The Luftwaffe came to know the Boeing B-17 Flying Fortress intimately. In the air they credited it with speed, load carrying, ruggedness and bristling defensive firepower. Based upon the principle that shooting down a single engine fighter gained the victor one point, the downing of a four-engine bomber was scored as three points. Two points were awarded for damaging a heavy bomber sufficient to force it to leave the safety of the combat box, what the Luftwaffe called "Herausschuss", literally meaning "shooting out." Only one point was awarded for "endgultige Vernichtung" (i.e. the final destruction) of a bomber that had become separated because this task was considered less hazardous. In the end, the Germans shot down over 4000 Flying Fortresses in combat. At first, American heavy bombers flew in combat boxes of 18 aircraft with succeeding boxes following 1.5 miles behind. To improve the defensive formation, this was replaced by the wing formation that combined three 18-plane groups. Also, instead of flying behind each other, the groups were positioned at high, medium and low level. The medium altitude group would fly slight ahead in the lead with the high squadron above and to the right while the low squadron beneath and on the left. The resulting 54 plane formation occupied a stretch of sky 600 yards long, a mile or so wide and half a mile deep. Other wings might fly identical formations to the target at six-mile intervals. The B-17 bristled with firepower. A combat wing of 54 aircraft, each carrying about 9000 rounds of ammunition, could bring to bear 648 50 cal machine guns firing 14 rounds a second with an effective range of 600 yds. The two-ounce bullets remained lethal against a human body at ranges up to 4 miles. B-17s had surprising little protective armor. Besides the armored seat backs, only the metal surrounding the waist gun cutouts and the bulkhead dividing the top turret gunners compartment from the bomb bay were reinforced with steelplate. The firewall dividing the cockpit from the navigators station was slightly reinforced but the nose section did not even have a steel deck for the bombardier. A B-17 formation, dubbed a "Pulk" (herd) by the Germans, was an unnerving sight for the novice sight for fighter pilots. With a combined closing speed of 500 mph both sides had only seconds to make their fire count. Barreling in at 200 yds per second a fighter pilot might have time for only a half-second burst before taking evasive action. "Fips" Phillips, a 200+ Eastern Front Ace wrote the following while in command of JG 1 defending against American Bombers over Northern Germany: "Against 20 Russians trying to shoot you down or even 20 Spitfires, it can be exciting, even fun. But curve in towards 40 fortresses and all your past sins flash before your eyes." The B-17s most vulnerable quarter of attack was from head-on, at least until the advent of the G-model with its twin gunned chin turret. The next best option was straight down from directly above and a bit behind but this technique called more precise flying. After mid 1944 there was an ever-decreasing number of Luftwaffe pilots who were cable of such precision on a regular basis. To reliably destroy a B-17, the attacker had to either break the integrity of the flight deck or explode the bombs in the bomb bay. Anything less only damaged the bomber. Hits on less vulnerable areas like the massive vertical stabilizer and rudder might cause the aircraft to slow but it would struggle on. Consolidated B-24 Liberators had a tendency to explode when hit but the B-17 rarely did. Attacking a formation of American bombers from the rear was foolhardy due to the coverging fire from the bombers tail and ball turret gunners. Tail attacks also exposed the fighter pilot to additional fire due to the reduced closure speed. The standard fighter approach from 1000 yards astern with an overtaking speed of 100 mph took over 18 seconds to close the distance down to 100 yards. Initially, head-on attacks were conducted with a flat angle of attack but this made judging the range to the target very difficult. German pilots were initially intimidated by the Fortress 104 ft wingspan. The urge to open fire from too far away and the breakaway too soon for fear of collision looming large in the gunsight was overwhelming. Further refinement of the tactic showed that the optimum angle of attack when approaching from head-on was from ten degrees above the horizontal, what American bombers crews came to call "12 Oclock High." This greatly simplified the problem of estimating range and permitted a constant angle of fire similar to ground strafing. When intercepting a bomber force, German fighter units initially flew a parallel course off to one side outside the range of the defensive guns. After reaching a point about 3 miles ahead, either three or four plane groups peeled off and swung 180 degrees around to attack head-on in rapid succession. It was critical for the fighters to maintain some semblance of cohesion, or at least visual contact, so after each pass they could regroup for repeated concentrated attacks. That was the theory anyway. In reality, many pilots ended the first pass with a split-S maneuver, inverting and diving down and away from the defensive fire above them. With increased experience, German fighters began to make their head-on attacks using either in line astern or with the entire unit spread out abreast in the "company front" formation. The recommended procedure was to pull up and over the bombers and then from their position of advantage above, the German fighters were quickly able to launch another attack. It was critical for the fighters to maintain some semblance of cohesion, or at least visual contact, so after each pass they could regroup for repeated concentrated attacks. That was the theory anyway. The huge tail fin of the Fortress posed a collision risk and many German pilots preferred to break away below. Either they dipped the noses of their aircraft and passed close underneath, or rolled inverted and broke hard down with the "Abschwung" (Split-S maneuver.) This took them well below the bombers and valuable minutes were lost before they could gain sufficient height to attack again. Lt Franz Stigler, a 500mission veteran describes a 1944 attack against American bombers in the excerpt below: "It was