Couple comments and a question or two from an RV-6/D100/D10A/AP-74/SV-32/G396/SL-40 user.
I concur with the thoughts on the AP-74. It makes setting the heading bug, the altitude bug and the altimeter very quick and easy. You can do it with the EFIS, but once you have the AP-74, you'll really like it for those selections. Selecting, preselecting, or changing AP modes is also very nice with the AP-74. It provides so much functionality in such a small package, its hard to beat (till the AP-76 comes along, eh Brian!
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The TRK mode simply holds the airplane on the current GPS track...in other words the track across the ground as calculated by the GPS. It will change heading to correct for wind to maintain that track (and that track is typically displayed at the top of the GPS azimuth arc...looks like a heading, but its the GPS track). In TRK, that track is independent and irrespective of any GPS waypoints or flight plan you have in the GPS...i.e., it does this with or without a magenta line on the GPS, and it doesn't follow the magenta line...it keeps the track across the ground the same. (I proably beat that up a bit.
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Quick question Barry, why do you use TRK to go around the cloud, versus HDG? Not a hit, just wondering...new techniques are always good to learn!
The NAV mode tracks the magenta line (GPS NAV flight plan from waypoint to waypoint). It makes heading changes to stay on the line. And the X96 does work just the way Barry described it with his Lowrance, and via serial.
I have found my Dynon AP to overshoot initially when capturing a Go To waypoint, but it settles down after a little bracketing. When following a flight plan, it flies over each waypoint, overshoots a bit when getting on the next leg, but also settles in after a little bracketing. Its not too bad, but not quite full-on GPSS, which leads the turns, rather than fly over each waypoint (I thought that was in a recent firmware update, but not sure...thoughts Brian...is that an AP-76 thing too?) But overall, it works fine for basic X-C nav.
I have an SL-40 versus an SL-30, but am considering the upgrade, so I can file /A and shoot the occasional ILS/VOR/LOC approach if needed to bust out of or into a docile marine layer (my personal need/limitation). I won't fly approaches with the 396, due to the legalities (of course), but also because it drops the NAV data about 500-600 feet above the last waypoint, when it pops up the message "Approaching VNAV Waypoint". Don't want my Nav Source going stupid as I approach mins, so I just don't want to go there. Hopefully my conservative flight planning and go/no-go criterion will keep me out of a position where I need to drop through clouds using a VFR GPS...very much an emergency situation in my book.
What Brian said about the HS-34 and being able to display both GPS (magenta) and VOR/ILS (green) data on the HSI is true...and tempting if I do the upgrade! But I was under the impression that if you want to switch between GPS and VOR/ILS (without the HS-34), you just need a toggle to switch the serial feed to the EFIS between the two sources. Is there also a need to go to the menus and switch the NAV Source, or is that an alternate method to do the same thing? Thanks!
Its a great package from Dynon though...great stuff!
Cheers,
Bob