Navigation
The MiG-21bis(b) in real life is equipped with equipment for navigation using internal systems, using NDB's, and using RSBN, which is similar to VOR's that was (and is) used in Russia. Due to a lack of RSBN stations in FlightGear, the MiG-21bis(b) being simulated can use VOR's.
The internal navigation system is a very simple system that uses airspeed and the heading on the gyro compass to calculate your position compared to a set destination.
The compass is driven by a gyro that can be slaved to a magnetic compass which is not displayed to the pilot. Before moving, press the FDS button to align the gyro to the magnetic compass. Be aware that deviations as of 30 degrees or larger are possible, especially if aligning the gyro while banking, climbing, or descending. Being 5 degrees off is quite within the realm of possibility.
To ensure the most stable gyro compass usage, be sure to set your latitude on the lower front panel.
developers note: the gyro compass is implemented using FG's property rules system, which may cause some issues with accuracy if frame rate is very low. this should be ported to use jsbsim instead, however this is low priority for me at this time.
All navigation display is shown on the compass on the front panel. The needle with large flags points either directly to the radio station, or to the setting of the internal navigation system.
All radios should be tuned before flight, using the in-sim F10 menu, under the MiG-21 submenu (NOT the Equipment->Radio menu). There are seperate dialogues for the comm radio, ADF radio, and VOR/ILS radio.
The internal navigation system uses indicated airspeed, air temperature, and bearing to triangulate your position.
On the left hand side of the cockpit is the radio used for VOR controls, and on the upper right hand of that are two switches labeled bearing and azimuth. These two switches control the system.
First ensure that the VOR system is not in use (neither green light should be illuminated) - preferably turn it off (coming soon) or tune it to an unused frequency.
Next, enter the desired azimuth using the azimuth switch, and observing the large flag on the compass.
Finally, enter the desired distance, observing the distance gauge near the gunsight on the upper front panel (you may need to either zoom out with 'x' or make some change, then rotate your view - I will keybind these switches in the future).
If you wish to enter your current position as the destination, simply reduce the distance to 0.
As you fly around, the azimuth and distance should continue to point towards that destination. It may be off due to errors in measuring your airspeed or the outside temperature, or due to compass drift.
developers note: this system is implemented using FG's property rules system, which may cause some issues with accuracy if frame rate is very low. this should be ported to use jsbsim instead, however this is low priority for me at this time.
Before flight, tune the radio channel presets via the dialogue in the F10 menu under the MiG-21 submenu. While in flight, ensure the RSBN/ARC switch on the left hand side of the cockpit is switched to ARC, and use the ADF panel on the right hand side of the cockpit to select which frequency to use. This panel has channels 1 through 9 available, and is located next to the comm radio which has a large orange knob in the shape of a cross.
Some airports use two NDB's in order to help aircraft align with the runway. If the INBOUND/OUTBOUND switch is set to OUTBOUND, the ADF radio will automatically switch to the closer NDB after crossing the outer NDB when flying towards a runway. The outer NDB should remain tuned. developers note: this is implemented wrong, and will be fixed in a future update. see this issue for more info.
To hear the ID of an NDB, switch the RSET/COMP switch located on the comm radio to COMP, and use the volume knob on the comm radio to set the volume.
Before flight, tune the radio channel presets via the dialogue in the F10 menu under the MiG-21 submenu.
While in flight, ensure that the NAVIG/PROCEED/LANDING switch on the left side of the gunsight is set to either NAVIG or PROCEED. Set the RSBN/ARC switch on the left side of the cockpit to RSBN. Set your VOR channel using the left knob on the VOR radio. If information is received from a ground radio station, the green lights on the radio will illuminate indicating whether bearing and/or distance information is being received. Note that this input overrides and overwrites the internal navigation system. If contact with a VOR is lost, the internal navigation system will still point towards that VOR, so be sure to use the green lights to make sure you are within range.
Using ILS is very similar. Ensure that the NAVIG/PROCEED/LANDING is set to LANDING, and select your ILS channel using the right nob on the VOR radio. ILS will illuminate the green lights, and override the internal navigation system, just like the VOR would.
Volume is controlled by the volume knob on the VOR radio panel.