The B29 Superfortress

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paul.mercer
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The B29 Superfortress

Post by paul.mercer »

Gentlemen,
I watched a documentary on the B29 the other day and it showed their gunnery arrangements being controlled by some sort of radar which directed the gunner how far ahead they should fire to hit an attacking aircraft, I'm not sure how it worked, but it looked to be quite effective ( particularly with all those '50 cal Brownings going off) until they were used in the Korean war against a MIG. Bearing in mind the hammering the B17's took on their daylight raids over Germany it made me wonder
if the B29 had been available if it would have fared any better against the German fighters who still had some of their best pilots using the FW 190 and their new jet fighters, whereas the Japanese had lost many of their best pilots by the time the B29's started their raids. ,
OpanaPointer
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Re: The B29 Superfortress

Post by OpanaPointer »

My first look at a real B-29 was at Chanute AFB, Illinois, back in the 60's.* My thought was "they're smaller than they look." David glared at me. :lol:

*My brother was there for some post-boot camp school.
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marcelo_malara
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Re: The B29 Superfortress

Post by marcelo_malara »

Hi guys.

First, there was no aircraft technology in WWII which could do that. The B-29s turrets were remotely controlled from plexiglass cupolas, away from the guns turrets, using RPC (remote power control), a novel tech in those years, not very different from the directors used in ships.

Second, the US developed a gyroscopic sight in WWII, used in fighters, in the 20mm Oerlikon naval guns, and on the director of the 40mm Bofors mountings. The sight consists on a transparent glass inclined 45" vertically, on which a an light pip sight is projected from below, so the operator see both the target and the pip in the glass. The functioning is, the operator of the system follows the target for a while with the sight (in a fighter the pilot needs to move the plane for this, in the 20mm the gun, and in the 40mm the director), the gyroscope reacts to this movement with the physical phenomena known as gyroscope precession, and with this a crude mechanical computer moves the pip behind the target. Then the operator moves the sight so the pip is on target, so that the bore will be pointing forward of it. This was the most advanced predicting sight used in WWII.

Question now is, was the gyroscope sight used in the B-29 gun director system?
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wadinga
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Re: The B29 Superfortress

Post by wadinga »

Hi All,

"Guns in the Sky" by Chaz Bowker has a chapter by a B-29 gunner describing raids on Japan. He mentions his position as CFC (Commander Fire Control) in the dorsal blister towards the tail of the aircraft, from which he could select and control several of the turrets (barbettes). Two blister gunners were located port and starboard behind the wing and their was a tail gunner in a mounting which at one time had a 20mm cannon as well as two -50 cal machine guns.

The system used optical sights only, with a black box computer calculating "lead" ahead of target based on gyro information plus allowance for windage. When firing on the beam, bullets would experience side draft equal to airspeed, a not insignificant factor plus a tendency to climb or dip based on side draft interaction with their spin.

The CFC could allocate turret control between various gunners, and even the Bombardier could take over the forward upper turret. One of the photos in the chapter shows a luckless side blister gunner who was blown out of his seat and left hanging by one leg and his safety strap in the freezing slipstream five miles above Japan. He was only hauled back aboard after 15 minutes but survived, albeit with severe frostbite injuries.

Very long endurance made the B-29 better suited to Pacific operations. The Japanese compensated for lack of experienced pilots by encouraging Kamikaze tactics in the sky.

At the end of the war a few RAF Lancasters had been equipped with the AGL (T) automatic gun laying radar codenamed "Village Inn " for their four gun rear turrets.

All the best

wadinga
"There seems to be something wrong with our bloody ships today!"
paul.mercer
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Re: The B29 Superfortress

Post by paul.mercer »

Gentlemen,
Thanks for the info,
Do you think that a B29 would have a better survival rate in daylight raids than the B17's over Germany against their 109's and 190's or their jets?
Byron Angel
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Re: The B29 Superfortress

Post by Byron Angel »

Complicated question, Paul. I don’t think that flak alone could have discouraged them. However, early in the Korean War, the USAF attempted daylight B29 raids over North Korea, escorted by early model “straight-wing” jet fighters. These raids suffered terrific losses to the better performing Russian MiG-15 interceptors (2x23mm + 1x37mm) and the bombers were forced to adopt night intruder operations.

FWIW

Byron
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marcelo_malara
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Re: The B29 Superfortress

Post by marcelo_malara »

Sure the B-29 system was far better than the B-17´s, and the B-29 could fly higher, so a reduction of casualties would have resulted from this. Anyway, there would be no immunity.
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Re: The B29 Superfortress

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Ran across an article last night that was highly critical of the B29 on several technical grounds -

- that the remote control fire control system was a calamitous unreliable failure, so bad that short circuits in the FC computer would cause one bomber to indiscriminately fire upon neighboring B29s in the formation. By the end of the war PTO B29s had had the remote control system and all armament removed, except for a manually operated twin-50cal tail position.

- that new model P&W R3350 radials were unreliable and subject to overheating at high altitudes and that any engine fire had a good chance of igniting the magnesium crankcase (think giant thermite grenade) that would burn at 5,000+ degrees F and destroy the wing spar in a matter of a few minutes. It is claimed that one of the reasons for altering to low altitude bombing operation over Japan was to reduce the load endured by the engines when flying at 30k+ ft. Another reason for low altitude operations was that daylight bombing accuracy from 30k+ ft was terrible - something like less than 1 in 3 a/c delivering their bombs within 5 miles of the target.

