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Old 06-12-2018, 12:57 AM   #1
Frederf
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Default Altimeter errors

#1. 1km hand of the altimeter does not align with the appropriate km markings after X rotations of the hectometer needle. The magnitude is proportional to the number of rotations X of the hectometer needle.

At indication 0m the km needle indicates approximately 0 km.
At indication 7.000m the km needle indicates approximately 7.5km (+7%).
At indication 10.000m the km needle indicates approximately 10.9km (+9%).
At indication 20.000m the km needle indicates approximately 22.4km (%12%).

#2. Altimeter pressure adjustment art does not extend to the bottom of the window and the sharpened "5" mark which doubles as the index for the pressure adjustment setting does not extend to the bottom of the window on the main gauge face. The result is a large gap exists between the index and the scale which makes setting difficult. Also the scale is misaligned about half a mmHg. Really, really bad texture edit shows what scales touching would look like and the misalignment (750mm is set).

Pictures in reverse order because I don't plan.
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Old 06-12-2018, 07:20 PM   #2
foxbat155
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Generally those accuracy values are incorrect only a little. According manual WDI-30 have typical accuracy errors:
Altitude 0 m - 600 m: -+20 m,
Altitude 6600 m - 10000 m: -+ 130 m,
Altitude 28000 m: -+600 m.
And those are general errors values, because every WDI is calibrated individualy after instalment on the aircraft. Technicians are using 28 separate measurements for altitudes and IAS and then are calculated average correction values.
When aircraft on the cruise altitude, 760 mm Hg ( 1013 hPa ) sholud be set, because this is standard pressure and WDI-30 is calibrated according that value.
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Old 06-13-2018, 05:25 AM   #3
Frederf
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When hectometer hand rotates by 7,200° (twenty times around the circle) then kilometer hand is not pointing at 20 km position. It is pointing between 18 and 19 km position. It is not an issue of accuracy but of the gear clockwork mechanism which connects the two hands.

When you set 745mmHg in editor and spawn MiG-21bis the altimeter pressure setting is 745mmHg automatically. There is no abnormal inaccuracy on the part of the instrument. But when you look at the visual art on the gauge it is showing a setting different than 745 even though you know it is set exactly 745.

I make a better one.
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Old 06-14-2018, 07:53 AM   #4
foxbat155
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I never checked MiG's altimeter so deeply, because i'm using this module only occasionally due many discrepancies with reality.
You will make new altimeter?, that great!. Maybe you are able do much more improvements, I promise I will find all needed papers for this work.
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Old 06-15-2018, 01:36 AM   #5
Frederf
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I am no professional texture artist. I've noticed though that lots of DCS modules are not super careful about needles and markings: leading edge, center, trailing edge are treated somewhat carelessly. It's not always aligned center of moving part to center of static part.

This behavior of km hand is new since cockpit art update. Km hand was matching each marking after N revolutions of hectometer hand just fine earlier. Real fix is to change relationship between input value and radians of needle rotation in cockpit animation.

Code:
H_indicator_needle_km = CreateGauge("parameter")
H_indicator_needle_km.parameter_name = "H_indicator_needle_km"
H_indicator_needle_km.arg_number = 112
H_indicator_needle_km.input = { 0.0, 30000.0 }
H_indicator_needle_km.output = { 0.0, 1.0 }
It is making 30,000m input equal "1.0" output which I think is a full circle of motion. But gauge 30km is 340° instead. I will change 1.0 to 0.9444 and check.

0.0 and 1.0 are definitely 0 and 360° rotation (same orientation, up). 0.9444 is almost exactly the 30 km mark. There is a lot of parallax from the camera origin surprisingly so I thought it was off until I moved the limits of camera translation to get closer to straight on.

Here are new "key" values to relate the input value to the rotation which produce better results
Code:
H_indicator_needle_km.input = { 0.0, 5000.0, 10000.0, 15000.0, 20000.0, 25000.0, 30000.0 }
H_indicator_needle_km.output = { 0.0, 0.1555, 0.3095, 0.4650, 0.6200, 0.77820,  0.9444 }
I am happy enough with these rotation key values. At least there is no confusion which 1,000m zone you are in anymore.

The gauge face I have changed a little. The window for pressure scale is a different shape than I have seen but this is in the 3D model so I cannot edit it. By making an indicator which reaches the edge of the cutout and moving the scale so that it overlaps with the cutout lower edge. This way the scale and pointer can be brought to meeting for precise setting as per the real instrument. But I do not like the color and brightness of my edited pressure scale. It is not matching the white-blue of the gauge face.

Last edited by Frederf; 06-15-2018 at 01:50 AM.
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Old 06-27-2018, 11:30 PM   #6
corn322
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About #2:
I collected images of the altimeter from the game, the manual, and from the internet by searching "Russian altimeter."


Note the difference in size of the pressure scale window between the game images and internet images. It appears the font used has changed as well.
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