early 1944 and an unescorted formation of about 100 B-17s came up from the Mediterranean to bomb Germany. Our group of 36 aircraft was ordered off to intercept with my squadron flying high cover to ward off any escorting fighters, while the other two went after the bombers. We made contact just north of the Alps, a few miles from Munich. We had a good chance to inflict maximum damage to the Fortresses below us and I led my 12-plane squadron down in a screaming dive. We flashed past the high combat box in an overhead pass, continuing through through in a breakaway before climbing back up for another attack. With high speed built up in a dive, my aircraft made aircraft made a very fleeting target and the more vertical my descent, the more difficult it was for the top turret gunner to get an angle on me. I targeted the pilots cabin, the engines and wings oil and fuel tanks. On this type of approach, the firing time was extremely limited. I could get in only one short burst. But I was going so fast that I was also harder to hit and the real danger was that I might collide with my quarry. I was through the formation before he even saw me and climbing back for another pass." Attacks from above had the advantage of placing the vulnerable oil tanks (inside of the inboard engine nacelles) and wing fuel tanks (inside the outboard engine nacelles) directly in the attackers path. By the summer of 1943, the Germans had deployed the Focke Wulf FW 190A4, a dedicated bomber killer armed with two 7.9mm machine guns and four 20mm cannons. With all guns functioning, a three-second burst fired about 130 rounds of ammunition. The Luftwaffe estimated that it took an average of 20 hits from the 20mm cannon to destroy a B-17. Analysis of gun camera film revealed that the average German pilot scored hits with only 2 percent of the rounds fired, thus on average, 1000 rounds were fired to score the 20 hits required. Seeking to stem the armada of Allied bombers, the Germans tried dropping pre-set bombs on them timed to explode when they were at the same height as the stream. The Germans also employed 210mm, tube-launched, spin-stabilized rockets employing 248-pound projectiles with 80-pound warheads (a version of the German Armys "Nebelwerfer"). The warheads were time fused to detonate at between 600 to 1200 yds from the launch point. To inflict damage the rocket need only explode within 50 ft of the target although the warhead would also detonate if it struck a bomber. Often an exploding B17 caused enough damage to adjacent planes to bring down another or even two. Although not particularly accurate, the rockets served well to break up the formation. The added weight and increased drag of the installation severely degraded the performance of the German fighters and made them vulnerable to Allied fighter escorts. With the advent of American long-range fighters, the Germans were forced to change tactics again. They need to inflict damage on the bombers was ever increasing and to accomplish this their planes needed additional and heavier armament. The weight of these additions decreased the performance of their fighters such as to make them easy victims if Allied Fighters were encountered. The Luftwaffe answer was the "Gefechtsverband (battle formation) consisting a "Sturmgruppe" of heavily armored and armed FW-190A8s escorted by two "Begleitgruppen" of light fighters, often Bf 109Gs. The task of the light fighters was to engage the escort while the heavy fighters attacked the bombers. It was a great theory but difficult to employ. The massive German formations were unwieldy and took time to assemble. They were often intercepted by Allied Fighters and broken up before they reached the bombers but when they did make it through the results could be devastating. With their engines and cockpits heavily armored, the Sturmgruppen pilots braved the storm of fire and attacked from astern. Later in the war, the Germans introduced the Mk 108 30mm heavy cannon capable of firing 600 11-ounce high explosive rounds per minute. Three hits with this weapon were usually sufficient to bring down a Flying Fortress. On the other hand it was a low velocity weapon and its effective range was shorter than the 20-mm cannon forcing German pilots to fly even closer to get hits. The jet propelled Me 262 introduced in the last year of the war was 100 mph faster than contemporary piston-engine fighters and well armed with four 30mm cannons. In a head-on attack, its 350 yards per second closing rate was too fast to allow accurate aiming or to allow optimum use of its short-ranged armament. To overcome this, German Jet pilots used the "roller coaster" attack. Approaching from astern at about 6000 ft above the bombers, the jets pushed over into a shallow dive starting about 3 miles away. They quickly built up speed such that the escorts could not follow them. Diving down until they were about a mile behind and 1500 ft below, they pulled up sharply to bleed off speed, leveling off at 1000 yds astern in position to deliver an attack. Desperate to inflict massive losses on the American Bomber stream and force a month long bombing pause, the Germans concocted a plan for a massive ramming attack. Late in 1944, Oberst Hans-Joachim Herrman proposed using 800 or so high altitude Bf-109Gs stripped of armor and armament to reduce weight for such an attack. Lightened in this manner, he calculated the planes could reach 36,000 ft well above the American escort fighters ceiling. German pilot losses were predicted to be around 300, more or less what was lost in a normal months fighting. Aircraft losses would be much higher of course, but by this point numbers of aircraft were not the Luftwaffes problem. Trained pilots and especially fuel were. Fully trained fighter pilots were too valuable to be wasted in these attacks, so volunteers were called for from the training units. The first ramming unit, "Sonderkommando Elbe" formed in April 1945 and flew a single mission with 120 aircraft. Its inadequately trained pilots were unable to inflict much damage. Fifteen bombers were rammed but only 8 were destroyed. References: Fw 190 Aces of the Western Front by John Weal. Osprey Aircraft of the Aces No.9 Fighter Pilot Tactics by Mike Spick Stein and Day Publishers 1983 Aircraft Versus Aircraft by Norman L.R. Franks Macmillan Publishing Company 1986