Copilot Course and Heading Bug Knob Behavior

[sardilli]

I recently noticed a possible bug related to the copilot HSI. Upon initial load of the aircraft, the copilot HSI course knob only changes the digital course readout on the HSI but the CDI needle itself is stuck and does not move. This can be rectified on the Glass and GNS versions by cycling the CDI of #2 Garmin 430 to GPS and back to VLOC which then causes the needle to move with the knob. In the OEM version, the needle is permanently stuck. Would it be possible to fix this in the next version?

Also, regarding the heading bug knob, the pilot's heading bug knob will move the heading bug on both the pilot and co-pilot's HSI but the knob on the copilot HSI does not appear to function. I'm not sure if the real aircraft has synchronized or independent heading bugs but it's certainly convenient to have them synchronized for sim purposes. Would it be possible to have the co-pilot's heading bug knob move the heading bug on both sides as well for times when the user is flying from the right seat?

Thanks in advance, I'm really enjoying flying this aircraft.

[tkyler]

On 9/23/2022 at 9:32 AM, sardilli said:

Also, regarding the heading bug knob, the pilot's heading bug knob will move the heading bug on both the pilot and co-pilot's HSI but the knob on the copilot HSI does not appear to function

This is by design.  HDG isn't one of those modes that couples to any 1/2 configuration, so they're sync'd.   As far as the copilot knob not being able adjust the HDG, that too was simply a design choice to avoid possible confusion that the pilot/copilot HDG adjustments were indendent of one another, but simple enough to implement...certainly for any shared cockpit functionality it would be necessary.

Also, I'll peek at the copilot HSI course indicator / CDI issue.

TK

[sardilli]

Sounds good, thank you sir.

[sardilli]

Hello, updates for the copilot HSI course knob look great on the GNS and OEM versions for both 4 and 5 blade versions of the plane.

There seem to be some inconsistencies on the 4 and 5 blade GLASS versions that perhaps could be considered for the next update.

On the 4 blade GLASS version, when the #2 GNS430 CDI mode is in VOR/LOC everything works perfectly (course needle moves and digital readout changes to match). When the CDI of the #2 GNS430 is changed to GPS mode, the needle correctly slews to the DTK however the digital course readout does not update to match and the digital course readout continues to update with knob movements vs. being locked to the GPS DTK.

On the 5 blade glass version the digital course readout is completely blank.

Thanks again for a great update, great to have Reality XP GTN available in the aircraft.

[tkyler]

thx.  issue logged.

-TK

[tkyler]

On 10/3/2022 at 11:45 AM, sardilli said:

There seem to be some inconsistencies on the 4 and 5 blade GLASS versions that perhaps could be considered for the next update.

On the 4 blade GLASS version, when the #2 GNS430 CDI mode is in VOR/LOC everything works perfectly (course needle moves and digital readout changes to match). When the CDI of the #2 GNS430 is changed to GPS mode, the needle correctly slews to the DTK however the digital course readout does not update to match and the digital course readout continues to update with knob movements vs. being locked to the GPS DTK.

@sardilli  hopefully I'm interpreting your concern correctly...if not I apologize for the lengthy post and we can keep working through it if need be.

First, a bit of nomenclature clarification going forward so we're on the same page.....we have the "course selector indicator/needle (I'll call it the CSI)" and the "CDI", which is the "deviation bar" that is (somewhat) slaved to the CSI mechanics.  The LED window shows the numerical value of the CSI setting.

When in VOR/LOC mode, the CDI becomes active when receiving a valid terrestrial nav signal and indicates deviation from said radial. With no valid signal, it will align with the CSI.  The course selector, being relevant for intercept purposes, primes the circuitry for intercept in the intended direction and the course LED value simply regurgitates the needle CSI setting.

When in GPS mode, the XTK error from the GPS path is known by the GPS and a 'proxy/emulation deviation signal' is then fed to the HSI's CDI circuit for display on the HSI.  The HSI doesn't know its getting a signal from the GPS, the GPS is simply "talking the language of the HSI".   This is a feature of the Garmin units...having the ability to send analog signals and 'talk to' these older nav displays, because the GNS units came out at a time when these analog instruments were ubiquitous and used as primary navigation instruments (vs Glass).    When using the GPSS mode,  the CSI serves no purpose for GPS DTK tracking, but is still required for intercepting a VOR/LOC while in GPSS mode (HDG mode really).. ..so you don't want it showing DTK information in GPSS mode as you need to know the CSI setting for intercepts.    So the LED value never slaves to the GPS DTK value, it.....it simply provides a numerical representation of the CSI setting.

-tkyler

 

[sardilli]

@tkyler Thanks for your message. Since the HSI on the MU2 copilot's side is mechanical, I assumed that the CSI automatically slewing to the GPS Desired Track (DTK) value would cause the CSI knob to physically move and the digital readout to match. It sounds like I made an incorrect assumption.

Since I made the original post, I have started flying a Piper Arrow IRL that has a Century mechanical HSI connected to a Garmin 430. In that airplane, the 430 has no ability to physically move the CSI needle and knob, the pilot has to manually set the CSI to match the GPS desired track.

It sounds like the MU2 must have some kind of servo or stepper motor that physically moves the CSI needle but is somehow not connected to the CSI knob. Otherwise how would the pilot be able to spin the knob and change the digital readout without the CSI needle physically moving.

Thanks in advance! Curious to know which of these methods is implemented in the real MU2.

[tkyler]

51 minutes ago, sardilli said:

It sounds like the MU2 must have some kind of servo or stepper motor that physically moves the CSI needle

I believe (speculating) the CSI knob employs a "light friction clutch".  See the following video:  Keep on eye on the copilot HSI in the very bottom right corner of the video when he connects bus power.  

You'll note both the CSI knob AND compass card move together when initially powered, but once the compass card synchronizes and stabilizes with the flux compass signal , the CSI knob then will not turn the compass card, only the CSI needle.  This is the reason you use the +/-  switch to adjust the HSI compass card when not operating in 'slaved' mode.   There is no servo mechanism to adjust the CSI needle that I'm aware of on this HSI, it has to be moved with manual input.  

 

[sardilli]

Thanks for the video. That makes total sense and it definitely appears to be some kind of clutch.

I guess the only remaining issue is that the LED windows showing the numerical value of the CSI setting and DME distance are extremely dim on the 5 blade glass version even with all of the interior lighting on full brightness.

Similarly, the 4 blade glass version shows normal brightness for the CSI setting but extremely dim for the DME distance, again with the interior lighting on full brightness Screenshots attached.

Do you still plan to update the transponder and stopwatch/chrono resolution in a future version?

 

Thanks!