Classic Aircraft profiled every issue -

Issue 8 - Boeing B-17: The B-17G - The thoroughbred emerges

As has already been discussed, the main identifying feature of the B-17G, the twin .50 cal Bendix nose turret, had already been introduced on the last 86 B-17Fs to be built. This had been a feature of the failed ‘Fortress Fighter’, the YB-40 project and had been adopted for use on the bomber version to overcome the early types’ vulnerability to head-on attacks. As production of the B-17G continued, further changes were made to the defensive armament positions throughout the aircraft.

The first of these changes to be introduced was that the waist gun windows were staggered, the starboard window being placed forward of the port. Experience had shown that the waist gunners were continually interfering with one another while operating their guns, making the waist occasionally seem like a wrestling match when the formation came under heavy attack.

The windows were now fully enclosed with a proper flexible mount for the gun in the centre at the bottom, which increased crew comfort enormously. The howling, freezing gale blowing in through the waist windows was no longer a feature of rear B-17 crew life. The mount was also fitted with a coiled spring device called an equilibrator, which balanced the gun at the mount, reducing the effort required to haul the manually aimed gun about in combat, and therefore crew fatigue.

The nose cheek gun positions were also modified and standardised during production, so the port gun mount was now in the front window, and the starboard gun was in the second window. This reversed the positions of the late model B-17Fs, as experience showed that the navigator was better placed to operate the starboard gun when required. The Sperry A-1 upper turret also got a new plexiglass dome, higher and less cluttered with framing, so the flight engineer gunner now had a far better view.

Lastly, a new tail gun turret was at last devised to replace the uncomfortable and limited stinger position that had been a feature of all B-17s from the E onward. Introduced on the block 80 aircraft at Boeing, the twin .50 cal machine guns were finally in a proper turret mount for better traverse and elevation. The gunner had a larger plexiglass housing around him with less framing that gave him a far better view and a reflector gunsight replaced the earlier ‘ring and bead’ type. This modification had been worked out at the United Airlines Modification Centre in Cheyenne, Wyoming, and gave rise to the new turret being known as the ‘Cheyenne tail’. Aside from aircraft being built with the new turret fitted, modification teams also upgraded aircraft in the field from kits.

The B-17G had the same R-1820-97 as had been fitted to the F model, but the new aircraft had a service ceiling of about 2000 feet less than the earlier model, even though an improved version of the General Electric turbosupercharger was fitted which gave the type a service ceiling of 35,600 feet (10,851 m). These new turbosuperchargers were controlled electrically rather than hydraulically as had been the case. The G’s rate of climb suffered too; it took the G 11 minutes longer to reach 20,000 feet than it had the F. The extra weight of the new turret and other additions to the defensive armament was taking its toll on performance. The undercarriage had also been strengthened, because the gross weight of the B-17G was now an extraordinary 9000lb (4082kg) greater than the F model, at 65,500lb (29,710kg).

Interestingly, partly because of the weight issue, and partly because the formations of B-17s were now so large, leaving such massive condensation trails in their wake that they could be seen from 200 miles away, it was decided to leave the aircraft unpainted from January 1944 onwards. The paint weighed about 80lb (36kg), but more importantly the matt finish increased surface drag and slowed the aircraft down. Commanders in the field were given the choice to remove the paint from their existing aircraft as they came up for maintenance or repair, or to patch the paint, whichever was deemed easier and faster to get the aircraft back on the line.

Consequently, the formations of the 8th Air Force began to be made up of a mixture of bright silver new natural metal aircraft, newly camouflage painted aircraft and patched and faded camouflaged aircraft. The veteran aircraft would be quickly spotted in any formation, and this led to a kind of reverse snobbery, as the hardy survivors of the grindingly long bombing campaign really did look the part.
New looking aircraft and people in new uniforms were regarded with suspicion as being untried. The first thing a new officer did to his peaked cap was to remove the wire stiffener and roll the cap up to give it a look called the ‘50 mission crush’. Wearing headphones over it or stuffing the cap into any handy container on the aircraft for 50 missions would certainly cause it to wear and become misshapen, which was the look the wearer was trying to achieve. New was bad, raunchy and lived in was good, because it had survived.

