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Guns R Us

New Trigger-Nonmetry

Flexible gunnery has been worked out to a mathematical formula, a system called "position firing" which is based upon speed, course, air density, deflection, and many other factors. Despite these calculations it is much simpler and more accurate than older sighting methods.

If the man behind the gun can't protect his plane from enemy fighters, the world's best pilots, bombardiers and navigators are rendered useless. There is no denying the importance of flexible gunnery to the accomplishment of our mission, and statistics from the combat areas are backing up that fact.

We also are more than ever aware of the difficult and complicated task facing the gunner. The bombardier, for example, aims at a stationary target from a plane being held on a straight and steady bombing run. But the gunner is firing from a platform moving 250 miles an hour in any direction and trying to hit an object moving perhaps 350 miles an hour in a different direction.

Every schoolboy knows that a hunter has to aim slightly in front of a flying duck - has to "lead" it - to allow for the distance the duck will have flown by the time the bullet reaches it. He also knows that if a newsboy on a bicycle aims directly at the customer's porch when he throws a rolled newspaper, it won't land on the porch but probably in the bushes next door because he has failed to allow for the forward motion of the bicycle.

Put these factors together, boost the speed up to hundreds of miles an hour, let the directions be forward, backward, up, down, toward you, away from you, or any combination of these directions, and you get the beginnings of an idea of the gunner's job. The problem is not easy. Nor is it impossible.

Good minds went to work on it long ago. What it Would take, all agreed, would be a means of simplifying the gunner's sighting methods. The task was undertaken simultaneously by three different groups of mathematicians, who took a system developed by the RAF, refined it, and came up with something interesting.

In Detroit, a Navy consultant worked on it. At the Aberdeen Proving Ground, the Ordnance Department provided new ballistic tables and then the National Research Defense Council worked on it. In North Africa, three operations analysts with the 9th Air Force developed an improved sighting system and checked its results in actual combat.

What these experts did was to work out the complicated mathematical formulas governing the relation between the bomber's direction and speed and the enemy fighter's course and speed. Then they calculated the amount of lead, or deflection, which the gunner had to allow to hit the fighter at any instant of attack. To do that, they had to make exact allowances for the bomber's speed, the muzzle Velocity of its machine guns, the varying density of the air at different altitudes, the direction of the fighter with relation to the bomber's line of flight, and the fighter's speed and range.

Despite all these variable factors, the braintrusters working independently in Michigan, Maryland, and North Africa came up with essentially the same equation for calculating deflection. The mathematics were formidable, but the answers - and the answers are the gunner's concern - are surprisingly simple. The result is a system known as "position firing." It is a development of great significance. And the beauty of position firing is that it is both simpler and more accurate than the older sighting methods. It proceeds upon the doctrine that while every enemy fighter is dangerous and needs watching, he becomes most dangerous and at the same time easiest to hit when he starts a direct attack. To hit your bomber, he must keep aiming at the spot where his target will be by the time his bullets get there. To keep aiming at this spot, he must fly in a slight curve. This is called the pursuit curve.

Broadly defined, position firing is a method of calculating lead or deflection based on the enemy fighter's angle of attack and the subsequent angles along a pursuit curve which the enemy fighter must follow to get continuous hits on you. More simply, it is a system by which the gunner's deflections are figured out for him in advance; he comes to use these calculations almost automatically.

As the enemy fighter flies along the pursuit curve, he slides in toward the tail of the bomber he is attacking. Because this curve is predictable, the fighter becomes vulnerable to the fire of the gunner who understands the principle that the forward speed of his own plane is added to the speed of his bullet. The bullet keeps this forward speed no matter what the direction of the aim - above, below, or to either side.

The drag of the air on the bullet is, of course, another factor. This air resistance we used to call trail; now we call it what it really is: bullet slow-down. It is important for some shots, but not nearly as important as the effect of the motion of the gunner's own airplane on the direction of the bullet.

