Question about НПП-МК on the Mig-21

[Esac_mirmidon]

Could someboy help me to understand the NPP needles from this picture?

 

 

Is this draw make by me correct?

 

Because i was searching for info about this instrument in several russian and english translated manuals from Mig-21 ( the egyptian one ) or L-39 Albatros and i´ve fond contradictions about the Bearing neddle, where it seems the circular top is the tail and the opposite side the head.

Edited August 26, 2014 by Esac_mirmidon

[mambo]

I think is the opposite that appears in the picture.

[mwd2]

Source: http://forums.eagle.ru/showpost.php?p=1470696&postcount=852

[Kayos]

NM - delete post.

[Esac_mirmidon]

So the head are the tail in both neddles?

 

Because in the graph from the Mig-21 Bis manual ( the egyptian ) it seems the opposite from my draw.

[uboats]

So the head are the tail in both neddles?

 

Because in the graph from the Mig-21 Bis manual ( the egyptian ) it seems the opposite from my draw.

 

The circle side is head, for another needle, the hollow side is head

so your mark is correct

Edited August 26, 2014 by uboats

[Esac_mirmidon]

But in the image from de english Mig-21 Bis manual that mwd2 has posted is the opposite.

[uboats]

But in the image from de english Mig-21 Bis manual that mwd2 has posted is the opposite.

 

 

that's sound weird. I compared two manuals and both show the same as your mark.

[uboats]

But in the image from de english Mig-21 Bis manual that mwd2 has posted is the opposite.

 

 

'narrow' for number 8 should denote the side with circle, so it is same as your mark (the pointer does not mean the head of needle)

I think you can check FC3 manual as well as Ka50 manual for comparison.

Edited August 26, 2014 by uboats

[Esac_mirmidon]

The Ka-50 has a different HSI with different neddles. For example it has an extra yellow RMI neddle.

 

The bearing mark is a yellow one on the outside ( no neddle ), and the course one is the typical hollow needle.

 

And yes maybe the manuals are only marking pointers not heads or tails. But i´m still confused because i don´t know for sure in this NPP model where are the heads and where the tails.

[uboats]

The Ka-50 has a different HSI with different neddles. For example it has an extra yellow RMI neddle.

 

The bearing mark is a yellow one on the outside ( no neddle ), and the course one is the typical hollow needle.

 

And yes maybe the manuals are only marking pointers not heads or tails. But i´m still confused because i don´t know for sure in this NPP model where are the heads and where the tails.

 

For this NPP, your mark is correct

[Esac_mirmidon]

Thanks Uboat.

[uboats]

Thanks Uboat.

 

you are welcome

su25 seems to use the same HSI, you can find it in FC3 manual

[Esac_mirmidon]

Well, i´m still having doubts about the NPP-MK behaviour. Sorry.......

 

I was searching videos about real cockpit footage where i could see this HSI working. And i´ve found this.

 

 

 

It´s a simulator of a real Su-24 with the same NPP-MK HSI model.

 

What i think it´s happening:

 

The RSBN distance indicator starts at 9 KM, and you can see that the distance is growing to 10-11 KM until sometime in the video is around 24-25 KM. So my guess is the Su-24 is flying AWAY from the NDB-VOR, that it´s behind.

 

Now the needles.

 

My theory:

 

If the hollow neddle (the large hollow part ) from desired track, is the head, and the circle is the head for direct interception of the NDB, NEVER from this position the circle could move towards the hollow needle, more near every second.

 

From this position, you can make a test with the Su-25A, if you put the needles to your right, first the hollow one, (for example 030º to the right) and a couple od degrees more right, the circle, (for example 060º to the right) and both were heads, they NEVER get moved one into the other. They circle would move to the right , moving AWAY from the hollow one.

 

 

Now in the Su-24 video:

 

You can see how the hollow part and the circle are getting closer each other. And the only way they can move like this is if the NDB or the beacon is BEHIND, so, the thin side of both needles must be the head and the hollow and circle sides the tail.

 

Another video from a Su-24 taking off.

 

 

The RSBN distance is 1 km to a point BEHIND the Su-24. At lift off the point is 3 KM behind. An the needles are the same way. The hollow side and the circle side are in front and, the thin parts are pointing to the beacon BEHIND.

 

So the heads are the thin part and the tails the hollow and circle parts.

 

Sorry for my english.

Edited September 1, 2014 by Esac_mirmidon

[159th_Viper]

Could someboy help me to understand the NPP needles from this picture?

 

 

Is this draw make by me correct?

 

No.

 

As you said, the other way round.

[lmp]

No.

 

As you said, the other way round.

 

Sooo the DCS Su-25 has it wrong?

[Esac_mirmidon]

So it´s the opposite from my draw?

 

Because in the Su-25A from DCS is like the draw.

 

PD: Imp gotcha ¡¡¡

[159th_Viper]

Sooo the DCS Su-25 has it wrong?

