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B-29 Cabin Pressurization

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rev_howe
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2003/02/02 19:46:45 (permalink)
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B-29 Cabin Pressurization

Ok, I've read all the B-29 books I can lay my hands on (except 'technical' books or documents), so I know about the "mishaps" & general info. However, I still have a couple of questions: Was there a danger of flak causing a rapid depressurization? Did the pressurized cabin do anything as far as on board temp.? What was S.O.P. for loss of pressure at altitude- what happened next?

'Ding Hoa!' (Very Best),

Bill Howe
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    jpeters140
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    Re: [rev_howe] B-29 Cabin Pressurization 2003/02/02 21:40:26 (permalink)
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    Bill :-) To obtain a good answer for the B-29...why not go to the experts on the B-29 Superfortress lists ? There are two, you know.

    try [url "http://b-29.org"]http://b-29.org[/url] You must subscribe...no cost.

    Jim :-)
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    rev_howe
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    Re: [jpeters140] B-29 Cabin Pressurization 2003/02/02 21:45:17 (permalink)
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    Thanks, M/Sgt.

    I already subscribe, but so far I've done more reading than asking! Thanks for the tip & look for the question on the 'B-29 Superfortress' list.

    Thanks again, Jim.

    Bill Howe
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    Re: [rev_howe] B-29 Cabin Pressurization 2003/02/18 19:19:50 (permalink)
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    I was reading an account of the flight engineer on a B29 and he mentioned that the plane would be depressurized on the bomb run with the crew going on oxygen and switching to heated flight suits.



    Fitz
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    billrunnels
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    Re: [Fitz] B-29 Cabin Pressurization 2003/02/18 23:33:58 (permalink)
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    [cool]Bill, I also have been told they depressurized over the target/flak area to prevent a rapid depressurization which could present all kinds of problems at altitude. I think they pressurized again after leaving the danger area.

    Bill Runnels, Bombardier (B-17)
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    rev_howe
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    Re: [Bill Runnels] B-29 Cabin Pressurization 2003/02/19 12:30:19 (permalink)
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    Hey, Guys, thanks for the info.

    I posted the question to the B-29 email groups and got back many varied answers. My main interest was SOP during WWII. A lot of the answers I got were from Korean B-29ers. Although this was all good and interesting info., I am sure that they had advanced their procedures through further development of the plane from WWII to Korea. That's the first I've heard of heated flight suits- very interesting...

    Thanks again for the info., it is much appreciated.

    Bill Howe
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    billrunnels
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    Re: [rev_howe] B-29 Cabin Pressurization 2003/02/19 14:05:25 (permalink)
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    Electric heated flight suits were constructed much like electric blankets today. The boots, pant, jacket and gloves all snapped together to form one circuit. The circuit plugged into the aircraft electrical supply system. A rheostat enabled you to set and maintain the level of comfort desired. The B-17 and B-24 aircraft were not pressurized and did not have heat. Consequently at 50 to 60 degree below(C) temperatures the heated suit was a very important part of the flight uniform.

    Bill Runnels, Bombardier
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    rev_howe
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    Re: [Bill Runnels] B-29 Cabin Pressurization 2003/02/19 17:59:21 (permalink)
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    Hi, Bill.

    Thanks again for the great information- I can't believe I hadn't heard of those flight suits before! Apparently I don't know as much as I thought I did!!! Oh, well, as long as I keep learning!

    Bill Howe
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    chassl
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    Re: [rev_howe] B-29 Cabin Pressurization 2003/03/07 15:53:39 (permalink)
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    The procedure for de-pressurization during the bomb run during the Korean War was undoubtedly the same as used in WWII. There wasn't much development of the B-29 from 1945-1951 except for several modifications to the engines in an attempt to improve reliability. In spite of the modifications, the engines were still a problem, requiring an extensive preflight testing of the fuel injection system to guard against leaks. The Wright R-3350 had problems in almost every aircraft that used it, many because of the direct fuel injection system (fuel was injected directly into each cylinder). Many of the B-29s used in the Korean War had been stored for several years, then refurbished at Sacramento Air Depot. About the only modification made was the installation of "Shoran" bombing equipment.
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    rev_howe
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    Re: [chassl] B-29 Cabin Pressurization 2003/03/07 17:10:21 (permalink)
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    Hi, Charles. Thanks for the post. I belong to Sallyann's B-29 email group, and I've corresponded with a few Korean War B-29 Vet's. I have never heard of the "Shoran" bomb equipment. What was it? No one has ever mentioned it and I'm just curious. Almost all of my B-29 knowledge is WWII era. I didn't realize that they never really "fixed" the Wright engine. Did they ever get the overheating & "dropped valve" problems taken care of? Thanks again for the info.