This is not to say that the principle of bullet slow-down may be disrcarded. The gunner should fully understand this factor. The combined effects of bullet slow-down and of the forward motion of the gunner's own airplane sometimes lead to faulty observation by the gunner. Many, having observed the behavior of a tracer bullet fired from an airplane, will argue that it moves in a curve. This is an optical illusion; it dues, indeed, appear to curve in the direction opposite that of the airplane from which it fired. Actually, except for the downward curve caused by the force of gravity, the bullet moves in a straight line. The explanation of the illusion is that the bullet loses speed as it flies, while the airplane from which it is fired continues to move at constant speed. If the relative speed of the airplane and that of the bullet remain constant, the bullet's path would appear to be the straight line that it is. Gunners, therefore, must not rely on tracers to disclose the behavior of their fire. What the gunner sees as his tracer flies out into space may not be in line with the facts.

Ways of teaching the new system of gunnery have been worked out by the Instructors School (Flexible Gunnery) at Fort Myers, Florida, and these instruction methods are being passed along to AAF gunnery schools. Existing training devices like the Waller trainer, in which the gunnery student bangs away with an electric gun at movies of fighter planes projected on the inside of a spherical screen, are being adapted to the teaching of position firing. Brand new practice gadgets, which will enable the student to fire real ammunition from a real turret at model airplanes and hit a target only if he has used the right deflection, are being devised.

Tracer Ammo In the military, past practices often take on a life of their own and soon become venerated truths. A fundamental truth in World War II, that may not have been so true, was that tracer ammunition in machine guns aided the gunner's accuracy. In fact, tracer ammo may have actually been more a hindrance than a help. Tracer ammunition, the bullets that leave a colorful trail behind then so the gunner can tell where his rounds are going, came into wide use during World War I. U.S. units generally had a tracer as every fifth round in a belt of machine gun ammunition. Quite naturally, this practice was carried over to WWII. After all, what was good enough to kick the Kaiser in the pants, was also good enough for the Fuhrer's rear end. However, WWII exposed some problems with tracer ammunition. One problem was that fighter pilots flew in enclosed cockpits and it can get pretty nippy at 30,000 feet or so. Sitting in what was essentially a sealed environment, wearing headphones and suffering the roar of a powerful engine, a German fighter jock couldn't hear the sonic "crack" of a bullet whistling past his ears like his daddy could in an open cockpit biplane in WWI and take it as a warning. Because he flew in a cocoon of sorts when GI Joe opened up on him, Fritz had no idea he was being stalked. At least he didn't know until lie saw a single tracer bullet rocket past his canopy. Suddenly, he suspected someone up there didn't like him and he would take evasive action. Since most air-to-air combat kills were the result of surprising the other guy, sneaking up behind him and hammering away with your guns, tracers let your enemy know he was a target and encouraged him to take corrective measures, and fast. To further aggravate things, most U.S. fighter groups placed fifteen or so tracer rounds near the end of ammo belts to let the fighter pilot know he was about out of ammunition and needed to call it quits for the day. Sadly, the enemy figured this out, so the bad guys could also tell when the the good guys were nearly out of fight. At this point, he who had previously been an opponent became "easy pickings." As far as anyone knows, no one has ever tried to determine how many pilots never made it back to base because the enemy was "reading the mail," watching for that grand finale that was intended to make it safer for the fighter jocks. Still, the biggest problem was that the guns used in WWII were a good deal larger, more powerful and consequently had a much greater range than the weapons used on the wood and fabric kites of WWI. In theory, this meant that the enemy could be engaged at a greater distance. But since the tracer rounds had a hollow base to accommodate their "flare," they had different flight characteristics at full range than the regular rounds in the belt. As the tracer chemicals burned themselves out in flight, the weight and balance of the bullet changed and this would change the trajectory. As a consequence, through no fault of the shooter, the tracer bullets had a slightly different flight path than the rest of the rounds. Since the fighter pilot expected the tracers to show him where his round were going, he concentrated on the glow of the tracer stream and consequently got relatively fewer rounds on the target. Before the Second World War, there hadn't been enough air-to-air combat to uncover the shortcomings of tracer ammunition, and since pilots didn't train by shooting live ammunition at each other, it wasn't until after a year or so of on-the-job training in WWII that it was determined what should have been an asset was actually a liability. When tracers were no longer used, the kill ratios of the fighter groups tended to increase and their losses declined. Ed. Note: Gunners attempting to defend their bombers during a mission experienced the same problems with accuracy as did their Little Friends. Had their bomber stood still, when they fired their guns, they would not see the misleading tracers "going around the curve" and appearing to be going into an enemy plane - they were really seeing the tracers from the side as the gunners flew away from their firing position. Reprinted From the Badger News. Tracer Ammo: Maybe not as much help as you thought! The Journal 2nd Air Division. Volume 43 Number 2, Summer 2004.

