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  #1  
Old 10-10-2019, 11:03 AM
Mitch757 Mitch757 is offline
 
Join Date: Aug 2005
Location: Falmouth, MA
Posts: 296
Default Safe-Fly GPS and Echo UAT

I have an RV which has a Trutrak Gemini autopilot and GRT Efis that gets GPS position from a Garmin 496.

I'd like to get rid of the Garmin and use the Safe-Fly GPS as a position source for both but can't determine for sure that the Trutrak will work with that configuration.

Has anyone used the Safe-Fly as a position source for the Trutrak AP?

Thanks for the help.

Mitch Garner
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  #2  
Old 10-10-2019, 10:46 PM
Lars Lars is offline
 
Join Date: Nov 2005
Location: Davis, CA
Posts: 1,100
Default

Quote:
Originally Posted by Mitch757 View Post
I have an RV which has a Trutrak Gemini autopilot and GRT Efis that gets GPS position from a Garmin 496.

I'd like to get rid of the Garmin and use the Safe-Fly GPS as a position source for both but can't determine for sure that the Trutrak will work with that configuration.

Has anyone used the Safe-Fly as a position source for the Trutrak AP?

Thanks for the help.

Mitch Garner
It'll work. Feed the GPS RS232 out line (don't recall the pin on the SafeFly offhand) to both. Which GRT EFIS model do you have? It matters in terms of configuration of the SafeFly.
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  #3  
Old 10-11-2019, 05:36 AM
Mitch757 Mitch757 is offline
 
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Thanks Lars,

I have the older Horizon WX in the plane.

Mitch
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  #4  
Old 10-11-2019, 07:09 AM
hevansrv7a's Avatar
hevansrv7a hevansrv7a is offline
 
Join Date: Jul 2005
Location: Detroit, MI
Posts: 1,585
Default It will not be legal for IFR

It's an in-between approval. Better than "var" such as a 496 but not legal for IFR. It does emit the standard (NMEA?) strings and can serve as a second GPS on the GRT stuff. Or that's what they told me, anyhow.
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  #5  
Old 10-11-2019, 08:48 AM
Canadian_JOY Canadian_JOY is offline
 
Join Date: Aug 2007
Location: Ontario, Canada
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Default

Let's see if we can get a more refined response to this question...

From an equipment standpoint, the TruTrak Gemini has the capacity to do both GPS NAV mode (via RS232 interface - does not do turn anticipation) and GPSS (via ARINC 429 interface - provides turn anticipation). If the OP's EFIS has an ARINC 429 interface module, the EFIS is capable of providing GPSS commands to the Gemini Autopilot. If the OP's EFIS does not contain the ARINC 429 interface module then the EFIS will output GPS Nav data to the Gemini Autopilot.

To be clear, the GRT Safe-Fly GPS is a position sensor. It provides position and rate data ONLY. It needs another box (like the EFIS) to do the actual computational work of navigation. That other box has to have a database of waypoints (NAV Database) to use in these computations.

In short, the Safe-Fly only knows the current "I am HERE" position and the "I sense I am moving in that direction" velocity information. The EFIS gets this "I am HERE" information and, through pilot input, is told "I want to go THERE". The EFIS does all the calculations necessary to provide a steering solution to get from HERE to THERE - that's how we get the magic magenta line.

The EFIS then spits this navigation solution out its digital interfaces to the Gemini autopilot which, in turn, drives the airplane down the magenta line.


1) VFR Use: The combination of the GRT EFIS NAV database and the Safe-Fly position data will allow a pilot to conduct autopilot-controlled flight from waypoint to waypoint. Depending on whether or not an ARINC 429 interface module is present, this navigation may take place with or without turn anticipation. With ARINC 429 interface the autopilot will also provide vertical guidance.

2) IFR Use: In this case, the situation is very much as noted for VFR, except that one needs to have new enough hardware to run the GRT IFR software, and one needs to pay to have that functionality enabled. One also needs to have all the necessary IFR databases loaded. In this situation the combination of Safe-Fly GPS and EFIS are acting like a GPS navigator (GNS, GTN, IFD navigator). This mode of operation should also enable the aircraft to fly coupled approaches if an ARINC 429 interface is available from the EFIS.

I won't comment on the legality or advisability of using the EFIS/Safe-Fly/IFR Database combination in IFR flight - that's up to the aircraft owner/operator to make that call.
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  #6  
Old Yesterday, 10:24 AM
Lars Lars is offline
 
Join Date: Nov 2005
Location: Davis, CA
Posts: 1,100
Default

Quote:
Originally Posted by Canadian_JOY View Post
Let's see if we can get a more refined response to this question...

From an equipment standpoint, the TruTrak Gemini has the capacity to do both GPS NAV mode (via RS232 interface - does not do turn anticipation) and GPSS (via ARINC 429 interface - provides turn anticipation). If the OP's EFIS has an ARINC 429 interface module, the EFIS is capable of providing GPSS commands to the Gemini Autopilot. If the OP's EFIS does not contain the ARINC 429 interface module then the EFIS will output GPS Nav data to the Gemini Autopilot.

