Chaff in rocket flares for collision avoidance - any history?

[Oen]

A thought occurred:

Has there ever been an attempt to use chaff deployed by a low-height rocket as an attention-getter from a small craft to a large ship equipped with radar? I'm well aware of the uses of chaff to avoid detection, but have never heard of its use to aid detection...

 

[cameronke]

I think that is an excellent idea!

May not need a rocket though, maybe a fire work type mortar or even a blast of compressed air.

Cameron

 

[Oen]

I should have added that I'm not at all sure it would be feasible - given the requirement to have it show only briefly (otherwise, the chaff would drift rapidly away from the vessel it was being used to attract attention to, causing all sorts of grief).

 

[AlJones]

The RN had some for a while called Chaff Echo!

It was a rocket used to divert a missile away from the ship.

A 1 1/2 inch schomoolly was thought about being 'converted' for the Phalynx close quarter weapon, it was fire controlled radar operated, I am sure there are some greenies on here that could explain.

Great idea, go for it!

Al.

 

[halcyon]

Why not a balloon ? inflate by canistor, chaff attached to line. Stays in place, simple, set hieght and attached to boat.

Brian

 

[martinb]

[ QUOTE ]
Why not a balloon ? inflate by canistor, chaff attached to line. Stays in place, simple, set hieght and attached to boat.

Brian

[/ QUOTE ]

Would that not be a radar reflector rather than chaff?

Martin

 

[fisherman]

I was off the Lizard one day, in fog, trying to work with shipping passing close by. Suddenly the radar was blotted out. After a minute or two I saw what looked like thistledown floating overhead, and began to think an aircraft might have disintegrated. Called the CG, who called the Navy in Plymouth, who admitted to running an exercise. CG told them to pack it in immediately.
Point is, your chaff may render you invisible to everyone.
Funny thing, the Navy did a similar thing again, testing a jamming device. They knew it worked because of all the squawking from ships losing their radars in the fog. Funny they always choose a foggy day for this sort of stuff. Sorry about the thread drift.

 

[halcyon]

Matalic coated large ballon, what if high wind, the ballon would have to large.

If strips of foil streamed of the line, you would have a large fixed column, without a lot of windage.

Brian

 

[salamicollie]

Pains Wessex used to make one that had a red star (can't remember if it was on a chute or not) and chaff, not sure if they still do but wasn't a standard leisure flare!!!

 

[martinb]

Any radar reflector or radar decoy's effectiveness is measureed by the Radar Cross Section presented. Chaff is only effective when it is deployed in such a way that it disperses to present a large bloom or RCS, as it has a small physical size. A bunch of tin foil, even if streamed on a line, would have to be big to offer an RCS exceeding that of a good radar reflector. As pointed out by others, deploying chaff would obliterate radars, effectively hiding your vessel and adding to your woes.

Martin

 

[Cruiser2B]

Chaff does not obliterate radars - the navy doesn't want to blind itself in the middle of a battle, now does it? Chaff creates a better target for an incoming missile. It could be used as Oen suggested, but chaff launchers are a little large for the typical yacht. Better bet is the SeaMe; a racon transponder would be even better.

 

[grumpy_o_g]

Not sure that's a good idea - the whole idea of chaff is to hide things from a radar. Why not just get a SART? Much lighter, cleaner, easier and probably cheaper in the long run too..

Modern chaff is usually monfilament nylon (think 1lb breaking strain fishing line) coated in aluminium foil. It's either packed tightly in cylinders like a big fibre rope with all the strands in parallel or as one huge massive long reel. It's actually cut to the right length for the radar detected on it's way out of the dispenser. It's really meant to confuse radar so missiles and the like can't get a lock on a target. Being near a chaff dispenser when it goes off is a bit like rolling in dry chopped strand mat - little bits of fibre get everywhere and it's generally not to be recommended /forums/images/graemlins/shocked.gif

I think the RAF had to drop tons of tin foil chaff to blank out the ground radars during the second world war.

 

[martinb]

Appologies, you are corrrect, chaff would not obliterate a radar, but if a yacht deployed a chaff payload it would present a much larger radar cross section than the yacht, therefore obscuring the yacht from the radar. There are many strategies when deploying chaff in a hostile situation, if chaff were going to present a better target, as you suggest, then this would mean presenting a greater radar cross section to the detecting radar. This is effective, when coupled with manouvers etc, to avoid missile attack but perhaps not ideal for announcing your presence on a channel crossing.
I agree that an active device is probably far more effective.

Martin

 

[martinb]

Most modern chaff is in fact glass fibres coated with aluminium. Whilst a few dispensers cut rovings of chaff to length as it is deployed, most methods of dipensing involve pre cut lengths of chaff.

You are correct about WWII, chaff, or window, was aluminium foil that was deployed in huge quantities to confuse German radar, mostly to fool them into thinking that large attacks were taking place to divert resources whilst the main thrust of the attack took place elsewhere.

Martin

 

[graham]

A large blob appearing on the Radar then dissapearing could be ignored as a rain squall or some other anomally. Personally I dont think the Chaff idea has much merit unless navigating in the Shat el Arab perhaps.

 

[fisherman]

[ QUOTE ]
Chaff does not obliterate radars -


[/ QUOTE ]

Perhaps I didn't explain too well: alright, if it didn't obliterate the radar, it filled the screen with the effect that no targets could be seen. The Navy admitted to spreading chaff, and were told to stop, as the CG did not want any 'chaff assisted collisions'.
If you spread chaff about your position, you will resemble a heavy rain shower, and ships will not avoid you.

 

[LymingtonPugwash]

After a close miss in the Med with a gert great cruise liner, we messed around with an old space blanket (about double bed size) as they are very light and have a metallic coating.... we set a running line up the back stay and had a quick clip on shackle system so that we could run it up very quickly if required, then got our oppos in their boat to make see the difference on their radar from roughly a mile off but found that when it was flying straight as a flag, it really depended on the angle between the boats.... we did also try just tying it off on a single corner and flying the blanket just held by that one corner which had it sort of 'bunched up'.... that improved the 'angles' problem all round, but the trace wasn't as good as getting it at exactly the right angle flying as a flag! So.... not perfect, but a degree of compromise is required......

 

[capt_courageous]

The Yanks used to sell a 'radar flag' similar to that which you devised. It too had a very mixed performance.. It only really worked when flat and at right angles to the radar beam - as you might expect.

 

[sailorman]

best place for chavs /forums/images/graemlins/laugh.gif

 

[webcraft]

Surely the best gadget for avoiding collisions with large ships is AIS?

You can see their ID so you can call them up on 16 or send a DSC message in plenty of time.

(Yes, I know it is no use for small fishing boats etc - but is anything?)

- Nick