An animated movie, which will make the theory of position firing almost as easy to understand as Mickey Mouse, is in the works. So is the new Gunner's Information File, a looseleaf textbook that will combine pictures and drawings with a simple text to teach position firing, as well as the complicated workings of machine guns and turrets. A pictorial manual, Written in terms simple enough for a fifth grader to grasp, is being distributed.

The men who know gunnery best are confident that the AAF soon will have thousands of aerial Annie Oakleys who will be able to push the fighters-downed-to-bombers-downed ratio up to the point where it belongs and keep it there.

Reprinted From Air Force, Febuary 1944. "Guns R Us": New Trigger-Nometry. The Journal 2nd Air Division. Volume 42 Number 4, Winter 2003/2004.

389th Gunnery Briefing

Many Eighth Air Force Groups are convinced that a thorough briefing for the gunners before each mission has a lot to do with keeping up their efficiency and morale.

To get some idea of how this works, we sent our best reporter - the one who can read and write - over to the 389th where the Gunnery Officer, Capt John Driscoll, keeps thirigs clicking Ike a six-pence slot machine.

Nobody's claiming this is the only Group that does a good briefing job, or that every Group should operate in exactly the same way. But here's how the 389th does it, and if you like these ideas, help yourself.

The gunners have a special briefing of their own. Driscoll never misses a briefing if he's at the station, and in addition there's a gunnery officer or an NCO from every squadron to settle any minor problems that may arise.

Did some guy forget his dog tags? There's a car available to run him back to his barracks pdq. If another guy doesn't have a flak helmet, or his mike switch isn't working right, or anything else is fouled up, it's handled on the spot. Prevents a lot of needless worrying on the part of the gunners.

Driscoll calls the role of the pilots' names, and the engineers answer. If any crew is short a man, the squadron representative, in liaison with squadron ops, arranges the replacement immediately.

The gunners get a time tick, same as the offcers on the crew That's because the gunners are told exactly when they should pick up the fighter escort.

If the visibility is bad that day, Capt Driscoll gives out with a few special precautions: wear chutes while forming, and be sure to stow the chute in the same place every time so you can grab it in a hurry. Driscoll should know - he's been in two mid-air collisions.

Then comes the general mission picture: target; flak; route in; method of bombing; withdrawal and route home; time and temperature at altitude; position of other 2nd Division Groups; length of the mission; gas load; bomb load and fusing; ammunition carried.

At the 389th, gunners charge two or three rounds through their guns before take-off to make sure they're feeding properly, first making sure the guns are pointed in a safe direction and that the trigger switch is off, or the adapter safety on. Many groups would object violently to this procedure; it's probably a more common SOP for gunners to charge their guns after the plane is airborne.

Except when there are solid clouds, gunners always test fire over the channel. The co-pilot of the navigator gives the OK and indicates a safe direction; if gunners don't receive an OK, they are instructed to ask for permission.

Then comes the important part: the latest dope on enemy tactics, and the most practical counter measures. Right now Capt Driscoll is stressing the mass nose attack, the company front tail attack, and the possibility of jet plane attacks.