To be clear, the GRT Safe-Fly GPS is a position sensor. It provides position and rate data ONLY. It needs another box (like the EFIS) to do the actual computational work of navigation. That other box has to have a database of waypoints (NAV Database) to use in these computations.

In short, the Safe-Fly only knows the current "I am HERE" position and the "I sense I am moving in that direction" velocity information. The EFIS gets this "I am HERE" information and, through pilot input, is told "I want to go THERE". The EFIS does all the calculations necessary to provide a steering solution to get from HERE to THERE - that's how we get the magic magenta line.

The EFIS then spits this navigation solution out its digital interfaces to the Gemini autopilot which, in turn, drives the airplane down the magenta line.


1) VFR Use: The combination of the GRT EFIS NAV database and the Safe-Fly position data will allow a pilot to conduct autopilot-controlled flight from waypoint to waypoint. Depending on whether or not an ARINC 429 interface module is present, this navigation may take place with or without turn anticipation. With ARINC 429 interface the autopilot will also provide vertical guidance.

2) IFR Use: In this case, the situation is very much as noted for VFR, except that one needs to have new enough hardware to run the GRT IFR software, and one needs to pay to have that functionality enabled. One also needs to have all the necessary IFR databases loaded. In this situation the combination of Safe-Fly GPS and EFIS are acting like a GPS navigator (GNS, GTN, IFD navigator). This mode of operation should also enable the aircraft to fly coupled approaches if an ARINC 429 interface is available from the EFIS.

I won't comment on the legality or advisability of using the EFIS/Safe-Fly/IFR Database combination in IFR flight - that's up to the aircraft owner/operator to make that call.
What he said.. ^^^ too much to write when typing on my teeny iPhone screen.

Adding a little bit of detail, if you want the SafeFly to supply information to the TruTrak, it needs to happen via an RS232 line from the EFIS. If you have an ARINC429 module on the EFIS, so much the better, for reasons described above. The only gotcha there is if the EFIS doesn't have enough serial ports available for that.

A couple of asides...

I upgraded to an HXr display earlier this year, which gets GPS info from a SafeFly module that I had installed previously. I paid for the IFR approach database upgrade and bought the Seattle Avionics approach plate database. It's impressive, though as pointed out, legality is something the pilot has to call. Note that unlike with the WS, the HXr can configure the SafeFly directly via an RS232 connection.

And.. I installed a Garmin 430W in an RV-6 earlier this year that already had a TruTrak Gemini autopilot installed. The owner wanted the turn anticipation and vertical guidance that could be provided with ARINC429 information, so I connected that along with an RS232 line, both coming (obviously) from the 430W. Mysteriously, when the 430W booted, it would crash the autopilot. We tried every fix imaginable, including the obvious tracing wires, tried a different 430W, sent the unit back to TruTrak, etc. In the end it turned out to be a bug in how the autopilot handled the ARINC429 data from the 430W, which TruTrak acknowledged. They were very good to deal with on the issue, but it was confounding and frustrating before we finally got it figured out.
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  #7  
Old Yesterday, 11:35 AM
Mitch757 Mitch757 is offline
 
Join Date: Aug 2005
Location: Falmouth, MA
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Thanks Lars,

I'm just trying to keep it as simple as it is right now: 496 sends position to Trutrak and WS efis. I don't want all the other "features" with this unit. (( purchased the plane wired this way, so I'm a little bit in the dark on the wiring.)

Just trying to find out just how and if the Safe-Fly can provide the same position info to both units....

The Trutrak docs mentions that it needs 4800 baud serial input. Is this possible coming from the Safe-Fly?

Thanks,

Mitch
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  #8  
Old Today, 10:19 AM
Lars Lars is offline
 
Join Date: Nov 2005
Location: Davis, CA
Posts: 1,100
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Quote:
Originally Posted by Mitch757 View Post
Thanks Lars,

I'm just trying to keep it as simple as it is right now: 496 sends position to Trutrak and WS efis. I don't want all the other "features" with this unit. (( purchased the plane wired this way, so I'm a little bit in the dark on the wiring.)

Just trying to find out just how and if the Safe-Fly can provide the same position info to both units....

The Trutrak docs mentions that it needs 4800 baud serial input. Is this possible coming from the Safe-Fly?

Thanks,

Mitch
Understand simple. As Mark described above, the SafeFly is only a position source. It can't feed the TruTrak directly. The position data has to be processed somehow; the WS can do that.

There is a bit of wiring work (power & ground for the SafeFly, 2 serial wires between SafeFly and WS, one serial wire from WS to TruTrak) and some configuration settings to adjust in the WS, but it will do exactly what you want. Some of the wiring already in place can probably be re-purposed. And yes, the TruTrak will get data at 4800 baud, though it will be coming from the WS, not the SafeFly.

Happy to do my best to describe in additional detail what is required. If you want clarification, send me a PM and I'll provide my email and phone. Feel free to contact me.
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