Smaller internal changes included upgraded and improved cockpit instrumentation and a more powerful engine fire extinguisher system. The number of B-17s who had last been seen turning for home with an engine on fire was a matter of concern. The engines were positioned forward of their oil and fuel tanks, so any uncontrolled fire could conceivably burn back through and ignite or explode the tanks. Either way, this would cause the loss of the wing and therefore the aircraft, so the new extinguisher system was capable of multiple discharges in the event of a serious fire. Since the oil system had proved vulnerable to combat damage, an emergency oil system for feathering the propellers was introduced. A number of B-17s had returned home with missing ‘run-away’ propellers that had torn themselves off the airframe because the oil system was shot out and the pilots couldn’t feather them. This was a dangerous situation for a number of reasons.

The over-speeding propeller of the shut down engine might break off and come through the fuselage like a bandsaw, as happened on a number of occasions, or the engine might seize, leaving the aircraft with a huge amount of drag on one side. If it was the outer engine and the inner was also damaged, the pilots may not have enough control authority to overcome the drag, and lose control. The new emergency oil system at least gave the aircrew a backup to prevent these disasters.

Like many other wartime aircraft at that time, the modifications the airframe was capable of taking without becoming overweight had about reached a peak. The G was to be the masterpiece, the truly combat capable version of the Flying Fortress, but it was also to be the limit of the types’ adaptability. The B-17G was to be used almost exclusively by the US Air Forces operating over Europe, where its inherent strength and heavy defensive firepower were put to best use against strong opposition.

The first B-17Gs began to roll off the production lines in late August 1943, and the last Boeing built example was delivered on 13 April 1945, meaning that the three production lines had produced 8760 aircraft in only 20 months, an average of about 14 aircraft a day. Considering how complex the B-17 was, this is a remarkable achievement by any standards. The first B-17G was handed over to the USAAF on 4 September 1943 and began to reach front line units later that month.

The 8th Air Force was now the largest of the US Air Forces, and was penetrating deeper into enemy held territory than ever before. Due to the poor weather in Europe in winter, a number of aircraft in each group had been modified to become ‘pathfinders’. These were specially equipped B-17s or B-24s fitted with a number of the radio and radar navigation aids that the British Bomber Command were using at night. Gee was a navigation aid and Oboe was a system that allowed an aircraft to drop markers on a target by receiving triangulated radio signals from transmitters in England. The range of both of these systems was limited, both by German jamming and by the curvature of the earth. An advanced version of the British H2S airborne radar, termed H2X and codenamed ‘Mickey Mouse’, was fitted to a number of B-17s. The radome containing the radar antenna was fitted instead of either the ball or nose turret to a number of aircraft, but 12 late production B-17Fs were modified in the field to have a retractable radome behind and below the nose turret, giving the aircraft a distinctly double chinned look.

The radar was fitted to enable pathfinder aircraft to identify targets even through the thick cloud of the European winter, then to mark them with parachute flares or other devices to allow the rest of the formation to bomb on their marker. This system was not ideal, as the whole point of the B-17 as a weapon system was to bomb pinpoint targets accurately, but it did allow the offensive to continue while the weather would otherwise have made it impossible, and some remarkable results were achieved with it.

Despite the weather, there was no slackening of the pace of operations for the rapidly growing 8th Air Force. More airfields were being built, and more units were arriving, including the 401st Bomb Group, the first to be completely equipped with the B-17G, who took up residence at Deenethorpe on 3 November 1943. This unit was to achieve the second best rating for bombing accuracy in the 8th Air Force in its brief history, as it was deactivated shortly after the end of the war.

The number of fighter units was also growing, so fighter escort became the norm even for deep penetrations, when the bomber force would be met at various stages of the route by different units who had flown directly to the rendezvous points to conserve fuel and extend their range to the maximum. This changed again from November 1943 with the introduction of the 357th Fighter Group and their new fighter, the P-51B Mustang. As more of these superb fighters arrived in theatre, long range escort too and from the target became possible, and the concept of a daylight bombing force able to roam at will across enemy territory became a terrifyingly powerful reality.

