EYE SHOOTING, PART 8: WIND

[Music] wind is the third case when the direction in which the fusel AR is pointing does not truly indicate the direction of sight of an aircraft the effect of wind on an Airborne object is to carry it to lurd at the same speed as the wind itself like this barage balloon if it breaks a drift the same thing happens to an aircraft its fuselage may be pointing in a certain direction and it may have a certain air speed in that direction but all the time it is being carried bodily down wind like this when viewing an aircraft Through Your Gun Site you know that you have to judge the aor from the appearance of the aircraft and your knowledge of its air speed you must still do so if the wind is blowing but it is obvious that in order to hit the aircraft you must aim to lure of where you would have done had no wind been blowing let us take a bird's eye view of three cases the there is an aircraft at p and it's pointing along this line but Dowing to the wind it will actually travel in this direction its future position being here if your ship or gun position were down here the aircraft at P would be pointing straight at you but would actually be moving to your left from your own ship it would look like this if your ship was on the left here the aircraft at P would be pointing to your right but would actually be coming straight towards you this is what you would see the aircraft craing towards you this is rather a special case the general case is if your ship here on the right the aircraft is already pointing to your left but because of wind it will actually move further to your left in the direction of the fuselage might lead you to suppose the Gunner would see this and obviously to hit the target he must aim to lure it of where he would have done had no wind been blowing this is sh Common Sense think of the balloon before explaining how much alarm to make the wind and how to make this alance I want you to consider two points the first is the effect of own speed here is a ship steaming along with the guns crew closed up obviously the speed of own ship in this direction will be imparted to the projectile as it leaves the muzzle of the gun this must be allowed for but fortunately the true wind is modif Side by own ship speed and you feel an apparent wind which is not the same as the true wind if you use this wind you feel in deciding how much wind alarms to make you automatically correct for the effect of own speed on the projectile so much for the first point effective own speed use apparent wind and you'll be all right this fellow is just testing the wind he feels the second point is the direction of apparent wind relative to the line of sight if the apparent wind is at right angles to the line of sight the aircraft will be blown sideways to this point during the time of flight of the projectile if however the parent wind though the same strength as before was in this direction the aircraft would be blown down here during the time of flight thus it would only be carried sideways this amount as compared with this amount in the first case that is because the apparent wind in this direction is not blowing across so much as in this direction therefore it's the strength of the apparent wind across which determines how much the target appears to be blown sideways this is the first case here is the second case with the same strength of apparent wind but not blowing across so much this brings us to the straightforward rule for wind alarms aim to lure allowing for 2/3 of the strength of the apparent wind across why only 2/3 why not the full strength because the projectile is also carried down wind a bit but nothing like so much of the aircraft therefore if the apparent wind is 15 knots directly across the line of sight that is a moderate wind allow a 10 knot correction if the apparent wind is 30 knots directly across the line of sight that's a strong wind allow a 20 knot correction and so on allowing 2/3 of the apparent wind to cross Having learned the rules how are we going to apply the necessary wind correction viewed through your sight you assess the aircraft in the normal manner of having a certain aim of speed in a certain direction the center of the site shows where the the gun is pointing to allow for a strong wind across in this direction we want the gun pointed say 20 knots to lured we can do this by imagining a point along this horizontal bar 20 knots to window to the center and make the aircraft fly towards this point instead of the center this obviously makes the guno 20 knots toed so you see that by selecting a point the required number of knots to Windward to the center the gun is actually aimed to lure by that amount if the windross is 20 knots in this direction you would select your point about 14 knots to windred and thus aim your gun to lure the right amount at two man gun L and trainer must agree beforehand on the allowance to be made for the apparent wind across so that each is thinking at the same point as the imaginary center of his sight and they can therefore cooperate in making the correct wind L here off foro that's all very fine but as a about to think of all this when he's been attacked now when I was in Norway yes I know when you were in Norway you found it was too late to make nice wind calculations when the enemy was in sight and that is precisely why I must always act as followed this is what you should do on All Occasions of closing up here's your ship and here's your gun we'll suppose it has this Arc of far you close up and at once you note the strength and direction of the wind you feel the our defense officer or in small ships the officer of the watch should pass through this but you must be prepared to make your own estimate we'll say it's 30 knots a strong wind now divide your Arc of far up into convenient sectors for most guns they will be bow beam and quarter and decide how much wind across to allow for in each sector on the bar you're firing into the wind no sideways alarms necessary in this sector here on the beam the wind is more across about 15 knots and on the quarter here the apparent wind is blowing almost directly across 30 knots knowing the wind across memorize the alance you're going to make when afterwards engaging Targets in these sectors on the B no l beam 10 knots quarter 20 knots 2/3 in each case here one coming in on the beam you know at once that in this sector you're going to allow a 10 knot correction because you thought it out beforehand don't forget however that if your own ship Alters cost you must think again the wind you feel is going to be different and the alliances necessary on B Beam and quarter are quite different you'll notice that even on a fat calm day a low-level bomber has to allow for the speed of his Target so as to come in on a steady bearing but you have engaged the wind you feel will allow for this here he is coming in the was lying about 15 knots he knew his apparent wind alance and was ready for all attacks yes but what about attacks up or downwind when I was in Norway you're quite right you've done it again when you were in Norway the aircraft always preferred to attack up or down wind didn't he definitely of course he did it makes his bombing more accurate that's it and if you want to hit him you must apply exactly the same rules as before now look let's have a quiet glance at this it's only Common Sense here's the ship and here for the moment is the aircraft approaching the blob indicates its future position and if there were no wind if you aimed there you'd hit it but if the wind is behind the aircraft it will increase its rate of approach and more up aor will be required so you aim here this is after all only aiming to lured as before conversely if the aircraft is flying into a headwind you'd aim here less up aim or required in the case of a dive bomber momently in this position with the wind behind it the aircraft will be carried forward like this rather as though there were an extra lift effect obviously more at aamos required have a look at it through the sight see him taking more up amamos to allow for lift and wind cu the winds behind the aircraft in this case note that when targets a downwind or up wind it is the angle of sight which affects the wind alarms necessary for a given wind speed with the aircraft up here the alliance for wind is greater than with the Target down here although the wind is the same both aircraft are blown the same amount but the effect of wind is that much as compared with that much this is because the hard the angle of sight the more the wind is across the line of fire in a vertical Direction down here the wind across in a vertical direction is very slight and so wind Alliance is almost nil but up here You' allow for the full strength of the wind using the same rule as before aim to lower 2/3 of the wind speed remember then that as the target approaches up wind or downwind you start making little alarms for wind the right hand picture should window LS being taken left hand picture not being taken this is a 200 knot aircraft parent wind 30 knots as the angle of sight gets high allow more and more until with the Target right over head or allowing 20 knots more so much for banking don't forget to forecast diving aircraft don't forget to allow a [Music] lift and wind don't be caught napping have your alarms ready beforehand and when in doubt allow 10 knots toer for a light wind and 20 knots toer for a strong wind for