Radio Magnetic Indicator
I am planning to build RMI(Radio Magnetic Indicator). I am starting by researching the documentation and understanding its functions.
VOR indicates the direction of an aircraft as an angle to magnetic north as seen from a radio beacon station.
VHF Omnidirectional Range (VOR)
Setting
I've tried looking at the settings available in Mobiflight from the FSUIPC list.The RMI pointer needs the relative angle to the compass, so the following might be useful:
・0x0C56 NAV1: relative bearing to VOR1, in degrees (0–359)
・0x0C6A ADF1: relative bearing to NDB ( *360/65536 for degrees, –ve left, +ve right)
NDB (non-directional beacon) is a medium wave non-directional radio beacon, the direction is detected by ADF.
I heard that VOR stations also transmit their station names in Morse code, but I wonder if it's possible to set it up so that I can hear the morse IDcode sound. I've practiced telegraphy with my radio operator license, so it would be fun to hear it. RMI Structure
I need to put three stepping motors on the same axis. The Altimeter had two motors, but I will use spur gears to transmit the movement of the three motors to the offset axis in the same way. In order to make the axis spacing 15mm, the gear ratio does not have to be 1:1, but it should be possible to adjust it in the Mobiflight settings. The motor axis spacing will be 14~15mm. I will combine two gears to connect this spacing. I chose two pairs of 0.7 module spur gears that we had on hand.
Also, with this arrangement of three motors, the protruding parts will not fit through the holes in the panel when installing. I plan to separate the panel surface and the motor part and assemble them from the front and back.
The gear axis and motor axis will be in a straight line, but with my machining precision it is very difficult to align three axes at the same time. Therefore, the connection point with the motor axis will transmit rotation to the gear axis via a simple universal joint. The connection is made with a 1.2mm brass rod, and the structure does not get in the way of disassembly and assembly. Step motors have a lot of torque and do not rotate very fast, so this mechanism works.
To control three motors, 4x3=12 Arduino output terminals are required. Therefore, Arduino MEGA2560 no.1 will use the terminals for two old Toque motors that are no longer needed. In addition, MEGA2560 no.2 has many spare terminals, so I plan to connect another stepping motor there. There are also spare terminals for the motor driver ULN2003 here.
VOR station
Some VOR stations have disappeared, and their frequencies and IDs have changed. This list is based on data from the Ministry of Land, Infrastructure, Transport and Tourism in 2003, with subsequent revisions.However, there is another issue: what point in time the VOR station data is reflected in MSFS2020.
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