Artificial Horizon, Russian Style
 

Had a ride in a Yak two seater trainor recently. The instruments in the front cockpit had been replaced to comply with local requirements, The rear cockpit however still had the original Russian instrumentation. The AH was depicted with the dark side up, light side down. No, we were not flying inverted. Can anybody tell me why this is so. Sensible answers only please.

At one point, western AH/AI used a uniform background, typically black, with just white horizon line ie no colour difference between 'ground' & 'sky'.

To make ground & sky referencing easier to perceive the areas below & above the horizon were given different colours.

Western manufacturers chose light blue or grey coloured sky & dark ground (dark blue? Can't remember) with even later versions opting for a brown ground depiction.

Russian also opted for a different coloured depiction of ground & sky to enhance readability. In their case they chose a dark 'sky' & a light 'ground'.

Why? Only surmising here, but one possibility is that they were trying to represent night sky & snow covered terrain. It could be argued that this is a more commonly found condition of flight that requires the use of the instrument, since daytime allows the possibility of visual reference.

Considering that the Western style depiction (blue over brown) is only representative of sky/ground colouring under something like a cloudless day over a desert(ish) area who's to say which is more correct?


BTW, I seem to recall that Russian AHs don't use a moving horizon bar with a fixed a/c representation. Instead the horizon bar is fixed & the a/c moves.

Just a different frame of reference.

[ 15 August 2001: Message edited by: Tinstaafl ]

Neil Williams Aerobatics

Thought that I would throw that into the discussion! :)

[ 20 August 2001: Message edited by: Checkboard ]

Thank you for your replies, Tinstaafl, I am old enough to remember the all black AH. From my, all to brief experiance in the Yak, believe you are right in that the bar is fixed and the rest of the intrument rotates, in the Russian version AH.

These instruments work differently from our 'western' ones, and I'll do my level best to explain...

The gyro keeps the instrument's 'globe' level with the local horizon - whereas 'western' instruments use a system of pivots and levers on the outer gymbal to cause the movement of the gyro to appear in a 'reverse' sense.

In the Yak, in level flight, the aircraft symbol is just about on the horizon line. There is brown above and blue below.

Now we pitch up into a 20deg ANU atitude. The horizon 'globe' remains static, under the influence of its gyro, but the aircraft rotates around the 'globe' in pitch. Now look at the instrument, and you will see there is MORE blue and LESS brown visible - draw yourself a little diagram if this is tough to comprehend. You are 'looking at' more 'sky', and you can 'see' less 'ground', as you would expect.

There are good technical reasons for designing your gyros like this, and they are more capable instruments (eg for aeros).

First time I flew with one, it took about two or three minutes maneouvreing looking out and in, before (with good bloke in other seat) I ventured into IMC. I found the IF easy, and quite natural, and had no problems the next day getting back into a 'western'-equipped aircraft.

HOWEVER, I wouldn't have liked to try my chances at recovery from UPs without a lot more time to get used to it, and even then, I think there would be a big danger of recovering to the inverted.

Yaks are top fun, too!

A few years back I was helping ferry an Antonov AN-2 Colt on an 1800nm journey. We ran into some nasty weather. I said to the captain, Let me give you a little break on the dials. He gives me control thinking my many years of flying EFIS jets around IFR is going to give him a little rest. Ha! I took about 4 minutes to end up in a classic spiral! Oh yeah was I good!??! Ugh... YOU HAVE CONTROL!!
Upon delivery the customer looked at me and said " I hope you didn't try and fly the dials" He knew the difference on the attitude indicator. The captain had very little actual IFR time and was totally able to figure out how to read that backwards AI.
On we go....

The description I liked most for the difference was: whereas Western AH's are of the "...inside, looking out..." type, the Russians use the "...outside, looking in..." variety...?

Once you get your head around it; it makes absolutely no sense!

I think it can be very difficult to adapt to a totally different display of attitude (little aircraft rolls with respect to the instrument panel as in the Russian system) if you just get airborne and hope you can cope.

For me the secret was to sit in the bath before hand and visualise what it would look like. There I realised that it would look as if I was flying line astern on my leader and he was changing bank angle in front of me. He would look (against the real horizon) exactly how the Russian attitude indicator looks in the panel.

So what to do?

Answer; fly your leaders aeroplane from your cockpit. If you want him to level "his" wings just do what comes naturally and "your" wings will do what you want.

Really old ex-RAF Bomber pilots will remember the peculiar display on the Smiths Military Flight System or MFS. A white line on black background version of the Russian display would look like that. Did we steal it from them or did they steal it from us?

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Through difficulties to the cinema

Further to what was said about flying the An2, I have heard that pilots of Russian built aircraft have a great deal of trouble converting to Western aircraft - especially when they are high time pilots. Russian aircraft generally use "ground pointing" AH's while western aircraft use the opposite. Hence when crews convert, the read the indications on the AH backwards and apply the wrong control inputs. Some ex-TU154 crews converted to 767's by Ansett apparently had lots of trouble and some of the older ones never made it.

Yes. I've converted ex-Vietnam A.F. pilots (Soviet equipment) to western equipment.

They all had great difficulty coming to grips with the western way of depicting/doing things.

Russian AI's do use a ground pointer. Forgot about that in my previous post.

Also the multi-crew philosophy isn't so much 'two pilots act as a safety buffer to each other's errors & can manage alone if necessary', as a case of 'no single crewperson can operate the a/c alone so it takes the whole crew en-masse to defect'. Awkward to arrange when one or more member(s) can be a political 'plant'.

This makes single pilot IFR quite a challenge to a someone only familiar with this Soviet method of operation.