The Boeing B-17 Flying Fortress

United States of America
United States of America

side view front view under view

No other bomber has gained more fame than the B-17. Not even being the best bomber available at the time, it's name alone already apealled more to the public than other names like "Liberator" or "Lancaster". A high number of defensive guns was intended to make the Fortress be able to defend itself, not needing additional escorts. The idea failed. Until the Allied forces were able to produce escort fighters which could go all the way and back, the bombers were vulnerable, resulting in heavy losses. The first version was of pre-war vintage, and during the course of the war this aircraft saw a large number of modifications and improvements.

Versions:

Further pictures:

Boeing B-17 Flying Fortress preparing for take-off
Boeing B-17 Flying Fortress preparing for take-off

 

Technical data on the Boeing B-17 B
Powerplant 4 × Wright R-1820-51 Cyclone with turbo superchargers, rated at 1200 hp (894.59 kW) each Role during war
  • Heavy Bomber
Length 67 ft 10 inch Height 15 ft 5 inch
Empty weight 27652 lb Operational weight 37997 lb typical,
46178 lb max
Wing Span 103 ft 9 inch Wing Aspect ratio 7.585
Wing Area 1420 sq ft Service ceiling 24620 ft
Maximum speed 292 mph at optimum altitude Cruising speed unknown
Initial climb rate unknown Range 2400 miles typical,
3101 miles max
Fuel capacity internal unknown Fuel capacity external unknown
Machine guns 5 × 0.30 inch flexible, in nose, dorsal, ventral and two waist positions 1 each Cannons -
Bomb load 8 × 600 lb internal Torpedoes/rockets -
Crew 9: pilot, co-pilot, bombardier, navigator, radio operator, 4 gunners Naval or ground based Ground
First flight (prototype) 28 July 1935, this version June 1939 Operational Service 1937 - 1960's
Manufacturer Boeing Aircraft Company Number produced 12,731 total, 39 this version
Metric system
Length 20.68 m Height 4.7 m
Empty weight 12543 kg Operational weight 17235 kg typical,
20946 kg max
Wing Span 31.62 m Wing Aspect ratio 7.585
Wing Area 131.92 m² Service ceiling 7504 m
Maximum speed 470 km/h at optimum altitude Cruising speed unknown
Initial climb rate unknown Range 3862 km typical,
4990 km max
Fuel capacity internal unknown Fuel capacity external unknown
Machine guns 5 × 7.62 mm flexible, in nose, dorsal, ventral and two waist positions 1 each Cannons -
Bomb load 8 × 272 kg internal Torpedoes/rockets -

Technical data on the Boeing B-17 E
Powerplant 4 × Wright R-1820-65 Cyclone, rated at 1200 hp (894.59 kW) each Role during war
  • Heavy Bomber
Length 73 ft 10 inch Height 19 ft 2 inch
Empty weight 32350 lb Operational weight 40260 lb typical,
53000 lb max
Wing Span 103 ft 9 inch Wing Aspect ratio 7.585
Wing Area 1420 sq ft Service ceiling 36600 ft
Maximum speed 318 mph at 25000 ft Cruising speed 224 mph at 15000 ft
Initial climb rate Climb to 10,000 ft in 7 min 6 sec Range 2400 miles typical,
3600 miles max
Fuel capacity internal 2,073 Imp gal (2,490 US gal) Fuel capacity external -
Machine guns
  • 1 × .30 inch flexible in nose
  • 2 × power turret in dorsal and ventral position, each with 2 × .50 inch
  • 1 × .50 inch in each waist position
  • 2 × .50 inch in tail turret
Cannons -
Bomb load Up to 8,000 lb all internal, consisting of either:
  • 26 × 100 lb, or
  • 16 × 300 lb, or
  • 12 × 500 lb, or
  • 8 × 1000 lb, or
  • 4 × 2000 lb
Torpedoes/rockets -
Crew 9: pilot, co-pilot, bombardier, navigator, radio operator, 4 gunners Naval or ground based Ground
First flight (prototype) 28 July 1935, this version September 1941 Operational Service 1937 - 1960's
Manufacturer Boeing Aircraft Company Number produced 12,731 total, 512 this version
Metric system
Length 22.5 m Height 5.84 m
Empty weight 14674 kg Operational weight 18262 kg typical,
24041 kg max
Wing Span 31.62 m Wing Aspect ratio 7.585
Wing Area 131.92 m² Service ceiling 11156 m
Maximum speed 512 km/h at 7620 m Cruising speed 360 km/h at 4572 m
Initial climb rate Climb to 3050 m in 7 min 6 sec Range 3862 km typical,
5793 km max
Fuel capacity internal 9425 liters Fuel capacity external -
Machine guns
  • 1 × 7.6 mm flexible in nose
  • 2 × power turret in dorsal and ventral position, each with 2 × 12 mm
  • 1 × 12 mm in each waist position
  • 2 × 12 mm in tail turret
Cannons -
Bomb load Up to 3628 kg all internal, consisting of either:
  • 26 × 45 kg, or
  • 16 × 136 kg, or
  • 12 × 227 kg, or
  • 8 × 454 kg, or
  • 4 × 907 kg
Torpedoes/rockets -

