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  1. #1
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    Please help! WW2 U.S. Navy Mk1 Mod2-3???

    Hello Collectors, and Thank You in advance!
    I do apologize as this is my first post on your site but I have been lurking for a minute. Anyways, I’ve recently purchased what I believe to be a WW2 era U.S. Navy Mk1 Mod2 or 3. Unfortunately I cannot find any photographic evidence to support my claim. The original advertisement said it was “garage art” and not real ordnance but my gut said it was real.
    https://militaryantiquesmuseum.com/z...35.archive.htm
    So my search began. I knew it looked like a WW1 bomb but other than that I hadn’t a clue? So I searched for info on WW1 bombs and found out it had more than a passing resemblance to a U.S. Mark 1 bomb but the added braces on the fins lead me to believe it was an interwar bomb (1919-1936) but there was absolutely zero info that I could find for U.S. ordnance during that period. My search ground to a halt...
    Until I came across this image...
    85CC1C30-A1F1-4E53-9148-2AE16FE37CCC.jpeg
    Yes, I know it’s a digitized image for a videogame or something but the little yellow bomb at the top looked a lot like my “garage art”. The bomb in the image was labeled as a U.S. Navy Mk1 Mod2 and that gave me hope.
    So I started looking again and I came across something called a “modified Mark” series of bombs used by the U.S. Army during WW2 but they all had box fins...
    9B8FA75A-126D-4E56-84DD-C5BD9049624A.jpg
    But then I thought maybe the Navy did things a little bit different? And that led me to this...
    4E606238-35B6-47B2-87EF-26D5BF61330E.jpeg
    Look at the fin construction on the Mk1 Mod2-3 but unfortunately there are no pictures...
    Does anybody have more info than what I’ve shown here because this is absolutely everything that I could find?
    Photographic evidence or even the differences between the Mod2 and 3 would be greatly appreciated!

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    Sir Roger (24th August 2018)

  3. #2
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    100lb MkI Mod 2&3 (Navy) - Navy has "Mod"s - data on 1st pic, drawing on the right of 2nd pic (left is the later Navy 100lbs MkIV - pay attention they are not at the same scale, look at the data, the MkIV is shorter by 1/4 than the MkI)
    100lb MkI data.jpg 100lb MkI.jpg

    100lb MkI MIV (Army "Mark" series) - Army has "M"s
    100lb MkI MIV.jpg

    The top yellow bomb 3D model on on the 1st pic on your post is indeed a tentative of reconstruction of the Navy 100lb MkI Mod 2-3 bomb, while the grey one under it is aimed at representing the Navy 100lb MkIV Mod 1-2.

    The bomb on display in your link seems indeed to fit the Navy 100lbs MkI Mod 2-3.
    Last edited by Dreamk; 18th August 2018 at 09:14 PM.

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    Sir Roger (24th August 2018), Tater (20th August 2018)

  5. #3
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    Thank you, Dreamk!

  6. #4
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    Anybody have any photos of these?

  7. #5
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    The only photos I know of are of the similar USAAF MkI MII (not MkI M2) that saw very limited use, not being officially adopted, even as a limited standard or a reserve standard - here tested on a Martin Bomber B10 (all US B10 served with the USAAC, none with the Navy, so these are army bombs not navy ones) - other 100lbs army bombs of the various Mk models had only one reinforcing bar between fins (or not at all on earlier models).
    41043v.jpg 41042v.jpg
    and here under a Curtiss B-2 Condor bomber
    26389624372_304c742cec_b.jpg
    The design of bomb fins was always a problem in US bombs development as they kept deforming during the fall - till the development of the "box" fin units that insured rigidity - this was developed and tested as early as 1931 but implemented only at the end of the decade.
    Last edited by Dreamk; 19th August 2018 at 08:06 AM.

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    Tater (20th August 2018)

  9. #6
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    Dreamk, maybe we cannot see the forest for the trees? I mean, maybe the explanation is right in front of us?
    I had assumed that the “Mark series” bombs used by the U.S.A.A.C. were all of the “box fin” variety... BUT your photos proved that theory wrong! So by looking at all of the images that you and I have posted here... I believe that there is no difference in the bombs used by either the U.S.A.A.C or the U.S Navy. The difference is in the “Mod”. I believe all the “Mark1” bombs had the fins along the body until the “Mod4” which used the “box fins”... What do you think? Or am I missing something?
    Last edited by Tater; 19th August 2018 at 11:24 PM.

