Flying without an HSI
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Hey guys,
short question relating to this subject: When flying with RNAV or KLN-90B where are the heading info does come from respectively what will happen if the DG is continually loosing it's correct heading thru drift?
I think at least the RNAV system is relying on the DG.Regards,
Zacke -
Yes, that’s how it is with old school instruments. During my flight training a long time ago we didn’t even had a heading bug! But if you fly the Commander with a GPS (530, 750 etc) you can use the OBS to visualise the runway heading
@Downwind you mean by having the OBS being displayed as a track on the ND? Would be cool to have an HSI integrated. As far as I'm aware it's not.
Even though I appreciate the effort of all the avionics, having an option for a HSI in the suite would be very welcoming.
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@Downwind you mean by having the OBS being displayed as a track on the ND? Would be cool to have an HSI integrated. As far as I'm aware it's not.
Even though I appreciate the effort of all the avionics, having an option for a HSI in the suite would be very welcoming.
@Gatlingorange As an option it would be nice as long as the more or less original state of the aircraft is also kept. I love old school flying. But flying IFR nowadays is hardly possible without a GPS and a mode S transponder
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Hey guys,
short question relating to this subject: When flying with RNAV or KLN-90B where are the heading info does come from respectively what will happen if the DG is continually loosing it's correct heading thru drift?
I think at least the RNAV system is relying on the DG.Regards,
Zacke@Zacke As far as I understand it, the RNAV 511 doesn't actually know the aircrafts heading. It identifies the radial you are on using the phase difference between the VOR’s reference and variable signals. That phase difference tells the receiver your magnetic azimuth from the station, regardless of which direction the aircraft is facing. Think of it like a rotating lighthouse with a separate “north” flash: the lighthouse flashes in every direction when its beam points north, the beam then rotates clockwise, the receiver measures how long after the north flash the rotating beam reaches you, the time delay tells you your direction from the lighthouse. It then combines that radial with DME distance to determine your position relative to the VOR and calculate the bearing and distance to the entered waypoint...
Regarding the KLN-90B and other GPS units, they can only gather directional track information from movement. IRL on initial startup while stationary, depending on the unit and if the unit is in track up mode, it will either face aircraft north, or at it's last known track until movement is made and a track can be identified. The GPS satellites themselves provide the aircraft with position, groundspeed, and ground track, not aircraft heading. I haven't really paid attention to how/if different GPS units simulate this properly in the sim.
*Side note: Some GPS units can be equipped with external inputs connecting the unit to the aircraft’s heading system allowing for HDG up display (this would connect to an AHRS/ directional gyro/ etc...).
CPL MIFR 🍁
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@Zacke As far as I understand it, the RNAV 511 doesn't actually know the aircrafts heading. It identifies the radial you are on using the phase difference between the VOR’s reference and variable signals. That phase difference tells the receiver your magnetic azimuth from the station, regardless of which direction the aircraft is facing. Think of it like a rotating lighthouse with a separate “north” flash: the lighthouse flashes in every direction when its beam points north, the beam then rotates clockwise, the receiver measures how long after the north flash the rotating beam reaches you, the time delay tells you your direction from the lighthouse. It then combines that radial with DME distance to determine your position relative to the VOR and calculate the bearing and distance to the entered waypoint...
Regarding the KLN-90B and other GPS units, they can only gather directional track information from movement. IRL on initial startup while stationary, depending on the unit and if the unit is in track up mode, it will either face aircraft north, or at it's last known track until movement is made and a track can be identified. The GPS satellites themselves provide the aircraft with position, groundspeed, and ground track, not aircraft heading. I haven't really paid attention to how/if different GPS units simulate this properly in the sim.
*Side note: Some GPS units can be equipped with external inputs connecting the unit to the aircraft’s heading system allowing for HDG up display (this would connect to an AHRS/ directional gyro/ etc...).
@SadBucket All 100% true. I was waiting for someone to post an excellent explanation. It's a common misconception that a VOR receiver needs some knowledge of your orientation to produce what you see in the cockpit, but it's completely heading-agnostic.
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@Black-Square would you consider adding an optional HSI such as the KI 525A?
An HSI would absolutely make the Commander one of my fav Black Square aircraft. Sadly, it's been rusting in my virtual hangar since purchase. I simply cannot convince myself to fly it, so much so that I somewhat regret I purchased it.
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