On nose attacks, the gunners are told: open fire at 1,000 yards and keep firing all the way in; pick the plane that's nearest dead ahead and concentrate on it; if there's a noticeable angle off, use the Position Firing rules; if not, fire point-blank, and if you see any relative motion, lead half a rad in that direction. Same rules apply to the tail attacks, except that bursts are limited to 1 to 2 seconds. "The main point we try to put over about the 163," Capt Driscoll said, "is that it's not something super human we can't do anything about. It's an airplane. It has a pilot in it. It has wings and controls we can shoot up. It has a lot of inflammable fuel that doesn't mix well API ammunition. If a gunner uses his head and his training, he can take the 163."

Miscellaneous gunnery instructions include: fire at any enemy aircraft within 1,000 yards, whether it's attacking or not, but don't waste much ammunition on non-attacking planes; fire at any unidentified airplane within range that points its nose at you; fire point blank at any plane that closes within 50 yards or less; on breakaway shots, lead one rad in the direction of apparent motion.

Each position is briefed on its zone of search and the types of attacks it may have to handle. Waist gunners are warned to keep a high and low search for climbing or diving jet planes. The top turret gunner's zone of search is primarily forward, because of the greater speed of nose attacks, but he also keeps an eye on clouds, contrails, or any other point from which attacks may be expected.

Gunners are then briefed on interphone discipline. Planes over 1,000 yards away are reported by the top turret gunner and by him only. If any other gunner spots planes out of range, he watches them but doesn't report them unless they come within 1,000 yards, or go out of his field of vision and should be picked up by another gunner.

This keeps interphone chatter to a minimum. If a group is broken by flak or fighters, and small elements of enemy aircraft start drilling in from all directions, it's important to keep interphone reports as few and as brief as possible.

... for the gunners and friends, this was always a dress up party ... Following briefing, into a locker room to dress. Long johns, then a silk tight fitting outfit, then an electric suit made of some kind of flannel like material with electric wire heating, heavy socks, silk socks and silk gloves, then felt socks and felt gloves with electric wiring. Each piece of the electrically heated clothing was connected to other pieces with metal snaps. If a connection went out, that extremity could be in trouble, even lost. Finally, a leather flying suit including helmet, boots and gloves. Then to the equipment room for a chute and emergency pack. In the emergency pack were maps of the location being bombed, currency for the area, some emergency rations including chocolate, buscuits, spam and cheese. A last move, grab your GI shoes, and with a snap, attach them to the chute so that if shot down, you'd have comfortable walking shoes.

That's about it. There may be brief reminders on cold weather precautions, New crews are briefed on chaff procedure - the chaff chutes are in the waist in the 389th. There's a Medical Officer at the briefing in case he's needed. And, finally, the crews split up for brief services conducted by the Catholic and Protestant Chaplains. The services are almost unanimously atttended.

Crews of the 389th like the briefings. They climb into their planes knowing where they are going, how long it'll take, and what to expect. When briefings were omitted around D-Day the gunners were pretty unhappy about it.

Capt Driscoll holds gunnery critiques about once a month. Gunners air their gripes about equipment, procedure, or anything else. Driscoll types up a list of all modifications requested by gunners, and it goes directly to the Group CO, Col Ramsey Potts, who gives the gunnery program plenty of cooperation. Gripes uncovered in the gunnery critique are taken care of, but immediately.

Occasionally a Gunnery Officer from some other Group attends one of the 389th briefings to see what it's like. Visiting firemen in this category are always welcome.

Short Bursts. 389th Gunnery Briefing. August 1944. 389th Bomb Group Newsletter. Vol., 18 #3 Summer, 2005.

Gunner An Illustrated History of WWII Aircraft Turrets and Gun Positions. Donald Nijboer with photographs by Dan Patterson. Remarkable photography puts you in the cramped, cold, exposed turrets in which many young men fought and died, as veterans describe in spirited detail what it was like to fly and fight in the war's most renowned aircraft. This book, unlike any other, allows you to imagine what it must have been like to be an air gunner in WWII.

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