GSA28/GMC305 vs Vizion 385 w/G3x Touch

This is a bit of a two-parter, probably for a combination of the g3xpert gang, and Lucas @ Trutrak. Assume I am designing a G3X Touch with a GTN connected by ARINC.

1) If I had a Vizion 385, I know the G3X Touch can connect to and do the typical syncing of autopilot functions. Do the new on-screen autopilot control buttons in the G3X Touch also work in this case, or are those controls solely meant for when being used with the GSA28 servos? I'd rather not touch the Vizion control head except in an emergency, which leads to the next part...

2) If I used the GSA28 with the GMC 305 control head, I know the vast majority of the time I can use the G3X Touch's on-screen buttons and such. Now, if the G3X Touch goes on vacation, I still have GPS Steering to drive the servos from the GPS flight plan, and could probably do a whole coupled RNAV approach. But unlike the Vizion's control head, there's no way on the GMC 305 control head to input a heading select or altitude select if the G3X Touch is inop, correct?

I'm thinking of a really-bad scenario where I'm on a GPS flight plan, the G3X Touch goes inop, but ATC gives me a vector or altitude off-plan for a while.

Thanks for the input!

sbalmos said:

This is a bit of a two-parter, probably for a combination of the g3xpert gang, and Lucas @ Trutrak. Assume I am designing a G3X Touch with a GTN connected by ARINC.
Thanks for the input!

Click to expand...

Hello Scott,

If I had a Vizion 385, I know the G3X Touch can connect to and do the typical syncing of autopilot functions. Do the new on-screen autopilot control buttons in the G3X Touch also work in this case, or are those controls solely meant for when being used with the GSA28 servos? I'd rather not touch the Vizion control head except in an emergency, which leads to the next part...

Click to expand...

Yes, the touch screen autopilot control page provided on the G3X Touch display also works to control the TT GX Pilot, and we assume the Vizion 385. It would be unusual to ever have to use the Vizion control head.

2) If I used the GSA28 with the GMC 305 control head, I know the vast majority of the time I can use the G3X Touch's on-screen buttons and such. Now, if the G3X Touch goes on vacation, I still have GPS Steering to drive the servos from the GPS flight plan, and could probably do a whole coupled RNAV approach. But unlike the Vizion's control head, there's no way on the GMC 305 control head to input a heading select or altitude select if the G3X Touch is inop, correct? I'm thinking of a really-bad scenario where I'm on a GPS flight plan, the G3X Touch goes inop, but ATC gives me a vector or altitude off-plan for a while.

Click to expand...

If you have a single G3X Touch display, and your display becomes unavailable, you may press the GMC 305 AP button to engage the autopilot, and then press the ALT button to engage altitude hold. Now sit back and think about what you will do next while the autopilot flies your plane straight and holds altitude.

If you were to lose your only display in IMC conditions, you would probably reach up and push the LVL button because that engages the autopilot and restores straight and level flight (bank angle = 0, vertical speed = 0). Following that action to restore a stable aircraft, you would probably push the ALT button to capture and hold the present altitude.

Remember that the GSA 28 servos are able to use 1 to 3 installed ADAHRS units even with no displays operational, so the servos always know the aircraft attitude even if you don't.

Should you receive a new heading vector from ATC, just press the CWS button, use your backup compass or other instrument to turn the plane to a new heading, and then release the CWS button to return control of the autopilot to fly the plane in that new direction. You could also push the AP button to disconnect the autopilot, turn the plane to a new heading, then press the AP button to re-engage the autopilot.

If you need to climb or descend to a new altitude, use the CWS button to hand fly the plane to a new pitch attitude, then release the CWS button and use your backup instrument to know when the new altitude is reached and then just push the ALT button to capture that new altitude.

While losing even one display is very improbable, if it is your only display and you have a GMC 305 autopilot control panel, you can still engage and use the autopilot in many ways. We are pretty confident that if you install the GMC 305, you will find that it is the very best user interface for the autopilot.

Let us know if you have additional questions.

Thanks,
Steve

Another thing to consider:
I had my G3X Touch connected to a Digiflight II VSVG for the first 20 hrs or so after a panel upgrade.
The issue I continually had was that when you hit A/P disconnect, then the A/P disengages and is no longer in EFIS mode.
So when you re-engage the autopilot via the screen or the GMC305, nothing happens until you turn the A/P back into EFIS mode. This 2 button process to re-engage the autopilot through 2 bits of equipment became annoying enough that I installed 2 GSA28's. Im very happy now.
Im not sure whether the Vision or GX pilot has the capability to remain in "EFIS" mode or whatever after you have hit the CWS or disconnect.
Cheers
Richard

Richard Connell said:

Another thing to consider:
I had my G3X Touch connected to a Digiflight II VSVG for the first 20 hrs or so after a panel upgrade.
The issue I continually had was that when you hit A/P disconnect, then the A/P disengages and is no longer in EFIS mode.
So when you re-engage the autopilot via the screen or the GMC305, nothing happens until you turn the A/P back into EFIS mode. This 2 button process to re-engage the autopilot through 2 bits of equipment became annoying enough that I installed 2 GSA28's. Im very happy now.
Im not sure whether the Vision or GX pilot has the capability to remain in "EFIS" mode or whatever after you have hit the CWS or disconnect.
Cheers
Richard

Click to expand...

This isn't the case with the Vizion. The Digiflight II doesn't communicate bi-directionally with the G3X, the Vizion does. So simply pressing any of the autopilot functions on the G3X display or GMC305 will automatically put the Vizion into "EFIS" mode, regardless of the Vizion's current state.

