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  #1  
Old 03-11-2020, 12:59 PM
psalys psalys is offline
 
Join Date: May 2017
Location: Eugene
Posts: 36
Default VNAV to the runway with Dynon Skyview HDX

I have an RV-12iS and the VNAV function on the Dynon autopilot does not fly me to the runway. It works fine to fly to the airport but when I put a runway as the final destination with a threshold height of 20 feet, it flies me to the middle of the the airport at about 1000 AGL. Am I doing something wrong?

Thanks
Patrick
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  #2  
Old 03-11-2020, 02:13 PM
skydiverlv skydiverlv is offline
 
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Are you selecting a runway? ie: 18,36, or whatever your runway .
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  #3  
Old 03-11-2020, 03:05 PM
Jpm757 Jpm757 is offline
 
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Check to see where the "minimums" altitude bug is set.
The autopilot will not descend below that setting.
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  #4  
Old 03-11-2020, 03:17 PM
Bob Y Bob Y is offline
 
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See pages 5-45 through 5-47 of the SkyView HDX Pilot’s User Guide and be sure you have the height above the runway value set low enough too.
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  #5  
Old 03-11-2020, 09:31 PM
RFSchaller RFSchaller is offline
 
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Location: Phoenix, AZ
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I don’t know about Dynon, but Garmin causes the GPS DERIVED glide path marker to disappear at about 3/4 mile on final to keep users from flying faux glide slopes. Might be a similar function on Dynon.
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  #6  
Old 03-12-2020, 09:08 AM
psalys psalys is offline
 
Join Date: May 2017
Location: Eugene
Posts: 36
Default Thanks for the comments

1. Yes, I have been selecting a runway.

2. When I push the VNAV button on the autopilot, an altitude of about 1000 AGL appears. I thought that was the problem so I tried turning it down to ground level but the autopilot still levels out high as if it is ignoring that change.

3. Yes, I am putting a low altitude in the setting, 20 ft at 0 miles from the theshold.

4. I wonder if this is some sort of safeguard to prevent us from flying glide paths to the runway but if so, why wouldn’t Dynon tell us about this limitation. As it is, this function is useless.

Thanks
Patrick
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  #7  
Old 03-12-2020, 10:01 AM
DHeal DHeal is offline
 
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Location: Windsor, California
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On my Skyview Classic (as I recall) there are two VNAV functions you can use -- have you appropriately preprogrammed these two functions?

One function can be programmed to take you to a point in space that is located at a user-specified distance and altitude above the published CENTER of the selected airport. I set my criteria for this function to 1,000' Above Airport Elevation and 3 nm from the airport's CENTER point -- this gives me a target point for entering a typical traffic pattern and also gives me the remaining distance and a Rate of Descent appropriate to reach that point from my current cruising altitude.

The second function can be programmed to simulate a precision approach to a selected runway end at a selected airport (sort of an ersatz-ILS). For this function (I may be a bit fuzzy here since I did this set-up a few years ago), you need to generically preprogram the distance from the runway threshold, the height above the runway threshold, and the angle of the desired approach. To simulate a typical ILS I defined a point 1/2 mile short of the threshold and 200' above the threshold elevation with a 3-degree approach slope.

The precise programming details can be found in the Skyview documents.
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Last edited by DHeal : 03-12-2020 at 10:04 AM.
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  #8  
Old 03-12-2020, 10:10 AM
PhatRV PhatRV is offline
 
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I am planning to use the Dynon HDX panel too.

Does the HDX require an approved GPS ILS such as Garmin 430 or other GTN to provide a VNAV guidance?

Or does it have VNAV built-in the HDX by default?

Thanks in advance
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  #9  
Old 03-12-2020, 10:43 AM
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Carl Froehlich Carl Froehlich is offline
 
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Quote:
Originally Posted by PhatRV View Post
I am planning to use the Dynon HDX panel too.

Does the HDX require an approved GPS ILS such as Garmin 430 or other GTN to provide a VNAV guidance?

Or does it have VNAV built-in the HDX by default?

Thanks in advance
I have a dual HDX install in the RV-8, and have been flying IFR behind SkyView displays for several years. While the HDX can be manipulated to simulate VNAV for an IFR approach, I recommend not doing it. Considering this is not approved for IFR flight, there is no practical reason for this - and may provide a false sense of security about “if I really had do an VNAV landing I could”. Banking on a non-tested or limited tested capability when you are in extremis is how people end up being the subject of NTSB reports.

To answer the above question, the HDX will fly an ILS or VP GPS approach using VNAV just fine - but you need an approved navigator. For ILS this could be and SL-30 or similar, for GPS you need a WAAS GPS navigator, like the 430W or GTN-650.

Carl
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