Parachute Flares

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Sailfree

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Bought the latest RYA DS & YM booklets at LIB and after a quick read noted that these flares should be fired downwind in strong wind conditions.

My memory of when I did the YM and Sea Survival was that they should be fired up wind so that the wind drifts them over your position to assist location. This made sense to me.

Was I told wrong or did I misunderstand or has this advice changed in the last 10 years?

Can anyone give the rationale for downwind?
 
Because if you fire upwind then all the crap that comes off it during launch ends up in YOUR FACE!!

I believe the parachute flares track into the wind (how?) so they end up above you anyway.
 
Yep, downwind, about 15 deg to the vertical; somehow the aerodynamics bring it back overhead. If you fire upwind it can dive into the sea.
 
I fired one off recently and stood with my back to the wind and pointed it upwards, it went as it should like a rocket. it went really high and stayed above us but slowly drifting to leeward for quite a while. Waste of time though 'cos the yacht only a mile away did not see it at all.
 
I was told once (don't know how true this is) that the wind pushes on the "tail" or exhaust of the flare and this tends to push the bottom of the flare downwind, consequently bringing the top of the flare back up into the wind.

Actually it was my father that told me so it is probably a load of bollocks.
 
The theory is that if you fire it upwind you are wasting some of the rocket's energy fighting against the wind and so it will not reach its maximum height.
I attended several updating courses at Pains Wessex at Old Sarum in the days when I was an RYA demonstrator (demos now done by RNLI) and this was shown to us on the firing range on Salisbury Plain. It was right, too.
So, fire about 10 to 15 degrees off the vertical downwind for maximum height, about 1000m.
 
Fire it slightly downwind.

Reason 1. The "launching crud" blows away from you.

Reason 2. It is a solid fuelled rocket where the fuel burns away from the bottom. During flight the Centre of Gravity moves upward but the Centre of Lateral Resistance stays in the same position because the tube containing the fuel remains unchanged.
When the CofG becomes above the CofLR then it turns into wind.

So you would expect it to follow a parabola when fired slightly downwind. It will initially go up wards with a slight downwind drift followed by a sharp curve upwind. Ideally you want it to burst a bit upwind of you so that it is seen as being above you as the para drifts down wind.

If you wonder about this, consider the flight of the 81mm mortar bomb which, on its descent , has more lateral wind resistance on the tail fins rather that the rounded body which causes it to descend to a point upwind of apex of its flight.

Simple answer;
Fire it with your back to the wind, aimed slightly away from you.(This will come naturally).

The "muck" will blow away from you and it will burst slightly up wind of above you and drift over your position.

Then use a hand held to pin-point your position.
 
Definitely fire down wind.

Interesting analogy, I wonder how many forumites are familiar with the flight characteristics of an 81mm mortar round. /forums/images/graemlins/smile.gif
 
a couple of years ago i watched pwllheli lifeboat man fire the maroon, it was blowing a hooly and it was pointing downwind, dont know what went wrong but it went horizontal with the wind, just cleared my mast head, headed for land and sea tin shed on the north side of the harbour, just missed the apex and scared the living [--word removed--] out of them just to the north of them when it went BANG!!
was hilarious when we realised that nobody had got hurt!!
Stu
 
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