Fixed rearward-facing defensive guns - any worth in it?
- Thread starter tomo pauk
- Start date
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SaparotRob
Unter Gemeine Geschwader Murmeltier XIII
I..I..I don't know...
MIflyer
Captain
REALLY! I think that rear guns on fighter type aircraft are pretty much useless. Unlike bombers, the maneuvers typically required for fighters would make it hard for a gunner to react as well as being a short trip to barf city. Even with the turreted top mounted guns in the P-61 they had a heck of a time even hitting anything in training, at least until a grizzled old gunner threw away the books and realized they had to "reverse" lead the target if they were the faster attacking aircraft.
I do recall Winkle Brown describing how he was out formation flying with another Audex early in the BoB and was quite startled when a BF-110 pulled up alongside and the rear gunner blew away his wingman.
Barrett
Staff Sergeant
I thought I remembered a P-47 pilot saying he was hit maybe even downed by rearward firing guns on a 410. Here's the AI entry:
The Me 410 had two rearward-firing guns: a pair of 13 mm MG 131 machine guns mounted in remotely controlled barbettes on the sides of the fuselage. These defensive guns were operated by a rear gunner using a remote control aiming device, a feature considered advanced for the time.
The Me 410 had two rearward-firing guns: a pair of 13 mm MG 131 machine guns mounted in remotely controlled barbettes on the sides of the fuselage. These defensive guns were operated by a rear gunner using a remote control aiming device, a feature considered advanced for the time.
- Type and caliber: The two guns were 13 mm (.51 in) MG 131 heavy machine guns.
- Location: They were housed in blister-like barbettes on each side of the fuselage, near the rear.
- Operation: A rear gunner, seated in a tandem cockpit, controlled the guns remotely using a specialized aiming device.
- Purpose: This remote-controlled defensive armament was designed to protect the aircraft from attacks coming from behind.
That is a good question.
I would also ask, without bias, what the actual accuracy of the remote aiming on the B-29 type of installations was found to be?
Eng
MIflyer
Captain
Odd thing about that. The USAAF concluded that they were not satisfied with that system. But the actual crews flying over Japan reported that while it took some tweaking and adjusting to get better performance the gunnery system enabled then to hit Japanese fighters much further away that had been considered normal for bomber guns. Even Japanese fighters trying to fly at a safe distance to pace along with the bombers were getting hit. So it must have worked pretty darn good.
Alan Stevens
Airman 1st Class
- 179
- May 24, 2023
x
The installations on the B-29 and the 410 were extremely different. The B-29 had an insane fire control computer that accounted for an astounding array of variables. Alexander the OK has an excellent video on it:
View: https://youtu.be/QKRszjV07ZQ?si=mJh31aBJYpsB4lCb
Unlike the bulk of YouTube videos, this goes far beyond reading off a bunch of sources or just combining them, and it uses video to good effect (versus just writing a web page with some illustrations).
MIflyer
Captain
Note that there were TWO different gunnery systems developed for the B-29 but I think the GE one was the only type used in combat. The B-36 had a gunnery system similar in concept, and it was even more like SF because the 20MM guns used were retracted and emerged through the use of sliding panels when required. Some B-29's had radar for the tail gun as well.
SaparotRob
Unter Gemeine Geschwader Murmeltier XIII
It was a great video. I was able to understand it. Pretty impressive hardware setup. It's amazing the B-29 could lug all that stuff 1500 miles and back.
Great video, very thorough explanation of the system!
MIflyer
Captain
Even more impressive than the Millennium Falcon. Which used a B-29 nose for the cockpit.
SaparotRob
Unter Gemeine Geschwader Murmeltier XIII
I love the Corellian Engineering Corporation YT-1300 almost as much as the PBY. Almost.
Yes, a good video on the B-29 fire control. Certainly, it would seem that the B-29 self protection system was effective against the Japanese fighters. I would note that the effectiveness against fighters in Europe at the time was not argued and that the effectiveness against Jet fighters such as the Mig-15 was described as obsolete and ineffective. Nonetheless, if I
had been in those bombers attacking Japan, I would be pleased to have that system working for me. In those circumstances, it would seem that it had effective guns that could be accurately aimed.
Eng
yosimitesam
Airman 1st Class
It's simply a conservation of momentum problem. Let m1=mass of aircraft (gross weight, for example), v1=velocity of aircraft, m2=mass of projectile, v2=muzzle velocity of gun projectile in ft/sec. Assume the aircraft is going 250mph. Then v1=(250 mile/hr)x(5280 ft/mile)/3600 sec/hour. Then v1=367 ft/sec. Then the total momentum will be (m1x367) + (m2 x (v2-367)). You have to subtract the ft/sec of the aircraft from the projectile velocity in the last term (v2-367) because the muzzle velocity is *relative to the barrel of the gun* and it is moving forward, i.e. the opposite direction of the projectile as it leaves the barrel. The added momentum will be the second term: m2 x (v2-367). Divide this by the aircraft momentum (m1 x v1) and you get the fractional increase in airspeed (in ft/sec) due to firing one projectile from the rear-pointing gun. It's going to be very small because (m2x(v2-367)/(m1 x v1) is a SMALL number. The mass of the aircraft (m1, denominator) is very large compared to the mass (m2, numerator) of the projectile. Both m1 and m2 must be in the same "units", i.e. kg or pounds, or even slugs (the imperial unit of mass.) I'm too lazy to look up the mass of the projectile or the mass of the aircraft.
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He has a video on the B-36 system. It was ... not good.
Would the Do 217 and He 111 have had a dead zone directly to the rear where the gunner couldn't shoot? You might not hit anything, but you would prevent an enemy from camping out in that spot and force him into an area where the gunner can get at him.
Also, where these introduced while daylight operations were common? I'd think probably not, particularly in the Do 217, but I don't know enough details. A night interception would almost certainly come with a low closure rate stern attack, which is the only conceivable situation where these guns had a chance of hitting anything.
Also, where these introduced while daylight operations were common? I'd think probably not, particularly in the Do 217, but I don't know enough details. A night interception would almost certainly come with a low closure rate stern attack, which is the only conceivable situation where these guns had a chance of hitting anything.
They were introduced for day bombing. Many of the late 30s/early WW2 aircraft that had them had no night capability at all.
In any case, the best tactic against night attacks was a diving corkscrew, hoping the interceptor would lost sight. The muzzle flash from a stinger would make it easy to keep sight of the bomber in the dark.
MIflyer
Captain
Bill Gunston pointed out that the best attack position for a nightfighter was directly below the targeted bomber, but that none of the RAF aircraft had so much as window in the belly to detect that kind of attack.
