F28 RMI - Selecting between VOR & ADF
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@dbw I have just tested this on my end and it seems to be working as expected. It's not the most intuitive system, but the position of the four-position rotary at the top left of each RMI determines what Navaid each needle points to. The way the RMI has been coded is:
- With VOR text reading the correct way up, the single needle will point to VOR1, and the double needle will point to VOR2.
- With ADF text reading the correct way up, the single needle will point to ADF1, and the double needle will point to ADF2.
- With the VOR text aligned with the single arrow, and the ADF text aligned with the double arrow, the single arrow needle will display the direction to the tuned VOR1 and the double arrow needle will display the direction to the tuned ADF1.
- With the ADF text aligned with the single arrow, and the VOR text aligned with the double arrow, the single arrow needle will display the direction to the tuned ADF1 and the double arrow needle will display the direction to the tuned VOR1.
The above is correct for the captain's RMI. The first officer's RMI will use the same logic, but will instead display ADF2/VOR2.
Hope that helps.
Mark - Just Flight
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Hi Mark,
At the risk of slightly hijacking the thread; I wasn't aware of this combined VOR/ADF ability on the RMI (I just thought it was both needles showing VOR or both showing ADF, and the intermediate positions on the rotary knob just didn't do anything). It will certainly be handy in the future!
But having just done a quick test flight, it doesn't quite work as you laid out above. With different stations tuned to each VOR and each ADF, I found the following:
With VOR text the right way up, the single needle indicates VOR1 and the double needle indicates VOR2 (as expected). Same for the ADFs when the ADF label is the right way up.
But when the VOR is at the single arrow and the ADF is at the double arrow, I get VOR1 and ADF2.
When the ADF is at the single arrow and the VOR is at the double arrow, I get ADF1 and VOR2.
That applies to both Captain and FO's side. The arrow label seems to be effectively a roman numeral, indication which station of the relevant type will be indicated.
On a related matter, is it possible to get confirmation on the function of the purple bug(s) on the HSI? The yellow arrow is obviously the course indicator/deviation bar, and the orange bug is the set AP heading. The purple ones (two bugs at 180 degrees to each other) aren't mentioned in the manual but seem to be a sort of integral RMI, pointing the direct course to whichever VOR is selected on the Remote Datum Selector (as opposed to the selected course). But they don't always seem to work that way, even when the VOR is selected and indicating on the RMI.
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@GroverJ41 Thanks for the clarification! The RMI turned into quite a headache during development and we had so little reference material regarding what each switch position stood for. Our coders must have found some reference material in the end to simulate the current logic.
With regards to the purple bug on the HSI, it will point directly to the active Navaid. So if you have a VOR tuned into the VHF NAV radios they will indicate the direction of the VOR. If you have a flight plan entered into the GPS, they will indicate the direction of the next waypoint.
Mark - Just Flight
