Black Shark I don't want to wait

[britgliderpilot]

Sorry... the thread has sort of been hijacked :(

 

Word.

 

 

 

Can YOU take on the Ninjas?

[Kusch]

This is ED Ninja?

[kabalah]

Here is the video about Russian forces in Checheniya. In the second half of the video you will see two kamovs being used.

http://video.google.com/videoplay?docid=-4347263657634930563&q=%22Chachnya+Video%22+playable%3Atrue

[504 Wolverine]

Here is the video about Russian forces in Checheniya. In the second half of the video you will see two kamovs being used.

http://video.google.com/videoplay?docid=-4347263657634930563&q=%22Chachnya+Video%22+playable%3Atrue

 

Yep, that it does. :D

 

Thanks for the link mate. Great Vid.

[Whisper]

"Thanks for your interest in Google Video.

 

Currently, the playback feature of Google Video isn't available in your country.

 

We hope to make this feature available more widely in the future, and we really appreciate your patience."

 

:( :( :(

[Chizh]

I have to disagree with you, the rotating blades give a very strong echo, and can be seen by radar from long ranges, a helo like Mi-8 have RCS of the rotor itself in 8m^2 range (6 or less for new composite ones). Two more and it shows like F-15 on your radar. The only problem is with tracking helos flying NOE, you got many interference from the ground, from trees, buildings etc. but using AN/APG-63v1 you can easily track Hip or Hind from 30-45nm as long as there are no obstacles between you and the target.

Whence such information? You are a F-15 driver?

[SwingKid]

I have to disagree with you, the rotating blades give a very strong echo,

 

True,

 

and can be seen by radar from long ranges, a helo like Mi-8 have RCS of the rotor itself in 8m^2 range (6 or less for new composite ones).

 

True,

 

Two more and it shows like F-15 on your radar.

 

Technically true, if the F-15 in question is using ECM. The rotating blades should look like ECM on the radar scope.

 

The only problem is with tracking helos flying NOE, you got many interference from the ground, from trees, buildings etc. but using AN/APG-63v1 you can easily track Hip or Hind from 30-45nm as long as there are no obstacles between you and the target.

 

False. The periodicity and Doppler spread of the rotating blades give a pulse-Doppler radar all kinds of range-measurement and Doppler-gating problems. The helicopter can be detected, but not tracked in range.

 

Thats enough for radar which wavelength is in millimeters.

 

Difficult to argue. The distance between the earth and the moon is also "millimeters." ;)

 

-SK

[GGTharos]

False. The periodicity and Doppler spread of the rotating blades give a pulse-Doppler radar all kinds of range-measurement and Doppler-gating problems. The helicopter can be detected, but not tracked in range.

 

What about some simple kinematic ranging?

Also he seems to imply that actually, you can track it without problems. After all, would spinning props and jet turbine blades create a 'jammer like' effect when aircraft using them are targetted?

[Kusch]

The newest information on Ka -50

 

Raport WTO 09/2006

 

"...the Production of competitive Ka-50 was also restored, the test of first of them just begun. Ka-52 and 12 Ka-50 which the army already bought, are meant to support the special forces."

[Rhen]

Technically true, if the F-15 in question is using ECM. The rotating blades should look like ECM on the radar scope.

 

Technically false:P . You actually get a distance and airspeed readout. When stationary, the spinning rotors generate a return. When we get an airspeed readout, we know they're airborne.

 

 

False. The periodicity and Doppler spread of the rotating blades give a pulse-Doppler radar all kinds of range-measurement and Doppler-gating problems. The helicopter can be detected, but not tracked in range.

 

Nope you get range and airspeed from the radar when looking at a helecopter, even one on the ground.

[SwingKid]

Nope you get range and airspeed from the radar when looking at a helecopter, even one on the ground.

 

That's interesting - what's the real reason Patriot radars not supposed to be located near airports then? The claimed reason is that returns from helicopter rotor blades interfere with their Doppler radar. Is that just a cover story to hide problems endemic to the Patriot system, and help prevent friendly fire? I took it at face value.

