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Turn Anticipation


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Skyview supports turn anticipation as part of it's Navigation software:

 

There are two types of leg transitions. A flyby leg transition causes the aircraft to fly by the 
leg’s destination waypoint in order to smoothly transition from one leg to the next with no 
overshoot. This is the default transition type for each leg. An overfly transition causes the 
aircraft to fly directly over the waypoint before transitioning to the next leg. The transition type 
can be selected for each individual waypoint transition in the Flight Plan.

 

 

GPS source can be any supported device.

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Just general information for those who are curious about the inner workings of turn anticipation and interoperability:

Navigation software is different than GPS positioning. They often come in the same package though. The problem we are seeing here with the "turn anticipation", is that the navigation software needs to support it. This is because we do not normally transmit all of the course information and waypoints between devices, therefore the trutrak autopilot only has limited data to work with. That said, if the navigation software waits until after you have passed over the waypoint before providing new course and position information, the TruTrak will have to compensate to get you back on the course line.

Since the 496 outputs position information as well, you could use a separate navigation package, such as the skyview system, to receive said position information and instead use it's own internal nav software to manage the flight plan.

I am reading conflicting information about the 496, supposedly it does begin transmitting new course information 30 seconds before waypoint arrival. I am looking for more data, will edit in a moment.

 

EDIT: I cannot find a setting for it. There's a setting for automotive, but I don't know if aviation mode also has such a beast.

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Just general information for those who are curious about the inner workings of turn anticipation and interoperability:

 

Navigation software is different than GPS positioning. They often come in the same package though. The problem we are seeing here with the "turn anticipation", is that the navigation software needs to support it. This is because we do not normally transmit all of the course information and waypoints between devices, therefore the trutrak autopilot only has limited data to work with. That said, if the navigation software waits until after you have passed over the waypoint before providing new course and position information, the TruTrak will have to compensate to get you back on the course line.

 

Since the 496 outputs position information as well, you could use a separate navigation package, such as the skyview system, to receive said position information and instead use it's own internal nav software to manage the flight plan.

 

I am reading conflicting information about the 496, supposedly it does begin transmitting new course information 30 seconds before waypoint arrival. I am looking for more data, will edit in a moment.

 

Appreciated.  Thank you.

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I scanned the manual for the 496 and at first glance could find no reference.

 

The 430/Avidyne/STEC combo in my Cirrus did it automatically, and it seemed like magic to me.

 

Remember, for many of us for decades you could not begin a turn until station passage regardless - you had to wait for the To/From to flip or the ADF needle to swing around. Then again, most airways are designed so you stay within them waiting for station passage to begin the turn at our speed.

 

As a personal note, it never occurred to me that I was missing anything when my 496 doesn't lead turns. Most of my on course turns are shallow enough that it makes little difference, unless I'm just going direct - which I very often am!

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Of course the Dynon can source GPS from other GPS devices, but FD offers Garmin, and the Garmin 796 is the source for the current product. The Skyview can also source navigation from a NAV radio. 

 

Don't see a 'turn anticipation' term in any of the documentation, can you docuement, page and paragraph where that is?

 

The autopilot can be set to limit the 'G' force limit, air speed limits, CWS for manual override to save the servos.

 

There is an 'expert' config mode which lets you manually set the Roll Axis, Pitch Axis or LEVEL buttom which forces level flight.

 

But I dont see the 'turn anticipation' you mentioned or how that differes from the config settings mentioned in the documents below:

 

Dynon's description of the navigation software package: http://dynonavionics.com/docs/SkyView_NavMapping.html..

 

You can also search the Dynon forum and support answered the question as well.

 

Search for "leg transition" in http://www.dynonavionics.com/downloads/User_Manuals/SkyView_Pilots_User_Guide-Rev_P_Software_v7.1.pdf for the previous quote.

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S3flyer, thank you, I checked and found on page 69 or page 74 (depends on the manual revision that you have) of the GPSMAP 496 manual for "Leg Transition", there is a distance setting and a manual override.

 

EDIT: Cancel that, that's the automotive function. Still might be worth a look in the route options though on your device in aviation mode, they might have something!

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From the User Guide as your link provided:

 

There are two types of leg transitions. A flyby leg transition causes the aircraft to fly by the

leg’s destination waypoint in order to smoothly transition from one leg to the next with no

overshoot. This is the default transition type for each leg.  An overfly transition causes the

aircraft to fly directly over the waypoint before transitioning to the next leg. The transition type

can be selected for each individual waypoint transition in the Flight Plan

 

----------------------------------------------------------------------------------------------

 

How does the above description accomplish a 'turn anticipation' as you imply?  The autopilot flys to the waypoint as I pointed out earlier.  The default is to 'fly by the leg's destination waypoint' and make a turn as necessary. 

 

Unless you use the Dynon flight plan capability, you cannot get the second one - the overfly transition option. 

 

No one uses the Dynon flight plan capability because its incredibly tedious to enter and is not as sophisticated as the Garmin flight plan software.  The Garmin flight plan is sourced by the Dynon autopilot just as the Dynon HSI is sourcing the Garmin GPS signal.

 

Sigh.  The "fly by the leg's destination waypoint" IS turn anticipation.  Note the definition of the word 'by':

 

 
by1  [bahy]  Show IPA
preposition
1.
near to or next to: a home by a lake.

 

 
 
Dynon's software calculates a route that flys 'near or next to' the waypoint to minimize the overshoot.
 
Overfly mode is where the route goes to the waypoint, then turns to the new route.  Large direction changes may cause the AP to overshoot the route and induce a correction or two.
 
Neither of these modes is available if you are using an external device for your flight plans.  You would be using the modes available to the particular device.
 
I do agree that Garmin's flight planning is easier to enter than Skyview.  But I'm aware of many pilot who do use the Dynon flight planning especially since some don't have an external gps.  They have to limp by on 2 10" Skyviews with integrated everything :)
 
 
 
 
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Anticipating the waypoint and turning to cut the corner, known as the "commercial turn" would be a nice to have feature, but not really an issue.

I find the autopilot quite clever at regaining the desired track after a change of heading at a waypoint.

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You are correct that the Dynon autopilot does not anticipate a turn. This type of functionality is done in the navigation software. The 796 and the other Garmin portables do not do this computation (as per Garmin Team X). Dynon's Skyview navigation software does anticipate the turn. Some may want this feature despite a different and/or more difficult user interface presented by Skyview.

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