
I went with the ADI Pilot 1 from Tru-Trak. Nice and simple, oh did I mention cost effective too! :eek:

roadrunner20
12-04-2007, 06:37 PM
[QUOTE=jmbaute;177039]I've never had the luxury of flying a plane with an autopilot.

1. I've heard that you should turn them off in turbulence and hand fly. True or False? Seems to me that the processor can react much faster to upsets than I could. I would also think that the servos would have some sort of clutch that would prevent control surface damage?

QUOTE]

I have a newly installed single axis autopilot(EZ-Pilot).
I never flew with one previously and have about 15 hours on it.
On my first few flights, I was very cautious as I went throught the eval process.

In turbulence, it flys my 7A much better than I do.
My wife confirmed it last weekend when she experienced the engaged AP
for the first time while in turbulance.
She likes the AP better than me.

n468ac
12-04-2007, 08:19 PM
1. I've heard that you should turn them off in turbulence and hand fly. True or False? Seems to me that the processor can react much faster to upsets than I could. I would also think that the servos would have some sort of clutch that would prevent control surface damage?

--> False for cruse and climb ... but true in turbulence during the decent, at lease when i try to make a nice 500 fpm decent in turbulence the autopilot will hunt for the 500 fpm mark, much easier and smoother to hand fly the plane.

2. How well does the altitude hold function work when you are flying in & out of clouds? I find that hand flying it takes some work to stay where you're supposed to.

--> auto doesn't care what it looks out side, it will stay within 20 feet of altitude and 2 deg of heading ... but will care if the pilot or static gets clogged.

3. How are these things typically used when flying approaches? I assume (?) you could use it to track a localizer in to the runway. What do you do when it is time to descend? If you push the stick forward to start down at the FAF, will the device disengage, leaving you in 'manual pilot' mode for the rest of the approach? If so, is that really an issue?

--> Don't fly IFR couldn't comment.

4. Same question as above, but for a precision approach like an ILS, can a 2 axis device keep you on the glideslope or is that just fantasy on my part?

--> Don't fly IFT couldn't comment.

I'd also be interested to learn how most of you use them to make your flight safer/more enjoyable. Others out there with similar questions, please chime in, I'd like to learn as much as I can from those who know about these things, to help frame my future purchase of an autopilot

--> It's really the only way to travel cross country in an RV ... you can read the map, plan you route around weather, and read a book (only kidding) and the plane keeps on track. Flying an RV for 2 or 3 hours at a time by hand can really wear you out.

FredMagare
12-05-2007, 09:14 AM
This is a link to S-Tec/Meggitt's website pamphlet on autopilots and workload which is worth reading:

http://www.s-tec.com/pdf/AutoPilotBook.pdf

IMO, with all the units available out there at very affordable prices, there's really no reason anyone should be without an autopilot.

(not really in line with the thread but worth reading.)

jmbaute
12-05-2007, 10:06 AM
Thanks to everyone who has replied. I have learned a lot.

Another few questions:

In looking at the TruTrak and Trio sites, it seems these autopilots are GPS only. So, how would one track a localizer? Dial in the magnetic heading to fly?

Am I correct that the 'glideslope' is flown just by dialing in a descent rate, and that the device isn't really tracking the needle? (Maybe not true for the GRT system?)

tc1234c
12-05-2007, 10:30 AM
John,

You need a Nav radio (Garmin SL30) that feeds the localizer and GS to an EFIS then to the AP (at least that is what in my setup). When you intercept the localizer, just switch the navigation source from GPS to Nav. I am not sure about how one does it with other setup. Basically, you don't have to dial in the heading and VS.

scottg
12-05-2007, 03:48 PM
Thanks to everyone who has replied. I have learned a lot.

Another few questions:

In looking at the TruTrak and Trio sites, it seems these autopilots are GPS only. So, how would one track a localizer? Dial in the magnetic heading to fly?

Am I correct that the 'glideslope' is flown just by dialing in a descent rate, and that the device isn't really tracking the needle? (Maybe not true for the GRT system?)


This reply is based on the Trio and Tru-Trak a/p's. The Navaid will track a loc very well, but I doubt the Navaid is getting many new installations.

You get to choose what functions you want. The a/p can be as simple as a wing-leveler that holds a ground track / course or as fancy as one that has every function imaginable. The Tru-Trak VSVG when properly coupled to a Grand Rapids EFIS and WAAS GPS (430/530/480) can perform altitude pre-select, alt hold, VS hold, Airspeed hold in climb and descent, heading hold, fly holding patterns, perform turn anticiaption, fly a procedure turn, perform a heading select to loc intercept/ GS capture, fly the ILS and then hit a button, advance the throttle and the AP will start the beginnings of a missed approach. It will also couple for an LVP approach.

Like anything else in aviation, you define the mission, determine how much you're willing to spend and that will dictate the final A/P.

Personally, I fly IFR with a NavAid A/P coupled to either a Garmin 296 or VOR/LOC of an SL-30 and Altrak for altitude hold. I don't have the VS option for the Altrak, but may add it this winter. I'll hand fly to/from altitude and use the A/P enroute. During a re-route in the climb/descent, the NavAid is engaged and the aircraft trimmed for pitch. Works well.

roadrunner20
12-05-2007, 06:45 PM
Thanks to everyone who has replied. I have learned a lot.

Another few questions:

In looking at the TruTrak and Trio sites, it seems these autopilots are GPS only. So, how would one track a localizer? Dial in the magnetic heading to fly?

Am I correct that the 'glideslope' is flown just by dialing in a descent rate, and that the device isn't really tracking the needle? (Maybe not true for the GRT system?)

On my unit, it tracks a magnetic heading when the gps is not available.
A left/right toggle switch alows you to tweak heading.

It also has an emergency 180 reverse course engage if the event you enter IMC.

Bevan
12-05-2007, 07:45 PM
Dan, Is it the Trio that will do a 180 course reversal just by pushing a button? How is it done on a TruTrak?

Bevan
12-05-2007, 07:50 PM
Will the EFIS Sport control an AP the same as the Horizon version? In other words, will the EFIS sport control the AP including VS, ILS, GPS "steering" (anticipate waypoint turns without overshooting)? If not, could I use a select switch to allow one of the GPS's (say 396) to directly feed data to the autopilot?

Bevan