 

-SK

[Rhen]

That's interesting - what's the real reason Patriot radars not supposed to be located near airports then?

 

Other reasons other than helicopters or friendly fire - although that's a pretty good reason.

[GGTharos]

SK, you can get the speed in two ways, and I think it would be -very- easy for the computer to choose which to use ... perhaps you can use both anyway:

 

One is sweep-to-sweep position tracking and the other is doppler shift.

 

Using both you could probably defeat some kind of jammer or another ;)

 

As for Patriot positioning, you could have anything from EMI to frying people with that antenna to not wanting your random aircraft landing at baghdad airfield to be able to veer off and fly into your Patriot system, or to collect short-range EM data...

[SwingKid]

Is this true of Russian Doppler radars also - they are able to track helicopters without difficulty? Or, western fighter radars have some special capability to allow this? Alex Zuyev referred to the AA-12 as having a "new anti-helicopter" capability, partly from which I had inferred that earlier air defenses lacked it.

 

-SK

[Alfa]

Is this true of Russian Doppler radars also - they are able to track helicopters without difficulty? Or, western fighter radars have some special capability to allow this? Alex Zuyev referred to the AA-12 as having a "new anti-helicopter" capability, partly from which I had inferred that earlier air defenses lacked it.

 

-SK

 

Don't know anything about this subject, but I have noticed that the ability to track a "hovering helicopter" is often being listed as a seperate feature item in fighter radar documentation - specifically I remember (in connection with the above R-77 quote) this being the case for the Zhuk-M airborne radar.

 

Cheers,

- JJ.

[GGTharos]

I suspect that there may be a couple reasons for this - if you recall, SK, you had told me that it is entirely possible that an ARH cannot actually range its target.

 

Secondly, there might be a low altitude fuzing issue, and this may be what is really being referred to.

[tflash]

Not to hijack this thread but, since the Dutch have Patriot systems, I don't venture there anymore. Not even on my bike. Still looking on ebay for a working IFF. :D

[SwingKid]

I just don't understand the physics of it. How does a medium- or high-PRF radar distinguish which pulse is which (for measuring target range by its round-trip travel time), when the second, third, etc. pulses are transmitted before the reflection from the first pulse is received? I thought this was supposed to be done by FM ranging - assign a slightly different frequency to each pulse. But when the reflected signals themselves contain a mish-mash of Doppler shifts from different parts of the rotor that have different apparent rates of closure, how can you tell which frequency shift is target Doppler, and which is FM ranging? It seems to be like finding a snowman in a blizzard.

 

Perhaps this is only a problem when the helicopter is very near the transmitter, so the rotor returns are detectable? e.g., for a Patriot based at an airport, or for a missile radar that must approach the target? Perhaps at longer ranges, the rotor has small enough RCS that it's ignored - but this would seem to contradict the other half of Rhen's comment above, that even when the helicopter is stationary, the rotor returns are still detectable.

 

Must be magic. :dunno:

 

-SK

[GGTharos]

You could simply filter on the highest return - consider that the blade's aspect to the radar might cause a significant drop in pulse reflection and as such you may -potentially- filter out a blade that's anything but practically head-on as noise. There might also be some averaging going on ... I honestly couldn't tell you right now, I'm not the expert, you are ...

 

However, as a starting point, consider submarine DEMON SONAR process ... :)

 

If you have the tools for it, I propose a simulation: Create a rotor blade model, and ping some radar pulses off of it to create a signal.

 

Once done, run a fourier transormation on it, I'm sure it'll be revealing :)

 

Also consider that ranging with radar has a certain resolution, and that doppler shift is irrelevat to getting range bearing and altitude. The doppler shift is relevant only for getting a vector, and, of course, breaking the helo out of radar clutter :)

[GGTharos]

http://www.freepatentsonline.com/5376940.html

 

http://adsabs.harvard.edu/abs/1987ifar.procR....W

 

http://www.freepatentsonline.com/4275396.html