B17 Flying Fortress
|The Boeing B-17F "Flying Fortress." This aircraft lacks the "chin" turret on the B-17G.
The Boeing B-17, and the
Consolidated B-24 were the United States' two standard heavy bombers until the introduction
of the B-29 Superfortress. B-17s were flown by the United States Army Air Corps (USAAC), throughout
the American participation in the Second World War. They were used by the US Eighth Air Force, based in the UK, to bombard
German targets in Europe during daylight hours, a method which resulted initially in very heavy losses of aircraft and crew.
As B-17 refinements progressed, along with better pilot training and tactics, it would become a formidable adversary in the
Allied war against Germany.
The Flying Fortress was designed for a USAAC competition, announced in 1934, to find a modern replacement
for the assorted Keystone biplane bombers, then in service.1 The requirement
was for a multi-engined bomber to be used mostly as a coastal-defense aircraft. Specifications required were: a range of at
least 1,020 miles (1,641 km), but preferably 2,200 miles (3,540 km); a speed of at least 200 mph (322 km/h), but preferably
250 mph (402 km/h); a capability of carrying a 2,000 lb (907 kg) bomb load.2
A Boeing design team began work on the Model 299 prototype in June 1934, and construction began in August of the same year.
(The most significant rival to the Model 299 was the Douglas DB-1, which later developed into the Douglas B-18 Bolo.) The
Model 299 was make-or-break gamble for Boeing,3 which first flew on July 28,1935,
and eventually won the competition. Boeing built a few preproduction Y1B-17s (later redesignated B-17As), followed by one
Y1B-17A, and then followed by thirty-nine B-17Bs. Since funding was lacking at the time, only thirty Flying Fortresses were
fully operational when Hitler's forces invaded Poland in September 1939.4
The US was not involved in the fighting in Europe at the time, so it did not seem to be a matter of urgency. However, as it
became clearer that US involvement was inevitable, after the Munich Crisis,5
orders for B-17s were increased. Thirty-eight B-17Cs and forty-two B-17Ds were built before the first large production run
began with the B-17E variant. Twenty B-17Cs were delivered to the RAF as Fortress Is, which quickly showed that defensive
armament was inadequate, (the B-17C carried seven 50-cal. machine-guns) and at high altitude raids of 30,000 ft. (9,144 m),
the defensive guns froze up, when they tried to fire them. Also bombs raids at high altitudes proved to be very inaccurate,
and most of the bombs were missing their targets. The airplane was revised as the Model 299O, with the most important changes
incorporated into the Model 299H (B-17C and B-17D).6 Modifications included
self-sealing tanks and additional armor for crew protection.
|Boeing B-17C Later versions incorporated a dorsal fin on the fuselage.
On August 17,1942, United
States B-17s carried out a bombing raid on the railway yards at Rouen in France. The real offensive, however, started on January
27,1943, when B-17s of the USAAF made their first attacks on Germany. Initially, casualties were very high because they attacked
during daylight hours to achieve greater accuracy, and because proper formation flying (to enable a group of airplanes to
defend each other with crossfire) had not yet been formulated. Also the B-17F lacked adequate defense against a head-on attack.
By September 1943, the Flying Fortress showed its final shape during firepower tests on the XB-40, a modified B-17F with the
advantage of a "chin" turret. The success of the chin turret, led to the delivery of the B-17G (the major production version),
which was the first production variant to have a chin turret installed, under the nose. The Bendix turret held two .50-cal.
guns, which increased the armament to thirteen guns.9 In all, there were 8,680
B-17Gs built by Boeing, Vega, and Douglas to make this the largest production variation. Produced in greater numbers than
any other single model, more B-17Gs were lost, than any other model.10 B-17G
specifications included a span of 103 feet 9 inches (31.6 m), length of 74 feet 4 inches (22.6 m), and a height of 19 feet
1 inch (5.8 m). The four supercharged Wright R-1820-97 Cyclones delivered 1,200 hp (895 kW) and gave a top speed of 287 mph (462 km/h),
cruising at 182 mph (293 km/h). Service ceiling was 35,800 ft. (10,850 m), with a max. range of 3,400 miles (5,471 km). Empty
and gross weights were 36,135 lb (16,390 kg)and 65,500 lb (29,710 kg). Maximum fuel load was 3,630 gallons (13,741 liters).
|Boeing B-17 cockpit controls.
