B-29 Engineering Flight book

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Pacific Historian
Jun 4, 2005
Orange County, CA
I started this thread to discuss anything about the B29 and the B50, good or bad. I invite anyone to add to it, just try to stay on topic.

My first post is from the B29 website. Its about the ballistics and aiming computer the B29 used.

The author of this gave me permission to copy it here.
Taigh Ramey
Proprietor, Vintage Aircraft
7432 C.E.Dixon Street
Stockton, California 95206
(209) 982-0273

Here are some more shots of the other side of the computer. On this side you can see the selsyn generators which are also in the turret and the sighting station (black cylinders with 5 wires attached). Please correct me if I am wrong, as I am eager to learn as much as possible about this system, but here is my simplistic explanation of how the system works:

There are two selsyns for determining azimuth and two for elevation. Two selsyns are mounted on and are geared to rotate with the turret and two are mounted on and are geared to rotate with the sight. These two selsyns (each rotates at a different speed) determine the position of the sight and the turret. If there is a difference between the position of the sight and the turret a voltage is created and the amplifier senses the voltage. The amplifier (square box in the DSC00436 photo) then applies a voltage to the field of Amplidyne (one of the two large motor generators on the DSC00436 photo) which puts out the voltage to drive the turret motor . There are two motors in each turret, one to drive it in azimuth and one for elevation. There is one Amplidyne for azimuth and one for elevation or a set of two for each turret. When the turret comes into alignment with the sight the differential voltage generated by the selsyns goes to zero and the amplifier reduces the field voltage to the amplidyne and thus the power to the turret drive motor is also reduced to zero.

The computer can be put in the system to make corrections to compensate for certain parameters like temperature, altitude, airspeed, range and the acceleration of the attacking plane (on later RCT systems). Barometric altitude, indicated airspeed and outside air temperature were entered into the system via the Navigators hand set, photos of which will follow in the next e-mail. The higher the altitude the thinner the air and the less resistance the bullet will have on its trajectory. The higher the airspeed the more the guns will have to be deflected upwind for the bullets to hit the target, assuming a broadside attack. The lower the temperature the higher the air density which also affects the path of the bullet. Later systems had two gyros mounted on the sighting stations which would sense the acceleration of the fighter by the sensing how fast the gunner was turning the sight while tracking the target. The computer would also take this into account to adjust the guns to hit the target.

The idea was for the gunner to keep a ring of dots centered on the target. The ring of dots was adjustable with the right hand wheel of the pedestal sight and the right grip on the upper ring sight. The gunner would turn a small knob just below the sight to the size of the wingspan of the attacking fighter. If it was a Japanese Zero then he would turn the knob until 36 (the wingspan in feet) was the number visible in the bottom of the sight glass. Then the gunner would adjust the ring of dots to the wingspan of the fighter as seen through the sight glass. This would give the computer basic range information. If the fighter was further out the guns would have to be elevated for the bullets to hit the target. If the computer was selected into the system the gunner would keep the sight centered on the target and keep the ring of dots adjusted to the wingspan while tracking on the target. He would thumb one of the triggers (on each side of the pedestal sight and a pull trigger on the ring sight) to fire the guns. The computer would compute the lead, elevation, range and parallax and would adjust the position of the turret and guns by deflecting them so the bullets would hit the target. The parallax was the difference in distance between the sighting station and the turret. The computer would adjust the guns so the bullets would converge to hit the target to compensate for this parallax. There were double parallax computers as well which would allow one gunner to use two turrets to shoot at a target. The double parallax computer would adjust the guns so that the bullets from both turrets would converge at the target.

With the computer switched out of the system (this switch is on the sighting station) the turret will simply point in direct alignment with the sight. In this mode the gunner would put in his own lead and elevation by deflecting the sight manually. The range, acceleration, altitude, airspeed and temperature information was not used in this manual mode and the gunner would use his experience to get the bullets on target. In this mode the parallax and double parallax was not computed so the bullets of both turrets would follow a parallel path.

I find it interesting that the four computers mounted under the floorboards in the radar compartment had lots of armor plate around them for protection. The computer for the bombardier's system was mounted in front of the Navigator or just behind the armor plate of the pilot.

