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L-39 and RSBN


Frag

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Hi guys,

 

I am interested in night/bad weather navigation without cheating and there is something that I can't figure out.

 

First here is how I set the RSBN, for example, at Krymsk (see attached picture), the navigation channel is 28 and the landing one is 26.

 

- So I set RSBN to ON on the electrical panel

- Set Channel 28 on RSBN for navigation channel

- Set Channel 26 on RSBN for landing channel

- Both light are turning green on the panel which is a good sign.

- The distance on the gauge under the RMI seems good.

 

If I follow the RSBN needle in the RMI, it always brings me directly to the center of the airport. I would be under the impression that it should bring me to the location at the entry on the "glide down path", where the channel 26 is.

 

I watched few tutorial on youtube, but they did not give any details about the external channel and the internal one. I am missing something. Is there a full tutorial very well explained somewhere? Even though I select, NAV, GlidePath, or LANDING. That RMI always point right center of the airport, which lead me right over it, but not in the correct descend path.

 

Also keep in mind that in my example I am coming fully perpendicular to the airfield at 90 degrees (at around 50 km)... with no clue where I am (full cloud and darkness). So if I follow the RMI, I am ending up crossing the runway at a 90 degrees angle.

rsbn.thumb.JPG.8f26807d46b3e82dc8fbf820df6d95ef.JPG


Edited by Frag
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The L-39 RSBN/PRMG system is similar to TACAN/ILS, except radials and bearings are aligned with True North.

RSBN Glide Slope mode

Is a 'penetration' mode used to descend from altitude to 500m @ approx 20km from the RSBN beacon, the NPP(HSI) deviation bars show deviation from the RSBN radial set by the course knob and vertical deviation from an 'electronic' glide slope generated from RSBN distance and the airfield QFE set on the RSBN Field Elevation gauge.

RSBN Nav mode

Is the basic RSBN navigation mode. The NPP(HSI) course needle sets the required radial, the NPP(HSI) vertical bar show deviation from the radial/course or when it is intercepted and the range indicator distance in km.

In bad weather you'd set the PRMG runway approach heading (i.e. Krymsk RWY 22 = 220°) and fly using the NPP(HSI), range indicator and course deviation to intercept the PRGM (ILS) signal.

RSBN Landing mode (PRMG(ILS) mode).

NPP(HSI) K and L flags clear if receiving valid PRMG signals - deviation bars now show deviation from the PRMG localizer and glide slope and the RSBN range indicator gives DME.

Landing in poor weather, inner and outer marker frequencies would also be set to give fixed ground references i.e. no lower than 200m prior to the outer marker (1m20s to touchdown), 70m at the inner marker, etc.

This is a self made chart for Krymsk, though I mostly fly non-precision NDB approaches these days due to the lack of Georgian RSBN/PRMG's

4_Krymsk Arrival RWY 22.jpg

The attached track is a rather poor RSBN/PRMG Krymsk landing but may be helpful none the less.

Note: Creating your own missions in 2.5, you need to use 0m/s or +4m/s headwinds to be sure that ATC and PRMG/NDB's are active for the same runway, otherwise results may vary.

L-39 PRGM Landing Krymsk.trk


Edited by Ramsay
Fix broken diagram link
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@SL PAK

 

I'm sure the OP appreciates all help and guidance to using the RSBN and PRMG system to it's fullest.

 

Turning on the SDU flight director helps fine tune the PRMG approach, provided you allow for the ADI needles increasing sensitivity as you get closer.

 

However, I didn't feel covering the SDU would help answer the OP's original question.

 

I watched few tutorial on youtube, but they did not give any details about the external channel and the internal one. I am missing something. Is there a full tutorial very well explained somewhere? Even though I select, NAV, GlidePath, or LANDING. That RMI always point right center of the airport, which lead me right over it, but not in the correct descend path.

 

As you might guess, I hardly ever use the SDU myself as I fly to 200ft-3/4nm minimums in DCS.


Edited by Ramsay

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Video demonstrating the above Approach chart and goes with the updated track file.

 

 

That demo is awesome Ramsay!!! Thank you very much to take the time to do this! Following your steps to A to Z made me realize that I was following and using the equipment correctly, but my technique was lacking.

 

I initially thought that at some point, the equipment would lead me directly to the entrance of the glide path (like 20 km away) but it is not the case. I understood it while looking at your video when you decided to let pass the airfield at your 9 O'clock, to fly perpendicularly to it (almost) ... then followed the instrument to roll in at the good moment.

 

The video resolved my issue. Thanks a LOT.

 

Maybe one last question if I may ... did you notice that the elevation bar between the RMI and the SDU are rarely agreeing on the elevation to keep? I noticed that you followed the one from the SDU so I am ok with this ... but just in case that I am missing something.

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  • 3 years later...
7 hours ago, Heyjax said:

Awesome.  I'll have to watch it a couple dozen times to get it though.  Thanks.

I've updated the link to the accompanying Krymsk diagram (must have broken when the forums were upgraded).

4_Krymsk Arrival RWY 22.jpg

Mission Briefing

Spoiler

Inbound to Krymsk from Smolenkaya NDB at 3000m with sunset approaching.

Fog 2km visibility should give visual on runway by decision height

Mission Editor headings = L-39 True  headings

-----------------------------

Approaching Krymsk (heading 284°T for 44km)
=============================
RSBN On and Tuned (Nav 28 / Land 26)
*RMI Course 284°
*Check Audio ID, Set RSBN volume
*Outer 408 kHz
*Inner  803 kHz

Tune Radio to Channel 18
Contact Krymsk, Arrival, Inbound
*Set Altimeter to QFE 768.2
*Set RSBN-5  Altimeter to QFE 768.2
*Radar ALT warning 200m

*if req'ed RSBN to GLIDE SLOPE (penetration) mode
to descend to 500m @20 km
--------------------------------------------
KRYMSK ARRIVAL + LANDING
==================
At 24km from Krymsk RSBN KW, turn RIGHT
Descend/maintain 500m AGL altitude
*Switch RSBN to Navigation mode
Maintain DME 20km
*Set RMI course to RWY 220°
When RSBN KW is at 230°
turn LEFT to landing course 220°T
*Switch RSBN-5 to Landing mode if required
---------------------------------------
RWY 22, STANDARD RIGHT HAND PATTERN

You may land visually on first approach.
Final Approach Fix is 10km/500m from RSBN
FAF., DME 10km KW

OR

In bad weather,
Initial Approach Fix is Outer Marker
IAF is LOM KW, 408.0kHz
Turn RIGHT to 40°T
3 min/ DME 18km KW
Turn RIGHT to 220°T onto Final
*Switch RSBN-5 to Landing mode if required

------------------------------
MISSED APPROACH
1. Climb to 200m
2. Turn RIGHT to 40°T
3. Continue climb to 500m
4. Rejoin Pattern

Note: In 2.5, use 0m/s or +3m/s headwind to be certain PRMG and NDB's match ATC's chosen runway.

Unfortunately the 2.5.3 track file doesn't playback correctly all the way to the landing and the weather/lighting is a little different in DCS 2.7.10 but you should be able to hit "ESC" and "take control" none the less.


Edited by Ramsay
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