Essentially, you get the benefit of an integrated system but you retain redundancy as the autopilot can fly the airplane without any input at all from any of the G3X components. For every day operation, the Vizion control head would never need to be touched beyond the initial setup and tuning. The Vizion also has its own level button that works independently from any EFIS commands.

Just a reminder, we are currently offering a special on the Vizion! I hope this helps!

Thanks Steve and Lucas. Mainly because I've already run out of buttons on my control stick, on paper, I'm thinking of maybe having an on/off toggle switch with indicator light on the instrument panel for CWS mode. In theory that would work since CWS is only engaged while the button is depressed - it's not a press-on-press-off.

I'm removing autotrim (both have it, whether directly in-servo or via add-on box) and direct AHRS communication (only matters when doing emergency LVL from an unusual attitude / bank / etc - and Vizion handles that case also) from the equation for now.

Seeing as both autopilots are, from what I can tell, feature parity, it comes down now to servo design - whether I care about the GSA28's clutch vs Trutrak's standard shear pin format.

Question for Lucas or others - Reading the manual, I'm guessing Vizion's altimeter does not continue to sync to the EFIS after the initial at-power-up setting? I don't think this is enough of a problem, since altimeter settings usually only vary a few points during a normal trip. Maybe I'm just barking up a pointless tree there.

sbalmos said:

Thanks Steve and Lucas. Mainly because I've already run out of buttons on my control stick, on paper, I'm thinking of maybe having an on/off toggle switch with indicator light on the instrument panel for CWS mode. In theory that would work since CWS is only engaged while the button is depressed - it's not a press-on-press-off.

I'm removing autotrim (both have it, whether directly in-servo or via add-on box) and direct AHRS communication (only matters when doing emergency LVL from an unusual attitude / bank / etc - and Vizion handles that case also) from the equation for now.

Seeing as both autopilots are, from what I can tell, feature parity, it comes down now to servo design - whether I care about the GSA28's clutch vs Trutrak's standard shear pin format.

Question for Lucas or others - Reading the manual, I'm guessing Vizion's altimeter does not continue to sync to the EFIS after the initial at-power-up setting? I don't think this is enough of a problem, since altimeter settings usually only vary a few points during a normal trip. Maybe I'm just barking up a pointless tree there.

Click to expand...

You're correct on the CWS, sort of. A toggle switch will give you access to the CWS mode just fine, however it'll be cumbersome for use as the disconnect for the autopilot. The CWS switch of the Vizion serves both purposes.

The Vizion's altimeter will continually stay synced to that of the G3X. So with a G3X in the loop, you won't need to even do that. If the serial output from the G3X disappears, you can set the altimeter in the Vizion manually.

OH! Okay, I wasn't reading the operating manual carefully enough. Actually, that's exactly what I was hoping to do - a combined AP disconnect / CWS button on the stick, depending on whether it was a momentary or held contact. That floated in my head after a while to using a switch on the panel. But it's unnecessary.

And I somewhat figured that an altimeter sync happened. Maybe put a revision to the Operating Manual that notes that if you're connected to an EFIS, the altimeter sync is automatic?

That's a good point, I'll notate that for the next manual rev. It doesn't sync with all EFIS units though, just a heads up. At least not that I know of. It'll work with the G3X and it will sync to the G900X. As for the other ones I can't comment as I just don't know. Other EFIS's CAN sync with it, if the data is there and in the same format. I'm happy to look into that for anyone needing the info.

Okay, hopefully last comparison. Is it possible to get the Vizion to run a Flight Director indicator on the G3X without the GMC 305? Or would I have to combine the two, a Vizion and GMC head, to get that possibility?

sbalmos said:

Okay, hopefully last comparison. Is it possible to get the Vizion to run a Flight Director indicator on the G3X without the GMC 305? Or would I have to combine the two, a Vizion and GMC head, to get that possibility?

Click to expand...

Hello Scott,

The Vizion follows pitch, roll, and vertical speed commands from the G3X system and doesn't provide flight director functions when following the G3X, but this may not be the question.

If you are asking if you may use the G3X Touch independent flight director feature by pressing the FD button on either the GMC 305 or the G3X Touch display autopilot control page, even when a Vizion is installed, then the answer is yes.

G3X Touch Autopilot Control Page

G3X Autopilot Servos and GMC 305

Again, just let us know if you have additional questions.

Thanks,
Steve

The Vizion does not provide a flight director output.

Yup, saw that Lucas. That's okay. According to Steve there, the flight director is handled by the G3X Touch screen itself. I guess the fact that the GMC 305 has flight director functionality also is because the "legacy" G3X doesn't have FD capability on its own? No matter, regardless, for my purposes.

If I'm thinking this correctly, the TO/GA capability is also handled directly by the G3X Touch screen itself, independent of the GMC 305 or Vizion. I'm mildly humored that it uses a discrete input line through the engine sensor module, but hey...

Lots to chew on and debate in my head this week.

Lucus,

Just a little clarification on the current Vision deal. Is it only for the 2-1/4" package or can I get the rectangular package for the same deal?

rapid_ascent said:

Lucus,

Just a little clarification on the current Vision deal. Is it only for the 2-1/4" package or can I get the rectangular package for the same deal?

Click to expand...

The $1800 is for the round 2 1/4". If you want the flat pack the deal is $1900, the flat pack costs a little more to build. Let me know!