Incidentally there were computing sight in turrets going into WWII. The B-17 and B-24 has computing sights in their upper and ball turrets. The K-3 sight was used in the upper turret of the B-17 and the K-4 was used in the lower ball turret. These sights were similar in their computations or range and deflection but they didn't take temperature and acceleration into account. These sights didn't use selsyns for position nor did they need to calculate parallax as they were mounted inside the turret in front of the gunner. He would manually input wingspan and range information and the sight would adjust the gun sight. The gunner would keep the sight on the target and adjust the range, typically with a range foot pedal. The sight was connected with flexible shafts to the azimuth and elevation gear boxes to receive position information. They even came out with compensating sights for the single waste guns in the B-17, B-24 and the B-25. These sights were also connected to the gun mount with flexible shafts to give them azimuth and elevation inputs.

I have found information documenting the use of video guided bombs being developed in WWII as well as the more common radio guided bombs. Everyone seemed to be fascinated to see the video from the nose of bombs hitting buildings in Iraq in Desert Storm. I enjoy the fact that they were doing that in WWII! I like to learn about the development of technology in WWII. From iron ring sights on 30 cal hand held guns to computers, radar and video guided ordnance in a few short years is amazing to me. I know that these systems were not in wide use in WWII but the B-29 is a great example of this technology. Remote turrets allowing the gunner to be out of the wind and in a more comfortable heated and pressurized environment so he could do his job better is pretty high tech considering what was used in 1941.


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Some of this will be reposts, but my intention is to make this a continual thread. Always good to chat about the same old stuff from time to time, as other people might have a different take on it.
The sights in early WWII bombers such as the B-17 were reflector sights, not "computing" sights. As far as I know the B-29 and the A-26, and the B-17G and later were the only operational bombers of WWII to have lead computing gunsights. On the B-17G+, only the chin turret was lead computing.


Good info and pics up there syscom. I dont actually have much that I contribute to this thread, just what is basic and known about the B-29 so I enjoyed reading it.
One of the many production battles in the US to get eqmt from the factory to the battlefield. It helps when the General of the Air Force is pissed and orders things be done and damn the procedures and paperowrk.

The Battle of Kansas

President Franklin Roosevelt promised China's Generalissimo Chiang Kia-shek that B-29 Bombers would be in India and China by January 1944 to begin Operation Matterhorn, the air war against Japan. Later, General Arnold was forced to revise the plan and set a new goal, March 10, 1944. The first bomb wing, the 58th, had begun training in July 1943 at the four Kansas airfields: Smoky Hill (Headquarters), Pratt, Great Bend, and Walker Army Air Fields. The training had been difficult due to the lack of B-29s. Many crews had fewer than twenty B-29 hours when they left for combat in March 1944. In fact, by mid-January only 96 B-29s had emerged from factories, but on many days, only 16 were flyable. On January 15, 1944, the 20th Bomb Command's assessment concluded that they did not have one combat-ready B-29. General Arnold, unaware of the gravity of the situation, planned to witness the departure of the 58th Bomb Wing, but upon his arrival, March 9, 1944, there

were no B-29s ready to depart. Because early B-29s were intended to be used for training purposes, they needed significant modifications to be combat-ready. There was a critical shortage of parts and mechanics to complete the needed upgrades. In fact, some planes needed fifty-four major modifications. The modifications ranged from the electrical system to the tires, plus the continuing problem, the engines. In spite of these difficulties, General Arnold knew the commitment had been made, and he would make sure it was fulfilled.

The Battle

General Arnold's aide, General B. E. Meyer, was placed in charge of the special project, commonly known as the "Battle of Kansas." Getting the B-29s into combat became the Army Air Force's top priority. When military mechanics could not complete all of the work, Boeing was asked to send as many trained technicians and mechanics as possible. Boeing complied, even though it slowed production. To add to the crisis, the weather turned bitterly cold. There were few hangars at the newly built Kansas airfields, so most mechanics had to work outside. High altitude suits and gloves helped, but many worked for only 20 minutes before needing relief.

The Battle of Kansas is Won

General Arnold compared the importance of "the Battle of Kansas" to the Battle of Stalingrad. It was a battle that had to be won and it was. It was won by people willing to work long hours in terrible conditions because they knew "the Battle of Kansas," like the war, had to be won no matter what the sacrifice.
I found this great link about how Chrysler/Dodge was brought on board to build the new R3350 engines.