  10. #7
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    Tater, it's a little more complicated.
    During the interwar period, the army bombs were only "improvements" on ww1 designs - based mostly on the French Gros-Andreau. These improvements included better metallurgical techniques, better fuzing, and strengthening the fins - generally using a single reinforcing strut for bombs up to 600lbs and 2 struts over that weight.
    The Navy introduced and put in service a number of new bomb designs. This was so for obvious reasons - they had budget while the USAAC was running at a minimum. However the Army experimented new designs and test it at the Aberdeen proving Grounds, but did not produce new bombs till the end of the thirties. The 1931 model was adopted for production at the end of the decade as the 100lbs M31 HE bomb. It used a cylindrical design that has began to be implemented by the Navy already during the mid 20s, then successfully improved.
    The need to do with what you have when there is no budget to produce new bombs, and the periodical changes in the structure of the USAAC bringing with them changes in designations (the well known "new broom effect" - no real change beyond the new name) led to a real mess that the following list may help to understand:

    US Army bombs 1918-1936
    1918-30
    Mk I Drop 100lb
    Mk II Drop 25 lb
    Mk III Drop 50 lb
    MkIV Drop 300lb
    MkV Drop 600lb
    MkVI Drop 1100lb


    1930s
    MkI series Demolition:
    welded joints circumferential and longitudinal. tail fuze only (no arming vanes)
    25lb (previously drop Mk II)
    50lb (previously drop Mk IIII)
    100lb
    MkI MI series Demolition:
    nose fuze with arming vanes (and for 300 and 600lb, tail fuze too with arming vanes)
    Fins strengthening braces
    100lb
    300lb
    600lb
    MkIII series demolition:
    both noze and tail fuzes with arming vanes
    No longitudinal welds, only circumferential ones
    Fins build at a single unit, with stengthening fin braces.
    100lb (previously drop Mk I-C)
    300lb (previously drop Mk IV-C)
    600lb (previously drop Mk V-C)
    1100lb (previously drop Mk VI-C)
    Cylindrical body series:
    Nose and tail fuzes with arming vanes
    fina ssembly designed as a unit, with strenghtening braces.
    2000lb Mk I,
    2000lb MkI MI,
    2000lb MkI MII


    Standard production 1930
    MkIII series demolition:
    100lb MkIII
    300lb MkIII
    600lb MkIII
    1100lb MkIII
    2000lb MkI MII
    Substitute standard for production
    100lb MkI MI
    300lb MkI MI
    2000lb MkI MI
    Obsolete (Training)
    25lb Mk I
    50lb Mk I
    Limited standard (War reserve)
    100 lb Mk I (previously drop Mk I)
    600lb Mk I MI
    2000lb Mk I


    1930 Fragmentation
    Standard production 1930
    30lb M5 (ring type body)
    Limited standard (War reserve)
    17lb Mk II (previously fragmentation drop Mk II-A)
    25lb Mk III (previously fragmentation drop Mk II-B)


    1930 Dummy bombs (empty)
    40 lb Incendiary Mk I
    40 lb Incendiary Mk II
    25 lb Demolition Mk I
    50 lb Demolition Mk I
    100 lb Demolition Mk I
    300 lb Demolition Mk I


    1930 Chemical
    Nose fuzes only 9with vane for 30lb)
    30 lb MI chemical
    50ln Mk I demonstration

    Bombs used in 1925 in the Billy Mitchell experiments - most are still basically ww1 bombs:
    US Bombs 1925 used on warships testing.jpg
    Bombs used by the navy in 1920s
    US Navy Bombs 1920 3.jpg
    US Navy practice bomb MarkVII from 1932
    US Navy practice bomb Mark VII - 1932.jpg

    US Army 600lb bomb from 1923 - new fin shape
    US 600lb MkIII from 1923.jpg
    US Army prototype for 100lbs with modified fins from 1925
    US 100lb Modified fins 1925.jpg
    US Army prototype from 1931 of what will become the 100lb bomb M31
    US 300lb M-31 with T3E5 Nose fuze 1931 .jpg

    The 100lb MkI seems to have been an exception - a bomb common bomb (except fuzing) to the Army (under the designation MkI MII) and the Navy - probably in expectation of the new cylindrical 100lb bomb being produced under the designation MkIV
    Last edited by Dreamk; 20th August 2018 at 06:37 PM.

  11. The Following 2 Users Say Thank You to Dreamk For This Useful Post:

    Sir Roger (24th August 2018), Tater (20th August 2018)

 

 

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