The B-17s continued to suffer sometimes heavy losses despite all these improvements, particularly to flak and to the ever present, or so it seemed, Luftwaffe fighters. The Luftwaffe had introduced new weapons to combat the massive force of armoured and heavily armed bombers facing them. Large air launched unguided rockets with fragmentation warheads were carried by Me 110 and FW 190 fighters, and were intended to break up the tight bomber formations rather than shoot down individual aircraft, although they frequently did so.

The deployment of these rockets required the attacking fighter to fly straight and level toward the B-17 formation while delivering them, and in the face of a determined fighter escort, this was nigh on suicidal. Heavy cannon were experimented with, including a massive 50mm cannon, but the additional armament made the heavy fighter versions of such aircraft as the Bf109 and the FW190 relatively sluggish and slow to manoeuvre, and again they fell prey to the fighter escort. Armoured versions of the FW190 armed with additional under-wing cannon packs or unguided rockets began to make an appearance, as did a whole new generation of aircraft, the first rocket and jet powered fighters.

The Me163 rocket powered fighter was a point defence interceptor armed with two 30mm cannon. Small and fast, the aircraft made an agile opponent, difficult to see but armed with a heavy punch. The first German jet fighter was the Me262, a twin engined fighter armed with four 30mm cannon in a close grouping in the nose and unguided R4M rockets under the wings. The firepower of this aircraft, coupled with its great speed, made it horribly effective against the bomber formations. Only a short burst of a few rounds could rip the wing off a B-17, even with its upgraded armour. Fortunately for the American aircrews, the Me262 suffered from engine problems and were only ever available in small numbers toward the end of the war.

The late model P-51 Mustangs were so fast they could even catch the jet if they had the advantage of height, and several were shot down by the escorts. Despite the overwhelming numbers they were facing on a daily basis, the Luftwaffe fighter pilots fought like lions, regularly diving in to attack formations where they were outnumbered not tens, but hundreds to one. No one in the 8th Air Force had cause to doubt their bravery, but towards the end there was a tragic element to that courage, as there is nothing so brave as a man defending his home, even though he knows his cause is lost.

In the midst of all these developments, the hard working B-17 crews had a never ending stream of missions to complete. In the early part of 1944 there was an all out offensive against the German aircraft industry. The aim was to cripple German fighter production, prior to the much anticipated invasion of the continent, and to draw the Luftwaffe into a series of decisive battles in defence of the vital factories to finally establish Allied air superiority over Europe.

Officially termed ‘Operation Argument’, but more commonly called ‘Big Week’, the massive raids took place between 20 and 25 February 1944. Many of the targets were in cities far from the UK, so the raids were split between the 8th Air Force, who flew over 3000 sorties that week, and the newly formed 15th Air Force based around Foggia in Italy, who flew over 500 more. Aircraft factories and their airfields and heavy industrial plants in Leipzig, Brunswick, Gotha, Regensburg, Schweinfurt, Augsburg, Stuttgart in Germany and Steyr in Austria were all attacked, including the ball bearing works in Schweinfurt, infamous since the heavy losses of the attack in October the previous year. The difference between the first raid and the ‘Big Week’ raids was a simple one. Numbers.

Imagine dawn on 20 February 1944, living in East Anglia. Snow showers have left a sprinkling across the fenland counties during the night, and it is bitterly cold under dark leaden, heavy clouds. The light north-easterly breeze has a real chill in it with the promise of more snow. Steadily, a rumbling grows, increasing in depth and volume until everything seems to be shaking in its strident thunder. The sky seems darker still as a shroud of aluminium is steadily unveiled across it.

Four thousand Wright Cyclones bellow insistently across the land. The ‘Mighty Eighth’ are going to war. 1000 bombers are airborne in 16 combat wings aiming for 12 separate targets in Germany, and this is just the first raid of the week, all the raids despatched were of this magnitude. On this first raid, only 21 bombers were lost out of the entire force, partly due to the German fighter force being confused by the multiple large raids and only successfully intercepting one of them in large numbers, and partly due to the sheer scale of the raid. It was also the only time three Congressional Medal of Honours were awarded to UK based aircrew in a single day.