Chrysler Corporation Requested To Participate

Shortly after the Pearl Harbor attack, on December 7, 1941, Army Air Corps planners determined that the large scale B-29 program would require a major new source of Wright Cyclone engines. Chrysler Corporation was contacted and asked to undertake the incredible task, with the first engines to be built in March, 1943, subsequently ramping up to an output of 1,000 per month by January, 1944. Chrysler was asked to get busy in the first few days of 1942--at a moment in time when there was no designated location, no plant, no machines, no tooling, not even a factory design (Stout, p. 10-13).

The size of the task ahead stimulated formation within the Dodge Division (Fred J. Lamborn, VP/GM) of a separate function. Mr. L. L. Colbert was named General Manager, followed quickly by selection of key support staff, also from within the Corporation. William C. Newberg became Chief Engineer; C. J. Synder, Master Mechanic; W. H. Eddy, Production Manager; H. J. Laidlaw, Plant Engineer; and A. H.Hilverkus, Planning Superintendent (Stout, p. 8-9).

Reality set in early, as a group of Chrysler engineers and factory people journeyed quickly to Wright's plant in Paterson, New Jersey to examine their new manufacturing challenge. The Model 23 Wright Cyclone 18-cylinder engine was just 37 running hours into its initial test program of 150 hours (Stout, p. 10). One can readily imagine the tremendous excitement and anticipation that must have been experienced by those automotive veterans! The big radial had to be brought under drawing control before there was any chance for successful mass production. Concurrently, the very FIRST XB-29 airframe was still nine months from completion out in Seattle!

War Production Board Designates Chicago: Factory Complex Begun

Within days, a Chicago site was selected by government officials, and frenzied activity got underway. The designation "Dodge-Chicago" was selected to identify the huge complex underway. A major initial question concerned factory design. Given the shortage of steel across industry, architect Albert Kahn and Chrysler people designed a pioneering reinforced arched-rib concrete configuration that used only 2.6 pounds of steel per square foot versus 5.5 pounds of then conventional design, thus saving about 9,200 tons of scarce material for other uses.

Factory construction (by the George A. Fuller Company, prime contractor) broke ground in June, 1942 and proceeded day and night, resulting in 6,300,000 square feet of floor space in a 19- building complex. Sixteen of the buildings were brought in by March, 1943, ready to receive more than 9,000 metal-working and fabrication machines plus complete support tooling (seven months before such machines and tools would be available). The main machining and assembly building was 82 acres in size, with 22 acres fully air-conditioned--necessary to the precision assembly processes required. Dodge-Chicago was the only aircraft engine factory that took in "raw" pigs of aluminum and magnesium at one end and pushed out finished engines at the other. Occupying an area of 30 city blocks, the buildings and related infrastructure cost $173,000,000 of 1942 money (Stout, pp.12-15).

Unique in comparison to other engine plants in the United States, after production got underway, Mr. Newberg coupled newly-completed engines under test directly to induction motors that were operated above their synchronous speed so as to generate electricity. The arrangement yielded 91,106,000 kilowatt hours, about 25 percent of the total electrical consumption for the entire project (Stout, p.48 ). Meanwhile, Boeing's operations in the Seattle area throbbed with action as Airframe Job One neared completion.
B-29 Power: Four Wright Cyclone 18- Cylinder 2,200 Horsepower Engines

The era of the Wright Cyclone engine actually began in 1927, as a nine-cylinder, hemispherical combustion chamber, air-cooled unit of 525 horsepower. About every two years thereafter, the engine was increased in output, including a doubling of its cylinders to 18, (Note: some sources, including Dammann, p. 247, and Flammang, p. 98, state, in error, that the B-29 engines were nine-cylinder units) but with no increase in bore and stroke, or, significantly, any enlargement of frontal area.

Cowling was tighter than on the B-17 Heavy Bomber, with its engines rated at 1,200 horsepower each at takeoff power setting (Ethell and Price, p. 10). Higher compression ratios and effective supercharging applied to those 3,350 cubic inches of displacement were the principal routes to the eventual 2,200 horsepower unit that Dodge was to learn to build under urgent, emergency conditions. In contrast, railroad Diesels of the time powered the crack Superchief, yielding only one horsepower per fifteen pounds of engine weight versus the Cyclone's nearly one horsepower per pound.