On 19 July 1943, US B-17s
and B-24 Liberators carried out the first bombing raid on Rome. US bombing in Europe reached
its high point in February 1945 with a 1,000-bomber raid on Berlin, escorted by 400 fighters, and the Dresden raid (alongside
RAF Lancasters) which, caused a massive fire storm to sweep the city. Meanwhile, B-17s
were also helping to win the war against Japan, although by mid-1943 the larger Boeing B-29 had begun to take over the major strategic bombing missions in the Pacific
Following the first Model
299, the Air Corps purchased 12,725 B-17 type aircraft, of which a few served with Royal Air Force Coastal Command and the
United States Navy for patrol, air-sea rescue, antisubmarine and other duties. Cargo conversions of the B-17 were known as
|The B-17G introduced new fire power in the form of the Bendix chin turret.
The First American
Missions From England
American air power made its
European debut during the summer of 1942. On June 12, Colonel Harry Halverson led thirteen B-24 Liberators on a first daring, long-distance raid against the oil refineries at Ploesti,
Rumania. Taking off from Egypt, 1,000 miles from the target, the bombers surprised the enemy. All the planes got safely away,
though one B-24 crash landed later.
The first American mission
from England took place, appropriately, on the Fourth of July. Six air crews, flying A-20 Boston bombers borrowed from the
RAF, joined six British crews on a low-level raid against air bases in Holland. The Germans were warned by radio from a picket
ship off the Dutch coast, and two of the bombers flown by Americans were shot down. The bombardiers of two of the other planes
were so confused by the camouflaged targets that they failed to drop their bombs at all.
|A B-17 being loaded at an English base with three-hundred pound bombs.
More auspicious was a raid
on August 17, against the railroad yards at Rouen. A dozen B-17 Flying Fortresses loaded with three hundred-pound bombs, completed
their mission without losses. In the fall, the North African invasion diverted planes and men and temporarily stalled the
buildup of US air strength in England. But as the Eighth continued to stab at the enemy, American crews matched the courage
and ability of veterans.
On one occasion, for instance,
nine B-17s, turning back from a canceled mission against Rotterdam, were jumped by more than twenty German fighters. The Americans
fought their way back to England, but in one bomber the pilot was injured and the copilot killed. The bombardier, who had
been washed out of flying school, took over the controls and flew the plane back home on two engines.
|In June 1944, the Americans dropped 120,000 tons of bombs on Germany.
|Boeing B-17G Flying Fortress |
||103 ft. 9 in (31.6 m) |
||74 ft. 4 in (22.6 m) |
||19 ft. 1 in (5.8 m) |
||1,420 sq ft (132 sq m) |
||36,135 lb (16,391 kg) |
||49,500 lb (22,475 kg) |
||65,500 lb (29,710 kg) |
||287 mph (462 km/h) at 25,000 ft (7,625 m) |
||182 mph (293 km/h) |
||35,800 ft (10,850 m) |
||2,000 miles (3,219 km) with 6,000 lb (2,722 kg) bomb |
load @ 220 mph (352 km/h) @ 25,000
ft (7,625 m)
|Four 1,200 hp (895 kW) Wright R-1820-97 Cyclones nine cylinder air-cooled single row radial engines. General Electric Type B-22 exhaust driven turbo-superchargers, installed
under engine nacelles. |
|Thirteen 50-cal. machine-guns plus a maximum of 17,600 lb (7,983 kg) of bombs.
Normal bomb load 6,000 lbs (2,724 kg).|
Largest bomb type carried was 2,000 lb (908 kg).
Click here for The Aviation History On-line Museum.
The B-17 was the first Boeing military aircraft with a flight deck instead of an open cockpit and
was armed with bombs and five .30-caliber machine guns mounted in clear "blisters."
The B-17E, the first mass-produced model Flying Fortress, carried nine machine guns and a 4,000-pound
bomb load. It was several tons heavier than the prototypes and bristled with armament. It was the first Boeing airplane with
the distinctive -- and enormous -- tail for improved control and stability during high-altitude bombing. Each version was
more heavily armed.
In the Pacific, the planes earned a deadly reputation with the Japanese, who dubbed them "four-engine
fighters." The Fortresses were also legendary for their ability to stay in the air after taking brutal poundings. They sometimes
limped back to their bases with large chunks of the fuselage shot off.
