B-17 w/ 20mm tail gun?!

[oakranger]

Was this a experimental or did they really used the 20 mm?  If so, how often?

[Ack-Ack]

Yes, there were about 5-7 B-17Gs with the 97th Bomber Group (15th AF) that converted the tail guns to 20mm cannons.  These planes were used as "tail end Charlie" planes at the rear of the formations.  The reasoning behind the conversion was that these tail end Charlie planes were usually hit with long range guns by the Luftwaffe attackers, and the 20mm cannons would give the tail gunner something with the range to fire back.  The 20mm cannons were added more for their psychological effect than destructive power.

Robert Freeman's, "The B-17 Flying Fortress Story" has more informaton about the 20mm equipped B-17Gs.

*edit* Seems the 99th BG also had at least one B-17G with a 20mm cannon in the tail.  Lil Abner (S/N 42-32046)

ack-ack

[oakranger]

Yes, there were about 5-7 B-17Gs with the 97th Bomber Group (15th AF) that converted the tail guns to 20mm cannons.  These planes were used as "tail end Charlie" planes at the rear of the formations.  The reasoning behind the conversion was that these tail end Charlie planes were usually hit with long range guns by the Luftwaffe attackers, and the 20mm cannons would give the tail gunner something with the range to fire back.  The 20mm cannons were added more for their psychological effect than destructive power.

Robert Freeman's, "The B-17 Flying Fortress Story" has more informaton about the 20mm equipped B-17Gs.

*edit* Seems the 99th BG also had at least one B-17G with a 20mm cannon in the tail.  Lil Abner (S/N 42-32046)

ack-ack

WOW!  Wonder how effective they where? 

[Krusty]

Considering many B-29s removed theirs, I'd wager "not very" -- most .50cals didn't open fire outside 500 yards, let alone 1.5k regular ranges in AH bomber tail chases.

It may have been more psychological from the side of the allies, rather than from that of the axis. Axis attackers wouldn't be able to tell there were 20mms in the tails during an attack.

[oakranger]

Considering many B-29s removed theirs, I'd wager "not very" -- most .50cals didn't open fire outside 500 yards, let alone 1.5k regular ranges in AH bomber tail chases.

It may have been more psychological from the side of the allies, rather than from that of the axis. Axis attackers wouldn't be able to tell there were 20mms in the tails during an attack.

If it is psychological, how the hell did the pilots tell the different between a 20mm and .50cal.  If i was that German pilot coming on a bomber, i would guess my mind would be so focus on that one shot and at the same time any fighter escorts near by.  Heck, being 15-20-25 k and worrier of being shot down has to be a burden to them.   

[Krusty]

That was my point too. I'm saying it was psychological for the allied gunners...

Same as RAF night bombers throwing out beer bottles and religiously thinking they pulled away the search lights from the bomber formations, keeping them safe.

[Ack-Ack]

If it is psychological, how the hell did the pilots tell the different between a 20mm and .50cal.  If i was that German pilot coming on a bomber, i would guess my mind would be so focus on that one shot and at the same time any fighter escorts near by.  Heck, being 15-20-25 k and worrier of being shot down has to be a burden to them.   

The psychological impact was two-fold.  1) It was intended to give the Luftwaffe pilot some cause for concern as he dove in on the tail end Charlie plane and 2) to give a boost to the tail gunner.  It was found that the B-17s flying in the tail end Charlie slot would often be engaged by the Luftwaffe fighters at long range, out of range of the tail gunner's .50 caliber machine guns.  It was felt that by replacing the .50 cals with a 20mm cannon would give the tail gunner a mental boost by giving him the impression that he could now engage the attacking fighters beyond the range the gunner was able to in the past and just didn't have to sit there and take it until the fighter got within range of the .50s.


Here are some photos that show the tail mounted 20mm cannons along with some other modifications to various bombers.

Top Row: Nose mounted 20mm cannon installation
42-5897, a B17F from the 385th BG, was given a 20mm cannon but the recoil was regarded as compromising the safety of the nose compartment and was found to be difficult to aim.
Bottom Row Left: Tail mounted 20mm cannon
42-38090 was one of five B17Gs from 97th BG which had a similar 20mm cannon fitted in their tails.
Bottom Row Right: 42-31435's six .50 caliber machine gun fixed turret
B17G 42-31435 of the 384th BG suffered damage to its nose and was fitted with a fixed battery of six .50 calibre guns to be fired by the pilot in the event of a head on attack. It did fly a few operational sorties in July 1944 but suffered a crash landing before it could be used.



While all three examples were field modifications, the nose and tail mounted 20mm cannons were an "official" field modification and not the work of some enterprising crews, like the B-17G with the fixed forward firing turret.

ack-ack

[Chalenge]

Considering many B-29s removed theirs, I'd wager "not very" -- most .50cals didn't open fire outside 500 yards, let alone 1.5k regular ranges in AH bomber tail chases.

It may have been more psychological from the side of the allies, rather than from that of the axis. Axis attackers wouldn't be able to tell there were 20mms in the tails during an attack.

The B-29s were ordered to remove AMMO for the tail guns when they were attacking at NIGHT at 8k and only the lower turrets had ammo for shooting at search lights by order of General Curtis LeMay.

[Ack-Ack]

The B-29s were ordered to remove AMMO for the tail guns when they were attacking at NIGHT at 8k and only the lower turrets had ammo for shooting at search lights by order of General Curtis LeMay.

Not true since B-29s had to defend themselves against night fighters, nor would B-29 crews fire at the searchlights since the chance of hitting one was pretty much on par with a snowball's chance in Hell.  B-29 gunners had orders at night not to fire their guns unless they were under direct attack to lessen the chances of being spotted and not to spoil unnecessarily the gunner's night vision.

ack-ack

[oakranger]

Same as RAF night bombers throwing out beer bottles and religiously thinking they pulled away the search lights from the bomber formations, keeping them safe.

LOL, they must had a lot of beer they where drinking in flight.

 

Bottom Row Right: 42-31435's six .50 caliber machine gun fixed turret
B17G 42-31435 of the 384th BG suffered damage to its nose and was fitted with a fixed battery of six .50 calibre guns to be fired by the pilot in the event of a head on attack. It did fly a few operational sorties in July 1944 but suffered a crash landing before it could be used.

ack-ack

6 x .50 on the nose!!  wow, they would do the job.   Was there any B-24, B-26 that equip them self with 20mm?

[Ack-Ack]

LOL, they must had a lot of beer they where drinking in flight.

 

6 x .50 on the nose!!  wow, they would do the job.   Was there any B-24, B-26 that equip them self with 20mm?

If I recall correctly, the field mod of the forward firing fixed 6x 50 caliber turret never saw any action as the plane crashed before the guns could be fired at any Luftwaffe fighter.

As for any of the B-24 or B-26 groups having any bombers with a 20mm cannon, I haven't found anything concrete that says they did other than some posts on a warbirds forum that some may have been but no sources to confirm.


ack-ack

[colmbo]

Was there any B-24, B-26 that equip them self with 20mm?

The RAF or RN equipped some anti-submarine/anti-shipping B-24s with an under the nose pod of 4X20mm.  No idea how widely they were used...or if used at all.

[oakranger]

The RAF or RN equipped some anti-submarine/anti-shipping B-24s with an under the nose pod of 4X20mm.  No idea how widely they were used...or if used at all.

Now that you bought that up, i do recall some RN B-24 equip with 20 mm.