Technical data on the Boeing B-17 G
Powerplant 4 × Wright R-1820-97 Cyclone radial with emergency output, rated at 1380 hp (1028.78 kW) each Role during war
  • Heavy Bomber
Length 74 ft 9 inch or 74 ft 4 inch with the "Cheyenne" tail position Height 19 ft 1 inch
Empty weight 38000 lb Operational weight 65500 lb typical,
72000 lb max
Wing Span 103 ft 9 inch Wing Aspect ratio 7.585
Wing Area 1420 sq ft Service ceiling 35600 ft
Maximum speed 302 mph at 25000 ft Cruising speed 287 mph at 25000 ft
Initial climb rate Climb to 20,000 ft in 37 mins 0 sec Range 1800 miles typical,
3400 miles max
Fuel capacity internal 2,340 Imp gal (2,810 US gal) with provision for 682 Imp gal (820 US gal) in a weapons bay tank Fuel capacity external -
Machine guns 13 × 0.50 inch trainable guns, consisting of:
  • 2 guns in powered Bendix nose turret, 300 rounds each
  • 1 gun each in 2 cheek positions, 500 rounds each
  • 2 guns in powered dorsal turret
  • 1 gun rearward firing in radio operator room, 500 rounds
  • 2 guns in powered ventral Sperry ball turret, 500 rounds each
  • 2 lateral-firing guns in the waist positions, 400 rounds each
  • 2 guns in the tail turret, 500 rounds each
The maximum number of rounds a B-17G could carry was 6380 pieces
Cannons -
Bomb load Up to 17,600 lb in weapons-bay rated 9,600 lb, and on two hardpoints under the wings rated 4,000 lb each. The load generally consisted of:
  • 6 × 1,600 lb bombs, or 8 × 1,000 lb bombs, or 16 × 500 lb bombs carried internal, and
  • 2 × 4,000 lb bombs, one on each hardpoint
Torpedoes/rockets -
Crew 10: pilot, co-pilot, bombardier, navigator, radio operator, 5 gunners Naval or ground based Ground
First flight (prototype) 28 July 1935, this version May 1943 Operational Service 1937 - 1960's
Manufacturer Boeing Aircraft Company Number produced 12,731 total, 8680 this version
Metric system
Length 22.78 m or 22.66 m with the "Cheyenne" tail position Height 5.82 m
Empty weight 17237 kg Operational weight 29711 kg typical,
32659 kg max
Wing Span 31.62 m Wing Aspect ratio 7.585
Wing Area 131.92 m² Service ceiling 10851 m
Maximum speed 486 km/h at 7620 m Cruising speed 462 km/h at 7620 m
Initial climb rate Climb to 6095 m in 37 mins 0 sec Range 2897 km typical,
5472 km max
Fuel capacity internal 10.637 liters with provision for 3.104 liters in a weapons bay tank Fuel capacity external -
Machine guns 13 × 12 mm trainable guns, consisting of:
  • 2 guns in powered Bendix nose turret, 300 rounds each
  • 1 gun each in 2 cheek positions, 500 rounds each
  • 2 guns in powered dorsal turret
  • 1 gun rearward firing in radio operator room, 500 rounds
  • 2 guns in powered ventral Sperry ball turret, 500 rounds each
  • 2 lateral-firing guns in the waist positions, 400 rounds each
  • 2 guns in the tail turret, 500 rounds each
The maximum number of rounds a B-17G could carry was 6380 pieces
Cannons -
Bomb load Up to 7.983 kg in weapons-bay rated 4.355 kg, and on two hardpoints under the wings rated 1814 kg each. The load generally consisted of:
  • 6 × 726 kg bombs, or 8 × 454 kg bombs, or 16 × 227 kg bombs carried internal, and
  • 2 × 1814 kg bombs, one on each hardpoint
Torpedoes/rockets -

Here is a quick overview of all different versions, without the full technical specifications:

Different versions of the Boeing B-17  Flying Fortress
Boeing Model 299 Flying Fortress First prototype of the B-17 flying Fortress, owned by Boeing, and therefor never designated in the B-17 way.
Number built: 1
Boeing YB-17 Flying Fortress First (test) operational B-17 for the USAAF. These bombers were powered by 4 × Wright R-1820-39 radials, rated at 1,000 hp (634 kW) each.
Number built: 13
Boeing Y1B-17 Flying Fortress Redesignation of the B-17 during initial operational trials.
Redesignated aircraft
Boeing B-17 Flying Fortress Redesignation of the Y1B-17 after initial operational trials, to signify their fully operational status
Redesignated aircraft
Boeing B-17B Flying Fortress After the initial trials a number of improvements were added to the design, and the type was called B-17B. Amongst the improvements were: hydraulically operated brakes in stead of pneumatically, redistribution of the crew positions, and the super charger placed upon the engines: 4 × Wright R-1820-51 supercharged radials. For further details see above.
Number built: 39
Boeing B-17C Flying Fortress This versions received added armor for the crews, self-sealing fuel tanks, and revisions in it's defensive and offensive armament. The weapon load was increased to 10,500 lb (4763 kg). Also the defensive guns were chaged to 1 × 0.3 inch (7.62 mm) and 6 × 0.5 in (12 mm) guns. The blisters in the waist were removed and changed to single-gun waist stations, the ventral blister was replaced by a bathtub with 2 guns.The single nose gun became two cheek guns, the forward dorsal position increased to 2 guns, and the rear dorsal position carried the single 0.3 in (7.62 mm) gun.
It was powered by 4 × Wright R-1820-63 supercharged radials, rated at 1,200 hp (895 kW) each. The max level speed was 323 Mph (520 km/h), cruising speed was 231 Mph (372 km/h). Initial climb rate was 1,300 ft (396 m) per minute.
20 aircraft were transferred to the RAF as Boeing Fortress Mk I's during the late summer of 1940.
Number built: 38
Boeing B-17D Flying Fortress Initially ordered as 48 B-17 C's, the modifications were big enough to assign it another model number B-17 D. This version had a lot of (internal) improvements including the electrical system and the introduction of cowling flaps, and was the first model to see a crew of 10 in stead of 9. This version carried 1 x .30 inch (7.62 mm) and 6 x 0.50 inch (12 mm) guns. The remaining 18 B-17C's (after the transfer of 20 aircraft to the RAF) were later converted to the B-17D standard.
The B-17D was also the first version to see action in service of the USAAF, when during the Japanes raid on Pearl Harbor 11 out of 33 were destroyed on the ground, and 2 days later the remainder attacked a Japanese convoy.
Number built: 48
Boeing B-17E Flying Fortress The B-17 E was the first version to see a tail-turret, thus eliminating a severe blind spot in the rear. Also was the electrical ventral turret replaced by a Sperry ball turret, in which a man could sit/hang. Due to spatial restrictions the gunner had to be a very small person (for more information, see above). The Dorsal turret was also replaced by a Sperry turret.
The B-17E Flying Fortress was the first USAAF bomber to enter service in Europe, and later in North Africa. It was used mainly on medium-range missions. About 45 B-17E's were transferred to Coastal Command.
Number built: 512
Boeing B-17F Flying Fortress Same as B-17 E externally, except for the glass nose out of 1 piece, but with different Powerplant again: 4 x Wright R-1820-97 Cyclones, each rated at 1,380 hp (1030 kW) emergency power. This version saw a lot of subversions, and was built by three different manufacturers. As a result, the armour and armament differed during this version, and the possible bombload. Armament was typically like: 1 × 0.30 inch (7.62 mm) nosegun, 2 × 0.50 inch (12 mm) waistguns (cheecks), 2 × 0.50 inch (12 mm) waistguns, 2 × 0.50 inch (12 mm) dorsal turret, 2 × 0.50 inch (12 mm) guns ventral turret (ball), and 2 × 0.50 inch (12 mm) guns in the tail.
In the field also a lot of modifications where made to the armour, especially to protect the crew from frontal attacks. Furthermore was the fuel capacity enlarged to be able to carry heavier bombloads, and to make up for the increase in weight of the plane (needed more fuel for more pounds). The famous Memphis Belle was an -F version. Also, 19 B-17F's were transferred to Coastal Command
Number built: 3405
Boeing B-17G Flying Fortress Experiences with the B-17F showed that German attacks on the B-17 were almost always head-on attacks, concentrated on the nose where there was the least armor and defensive armament, and the most vulnerable parts. Therefor a Bendix noseturret with 2 × 0.50 in (12 mm) guns was installed, enhancing the field of vision and punch the B-17 could deal out up front.