    Sincerely,

    Bill Howe
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    chassl
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    Re: [rev_howe] B-29 Cabin Pressurization 2003/03/07 17:42:34 (permalink)
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    Shoran was a system that utilized two ground stations to determine the aircraft position. A predetermined release point was used, corrected according to actual wind at the bombing altitude. The radar observer was also the shoran operator. The aircraft flew along a path that was the predetermined distance from the ground station until it reached the distance measurement from the other station. This required the plane to be flown on a curved path or arc to stay at the proper distance point and then level off just prior to bomb release. This was a night operation and each aircraft bombed individually. The whole operation depended on the skill of the Shoran operator and his coordination with the pilot and bombardier who actually dropped the bombs. Shoran was similar to the Gee-H system used in the ETO, mostly before airborne radar became widely available. Some of the shoran receiving equipment was actually bought back from people who had purchased it as surplus.

    The engine overheating problem persisted with the B-29 and, on Okinawa, required a period of flight at about 1500 feet after takeoff until the engines cooled and climb could be initiated. In my opinion, the overheating was a problem with the engine installation in the B-29. Later versions of the 3350 suffered from a broken piston ring problem - a ring would break and then a piece of it would work its way upward until it broke out of the top of the piston. Engine analyzers allowed the flight engineer to detect this when the pieces would short out the spark plugs in a cylinder. If the engine was shut down immediately when this was detected, then only a cylinder change would be necessary. If not, then the engine had to be changed. This problem was believed at the time to be caused by fuel dripping from the injector in the cylinder wall and washing away the lubrication at that point. I read a report many years ago about the Douglas DC-7 which used an advanced version of the 3350 which said that one airline operator reported that 70% of those engines had to be removed prematurely (before the 1200 hour overhaul schedule).
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    rev_howe
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    Re: [chassl] B-29 Cabin Pressurization 2003/03/07 18:04:25 (permalink)
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    Thanks for educating me on the Shoran system- very interesting.

    I can't belive that they never got those engines working right... that seems odd to me. Sounds like VERY little changed from the end of WWII to the Korean Conflict with regard to the engine reliability. I read in Birds From Hell, by Wilbur Morrison, that when the B-29's first got to the CBI in mid-'44 they obviuosly found out quickly about the severe engine overheating (obviously made worse by the Indian climate). When the crews complained enough for it to get back to Wright, Wright essentially told them that "it wasn't a problem"!!! Sounds like they didn't EVER fix it.

    Thanks again for the reply.

    Bill
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    Re: [rev_howe] B-29 Cabin Pressurization 2003/03/11 21:59:41 (permalink)
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    Explosive cabin depressurization was only a problem if you blew out a blister or had a VERY large hole. Small holes were dealt with by placing a piece of cardboard or other material over the hole. Air pressure would hold it in place. As for depressurization on the bomb run, initially this was done on high altitude runs. The crew did not fly in heated suits in the 29. It was unnecessary due to cabin heater. Later in the war the bomb runs were made at low level and so, pressurization/depressurization was no longer an issue.
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    rev_howe
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    Re: [jsmccall] B-29 Cabin Pressurization 2003/03/12 13:55:01 (permalink)
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    Hi, Scotty!

    Glad to see you made it over to the forums. We need to get all the B-29ers to sign up for OUR forum!

    Thanks for the info. on cabin pressurization. You also confirmed what I thought- that you guys didn't wear the heated flight suits... you're always a wealth of info.!

    Take Care, Scotty.

    Bill Howe
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    Smiley
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    Re: [rev_howe] B-29 Cabin Pressuriz 2003/11/24 17:03:12 (permalink)
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    There were plugs on the aircraft for heated suits though right? I have talked to several crews that said they were pressurized until over target.., then they would repressurize for trip home.

    Did it effect fuel at all? Running pressurized or depressurized?
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    Jess Richey
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    Re: [Smiley] B-29 Cabin Pressuriz 2003/12/05 14:02:29 (permalink)
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    I think the engine reliabilty was greatly over blown after WW@2.Early 3350s had Carburetors and there was an over heating problem,but later versions had fuel injection systems and that helped.
    I flew was a flight engineer on B-29s during the Korean war and only lost one engine in over two years.
    the engineer had to stay awake.
    The Shoran system was added about Oct 51,when the MIGs made it nessesary to fly at Night.and I think the bombing accuracy improved.We always depressurized
    about time we hit the I.P.and stayed depressirized until we got off the bomb run.
    It took about 10 minutes to depressurize normally
    and about the same time to repressurize.The air was bleed off the turbo superchargers and didn't effect engine operation much.
    The electric suits were pretty good especially the boots
    the Engineers feet was about two feet from the skin of the plane and the coldest place in the world.
    Favorite tricks was to switch the pilot and co-pilots
    thermostats so they would turn it up while theother would turn it down,but it only lasted one time.
    Jess Richey
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    Jess Richey
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    Re: [rev_howe] B-29 Cabin Pressurization 2003/12/05 14:51:05 (permalink)
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    I put a post on this question this morning,but I thought
    I should put the limits of the pressurization system here.We could maintain 8000 ft Cabin altitude up to 30,000 outside altitude.Very seldom got about that
    once I think.
    The regulator kept the press to a maximum of 13.34hg
    or about 6.67psi.

    Jess
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