Dodge-Chicago Production Meets Challenges

Machinery and tooling for pilot production at Dodge-Chicago was promised finally to be allocated and in place by November 20, 1943. As 1944 opened, manufacturing was at last able to get underway, with 60 engines promised by the end of January and a target of 1,000 engines per month by December, 1944. Already in process, was the additional tooling needed to raise production to a newly-requested, increased rate of 1,600 per month. Preparation paid off. In June, 344 engines were delivered versus a schedule of225. On July 13th, the 1,000th engine was shipped. In October, 957 engines were delivered, nicely exceeding the schedule of 850. Momentum was building and engine storage became a new, but very happy, problem!

In eleven months, beginning in January, 1944, Dodge-Chicago completed 5,000 engines. As January, 1945 closed, the pace quickened: More than 7,500 engines had now been delivered. By July 15,1945, Dodge-Chicago output passed 16,000 engines, reaching contract closure with Japan's surrender at a total of 18,413 engines (Stout, pp. 41-45).

Given wartime conditions, bringing the Cyclone to full flying status as a mass-produced engine required continuing revisions and re-designs following initial release to Dodge-Chicago. Amazingly, 6,427 design changes (Note: Stout states two figures, 6,427, p.46; 6,274, p. 23--either total is stunning) were issued, usually involving groups ofparts--some with as many as 150 separate items. In turn, these design changes generated 48,500 engineering releases and change notices--almost always resulting in methods, materials, or tooling changes.

The press of events forced unusual steps throughout the entire program. The engine had to be virtually re-engineered while in production. Dodge assigned 120 graduate engineers, well supplied with assistants, in support. They were occupied fully with 26 major improvements--including pre-stressed pistons, shot-peened connecting rods, high-pressure polishing using powdered stone in water, fuel injection at 2,500 psi with tolerances often-millionths of an inch, increased oil pressure to help with cooling, and supercharging--to name only a few. Many parts exceeded the dimensioning and finishing of the best watch manufacturing of the time. Industrial diamonds were used in the boring of piston pin holes. Chrysler's Superfinish was used and magnetic inspection blossomed.

Cooling was a principal vexation that no simple solution could clear. Wright engineers wrestled with cooling challenges that included increasing the aluminum fins on each cylinder barrel from 40 to 54, thus enlarging cooling area to 325 square feet per cylinder head and barrel--for a total of 5,850 square feet per engine. Exhaust valve design was improved continuously throughout the program. Dodge-Chicago designed the ignition harness that went into production. Steadily, the problems began to yield. Engine life was gradually extended, from 200 hours before overhaul was needed, to about 400 in the early spring of 1945.
Very interesting about the remote controlled turrets and the computing gunsights. The B-29D was supposed to be powered by the new Pratt and Whitney R-4360 28 cylinder radial. Even though many of the R-3350's problems had been solved during the course of the war, it could never be said that the B-29 possessed a great reserve of power, particularly at take-off with a heavy load and high temperatures. The R-4360 was seen as a possible solution, as was the Allison V-3420. The Allison didn't pan out, but the R-4360 showed much promise. After the war, Boeing proposed an advanced version of the B-29, powered by the R-4360 and equipped for carrying atomic bombs. The Air Force was a bit reluctant going to Congress to ask for funding more B-29 purchases, with many B-29's in storage since the end of WWII. Not to mention, Congress had just elected to fund the jet B-47 project. So, instead of calling this improved version a B-29 derivative, it was decided to call the new version the B-50. It wasn't really out of line, considering that much of the B-50 was a new design. Though B-50's had entered service during the Korean war, none were used in combat.
You beat me to the punch on this story!! I was going to go into detail on this later. :lol:

I was looking at the specs for the B29 with the proposed Allison engine, and it had a top speed of about 406mph with a corresponding increase in cruise speed.

The AAF wasnt interested in it though as the improvements in performance just werent worth the efforts to change the assembly lines yet again.
well they did have allot of experience with engines, trying to get the most power as possible out of them, i'd imagine most of these car companies that had been using other company's engines in their cars for years had always wanted to make their own engines as they could design them to be just right for their cars, but it was too risky to try, but if the military asks that gives you an excuse!

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