B-17 Flying Fortress version evolution

Dear All,

As I told you, from China my means to find information are really limited...therefore I'm on this forum for some help.

My question is:
What are the modification (structure, armament, engine,...) making a change of version of the Boeing B-17 Flying fortress.
Y1B-17, to Y1B-17A, to B-17B, to B-17C, to B-17D, to B-17E, to B-17F and to B-17G.

Thanks in advance

Philippe

 

The Y1-B-17's and Model 299 were prototype test airframes for evaluation by the USAAF. The C-D's had the smaller tail and lacked the upper/lower ball turrets and had side blisters for the waist gunners. E's added the the ball turrets and strengthened tails. F's added more pronounced cheek gun mounts, G added the distinctive chin gun mount.

In each variant minor internal changes also occurred the might make production easier/cheaper, greater speed or range.

 

You might start with the Wikipedia article. Wiki's good for basic information, though not definitive:

Boeing B-17 Flying Fortress - Wikipedia

@belasar gave a good description. The big change was with the E model, in which the after part of the aircraft was redesigned to provide a tail gun position. The earlier B-17s had a tapered tail, very good for streamlining. When the -17 was conceived, its speed and altitude were just as important as armament; most fighters at the time were still biplanes, and there was no radar to guide them to interceptions.

A brand-new aircraft often is superior to what exists at the time, but development continues across the spectrum of weapons. By 1940, fighters were vastly superior in performance and armament to those of a just a few years earlier. The RAF's early war experience confirmed that the B-17 needed more defensive armament, leading to the redesign of the -E with top turret, ball turret, and tail positions, each with twin .50-caliber machine guns. These gave good coverage against the classic attack from behind, which in turn led the Luftwaffe to develop the tactic of attacking from ahead. This was facilitated by the bomber having to fly over several hundred miles of German-controlled territory to hit targets in the Reich, which allowed controllers using radar to position fighters for head-on attacks. This in turn led to the increase in nose armament in the B-17F and -G already mentioned.

 

The problem is that Wikipedia I cannot access to this website from here in China

 

I have another trivial question
For the prototype Model 299 it was 9 crews, for the B-17F and G it was 10 cews
For the Y1B17 I read 6 crews
My question is"
what is the number of crew and function for the Model 299, Y1B17, Y1B19A, B-17-B, B-17C,

Thanks in advance

 

A large multi engine bomber had a pilot, co-pilot, navigator, bombardier and a number of crew needed to operate defensive machine guns it was equipped with. At times the navigator/bombardier could also man guns (usually near the nose) when not otherwise engaged with their primary duties.

Generally speaking as new variants came on line, more guns were added to cover areas not originally seen as threatened in the design phase. Usually every additional gun mount required a new crewman to operate it.

 

Before he passed about a decade ago I frequently talked with a grand old gentleman who served as a waist gunner on a B-17 late in the war, he said toward the end they flew with only one waist gunner who had to move move from side to side as needed. A mixture of manpower issues and greatly reduced German fighter opposition.

 

As noted most B-17s had ten crewmen, eight of whom operated guns, and four of whom had no other function. -Fs and -Gs had nine gun positions, with the navigator and bombardier in the nose having to work three.

The waist guns were side by side, and the gunners got in each other's way often enough that there was a term for it, "fanny bumping". In the later -Gs the starboard waist gun was moved forward to just behind the wing to prevent this. Ironically about the same time the forces in the field starting flying with only one waist gunner as @belasar mentioned. I'm not absolutely sure how this relates, but the "air force" at this time was still the Army Air Forces, and the ground troops were suffering a shortage of infantrymen; the reduction freed up a couple of thousand men who knew how to handle machine guns.....

I'm skeptical of the value of carrying extra crewmen in any aircraft just to man guns, except for the tail gunner. The tail was the most useful defensive position, and the man back there couldn't easily perform any other function.

Lower hemisphere defense was a difficult issue. The American ball turret in theory provided 360/90 degree coverage, but it was uncomfortable, potentially dangerous, and had an extremely restricted field of view. Many B-24 groups removed the ball turret, sometimes replacing it with a single or twin .50 firing through the hole. Some bombers had unmanned turrets aimed through periscopes, also unsuccessful. The Luftwaffe's lower gondolas were nicknamed "bathtubs" or "coffins" and had restricted fields of fire.

The best means of covering the lower angles, outside the arcs of nose or tail guns, might simply be waist guns that could aim well below the horizontal. The waist guns in the B-26 are a good example. These guns would also allow planes in formation to cover each other against attacks from below.