The B-17F immediately followed the E-model off the production line. It was externally almost identical to the earlier B-17E. Externally, the F could be distinguished from the E only by the use of a single piece plastic blown transparent nose. Apart from the optically-flat bomb aiming panel, the nose transparency was frameless.

However, there were over 400 internal changes, designed to make the bomber a more effective fighting machine. A new ball turret was fitted, external bomb racks were provided, wider paddle-bladed propellers were fitted, an improved oxygen system, carburetor air intake dust filters, dual brake system, more photographic equipment, an electronic link between the autopilot, and additional ball-and-socket machine gun mounts in the nose. The engines were the newer Wright R-1820-97 Cyclones, which could offer a war emergency power of 1380 hp for brief intervals. Revisions to the engine cowlings were required to make it possible to feather the wider propeller blades. A stronger undercarriage was installed which allowed the maximum weight to increase to 65,000 pounds, and later to 72,000 pounds.

The first B-17F (41-24340) flew on May 30, 1942. Because of the great number of relatively small changes constantly being introduced on the B-17F production line, the production block designation scheme had to be introduced to make it possible for field maintenance units to keep track of the multitudinous numbers of different varieties of B-17Fs that were in service. The first 50 were B-17F-1-BO, the second 50 were -5, and the third 50 were -10, but the numbers varied from this point on. A total of 2300 B-17Fs were built by Boeing, the last production block being -130-BO.

After receiving a B-17E pattern aircraft and all necessary blueprints from Boeing, the Vega division of Lockheed began production of the B-17F in its new A-1 plant at the edge of the Lockheed Air Terminal in Burbank, California. The first B-17F-1-VE (42-5705) flew on May 4, 1942. A total of 500 B-17Fs were built by Lockheed-Vega (with the production block numbers reaching -50) before production switched to the G-model. The Lockheed-built B-17Fs were essentially identical to the Boeing-built version, and the planes could only be distinguished from each other by an examination of their serial numbers.

The Douglas plant at Long Beach, California also began production of the B-17F. Douglas manufactured a total of 605 B-17Fs (B-17F-1-DL thru -85-DL). The Douglas-built B-17Fs were externally identical to the Boeing- and Lockheed-built models, and could only be distinguished by an examination of their serial numbers.

Only the first three Douglas-built B-17Fs and the first five Vega-built B-17Fs were block number 1. The details of similar B-17F block numbers as built by the three companies did not correspond, so it was necessary to include the manufacturer's code (BO for Boeing, DL for Douglas, VE for Vega) for complete determination of detail from service publications.

The B-17F went into action with the 8th Air Force in Europe, and were used for the first American bombing raid against the German homeland on January 27, 1943 in a raid on Wilhelmshaven. Combat by the B-17F over Europe soon revealed that it was vulnerable to attack from the front by enemy fighters. It turned out that most of the factory-installed pieces of heavy armor plate and flak curtions were not well positioned to protect the crew against frontal attacks. When hit from the front by machine gun or cannon fire, the crew of the B-17 was relatively unprotected. Hasty modifications were made in the field in an attempt to beef up the armor protection, but were not entirely successful. Another option that was explored was an increase in the number of forward-firing machine guns. In order to beef up the forward defensive firepower, various installations were made in the field to increase the armament in the nose. Additional flexible machine guns installations were fitted in the nose, firing from sockets cut into the side or from windows cut into the side of the nose. The famous "Memphis Belle", a B-17F-10-BO (41-24485) of the 324th Bombardment Squadron, 91st Bombardment Group had no less than four guns sticking out of its nose, two in sockets cut into the Plexiglas nose and two firing from windows cut into the left and right sides of the nose.

Later models of the B-17F could be fitted with extra cells (called "Tokyo tanks") to the fuel tanks in the wings.

The B-17Fs built by the three companies differed slightly in internal details, particularly in armament. The most commonly used initial arrangement was a 0.30-inch gun in the nose with 500 rounds, two 0.50-inch with 300 rpg in the waist, two 0.50-inch with 400 rpg in the wait, two 0.50-inch guns with 400 rpg in the dorsal turret, two 0.50-inch guns with 500 rpg in the ball, and two 0.50-inch guns with 565 rpg in the tail.

The maximum bombload of the first B-17Fs was 9600 pounds, but the range over which such loads could be carried was quite short. On typical missions the load was 4000-5000 pounds over operating ranges of 1400 miles. Beyond these distances, the bombload fell off quite rapidly

Many modifications were introduced at modification centers before the planes reached the field. These changes were largely dictated by experience in Europe, and were mostly concerned with armor, armament, and fuel capacity.

Beginning with the B-17F-30-BO, another gun was added at the opening on the top of the radio compartment, firing upward from the transparent hatch just above the wing trailing edge.