 

We're dealing with the Mig-21 here. I cannot comment on the Frog - have not looked into it.

[Esac_mirmidon]

I think the Mig-21 Bis and the Su-25A had the same NPP-MK HSI instrument.

 

From the preview videos of the LS Mig-21 posted here, it looks like the same HSI in both aircrafts, and in DCS the Su-25A, now, works like my previous draw. I don´t know how it works in the LS Mig-21 because there are no videos about navigation already.

[159th_Viper]

What I told you comes from the Mig-21 Flight Manual.

[159th_Viper]

OK had a look at this issue which is receiving attention behind-the-scenes and it appears that I am incorrect (apologies) and that your first pic is correct.

 

It is apparently a common misconception. I still do not understand it mind you as the wording in the flight manual seems pretty clear to me.

 

If and when I've figured it out then I'll try and explain if someone does not beat me to it.

[Esac_mirmidon]

Thanks Viper .

 

Maybe someone with a wider knowledge than me could comment the Su-24 videos where it seems the HSI works the opposite way than my draw.

 

Or maybe i´m totally wrong. XDDD

 

Thanks Viper again.

 

Waiting for the manual release sooooon ¡¡¡

[uboats]

Thanks Viper .

 

Maybe someone with a wider knowledge than me could comment the Su-24 videos where it seems the HSI works the opposite way than my draw.

 

Or maybe i´m totally wrong. XDDD

 

Thanks Viper again.

 

Waiting for the manual release sooooon ¡¡¡

 

You can write to dolphin or ask anyone who received a promo copy to test the navigation.

 

Regarding the su-24 video, I don't know what nav mode it was in. But in general thinking, bearing needle pointing to front right, and once AC turned left, the bearing needle should rotate in clockwise, while in video, it seems in counter-clockwise.

Edited September 1, 2014 by uboats

[PE_Tigar]

I've spent ~25 hours in An-28 simulator with a HSI similar to this one (needles were yellow and green though) and can't remember what's head or tails with certainty... but I bet if I sat back in the cockpit I'd remember immediately :).

 

Anyway, that thing is super useful, especially when flying an NDB approach with two NDBs or VOR-DME with NDB available... and many other things. I actually loved using that HSI, and prefer it to G1000.

[Esac_mirmidon]

After reading the real Mig-21bis I can finally conclude that tail of the relative bearing indicator is the one with a circle and head is the narrow arrow as follows:

 

 

The real Mig-21bis flight manual was easily accessible with the former DCS-Mig21bis webpage. Unfortunately the link has disappeared but for those who want to take a look to double check my words here's is the link:

 

Mig 21 Bis manual

 

Which is this:

 

 

Well, If we go to page number 45, that describes the "POLYOT-OI navigation system" and the NPP or combined course indicator (basically the russian HSI), we can read on points "a" and "c" the description of the bearing pointer needle:

 

 

(A) Aircraft present azimut from the navigational beacon (means de radial from the station), to be read off the tail (which is thickened and provided with a circle) of the relative bearing pointer, against the movable scal; the pointer tail is sometimes called the azimuth end of pointer."

 

© Navigational beacon relative bearing (or homing beacon relative bearing, when the pointer is connected to the radio compass), to be read off the tip (thin end) of the relative bearing pointer, against fixed scale.

 

This is not a personal guess, but is what the real manual of the Mig21-bis says.

 

Now the question is, why there is a circle in the tail? Well, as the manual describes in page 103,

one of the uses of it is to align it with the localizer bar during the localizer intercept of a PRMG system (russian ILS).

 

This means that when you are in interception heading, for the ILS (PRMG)...

 

 

The localizer bar will start moving towards the center. The relative bearing pointer (thin end) will be pointing to the RBSN. The flight director will command a turn at that time, maintaining the bar aligned with the circle (tail) and that will give you a 30º bank smooth interception.

 

 

 

 

 

Furthermore, you can check this same instrument installed on different russian airplanes NPP-MK is an standard navigation instrument among russian jets:

 

Mig21

 

L-39C (same instrument)

 

Unidentified airplane:

 

Regarding the Su24 video. The most important think is the DME behaviour. You all will agree that DME is always coupled to the NPP (HSI). And you all agree that if a DME increases distance, means that the airplane is flying away from the station. Thus, the tail needle should be pointing somewhere in the front hemisphere. And the head of the needle shoud be pointing somewhere behind.

 

This a picture taken from the video in the minute 0:30 when you can see the DME increasing the distance from minute 0:11 to minuto 1:30

 

 

And also, as all bearing pointers behave in instrument flying. Heads move always down when they are not aligned, and tails always move up.

 

 

 

So for me its crystal clear that the head of the bearing pointer needle is the narrow pointer and the tail is the circle ended side. It's not my guess, again, is what the real Mig-21bis flight manual says.