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WARDOG

MiG-25P/PD differences

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Hi All,

 

Are there any major external differences between the MiG-25P and PD besides the underside OR detector?  I know the engines were up-dated and that the PD can carry R-60s on the outer pylons but wanted to know if there was anything else I need to do to make my P into a PD.

 

Thanks,

 

WARDOG

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If I remember right the upgrade was rushed b/c the friend or foe codes were leaked as a result of Belenko's MiG-25P being disassembled and analyzed. I beleive PDS was almost identical to P except heat detector, r-60 pylons, KM-1M ejection seat and not sure if it had longer nose cone. Early PD had all of those (including longer nose cone) plus a center fuel tank http://www.airwar.ru/other/draw/mig25aiv.html

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Thanks Doom3r,

 

I had forgotten about the nose cone and will probably leave off the under-belly fuel tank.  I'll see if I have to lengthen the nose cone a bit.

 

Appreciate it,

 

WARDOG

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Be very careful of drawings.  All of the interceptors had the same length.  The length of the radome itself was different, but that was only because of the point where the radome mounted to the fuselage, not the overall length of the aircraft.  There have been lots of really bad drawings of the MiG-25 published.  

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The pitot is also different. PD has a plain needle like pitot, but P has multiple vanes attached (ILS antennas were they?). PD would likely carry R-40RD/TD missiles instead of R-40R/T. RD has quite different radome compared to R. Not sure if there are visible differences between TD and T.

 

Then there is the thing called PDS, which is an existing P airframe upgraded to PD standard. My understanding is that things like wingtips and drag chute containers were not changed during the upgrade.

 

Are you planning to convert the Condor kit? It is a weird one: clearly MiG-25P panel lines, old style wingtips, late style chute container, R-40RD missiles (incompatible with MiG-25P, also missing rocket exhausts!). Very plain, almost crude plastic, but somehow I like it.

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Not ILS antennas.  You can’t put antennas on a pitot tube.

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I'm not saying you are wrong or I am right, but why can't one put antennas on a pitot tube?

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Hi Apex,

 

Yes, I am considering modding the Condor kit but MIGHT try to trade it off for a PD model with the under nose IR sensor.  I'm getting farther and farther behind on my model BUILDING and need to get cracking on some of these piles!  Probably need to do less nodding! 🙂 I'm not getting any younger and I have kits I bought in the early 80's still un-built!

 

WARDOG

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2 hours ago, WARDOG said:

Hi Apex,

 

Yes, I am considering modding the Condor kit but MIGHT try to trade it off for a PD model with the under nose IR sensor.

At the moment, the ICM is the best kit for a PD:

 

https://www.scalemates.com/kits/icm-72171-mig-25pd--130157

 

Do note that this is their somewhat older but stlll nice tooling - ICM has released a newer tool, but so far only in Ye-155R based recce versions ( with a MiG-25BM Weasel imminent).

 

https://www.scalemates.com/kits/icm-72172-mig-25rbt--1123405

 

 If their 1/48th program is any indication, interceptor boxings of their new tool will follow.

 

Cheers,

 

Andre

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On 8/6/2019 at 4:25 AM, Apex said:

The pitot is also different. PD has a plain needle like pitot, but P has multiple vanes attached (ILS antennas were they?).

Hello Apex,

 

horizontal ones are Angle of Attack (AoA) vanes and vertical ones for the Yaw (sideslip). In this form a standard feature in MiGs (you can find them in all fighter aircraft; they just come in different forms. Like in Phantom or BAe Hawk).

 

Antennas on a pitot tube are a "no-no" mainly because of the heat generated by compressibility (can exceed 100 Centigrades) and by the fact that pitot tubes are always heated; there is an electrically heated element inside the tube.

 

Kind Regards,

Antti

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11 hours ago, Antti_K said:

horizontal ones are Angle of Attack (AoA) vanes and vertical ones for the Yaw (sideslip). In this form a standard feature in MiGs (you can find them in all fighter aircraft; they just come in different forms. Like in Phantom or BAe Hawk).

I guess you mean the vanes like found on this MiG-21SMT:

img_2172.jpg

 

The ones on this MiG-25RBS look quite different; they are static, so I wonder how could they be used for AoA/yaw measurement:

img_2225.jpg

 

They are not really attached to the pitot itself, which is located further forward of these vanes.

 

However these vanes look like they could be used for AoA/yaw measurement:

img_2226.jpg

 

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18 hours ago, WARDOG said:

Yes, I am considering modding the Condor kit but MIGHT try to trade it off for a PD model with the under nose IR sensor.  I'm getting farther and farther behind on my model BUILDING and need to get cracking on some of these piles!  Probably need to do less nodding! 🙂 I'm not getting any younger and I have kits I bought in the early 80's still un-built!

Oh I know what you mean all too well. Discussing the shortcomings of various kits does not help at all. :)

 

The Condor MiG-25PD is exactly the same plastic as their MiG-25P with one extra sprue for IR sensor, new wingtips, R-60s + rails, the giant fuel tank and chaff/flare dispensers. So still MiG-25P fuselage, though I would not consider this a major difference. As @Hook said the ICM kit is much nicer, but not exactly state of art either.