Joe Baugher's B17 Report
It was to be in the European
theatre of operation that the B-17 Flying Fortress would acquire its reputation.
The Eighth Air Force was
formed in Britain to carry out daylight bombing raids against German targets in Europe. These raids were to be carried out
by unescorted Fortresses flying at high altitude in tight formations for protection against enemy fighters. The defensive
firepower of the B-17 was thought to be sufficient to fend off Luftwaffe attacks. At the same time that the USAAF carried
out its daylight attacks, the Royal Air Force was to fly coordinated nighttime raids.
The first Eighth Air Force
units arrived in Britain on May 12, 1942. The first USAAF Flying Fortress (B-17E serial number 41-9085) arrived at Prestwick
in Scotland on July 1, 1942. The first Flying Fortress raid over Europe was launched on August 17, 1942 by 18 B-17Es of the
97th Bombardment Group against railroad marshaling yards at Rouen-Sotteville in France. Twelve planes made the actual attack
and the remaining six flew a diversionary sweep up the coast. Brig Gen Ira Eaker flew along on this raid in B-17E 41-9023
"Yankee Doodle". The formation was escorted by Spitfires. No opposition was encountered from the Luftwaffe.
On August 19, twenty four
Fortresses took part in an attack on the German airfield at Abbeville in support of the disastrous raid at Dieppe. All planes
returned safely to base, but the landing force at Dieppe was decimated.
The next ten raids went fairly
well, with only two planes being lost.
Deteriorating weather and
the needs of the North African front caused a change in plans, and most of the Eighth Air Force B-17s had to be diverted to
the fight against Rommel. The two most experienced bomber groups, the 97th and 301st were committed to *Operation Torch* as
the nucleus of the newly-formed Twelfth Air Force. On September 20, 1942, General James Doolittle formed the nucleus of the
12th Air Force in England, and early in October the 97th, 99th, 301st, and 2nd Bombardment Groups were transferred to the
new formation. The air war against the Germans in Europe had to be given a lower priority.
In October 1942, attention
of the depleted 8th Bomber Command was concentrated against German submarine pens situated along the French coast. These pens
were constructed of thick concrete and were highly resistant to bomb damage. The attacks against these pens were largely ineffectual.
Many raids against the sub pens had to be scrubbed on account of bad weather, and those raids which were carried out were
often inaccurate because of poor visibility over the target. The bombing campaign against the submarine pens was extremely
costly in terms of lost airplanes and crews and had no real effect upon the German submarine campaign. It turned out that
the submarine threat was best met at sea.
On January 3, 1943 the new
bombing-on-the-leader technique was introduced. Instead of each plane dropping its bombs individually, all bombardiers released
their bombs when the saw the bombs leave the bay of the lead aircraft. This technique usually resulted in better accuracy,
since the most skilled bombardier was generally in the lead plane.
The successful completion
of the North African campaign resulted in the resumption of the bomber offensive against the Germans in northern Europe. The
first USAAF mission over Germany was a raid on January 27, 1943 against the U-boat construction yards at the port of Wilhelmshaven.
It was carried out by a force of B-17Fs drawn from the 92st, 303rd, 305th, and 306th Bomb Groups.
March 18 saw first use of
Automatic Flight Control Equipment (AFCE) in a raid on the Bremer Vulkan shipbuilding yards at Vegesack. AFCE was a system
in which the Norden bombsight controlled the aircraft during the final bomb run via a link with the autopilot. Luftwaffe fighters
put up strong opposition that day, but their attacks were relatively uncoordinated.
On April 17, 1943, the Focke-Wulf
plant at Bremen was attacked by a force of 115 Fortresses. The Luftwaffe came out in full strength that day, and 16 B-17s
did not return, the heaviest loss rate to date. After that date, German fighter attacks began to become increasingly more
effective and better coordinated, and bomber losses frequently were over ten percent of the attacking force, especially whenever
the Fortresses went beyond the limited radius of their fighter escorts. The German fighters began to attack the Fortress formations
from the "twelve o'clock high" spot directly head-on. This innovation was supposedly introduced by Luftwaffe Oberleutnant
Egon Mayer, who had noticed that the firepower from the B-17 was weak in the nose area, with there being significant blind
spots that neither the nose guns nor the top-turret gunner could adequately cover from the front. Additional guns were hastily
added to the nose in an attempt to beef up the forward firepower. However, the much-publicized vulnerability to frontal attacks
was due more to the lack of armor that was properly positioned to protect the crew against gunfire coming from the front than
it was due to the lack of enough front-firing guns. Another problem was the unfortunate tendency of the B-17 to catch fire
when hit by flak or cannon fire, which was never really cured.
