B-25 modifications

Discussion in 'Technical' started by Maxrobot1, Feb 25, 2010.

  1. Maxrobot1

    Maxrobot1 Member

    Joined:
    Sep 28, 2009
    Messages:
    138
    Likes Received:
    7
    Trophy Points:
    18
    On B-25s, when they moved the turret to behind the pilots and the added package guns and all those nose guns (and the cannon on the G and H models) that must have played hell with the center of gravity compared to the original design. Did these add-ons make the craft nose heavy?
     
  2. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
    Staff Member Moderator

    Joined:
    Apr 9, 2005
    Messages:
    23,197
    Likes Received:
    779
    Trophy Points:
    113
    Gender:
    Male
    Occupation:
    Aircraft Maintenance Manager/ Flight Instructor
    Location:
    Colorado, USA
    Ballast was probably added in the tail to keep the aircraft within the center of gravity envelope.
     
  3. Maxrobot1

    Maxrobot1 Member

    Joined:
    Sep 28, 2009
    Messages:
    138
    Likes Received:
    7
    Trophy Points:
    18
    I know the tail gunner position added some counterbalance and in the Pacific they added a fuel tank behind the bomb bay but I can't imagine just adding dead weight to a combat aircraft!
     
  4. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
    Staff Member Moderator

    Joined:
    Apr 9, 2005
    Messages:
    23,197
    Likes Received:
    779
    Trophy Points:
    113
    Gender:
    Male
    Occupation:
    Aircraft Maintenance Manager/ Flight Instructor
    Location:
    Colorado, USA
    It’s a common practice to all aircraft. There is a specified CG envelope that must be maintained. Adding ballast (usually lead bars) was and still is a common practice to maintain the CG envelope. Depending on the weight forward of the CG point will determine how much aft ballast in needed. Sometimes only a few pounds way aft of the CG will counter a significant weight forward of the CG.
     
  5. comiso90

    comiso90 Active Member

    Joined:
    Dec 19, 2006
    Messages:
    3,672
    Likes Received:
    2
    Trophy Points:
    38
    Occupation:
    Video and multi-media communications expert
    Location:
    FL
    Not sure a fuel tank to stabilize the center of gravity is a good idea. an empty fuel tank weighs a lot less than a full one1
     
  6. FLYBOYJ

    FLYBOYJ "THE GREAT GAZOO"
    Staff Member Moderator

    Joined:
    Apr 9, 2005
    Messages:
    23,197
    Likes Received:
    779
    Trophy Points:
    113
    Gender:
    Male
    Occupation:
    Aircraft Maintenance Manager/ Flight Instructor
    Location:
    Colorado, USA
    Very true.
     
  7. Colin1

    Colin1 Active Member

    Joined:
    Jan 2, 2009
    Messages:
    3,541
    Likes Received:
    0
    Trophy Points:
    36
    Occupation:
    Engineer and overgrown schoolboy
    Location:
    United Kingdom
    When the Spitfire reached the point of development that required the contra-prop, that required a fair amount of aft ballast in the form of lead bars, the reduction gearbox was a pretty hefty item to have pinned on your nose.
     
  8. DBII

    DBII Active Member

    Joined:
    Oct 16, 2007
    Messages:
    2,191
    Likes Received:
    4
    Trophy Points:
    38
    Occupation:
    unemployed again, health insurance
    Location:
    The Woodlands, Texas
    My understanding is that the turrent was moved forward because after the waist guns and tail gun was added, it was tail heavy. The early models did not have the waist guns or tail guns.

    DBII
     
  9. Airframes

    Airframes Benevolens Magister

    Joined:
    Aug 24, 2008
    Messages:
    47,627
    Likes Received:
    1,415
    Trophy Points:
    113
    Gender:
    Male
    Occupation:
    Retired
    Location:
    Cheshire, UK
    Also, re-location of some electrical and radio equipment to aft of the bomb bay helped the weight and balance. One aspect sometimes overlooked though was performance. When the R.A.F. received Mitchell III's (B25J), they were in service alongside the Mitchell II's (B25C and D) already in the squadrons. Many RAF pilots flying the Mitchell II in formation alongside the III complained that they had to keep 'throttle jockey-ing', thereby using up fuel, to maintain formation, as the III was slower than the earlier II.
     
Loading...

Share This Page