Besides the chin-turret there were numerous other improvements, including a different navigator position, refined bomb-control systems, electric control of the turbo chargers, an electrically boosted control column and other changes to the defensive armament.
This was the final production version, because of the nearing end of the war, and the rise of the Boeing B-29 Superfortress. 85 B-17G's were transferred to the RAF for maritime reconnaissance at Coastal Command, and electronic warfare in Bomber Command
Number built: 8680
Boeing B-17H Flying Fortress After the war it was planned to convert 130 B-17G's to search-and-rescue aircraft, fitted with a self-righting and self-bailing lifeboat in the weapons bay. This boat would be dropped with 3 parachutes near downed crew. Only 12 were converted
Number converted: 12
Boeing YB-40 Flying Fortress During the first days of the Americans in Europe, there were no escort fighters available with the range needed for the defence of the B-17's. Looking back at the loss rates of unescorted bombers it was deemed too dangerous to start daylight bombing with unescorted bombers. The only plane able to follow the B-17 all the way was.. a B-17!
Starting as B-17 F's, some 20 bombers were refitted. typically they carried 14 0.50-inch machine guns. Additional protective armor was fitted for better crew protection. Some fortresses had up to 30 guns, or carried heavy cannons. Due to drag of additional turrets, and increased weight, the top speed was so low that the YB-40's could not maintain formation after the normal bombers had dropped their loads, failing in their defensive role.
In a number of test missions they claimed some air-to-air kills, and some damages, but one YB-40 was lost. After this and the fact they could not keep up with the returning formations the project was abandoned. The remaining YB-40's were converted back to standard bombers, or were used as gunnery trainers.
This version however saw the first use of the Bendix chin turret, later installed in all B-17G's
Number converted: 20
Boeing C-108 Flying Fortress 3 B-17's of various types were converted as VIP transport
Number converted: 3
Boeing CB-17 Flying Fortress New designation applied to a number of B-17G's that were converted for transport duties
Number converted: unknown
Boeing DB-17 Flying Fortress A number of B-17's were fitted to act as drone-control aircraft
Number converted: unknown
Boeing DB-17P Flying Fortress Redesignation of the DB-17 Flying Fortress
Redesignated aircraft
Boeing EB-17G Flying Fortress A Curtiss owned B-17G used as a testbed for turboprop trials
Redesignated aircraft
Boeing FB-17F Flying Fortress Redesignation of the F-9 Flying Fortress
Redesignated aircraft
Boeing JB-17G Flying Fortress Redesignation of the EB-17G Flying Fortress
Redesignated aircraft
Boeing QB-17G Flying Fortress Redesignation of the BQ-7 Flying Fortress "Aphrodite"
Redesignated aircraft
Boeing QB-17L Flying Fortress A number of B-17G's were converted to this standard to operate as remote controled targets for weapons tests. The aircraft were fitted with a TV camera system to provide air and/or ground controlers with a view of the approaching missile
Number converted: unknown
Boeing QB-17N Flying Fortress Like the QB-17L, but without the TV system
Number converted: unknown
Boeing QB-17P Flying Fortress Starting as Target drone controllers (DB-17P's) a small number were converted to targets themselves.
Number converted: unknown
Boeing RB-17F Flying Fortress Redesignation of the FB-17F Flying Fortress reconnaissance aircraft
Redesignated aircraft
Boeing RB-17G Flying Fortress Redesignation of the FB-17G Flying Fortress reconnaissance aircraft
Redesignated aircraft
Boeing SB-17G Flying Fortress Redesignated B-17H's after the war
Redesignated aircraft
Boeing TB-17G Flying Fortress Conversions of B-17G's to act as crew trainer
Number converted: unknown
Boeing TB-17H Flying Fortress Conversion of the B-17H to act as trainers for the B-17H
Number converted: 5
Boeing VB-17G Flying Fortress Conversion of the B-17G to act as staff transports
Number converted: unknown
Boeing CQ-4/CQ-17 Conversion of B-17G's to act as QB-17 drone control aircraft.
Number converted: unknown
Boeing MQ-17G Flying Fortress Improved version of the BQ-7 guided bomb
Number converted: unknown
Boeing DP-17G Flying Fortress Redesignation of the CQ-4 Drone control aircraft
Redesignated aircraft