- that the fully pressurized fuselage of the B29 (a technical first) made both plane and crew subject to the dangerous effects of explosive decompression when hit by heavy AA.

- that, of 414 x B29s lost during the bombing campaign against Japan, only 1 in 3 was lost to enemy action; the other 2/3ds being lost to mechanical failures and accident. As well, the early raids over Japan were averaging loss rates of 8-10 pct.

Sounds crazy, I know. But the author seemed to be quite knowledgeable.

B
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marcelo_malara
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Re: The B29 Superfortress

Post by marcelo_malara »

Byron Angel wrote: Sat Dec 10, 2022 5:16 pm Ran across an article last night that was highly critical of the B29 on several technical grounds -

- that the remote control fire control system was a calamitous unreliable failure, so bad that short circuits in the FC computer would cause one bomber to indiscriminately fire upon neighboring B29s in the formation. By the end of the war PTO B29s had had the remote control system and all armament removed, except for a manually operated twin-50cal tail position.

- that new model P&W R3350 radials were unreliable and subject to overheating at high altitudes and that any engine fire had a good chance of igniting the magnesium crankcase (think giant thermite grenade) that would burn at 5,000+ degrees F and destroy the wing spar in a matter of a few minutes. It is claimed that one of the reasons for altering to low altitude bombing operation over Japan was to reduce the load endured by the engines when flying at 30k+ ft. Another reason for low altitude operations was that daylight bombing accuracy from 30k+ ft was terrible - something like less than 1 in 3 a/c delivering their bombs within 5 miles of the target.

- that the fully pressurized fuselage of the B29 (a technical first) made both plane and crew subject to the dangerous effects of explosive decompression when hit by heavy AA.

- that, of 414 x B29s lost during the bombing campaign against Japan, only 1 in 3 was lost to enemy action; the other 2/3ds being lost to mechanical failures and accident. As well, the early raids over Japan were averaging loss rates of 8-10 pct.

Sounds crazy, I know. But the author seemed to be quite knowledgeable.

B
Hi Byron. I agree wtih some points.

-the engine, Wright, not P&W, was troublesome, this is a very well known fact, it led to many overheating failures. The cause was the massive increase in size from other extant engines, the displacement volume went from 2800 cubic inches in the previously biggest engine to 3350, and the power increased by 50%. But, when all this was ironed out, it turned to be a well liked engine, powering civilian aircraft as the Lockheed Constellation and Douglas DC-7.
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marcelo_malara
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Re: The B29 Superfortress

Post by marcelo_malara »

-the change to lower altitude bombing is well known too, main reason was the cloudy skies over the targets.

-the rate of loss due to accidents is true too. The low casualty rate due to enemy action led to the elimination of the defensive armament, in order to increase fuel/bomb load.

-only think I had not heard was the trouble with the FC.

Regards
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marcelo_malara
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Re: The B29 Superfortress

Post by marcelo_malara »

Bear in mind that the B-29 was very fast, almost as a fighter, so it was difficult to intercept. It has to be done from the front, once it has passed the Japs airplanes they had trouble keeping up. And its turbo charged engines enable it to fly higher than the mechanical supercharged Japs fighters.
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Re: The B29 Superfortress

Post by Byron Angel »

Hi Marcelo,
I will try to locate the B29 web page I was referencing and pass it along to you.

Re the flammability of the Wright R3350 engines (thank for mfr correction BTW), I recall the failed attempt to resurrect the abandoned B29 in Greenland. When they tried to start the engines, one (or more?) caught fire and it was found impossible to extinguish the flames. I wonder if the magnesium crankcase problem was, for one last time, the culprit.

Re the FC system aboard the B29, the author of the article described it as a wonderful theoretical concept, but very shoddily built and, as a result, subject to unpredictable short-circuits that would randomly activate the guns and direct them at nearby friendly B29s. According to the article, Colonel Tibbets (pilot of “Bockscar”?) himself went to General Le May and proposed removal of the FC system and most of the armament, allegedly prompting Le May to first have Tibbets undergo a psychiatric evaluation for combat fatigue. There may well have been multiple reasons for removal of the guns, though ... with the technical problems of the FC system swept under the bureaucratic rug for “political” reasons ... it would not be the first time.

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Re: The B29 Superfortress

Post by Byron Angel »

Hi Marcelo,
Not the article I originally came across, but a very good read none the less -
https://www.historynet.com/superbombers-achilles-heel/

The original article -
https://theaviationgeekclub.com/heres-w ... y-in-1943/

More on the R3350 from NASA -
https://www.nasa.gov/feature/glenn/2020 ... rld-war-ii


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Re: The B29 Superfortress

Post by OpanaPointer »

Byron Angel wrote: Thu Apr 28, 2022 12:19 pm " ...the better performing Russian MiG-15 interceptors... "

Byron
Chuck Yeager flew against the MiG and beat it. Then he flew the MiG and won.

https://theaviationgeekclub.com/in-1953 ... tested-it/
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marcelo_malara
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Re: The B29 Superfortress

Post by marcelo_malara »

Byron Angel wrote: Mon Dec 12, 2022 10:40 pm Hi Marcelo,
Not the article I originally came across, but a very good read none the less -
https://www.historynet.com/superbombers-achilles-heel/

The original article -
https://theaviationgeekclub.com/heres-w ... y-in-1943/

More on the R3350 from NASA -
https://www.nasa.gov/feature/glenn/2020 ... rld-war-ii


Byron
Thanks Byron! I will take a look at them.

Regards
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