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Attitude indicator


lmp
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Thanks for asking lmp, I was wondering too.

 

I still don't understand.

 

Western rationale: Blue = sky, Brown = ground

 

Russian rationale: ???

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Not Confusing for commissars only westerners :)

 

 

This methodology was pretty standard for most Eastern Block aircraft of the time period both Russian and Chinese. Look at he Mig 15 in DCS same arrangement

 

Doesn't seem like this is the case to me. The Yak is a 1970s aircraft, so a contemporary of the Albatros (which would be the next aircraft the student learns), MiG-21 and newer Soviet combat aircraft. The L-39 AI looks like this:

 

https://www.digitalcombatsimulator.com/upload/iblock/5fe/Screen_180712_160404.png

 

White "sky" on top, dark "ground" on the bottom. When you pull the nose over the horizon, the "sky" portion fills the AI.

 

The MiG-21bis, Su-27, Mi-8, MiG-29, Su-25 etc. all have a similar arrangement, despite being from different manufacturers:

 

https://www.digitalcombatsimulator.com/upload/iblock/281/Screen_140720_054805.png_Thumbnail0.jpg

https://www.digitalcombatsimulator.com/upload/iblock/ab1/Screen_141023_104547.jpg_Thumbnail0.jpg

https://www.digitalcombatsimulator.com/upload/iblock/73a/Screen_170824_125901.jpg

https://www.digitalcombatsimulator.com/upload/iblock/2c3/FC3_SCR_41.jpg

https://www.digitalcombatsimulator.com/upload/iblock/e00/FC3_SCR_35.jpg

 

The MiG-15bis is different indeed, but there's no sky/ground background at all, the plane symbol moves against a statick horizon line. In some of the early WIP shots we did indeed see an AI similar/identical to the one in the Yak: https://www.digitalcombatsimulator.com/upload/iblock/79c/Screen_141220_000359.png_Thumbnail0.jpg

 

So clearly this design isn't unique to the Yak, but it isn't exactly standard either. I find it very odd from an ergonomics and even safety point of view. Even the "inverted" roll indication (compared to Western AIs) that we see in most Soviet aircraft has gotten people killed. This is far more difficult to adjust to and easier to misread.

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I find it very odd from an ergonomics and even safety point of view. Even the "inverted" roll indication (compared to Western AIs) that we see in most Soviet aircraft has gotten people killed. This is far more difficult to adjust to and easier to misread.

One usually get used to it rather quickly and for me it was interestingly IRL less vertigo inducing than the western AHs. All the Zlins I've flown (226, 526, 42) and even the L-13 have this AH.

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The colour becomes logical, if you see it moving.

Climbing the plane which shows the sky in blue on the artificial horizon.

Ground being brown/earth, if you see this, the nose of the plane is pointing downwards.

 

Colors are fine. Blue is sky and black is ground. Check the "climb" and "dive" words in each region. When climbing the miniature airplane will be in blue climb region.

 

What's unusual is that pitching up causes the boundary between the colors to move upward. The boundary represents the nose of the airplane and not the horizon.

 

I agree with you guys, the colours are "right" (brown = earth, blue = sky), and so is the relative position of the miniature "within" earth or ground when diving or climbing.

 

However earth and sky are inverted on the attitude indicator compared to what is observed outside of the cockpit and I don't get the rationale or advantage of that choice.

 

attachment.php?attachmentid=191018&stc=1&d=1532976755

2018-07-30_20-46-30.thumb.png.8ddfa1fda883b30d304195d172b9c156.png

- Tony -

. My Reviews: Oilfield Campaign - Argo Campaign l My Mission: Huey Ramp Start Voice-Over New!

. Microsoft Force Feedback 2 base modded with a CH Fighterstick - VKB Sim T-Rudder Mk.IV Pedals

. Intel i5 4670K @4.3 GHz - 32 Gb DDR3 - MSI GTX 1080 - ASUS PG278QR 27" 2K @165 Hz G-Sync

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I don't get the rationale or advantage of that choice.

 

 

It makes the instrument less complex. The way it is built means you do not have to invert the pitch axis movement of the gyro, which is the case for "conventional" artificial horizons.