1st Lt William R Lawley of the 305th BG brought his crippled B-17 back, despite being severely wounded in the face and his co-pilot killed. He landed the aircraft at Redhill, with two engines out and another on fire, to successfully save his seven wounded crewmen who could not parachute to safety. On board a 351st BG B-17, a cannon shell exploded in the cockpit, killing the co-pilot and rendering the pilot unconscious. The aircraft began to fly erratically, so the bombardier ordered the crew to bale out and jumped himself. Ball turret gunner and flight engineer Sgt Archie Mathies and navigator Walter Truemper regained control, and with the rest of the crew set course for England, despite neither Mathies nor Truemper having any real flying experience. The cold blasting air in the shattered cockpit meant that the crew had to take it in turns to keep the aircraft straight and level, no-one could stand the numbing airflow for long. On arriving over Polebrook, the rest of the crew were ordered to bale out, and the two men tried to land to save the wounded pilots life. They were talked down on the radio twice, but both times were too high and had to abort. Sadly, on the third attempt, the aircraft stalled and crashed, and the brave Mathies and Truemper were killed. The unconscious pilot was recovered alive from the wreckage, but died later of his wounds.

Tales of extraordinary heroism like these were happening every day among the B-17 crews, this is simply how life was for them. Their utter determination to succeed, regardless of odds or wounds, is what makes up a large part of the B-17 legend. It was the quality of the people as much as the machine that made the daylight bombing campaign both possible and ultimately successful.

‘Big Week’ cost the 8th Air Force 97 B-17s and 40 B-24s, with another 23 aircraft having to be written off and scrapped due to the nature of the damage inflicted on them.  The 15th Air Force lost 90 aircraft on their raids, the numbers being exacerbated by the fact that damaged aircraft had to negotiate the Alps to return to their bases in southern Italy. Although these numbers seem high, in terms of the size of the raids, losses were extremely light. The best example is the second raid on Schweinfurt; the first raid on 17 August 1943 had cost the 8th Air Force nearly one third of the attacking force, on the ‘Big Week’ raid, this fell to under seven percent.

A great deal of damage was done to the German aircraft industry, but this was to recover by dispersing the factories, many to underground and secret sites. The Luftwaffe pilots were feeling the attrition effects of fighting a war on three fronts, and never again really challenged the bomber raids in the way they had in 1943. The twin-engined fighter units had suffered horrendous casualties to the Allied fighter escorts, and were withdrawn from the air defence role completely. Air superiority was now with the Allies, and the Luftwaffe was never to regain it.

The 8th Air Force, now with 30 heavy bombardment groups and the largest US Air Force by far, began to roam at will over Germany, trying to force the remaining Luftwaffe fighters up to fight. The first raid on Berlin took place on 4 March 1944. 730 heavy bombers, mostly B-17s, were escorted by 800 fighters. Although 69 B-17s were lost, it was a strike against the German capital in daylight. It is said that the leader of the German fighter forces, Major General Adolf Galland was outside the Air Ministry building when the air raid sirens sounded. He looked up, and saw single engined fighters escorting the bombers over Berlin, and knew they must have come from England. He turned to his companion and said, “That’s it, we’ve lost the war.”

Sadly, it was to take over another year of fighting and many more lives before that statement became true. The CBO finished on 1 April 1944, and the Allied Air Forces went over to sorties aimed at preparing the way for the invasion of the continent in June. The strategic bombing campaign continued, but the priority of targets had changed. Many B-17s would be lost, but never in the numbers that had stricken the 8th Air Force previously.

The end was in sight, and when it came the massive B-17 force was to almost completely disappear within a year. The B-17G was produced in greater numbers than any other model, right up to the end of the war, but it was already rendered obsolete by aircraft like the B-29. Small numbers of the aircraft ended up in secondary roles, but many were scrapped, or put out into the desert airfields to await disposal. A sad end for a strong and reliable machine. However, some were to survive, some in very unusual ways, as will be discussed in the next articles.

Words: Tim Callaway