Doppler query

Hi I want to use the Doppler to follow my own waypoints. I can see how to get from the start to the first waypoint - but how do I get to the remaining waypoints? Chucks guide only mentions what it can be used for & DCS does not even mention it at all. A guide please! Thanks. ChrisJD

When you arrive to the first waypoint, you have to setup again the doppler navigation system to go to the next waypoint, and so on.

It can manage one destination only at a time.

There are youtube videos detailing the use of the doppler navigation. It will only tell you where you are reference to the point you activated the doppler system, nothing more, nothing less. It can't tell you where to fly to for a waypoint, just the next waypoint but setting that is manual labour and will need to be redone everytime you change course to the next waypoint.

I thought that would be the case. Thanks for your help Will look for a youtube video as suggested ChrisJD

I'm going to go into depth with a different technique (apologies if it's too off topic), but to answer your question, the most efficient way to navigate by waypoints is to turn off, then set up the ДИСС-15 for the next leg of the route as soon as your current waypoint comes into sight. That way, you can simply push the ВКЛ button as you overfly the waypoint and immediately start heading towards the next one.

I'll assume you're already familiar with the basic operation of the ДИСС-15, but if not, here is one excellent resource:

http://www.mudspike.com/how-to-use-the-doppler-navigator-in-dcs-mi-8mtv2/

I want to focus on the "GRID" method described in that guide, because it has the advantage of allowing one to arbitrarily determine their location even if they aren't following a particular course. This makes it very useful for combat, reconnaissance, and generally any situation in which you may not be following a predetermined route or may heavily deviate from it. Also, the ДИСС-15 can be left alone after takeoff (unless using a fixpoint). My method uses a slight alteration, though: course angle is set to true north rather than magnetic north to allow easy use with the F10 map. This lets the ДИСС-15 be used much like an INS.

Before that, I want to quickly discuss magnetic bearings in DCS. As you know, all navigation using the Mi-8 is done relative to magnetic bearings, which requires knowledge of the local magnetic declination of the area if you want any significant accuracy. Contrary to the Caucasus approach plates which all claim a local declination of 6° (for 2010, no less!), DCS actually features a detailed implementation of the World Magnetic Model to simulate magnetic variation; the coefficient files can be found at DCS\Data\MagVar\COF. Demonstrated here courtesy of the A-10's CDU:

As mentioned in the linked guide, this unfortunately seems to be the easiest way to get the declination of a specific area (obviously a problem for those without the A-10). Also shown in the linked guide is a declination map, the latest of which may be obtained here:

https://www.ngdc.noaa.gov/geomag/WMM/data/WMM2015/WMM2015_D_MERC.pdf

There's two problems with this, however: the map isn't very precise, and the data is only for 2015 and later. Even the calculator shown in the above image is only designed to work with the 2015 data. I haven't found a simple method of getting precise declination figures without the A-10, but maybe someone else could chime in with an answer.

Why's this all so important? Well, the Grid method has another advantage: it can make better use of a precise declination figure. The F10 map ruler usually used to get bearings for navigation is only precise to the nearest degree. If the course angle drum of the ДИСС-15 is set up using a precise declination figure (since it accepts minutes as well as degrees), the added precision can make a significant difference for long flights. With that in mind, here's how to use the Grid method:

The F10 map, ruler, and digital counters of the ДИСС-15 will be used to determine location. I'll start with an example:

For demonstration purposes, we'll be flying from Beatty Airport to Area 51. The reference point will be the Beatty Airport apron (giving us 1 quadrant to work in). The helicopter will be shown on the map to illustrate how the technique works (obviously this wouldn't be the case in a practical scenario).

Because the reference point is our starting point, the lateral deviation and distance counters will be left alone. 12.5° is a good approximation of the declination over our expected flight area over the NTTR, so we'll enter 347°30' as our course angle. This is the only time we need to mess with course angle using the Grid method!

Now we push ВКЛ to start operating the ДИСС-15, checking that the ДИСС ОТКАЗАЛ annunciator is not illuminated. Note that a nearby landmark can also be used as the initial fixpoint, but this is unnecessary since we know our starting location with a high degree of accuracy.

Takeoff! We must be careful not to exceed the ДИСС-15's attitude limits of 7° pitch or 30° bank, or the quality of the navigation solution will be degraded. This is another reason why you may wish to start operating the system at an initial fixpoint instead.

After stabilizing at altitude, let's take a reading (while paused for demonstration):

About 14.5 ВПРАВО (right) and 6.25 ВПЕРЕД (forward). Since we're working in 1 quadrant, we can ignore the directions and interpret the values as x and y on a Cartesian coordinate system.

Next we open the F10 map and use the ruler to draw lines corresponding to the coordinates (once again, pretend the aircraft isn't visible!). Since the ruler seems to lack the ability to draw lines at vertical and horizontal angles, we use the edge of the screen as a guide:

Drawing the line (look carefully at bottom edge of image)...

The resulting line

Drawing the vertical line (on the left edge, not visible this time)...