In June of 1943, the famous
"Memphis Belle" (B-17F-10-BO serial number 41-24485 of the 324th Bombardment Squadron of the 91st Bombardment Group) became
the first B-17 to complete its crew's quota of 25 missions. A film crew had gone along on the *Memphis Belle's* mission to
Wilhelmshaven and this film was widely shown throughout the war. After the last mission, the *Memphis Belle* returned to the
United States and carried out a morale-building tour selling US War Bonds.
The next phase of the air
war against Germany was to be the destruction of its aviation industry. A critical part of the strategy was to be the elimination
of the German ball-bearing industry, since just about any machine which had moving parts required ball-bearings. On July 24-31,
1943, the 8th Air Force attacked 16 major industrial targets in the greatest sustained air offensive to date. On August 17,
1943, a simultaneous attack was carried out on the ball-bearing factories at Schweinfurt and the Messerschmitt factories at
Regensburg. It was the deepest penetration into Germany to that date and was the largest force of B-17s yet dispatched. The
losses were catastrophic--the 8th AF lost 60 aircraft out of a force of 376 bombers. The crews claimed 288 German fighters
shot down, which was undoubtedly grossly exaggerated.
The Regensburg force went
on to North Africa, and returned to England via the Focke Wulf works at Bordeaux. The total losses for the week were over
hundred B-17s. Losses like this could clearly not be sustained--a couple of more weeks like this, and the 8th Air Force would
During August and September
of 1943, the new B-17G began to arrive in England. The new chin turret helped meet the head-on attacks by the German fighters.
On September 6, a force of
over 400 bombers hit the VKF ball-bearing works at Stuttgart. Weather prevented the attacking force from seeing the target,
and bombs were released over the city in a haphazard fashion. A total of 45 bombers were lost to fighters and to accurate
On October 14, 1943, Schweinfurt
was visited again, and 60 Fortresses were lost out of a force of 291.
In late 1943, the appalling
losses and the meager results that had been obtained led USAAF commanders to rethink the wisdom of continuing with the daylight
bombing offensive. Winston Churchill was never a believer in precision daylight bombing and wanted the USAAF to go over to
nighttime raids, as the RAF had done from the start. In spite of the attacks on the German aircraft industry, it seemed that
the numbers of German fighters rising to meet the attacking Fortresses actually increased rather than decreased. The German
aircraft industry was amazingly recuperative. An efficient German labor force, plus the forced labor of captives, was able
quickly to repair the damage and to get the damaged facilities back in operation within a few days. In addition, a very effective
decentralization program was carried out under the direction of Minister of Armaments Albert Speer.
It soon became apparent that
without fighter escort, deep penetrations into Germany would have to be seriously curtailed, if not abandoned altogether.
However, in spite of extreme losses, the B-17Fs were never turned back from a raid by enemy fighters or flak, although bad
weather caused frequent mission cancellations and callbacks. During the latter weeks of 1943, the 8th Air Force restricted
its missions to targets that were within the range of the escort fighters that were beginning to become available, and there
were no penetrations into Germany.
In spite of the high losses,
the decision was made to continue with the attacks on German industry. In late 1943, the US Strategic Air Forces were organized
in Europe under the command of LtGen Carl Spaatz to carry out heavy bomber attacks from England and Italy and to coordinate
their efforts with the night attacks of the RAF.
Effective fighter escort
did not appear until late 1943 with the arrival of large numbers of Republic P-47 Thunderbolts and Lockheed P-38 Lightnings.
These aircraft were able to escort the B-17 considerable distances into Germany. The North American P-51D Mustang was the
most effective of all the escort fighters, and began to appear in the spring of 1944. It was able to escort the bombers all
the way to Berlin.