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One usually get used to it rather quickly and for me it was interestingly IRL less vertigo inducing than the western AHs. All the Zlins I've flown (226, 526, 42) and even the L-13 have this AH.

 

I'm sure you can get used to and even prefer it over the other designs. Contrary to a lot of people I prefer the style used in the L-39 over the Western AIs. What I find strange is Russian cadets being exposed to two different designs throughout their training. Sounds like a recipe for spacial disorientation.

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What I find strange is Russian cadets being exposed to two different designs throughout their training. Sounds like a recipe for spacial disorientation.

Very good point. Furthermore this design has a significant disadvantage during approaches to very low minimums where you are constantly switching between looking outside and inside.

 

Thinking about it, I've never seen an Eastern Block airliner that has this kind of AI! Even the super old Tu-104 and 124 already had a 'correct' AI.

 

Maybe Sobek is correct that this AI is being used in VFR planes, simply because it's less complex (and hence most likely cheaper and lighter). I was always wondering why a glider has an AI.

 

Last but not least, the old AIs e.g. on the Caravelle, 707 etc, didn't have any colors. The AI had a black background like every other instrument.


Edited by bbrz

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It makes the instrument less complex. The way it is built means you do not have to invert the pitch axis movement of the gyro, which is the case for "conventional" artificial horizons.

 

Can you please specify? We all know at least how a gyroscope acts, so there would be no need to explain it. But gyroscopes are always stable, assuming this is in some spherical casing to allow the spinning, so it is acting as a "stuck" piece while you could imagine the plane moves around it. (Obviously not the case, but to imagine it though.) There would no need at all to invert the colors, except confusing the pilot.

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When the Mig-21F-13 entered service it didn't have a two seater version, so every new Mig-21 squadron had some Mig-15 trainers in order to conduct prof checks, IF training, etc. And that's when this instrument became a problem. The Mig-21F-13s had the AGD-1 attitude indicator with the blue on top while the Mig-15UTI still had the old AGI-1 blue on bottom indicators. After some time these two seater Mig-15s got the new AGD-1 indicators to eliminate the confusion. I don't think many Mig-15UTIs got this instrument since the 2 seater Mig-21U also entered service a few years after the F-13 started and there was no need to have Mig-15s in the Mig-21 squadrons anymore.

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Thanks for all your input, guys!

 

@Sirius

 

Imagine this. If the sphere of the AI is stabilized to the ground and you enter a climb - so you're looking up - which half of the sphere you will see more of? The bottom part. And that's exactly what's happening in the Yak-52's AI. In a Western AI you want to see the top side of the sphere in a climb, so if you pull up 45 degrees the sphere needs to rotate 90 degrees relative to the real horizon.

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contrary to popular presumption, russian and eastern designers in general, did quite extensive studies in area of instrument and cockpit design. They did excelent job within the parameters of what was main purpuse of the aircraft. The layout was very good, the quality unfortunately much less that.

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If the sphere of the AI is stabilized to the ground and you enter a climb - so you're looking up - which half of the sphere you will see more of? The bottom part. And that's exactly what's happening in the Yak-52's AI. In a Western AI you want to see the top side of the sphere in a climb, so if you pull up 45 degrees the sphere needs to rotate 90 degrees relative to the real horizon.

 

Oh, I got it then! Why do they have a problem with inverting the axis then? Having an ADI that is more logically appealing is better than by wanting a simplistic design. And following with the statement earlier, putting pilots in two completely different aircraft with different types of this ADI makes absolutely no sense.


Edited by Sirius
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Oh, I got it then! Why do they have a problem with inverting the axis then? Having an ADI that is more logically appealing is better than by wanting a simplistic design. And following with the statement earlier, putting pilots in two completely different aircraft with different types of this ADI makes absolutely no sense.

 

Less moving parts = cheaper to produce and easier to maintain.

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This AI was called in some books as a "fighter type" AI. Imagine, that the "bird" on the AI is a plane flying in front of you. If you start your climb, the plane goes down. And the blue and brown colours are just to tell you is your plane climbing or descending. The idea was to synchronize the picture on the AI and on the gunsight when you follow a plane.

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