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Hello Apex,

 

Great photos, thank you for sharing. You are right: AoA and Yaw vanes visible in the MiG-21. And yes, AoA and Yaw vanes on the MiG-25 are located at the bottom and on the side of the nose. Those "blades" on the pitot tube don't look like western ILS antennas at all. And as I mentioned earlier there is quite a few problems to overcome if antennas are attached on a part the is heated and which contains a powerful electrical component in it.

 

I'm wondering whether these "blades" (in MiG-25) could be fins that create turbulence around the pitot tube to prevent flutter. It certainly looks that the blades are firmly attached and are fixed (not pivoting).

 

Then there seems to be a "traditional" pitot tube just below the wind shield quarter panel. Is it possible that the tube on the nose isn't a pitot at all?

 

Cheers,

Antti

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Hello Antti,

6 minutes ago, Antti_K said:

Great photos, thank you for sharing. You are right: AoA and Yaw vanes visible in the MiG-21. And yes, AoA and Yaw vanes on the MiG-25 are located at the bottom and on the side of the nose. Those "blades" on the pitot tube don't look like western ILS antennas at all. And as I mentioned earlier there is quite a few problems to overcome if antennas are attached on a part the is heated and which contains a powerful electrical component in it.

 

I'm wondering whether these "blades" (in MiG-25) could be fins that create turbulence around the pitot tube to prevent flutter. It certainly looks that the blades are firmly attached and are fixed (not pivoting).

 

Then there seems to be a "traditional" pitot tube just below the wind shield quarter panel. Is it possible that the tube on the nose isn't a pitot at all?

I don't know - there is confusing, there is totally confusing, and then there is Russian technology :). I don't really know much of this stuff, but I guess that is part of the fun in building Russian planes. Admittedly it would be strange to remove ILS antennas from the MiG-25PD, however turbulence generating fins could have been removed if deemed unnecessary.

 

I mentioned ILS as several cutaway diagrams indicate these blades are ILS antennas. For example (see item 101, инструментальной системы посадки):

mig25p-2.gif

 

So how about a Su-22M4?

img_2477.jpg


Looks like there are two pitot tubes, attached to two "masts" of different length, one of which has AoA/yaw vanes plus the antenna/fins.

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I'm more and more interested... The picture of a SU-22 indeed proves that vanes are always movable in Russian fighters (as there are "fixed" vanes as well; like in Phantom or Hawk).

 

In the cutaway drawing number 101 indeed says something about "Instrumentalnoi sistem posadki". The Russians have an ILS of their own called KRS. Have a look at number 94 as it looks like an ordinary pitot tube. It is in fact very much the same as in SU-24s. Number 93 is one of the IFF antenna units (there are usually two of these on Russian aircraft). Unfortunately I don't have a clue what the key tells about number 102 although I can read the letters.

 

As you said: the Russians can make things work when we in Europe say it can't be done. They are very bright engineers. Especially when they design something for the armed forces.

 

Cheers,

Antti

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On 8/6/2019 at 6:13 PM, Apex said:

I'm not saying you are wrong or I am right, but why can't one put antennas on a pitot tube?

Because a pitot tube is heated (and gets hot enough to burn you quite badly if you grab it).  

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Posted (edited)
On 8/8/2019 at 2:01 AM, Antti_K said:

The Russians have an ILS of their own called KRS

Not KRS - KGS (

do not confuse with KGB!!!😁)

"Kurso - Glissadnaya sistema" - Course- Glide system:

 https://ru.m.wikipedia.org/wiki/Курсо-глиссадная_система

English version Wikipedia say about ILS:

https://en.m.wikipedia.org/wiki/Instrument_landing_system

 

On 8/8/2019 at 2:01 AM, Antti_K said:

Unfortunately I don't have a clue what the key tells about number 102 although I can read the letters.

102 on MiG-25 cutaway key?

It's ordinary: 

https://en.m.wikipedia.org/wiki/Pitot-static_system

On 8/5/2019 at 5:50 AM, WARDOG said:

Are there any major external differences between the MiG-25P and PD

Oh, answer on this question somewhere here inside:

http://scalemodels.ru/modules/forum/viewtopic.php?t=1329&postdays=0&postorder=asc&start=0

 

And see also:

http://scalemodels.ru/news/12822-tekhnicheskoe-opisanie-mig-25.html

 

On 8/8/2019 at 2:01 AM, Antti_K said:

As you said: the Russians can make things work when we in Europe say it can't be done. They are very bright engineers. Especially when they design something for the armed forces.

You live by old-mode concepts! 😁 Now there is no difference between Russian Federation and the West ...in fact, the main part of the majority of technical achievements RF is inertial development due to ideas and technologies laid down during the USSR period as a highly developed technical civilization ...I do not want to develop this topic further, but there are many examples of this ....

 

B.R.

Serge

 

Edited by Aardvark

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Thank You, Aardvark.  That is very helpful information!

 

WARDOG

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Jordi,

 

I can personally testify to the fact that pitots can get very hot!  I mistakenly grabbed one on a Huey helicopter when returning from working off-shore.  I walked around the front of the Huey because I rode in the right front seat and while not paying attention when talking to the pilot, I grabbed the pitot.  After a nice static shock, I got a nice burn in the palm of my hand.  It was so hot that it turned the upper layer of skin into a white ash.  It didn't hurt after the shock though.

 

WARDOG

 

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I, too, have the scars to prove how hot a pitot tube can get!

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