During the winter in Europe,
the weather is generally atrocious. In order to permit bombing during inclement or overcast conditions, a number of Fortresses
were fitted with a British-devised radar installation known as H2S which scanned the grounds under the clouds and which could
be read by a trained operator like a map. The American version of this device was known as H2X "Bombing Through Overcast"
radar, and was installed in the fuselage belly in place of the ball turret. These planes acted as pathfinders, the remaining
aircraft in the formation releasing their bombs on visual signals from the radar-equipped Fortresses. This equipment was used
for the first time in a raid on the port at Emden.
On January 11, 1944, a 600-plane
force of bombers were sent against German aircraft industry targets. Because of the weather, only 238 B-17s actually succeeding
in reaching the target. Sixty B-17s were lost.
On February 20, 1944, five
days of coordinated USAAF/RAF assaults on the German aircraft industry began, that historians later named "The Big Week".
On that day, the first thousand-plane raid took place, with fighter plane factories at Brunswick, Oschersleben, Bernberg,
and Leipzig being attacked. The cost of the "Big Week" was heavy, with 244 heavy bombers and 33 fighter planes being lost.
However, these raids played an important role in helping to reduce the strength of the Luftwaffe, paving the way for the D-Day
landings. The onset of bad weather brought an end to the "Big Week", which was merciful since crews were exhausted and losses
had been high. Nevertheless, during this offensive, the back of the Luftwaffe was broken. After this date, the Luftwaffe was
never able to throw up the same amount of strength that it had before, and was generally effective only on sporadic occasions
or when targets of critical importance were being attacked.
The first B-17 raid on Berlin
took place on March 4, 1944. P-51 Mustang fighters escorted the bombers all the way to Berlin and back. On March 6, 600 B-17s
returned to Berlin. The Luftwaffe was out in force, and accounted for 69 B-17s and 11 fighter escorts.
In May of 1944, the priority
shifted to oil. On May 12, 1944, attacks were begun on German oil-production facilities and synthetic oil-production centers.
These attacks caused a sudden and catastrophic drop in German fuel and lubricant supplies. In only two months of attacks,
German oil production was cut in half. Especially successful were the attacks on the stubborn oil production facility of Ploesti
in Rumania, which had been so resistant to previous attacks. By the time that Ploesti was taken by the Russians, 90 percent
of this Rumanian oil production facility had been destroyed. Destruction of the synthetic oil centers had the additional beneficial
side effect of cutting the supplies of nitrogen and methanol, which essential in the manufacture of explosives. The postwar
Strategic Bombing Survey judged that the oil offensive was the most effective of all the strategic bombing attacks in helping
to shorten the war.
The B-17 was less widely
used in the Mediterranean theatre. The brunt of the air war in the Mediterranean was borne by the B-24 Liberator, although
a few B-17s groups were also involved. The four Bombardment Groups that had been diverted from the 8th Air Force to Africa
participated in the Bizerta and Kasserine Pass battles in North Africa. 12th AF B-17s took part in the June 28 raid on Messina,
the Sept 5 and 8 raids on Naples, and against the Wermacht counterattack at Salerno between Sept 13 and 18.
Advances up the Italian boot
brought German targets within the range of B-17s based in the Mediterranean theatre. In November of 1943, the 15th Air Force
was organized to carry out raids on Germany from bases in Italy. It resulted from a reorganization of Doolittle's 12th Air
Force into the 15th Air Force with Doolittle in command, and the 9th Air Force with Lewis H. Brereton in command. It was hoped
that the 15th AF stationed in the Mediterranean would be able to operate when the 8th was socked in by bad English weather.
The 9th AF would later move to England to serve as a tactical unit to take part in the invasion of Europe. Once bases around
Foggia in Italy became available, the 15th was able to reach targets in southern France, Germany, Poland, Czechoslovakia,
and the Balkans, some of which were difficult to reach from England.
The 15th Air Force began
its operations on November 2, 1943, attacking the Messerschmitt factory at Weiner-Neustadt in Austria. One of the important
achievements of the 15th Air Force was the reduction of the oil fields at Ploesti in July-August 1944.
By early 1945, the Wermacht
and the Luftwaffe had been reduced to near impotence by the lack of fuel and supplies, due in no small part to the strategic
bombing offensive against Germany carried out by the Lancaster, Halifax, and Stirling bombers of the RAF and the B-24 and
B-17 bombers of the USAAF. Due credit must be given to their crews who bravely went out day after day even in spite of appalling
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