Beginning with B-17F-30-BO, B-17F-20-DL, and B-17F-20-VE, external bomb racks were fitted under the inner wings for the carriage of two 4000-pounds bombs. This brought the maximum short-range bombload to 17,600 pounds. Under certain conditions, eight 1600-pound bombs could be carried internally and two 4000-pound bombs externally, raising the total load to 20,800 pounds. However, with such a load the effective range was quite small and all maneuvers were severely restricted. Consequently, external bombs were only rarely carried by the B-17F. Although all subsequent models had lugs and controls for their attachment, the underwing racks were not installed at the factory.

The fuel capacity of the B-17F was increased from 2550 to 3630 US gallons in later modification.s

A total of 3405 B-17Fs were built--2300 by Boeing, 605 by Douglas, and 500 by Lockheed-Vega.

One B-17F (Serial number 42-3521) was transferred to the US Navy. It was given the Navy serial number of 34106, but was operated under its Army designation. It was later modified to B-17G standard and redesignated PB-1. It was later stripped of all armament and used as a flying aeronautical laboratory.

B-17F 41-24613 was turned over to the National Advisory Committee for Aeronautics (NACA) for extensive performance testing under the designation XB-17F. Despite its designation, it was not a prototype.

Only three B-17Fs remain in existence today.

The famous "Memphis Belle", a B-17F-10-BO (41-24485) of the 324th Bombardment Squadron, 91st Bombardment Group was the first American bomber to complete 25 missions over Europe and survive. This 25th mission was flown on May 17, 1943. Following this mission, the plane returned to the USA to take part in a war bond tour. Upon completion of the tour, the *Memphis Belle* was turned over to a training group at McDill Field in Florida. In 1945, it was redesignated TB-17F. In August of 1945, it was consigned to the Reconstruction Finance Corporation for disposal. It was about to be scrapped when a citizen of Memphis happened to note that it was the famous *Memphis Belle* and should be saved. The plane was rescued from the scrap heap and was flown to Memphis, Tennessee where it was put on display outdoors on a pedestal. Over the succeeding years, *Memphis Belle* began to show signs of wear and tear as the inevitable effects of weather and vandals took their toll. Public outcry at the sorry state of *Memphis Belle* led to a major restoration effort. Finally, in 1987, a fully-restored *Memphis Belle*, now sporting a more- accurate paint scheme, was put on permanent display underneath a protective dome.

B-17F-50-DL serial number 42-3374 is currently in storage at Offutt AFB, Nebraksa awaiting restoration and display. It was a Douglas-built machine which never went overseas. Following the war, it was transferred to the Metro-Goldwyn-Mayer (MGM) film studio to be used in making the movie *Footprints in the Sky". In the event, this film never got made and 42-3374 sat in storage at MGM until the 1960s. At that time, it was transferred to Ed Maloney's "Planes of Fame" air museum at Chino Airport in California. Ed Maloney traded the plane to the Beale AFB museum in 1981. In 1989, 42-3374 was trucked to Offut AFB to be displayed as a gate guardian. It is currently in storage awaiting further plans.

There is only one flyable B-17F currently in existence. It is B-17F-70-B0 serial number 42-29782, which spent the war stateside with training units. It was surplused in November 1945. In 1946, it was given to Stuttgart, Arkansas for display. However, Stuttgart city government tired of the display and turned the plane over to civilian operators. The civil registration N17W was assigned. It operated for a number of years as a pesticide sprayer and as an aerial tanker. It appeared in the films *1000 Plane Raid*, *Tora, Tora, Tora*, and the 1989 remake of "The Memphis Belle". In *The Memphis Belle*, it appears as *Kathleen*, and was the only genuine B-17F used in the making of the film.

Serials of the B-17F:

