This may be stupid...

[DTWD]

I am in the middle of hoovering and this just came to me:

 

Do IR missles ever have a tendency to follow/lock onto the sun? Is there some logic programmed into them to not do it, is the sun just not hot enough, are pilots just told it's best not to shoot the sun down, or is there something else?

 

It just randomly popped into my head, things usually do when I am cleaning. Last weeks was "what language do deaf and dumb people think in?".

 

I think it's boredom that fires off these random thoughts.

 

Anyway, IR missles and the sun.

[Fabri91]

As far as I know, very early missiles had the annoying tendency to follow whatever strong ir source was they came across, including the sun and glasshouses. This would also be why such early missiles are easily deceived by flares. More moden missiles use also digital imaging techinques to ensure they're following the right target, if I'm not mistaken. Remember reading something to that effect about the AIM-9X a while ago.

[Boberro]

Yes it can go to the Sun as it is strong energy source. As far I know IR missiles can lock even water (when it's shined by Sun).

 

In LO it is modelled, it is much harder to kill opponent firing missile where the Sun is on the enemy's background.

[sobek]

I'm sure that modern heatseekers have sophisticated signal processing to reject any false positives once locked. If you try to lock an oponent directly in front of the sun, there might of course be masking, or bad SNR, so to say, so it could prevent you from locking him up in that very moment.

Edited November 13, 2010 by sobek

[Eddie]

Older generation IR missiles certainly had this problem, they also had issues with reflected ir energy from the ground. This problem has largely been solved in modern IRAAMs by the use of advanced software and imaging infrared sensors. In fact if you ever find youself being locked onto by an ASRAAM or AIM-9X, you may as well eject because once the sensor has it's teeth into you, it won't let go no matter how many flares you put in front of it.

[kaiserb_uk]

In fact if you ever find youself being locked onto by an ASRAAM or AIM-9X, you may as well eject because once the sensor has it's teeth into you, it won't let go no matter how many flares you put in front of it.

 

Personally I'd wait until it was actually launched before ejecting... ;)

[bumfire]

Personally I'd wait until hit before ejecting :)

[Brit_Radar_Dude]

It isn't exactly relevant to your question, but did you know that the Sun is not only a source of IR energy but also other wavelengths?

Some mobile ground based military radars take advantage of this. One of the issues you have with setting up mobile ground based radars is telling the radar which way is North with serious accuracy. If you are 1 degree out, then a target that you detect at 200 miles range will actually be 3 or 4 miles away from where you think it is.

 

If you increase the sensitivity of the radar (just after sunrise or just before sunset when the sun is low to the horizon), then it will pick up the Sun as a point source of radar jamming. You then record a few minutes of this data. If you have an accurate (GPS or similar) clock, then you can use this "jamming data" to calculate which direction the Sun appears to be according to the radar. From that plus astronomical tables telling you where the Sun actually should be on this day, this time at this location, then you can calculate an error correction value.

The more modern radars have a software package (complete with 10 or 20 years of astronomical tables built in) that can do all this automatically.

Edited November 13, 2010 by Brit_Radar_Dude

[Jinro]

....why can't they just use a compass? If a ground radar unit is using the above method, and tells an airborne unit that something is somewhere, and that airborne unit is using a compass instead of the radar's method, then the airborne unit will end up going to the wrong place.

[vanir]

As I understand it...

Magnetic north isn't axial north and it moves around relative to axial north because of a dynamic core producing the magnetic fields, when planning flight paths you're supposed to get correctional data from a meteorological authority, but Brit Radar Dude's method is more independent and surefire.

Magnetic north doesn't actually move as predictably as the regular corrections used for it (there's an error margin) but it's close enough for things like flight planning, given the atmosphere is a dynamic fluid itself (so involves an inherent error margin anyway where aircraft flight planning is concerned). But for something like radar telemetry (?) or say, satellite databasing (eg. satellite communications using lasers, which need very precise target locations) you have to use astronomical corrections, and even recalibrate for relativistic effect.

 

Also from what I know modern military aircraft navigation uses a combination of magnetic, radio and gyroscopic compasses, datalinking and satellite navigation. Even civvy types pretty much all have GPS these days and fewer wind up running out of fuel over wheat fields as a result.

 

So a military airborne unit doesn't rely on magnetic compasses alone for navigation since about 1941 and many manufacturers before then, carrier aircraft for example. Even the Russians used a simple radio broadcast nav system and they often lacked reliable communications radios in fighters or even telephones at forward airfields (no kidding, telegraph lines built in the 19th century ergo the German invasion was such a breeze).