The resulting line, again

About 310m off. Worse than I'd prefer, but we can always create a fixpoint to regain accuracy.

We'll change course and set our next waypoint to be the Pahute Mesa Airstrip. Note the advantage the Grid method proviedes here: we can change our route at will without needing to reset the ДИСС-15, while still being able to arbitrarily determine our position along the way.

Oh no! Our navigator's been resting on the ВЛ button! We'll have to use the Pahute Mesa Airstrip as a fixpoint. Fortunately, it's just up ahead.

Taking a fixpoint:

1: Select a landmark! Hint: the satellite layer of the F10 map is very useful for this

2: Turn off the ДИСС-15 by pressing the ОТКЛ button

3: Enter the x (lateral deviation) and y (distance) coordinates of the fixpoint in relation to the reference point (place the fixpoint along the side of the screen and reference point along the bottom to get straight lines)

4: As you overfly the fixpoint, push ВКЛ to reengage the system. You now have your precision back!

Note: The Mi-8 crew died on the way to Area 51. They didn't get clearance to enter the airspace.

Let's review:

Step 1: Pick a reference point to be used for the duration of the flight; this is somewhat like a bullseye. A simple choice is the starting airfield, but this may not be as precise as other candidates. There's a few considerations here:

—The reference point needs to be easy to remember. You can use a Mark Label if you think you'll forget (but this introduces a difficulty later on)

—The reference point should be easily located even when zoomed out. You'll be drawing lines using the ruler from this point, so make sure it isn't too small!

—The reference point will be used as the origin of a Cartesian coordiate system; you can therefore choose to work in 1 or more quadrants. If you would like to work with only 1 quadrant (so you don't need to pay attention to whether the ДИСС-15 is indicating ВЛЕВО or ВПРАВО, for example) choose a reference point which contains your entire likely flight area in that quadrant (e.g. if you want to work in quadrant I only, choose a reference point further southwest than any location you will likely be at)

—You can locate yourself more precisely if you place the reference point in the middle of your likely flight area, because you won't need to zoom the map out as far. You will have to pay attention to quadrants, though

Step 2: Determine your location relative to the reference point and enter the coordinates into the system. If you can't determine your starting location precisely, pick a nearby landmark and enter those coordinates instead (this can be done in flight as well, though it's easier on the ground). Once again, a few considerations:

—If your starting location is the reference point, you can skip this step

—If you intend to perform a running nosewheel takeoff or other high-performance takeoff maneuver requiring excess pitch and/or bank angles, opt for the landmark as a starting fixpoint. This way, you won't immediately have to take the attitude limitations of the ДИСС-15 into consideration

—If you're performing a ground taxi or hover taxi below 2m, the ДИСС-15 will not be operable during this time and you should instead opt for a landmark fixpoint (the center of the runway or a radio NAVAID station past the runway is a good choice)

—If there's no suitable landmark visible from the cockpit, use the F10 map's satellite view to locate one

Step 3: Activate the ДИСС-15 system by pressing the ВКЛ button. If you're fixing on an initial point instead, activate the system as you overfly it. Watch for the ДИСС ОТКАЗАЛ annunciator as you take off; this indicates a possibly degraded naviation solution and you should seek to take another fixpoint as soon as possible

You are now ready to go! Determine your location and take new fixpoints as needed.

Addendum----

For those very serious about determining their location precisely while moving, the Mi-8 is not for you! Just kidding, but you've probably noticed that my demonstration only showed the result of measuring coordinates with the sim paused. If you want to get an accurate result while moving, grab a calculator; the process is much more complex:

To find your location at a specific time:

Maintain constant speed and heading (use all autopilot channels). THIS IS CRITICAL!

Prepare to start stopwatch. Read DISS coords and start stopwatch as quickly as possible to minimize error, then mark location (simply leave the ruler line intact)

Divide ground speed by 3600 to obtain speed in kps. Record result.

Read heading on gyrocompass, add declination, and subtract left drift angle (or add right drift angle). Record result.

(Note: "time" here refers to time in seconds, e.g. 1m30s = 90s)

Look at the stopwatch and choose a time about 30s in the future (to allow time to do the following):

-Multiply said time by result of first calculation to get distance travelled

-Using ruler on map, draw line from marked location using bearing of second calculation to obtain predicted location

Perform these tasks

Wait until stopwatch reaches designated time. You should now be at the predicted location.

Laconic version:

—Stabilize speed/heading

—RAPIDLY read coords & start stopwatch

—Mark location

[Ground Speed] / 3600 -> s

[Magnetic Heading] + [Declination] ± [-L or +R Drift Angle] -> b

[Elapsed Time] + 30 -> t

t * s -> d

Mark map (b bearing for d km)

Wait until t to arrive at location.

As continuous calculations:

Distance: ([Ground Speed] / 3600) * [Elapsed Time] + 30

Bearing: [Magnetic Heading] + [Declination] ± [-L or +R Drift Angle]

Where's that +1 gone :)

oh god this is a cute headache! yeah where is that rep button?