Boeing PB-1 Flying Fortress Originally the B-17 was intended for use as a maritime rpatrol and reconnaissance aircraft, until the USAAF started to use them as heavy bombers. During 1942 the US Navy was in need of patrol aircraft, anf\d the B-17 could fulfil this role because of it's performances. Thus a number of USAAF aircraft were transferred to the US Navy, and wherre redesignated PB-1
Number transferred: 2
Boeing PB-1G Flying Fortress After the first trials with 1 B-17F and 1 B-17G, 17 more B-17G's were transferred from the USAAF to the US Navy.
Number transferred: 17
Boeing PB-1W Flying Fortress The final version of the navy Fortresses was converted from B-17G's, and were fitted with underwing fuel tanks, APS-20 search radar, and powered by 4 × R-1820-97 radials, rated at 1,200 hp (895 kW) each.
Number converted: 31
Boeing F-9 Flying Fortress Conversions from B-17F's for photo-reconnaissance roles. All bombing equipment was removed, and some of it's defensive armament. In stead they were fitted with trimetrogon cameras in the nose, and additional cameras in the weapons bay and rear-fuselage.
Number converted: 16
Boeing F-9A Flying Fortress Conversions from B-17F's for photo-reconnaissance roles, but with different camera setup as the F-9.
Number converted: unknown
Boeing F-9B Flying Fortress F-9A's but with revised camera setup. Also 25 additional B-17F's were converted to this standard
Number converted: 25 + unknown number of redesignated aircraft
Boeing F-9C Flying Fortress The final conversions to the F-9 series, from B-17G's
Number converted: 10
Boeing Fortress Mk I for the RAF 20 B-17C's were transferred form the USAAF to the RAF. At the time the RAF was in dire need of bombers to take the battle to Germany in July - November 1940. After the RAF had decided that the Fortress Mk I was too vulnerable both in defense, offense and technically, it was deemed unfit for the European Theatre, and transferred to Coastal Command for Maritime reconnaissance.
Number transferred: 20
Boeing Fortress Mk II for the RAF About 45 B-17E's were transferred to Coastal Command
Number transferred: 45
Boeing Fortress Mk IIA for the RAF About 19 B-17F's were transferred to Coastal Command
Number transferred: 19
Boeing Fortress Mk III for the RAF 85 B-17G's were transferred to the RAF for maritime reconnaissance at Coastal Command, and electronic warfare in Bomber Command
Number transferred: 85
Dornier Do 200 Since thousands of Bombers were deployed over germany, it is hardly a surprise that the luftwaffe had a couple of B-17 in it's stock. Some were forced to land due to damage, other were reconstructed using pieces of crashed planes. In total, the Luftwaffe had 40 B-17's in use, redesignated as "Dornier Do 200". A number of these served in the Luftwaffe to develop new tactics for fighters, a couple of the bombers were used for clandestine operations in order to drop agents and goods over enemy (Allied) territory. At least 1 captured B-17 was used as a decoy: it would follow damaged stragglers and winning their trust by flying "cover" for their damaged counterpart. As soon as the Allied bomber flew in tight formation, the gunners of the Luftwaffe would start firing at it using the guns on board, destroying the unsuspecting bomber.
Also Japan had a small number of B-17's in its arsenal, which were used for study and development of fighter tactics.
Number captured and repaired: 40+
Boeing BQ-7 Flying Fortress In June 1944 a plan concerning radio controlled B-17's was approved. The goal was to attack V1 sites and other heavily protected and fortified structures, such as Sub-marine pens. These sites were difficult to destroy from the air. Around 25 old Fortresses of all kinds of versions (mainly the -F version though) were prepared for this task.
Up to 9 tons (9.144 kg) high explosives were packed inside a stripped Fortress, with added radio controled flight system and 2 TV cameras (1 for the instrument panel, 1 for looking up the target).
The BQ-7 were to be controled by crewmen in the first leg of the trip (still over Britain), who would subsequently bail out with parachutes. The controls would then be in the hands of "Command Aircraft", other B-17's, flying in the vicinity. After a number of tries and fatal accidents, without any firm results, the project was abandoned. One drone evel fell to German hands after the BQ-7 crashed and failed to explode, enabling the Germans to study the radio controlled systems aboard.
Number converted: unknown

Remarks:

This aircraft has seen a lot of different roles, but the most successfull one was the role of ordinary bomber. The B-17's were able to resist heavy damage, from day 1 on. It was this fact that made the USAAF decide they would continue with the B-17, even though it lacked on a number of points compared to other bombers.

Strengths:

Weaknesses:

 

 

© by Frans Bonné, 2000
Last revision: 9/20/00