 

Magnetic compass navigation persisted in civil aviation based between small airfields with basic facilities, but really flightplans are no more than a couple of hundred miles in good visibility at daytime within eyeshot of land features, with really only highly experienced pilots using better aircraft equipment flying in poor weather or at night.

It's also worth considering that other WW2 technologies were still new and highly advanced in civil aviation when they hit the scene in the 70s, things such as the aeromechanical screw (one touch throttle/pitch control) which is still pretty trick even today, standard on all German fighters by 1941. By this measure military aviation standards are almost half a century ahead of civil aviation.

Edited November 14, 2010 by vanir

[DTWD]

Maybe not such a stupid question then :D

 

Thanks for the replies chaps.

[DTWD]

It's also worth considering that other WW2 technologies were still new and highly advanced in civil aviation when they hit the scene in the 70s, things such as the aeromechanical screw (one touch throttle/pitch control) which is still pretty trick even today, standard on all German fighters by 1941. By this measure military aviation standards are almost half a century ahead of civil aviation.

 

I am reading a book now about the BOB which has mentioned several times about the WW2 tech. I was suprised that IFF was around and before the end of the BOB it was standard kit. I always thought IFF was a product of the 80s, no real reason why I thought that, just did.

[nscode]

Does the book say how usable the WW2 IFF was? ;)

[flydragon126]

It just randomly popped into my head, things usually do when I am cleaning. Last weeks was "what language do deaf and dumb people think in?".

 

i guess people don't need to think in any literal language. a literal language in head is a repeat of thought only to make oneself more clear of the idea.

deaf and dumb people can still think in picture, color, sound, or other forms.

:huh:

 

edit: deaf people can't think in sound if they were deaf since born

Edited November 14, 2010 by flydragon126

[flydragon126]

As I understand it...

Magnetic north isn't axial north and it moves around relative to axial north because of a dynamic core producing the magnetic fields, when planning

 

 

interesting read :thumbup: :book:

[Brit_Radar_Dude]

....why can't they just use a compass?

 

Vanir's post has touched on the main reaons why.

 

Something else you should consider is that modern long range radars dont usually work as a standalone system. More likely they feed their data, along with other radars, into a central command and control system that builds up what is known as a RAP (Recognised Air Picture). Think of it as a map of the position of everything friendly and not friendly, their height, speed, course, etc.

 

To build a RAP from multiple radars, you need very accurate positions of exactly where those radars are and very accurate plots of the aircraft that those radar can see. The command and control system needs that accuracy so it can figure out whether an aircraft that radar A can see is the same aircraft that radar B can also see. Or maybe they are two seperate aircraft only visible to one radar each?

 

As Vanir's post mentioned - a compass and magnetic north is fine for dealing with short distances. But when you have a system such as NADGE - Nato's air defense command and control system that is building up a huge RAP from dozens of radars stretching right across Europe, then it isn't.

[Vault]

Most commercially available IRCCD and CCD cameras have electronic filters that block out the sun. You can see these filters overlay the sun @38 seconds in this video. I'd guess the filters on military grade cameras will be far more advanced.

 

Edited November 17, 2010 by Vault

[Jinro]

I thought this was why magnetic declination was calculated and put onto maps....

[GGTharos]

Yes, they do. In fact a valid fox two shot criteria is to not have the sun within x degrees of target.

 

When you get to the IIR seeker (AIM-9X), that can change in terms of the missile tracking a target, but no one's telling about what the algos do. All we know for sure is that it will happily ignore flares and strobe jammers.

 

 

EDIT: Hah. Already answered by Eddie :P

 

I am in the middle of hoovering and this just came to me:

 

Do IR missles ever have a tendency to follow/lock onto the sun? Is there some logic programmed into them to not do it, is the sun just not hot enough, are pilots just told it's best not to shoot the sun down, or is there something else?

 

It just randomly popped into my head, things usually do when I am cleaning. Last weeks was "what language do deaf and dumb people think in?".

 

I think it's boredom that fires off these random thoughts.

 

Anyway, IR missles and the sun.

Edited November 17, 2010 by GGTharos

[Shaman]

Personally I'd wait until hit before ejecting :)

 

Hehe..I wouldn't wait, but go defensive.

And if someone makes claims like wunderwaffe-IR-missile I am like *doh*

If weapons were so effective, wars would end within hours.

Edited November 17, 2010 by Shaman