41-24340/24389		Boeing B-17F-1-BO Fortress
41-24390/24439		Boeing B-17F-5-BO Fortress
41-24440/24489		Boeing B-17F-10-BO Fortress
41-24490/24503		Boeing B-17F-15-BO Fortress
41-24504/24539		Boeing B-17F-20-BO Fortress
41-24540/24584		Boeing B-17F-25-BO Fortress
41-24585/24639		Boeing B-17F-27-BO Fortress
42-2964/2966		Douglas-Long Beach B-17F-1-DL Fortress
42-2967/2978		Douglas-Long Beach B-17F-5-DL Fortress
42-2979/3003		Douglas-Long Beach B-17F-10-DL Fortress
42-3004/3038		Douglas-Long Beach B-17F-15-DL Fortress
42-3039/3073		Douglas-Long Beach B-17F-20-DL Fortress
42-3039/3073		Douglas-Long Beach B-17F-20-DL Fortress
42-3074/3148		Douglas-Long Beach B-17F-25-DL Fortress
42-3149/3188		Douglas-Long Beach B-17F-30-DL Fortress
42-3189/3228		Douglas-Long Beach B-17F-35-DL Fortress
42-3229/3283		Douglas-Long Beach B-17F-40-DL Fortress
42-3284/3338		Douglas-Long Beach B-17F-45-DL Fortress
42-3339/3393		Douglas-Long Beach B-17F-50-DL Fortress
42-3394/3422		Douglas-Long Beach B-17F-55-DL Fortress
42-3423/3448		Douglas-Long Beach B-17F-60-DL Fortress
42-3449/3482		Douglas-Long Beach B-17F-65-DL Fortress
42-3483/3503		Douglas-Long Beach B-17F-70-DL Fortress
42-3504/3562		Douglas-Long Beach B-17F-75-DL Fortress
42-3563/3562		Douglas-Long Beach B-17F-75-DL Fortress
42-5050/5078		Boeing B-17F-30-BO Fortress
42-5079/5149		Boeing B-17F-35-BO Fortress
42-5150/5249		Boeing B-17F-40-BO Fortress
42-5250/5349		Boeing B-17F-45-BO Fortress
42-5350/5484		Boeing B-17F-50-BO Fortress
42-5705/5709		Lockheed/Vega B-17F-1-VE Fortress
42-5710/5724		Lockheed/Vega B-17F-5-VE Fortress
42-5725/5744		Lockheed/Vega B-17F-10-VE Fortress
42-5745/5764		Lockheed/Vega B-17F-15-VE Fortress 
42-5765/5804		Lockheed/Vega B-17F-20-VE Fortress 
42-5805/5854		Lockheed/Vega B-17F-25-VE Fortress 
42-5855/5904		Lockheed/Vega B-17F-30-VE Fortress 
42-5905/5954		Lockheed/Vega B-17F-35-VE Fortress
42-5955/6029		Lockheed/Vega B-17F-40-VE Fortress
42-6030/6104		Lockheed/Vega B-17F-45-VE Fortress
42-6105/6204		Lockheed/Vega B-17F-50-VE Fortress
42-29467/29531		Boeing B-17F-55-BO Fortress
42-29532/29631		Boeing B-17F-60-BO Fortress
42-29632/29731		Boeing B-17F-65-BO Fortress
42-29732/29831		Boeing B-17F-70-BO Fortress
42-29832/29931		Boeing B-17F-75-BO Fortress
42-29932/30031		Boeing B-17F-80-BO Fortress
42-30032/30131		Boeing B-17F-85-BO Fortress
42-30132/30231		Boeing B-17F-90-BO Fortress
42-30232/30331		Boeing B-17F-95-BO Fortress
42-30332/30431		Boeing B-17F-100-BO Fortress
42-30432/30531		Boeing B-17F-105-BO Fortress
42-30532/30616		Boeing B-17F-110-BO Fortress
42-30617/30731		Boeing B-17F-115-BO Fortress
42-30732/30831		Boeing B-17F-120-BO Fortress
42-30832/30931		Boeing B-17F-125-BO Fortress
42-30932/31031		Boeing B-17F-130-BO Fortress
42-37714/37715		Douglas-Long Beach B-17F-80-DL Fortress
42-37717/37720		Douglas-Long Beach B-17F-85-DL Fortress

Specification of B-17F:

Four Wright R-1820-97 Cyclone radials rated at 1200 hp for takeoff and 1000 hp at 25,000 feet.For brief intervals, a war emergency power of 1380 hp could be delivered.
Maximum speed 299 mph at 25,000 feet, 325 mph at 25,000 feet (war emergency).
Cruising speed 200 mph.
Landing speed 90 mph An altitude of 20,000 feet could be attained in 25.7 minutes.
Service ceiling 37,500 feet.
Range 1300 miles with 6000 pounds of bombs, maximum range 2880 miles. A range of 4420 miles could be attained with 3612 gallons of fuel at 5000 feet.

Dimensions: Wingspan 103 feet 9 3/8 inches, length 74 feet 9 inches, height 19 feet 1 inches, wing area 1420 square feet.

Weights: 34,000 pounds empty, 40,437 pounds loaded, 56,500 pounds maximum. Normal fuel load was 2520 US gallons, but extra fuel tanks could be installed which raised total fuel capacity to 3612 US gallons.

Specified defensive armament was as follows: six ball-and-socket mounts in the nose and front windows. One 0.30-inch M2 machine gun with boxes for 5100 rounds of ammunition. One Sperry No. 645473E power turret in dorsal position with two 0.50 Browning M2 machine guns with 500 rounds per gun. One Sperry No. 654849-J power turret in ventral position with two 0.50-inch Browning machine guns with 500 rounds per gun. One 0.50-inch Browning M2 machine gun is each of the two waist windows, 400 rounds per gun. One ball and socket mount was fitted to the roof of the radio operator's compartment for a 0.50-inch Browning M2 machine gun. Two 0.50-inch M2 Browinging machine guns were installed in the tail position, with 500 rounds per gun. Later production batches (B-17F-70 to 130-BO, B-17F-35 to 65-DL, and B-17F-35 to 50-VE) had a single 0.50-inch machine gun installed in a cheek mount on each side of the nose. Additional flexible machine guns installations were often mounted in the nose in the field, firing from sockets cut into the side or from windows cut into the side of the nose.