Results 1 to 5 of 5

Thread: "Bombing error of 100x"?

  1. #1
    Join Date
    Feb 2010
    Posts
    85
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Default "Bombing error of 100x"?

    A question for the bomber boys - my uncle flew Liberators after the war with 37 Sqdn; he took part in a bombing display for Greek Air Force personnel at Hassani in early 1946, and his crew "did quite well, having a bombing error of 100x with a stick of 12 x 500lb bombs" (from the ORB).

    How to interpret the bombing error, please? I could guess, of course, but I'd rather learn.

    Cheers, Pat

  2. #2
    Join Date
    Nov 2007
    Location
    Reading, Berkshire, UK
    Posts
    3,503
    Thanks
    2
    Thanked 10 Times in 10 Posts

    Default

    Pat, nobody seems to want to talk to you!

    The physics/maths of the aerial delivery of personnel, stores, or bombs, is very much the same.

    I spent many hours/days on Salisbury Plain working with the parachute delivery of personnel and stores. The para Drop Zone (DZ) is usually a long, narrow, area. The a/c flies along it (at various heights – for various operational reasons) and releases the para either by GRP (Ground Release Point) or CARP (Calculated Air Release Point). On each DZ there is usually a marked primary impact point (the “Alpha” for personnel, and the “Juliet” for stores - I don't know how they originated.). The intention is to get the first paratrooper in any stick down on to the Alpha, and the first of any series of stores containers down on to the Juliet. The rest of the personnel/stores were then strung out down the DZ (It used to be said that the safest place on any DZ was to stand on the Alpha, or the Juliet!!!!!!).

    Same with dropping iron “dumb” bombs – except that you arrange the initial impact point so that the “stick” of bombs goes across the ‘target’ (I was at El Adem when the Vulcan dropped the first stick of 21 x 1000lb iron bombs on to the bombing range at Hellsacre Farm (not far from El Adem!). It rattled the windows and Nissen-huts I can tell you!). There are all sorts of complications like Retard Bombs, Steerable Parachutes, and HALO drops – but you get the scene? 38 Grp just toward the end of WW2 tried to drop 1-ton containers from 14,000ft - total and utter disaster!!!

    So your 100x (100 yds?) error would be that the first bomb impacted only 100 yards(?) from the designated impact point. At least, that’s how I see it!!

    HTH
    Peter Davies
    Meteorology is a science; good meteorology is an art!
    We might not know - but we might know who does!

  3. #3
    Join Date
    Feb 2010
    Posts
    85
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Default

    Thanks, Peter - very interesting, and it certainly makes sense. As it happens, El Adem was one of the airfields my uncle used with 37 Sqdn when, immediately after the war, they were engaged in a variety of trooping runs. I should imagine he'd have been familiar with Alpha and Juliet, too, as his operational service was dropping stores and "Joes" into occupied Europe.

    Cheers, Pat

  4. #4
    Join Date
    Mar 2010
    Location
    SW Wiltshire
    Posts
    222
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Default

    Hi Pat, from 'V Group News', Jan '44, gives an account of the causes of 'bombing errors':

    September heralded the introduction of bombing analysis. An expert from 25 Group was attached to us, travelling from squadron to squadron to improve the Group’s very sketchy knowledge of assessment of bombing. Thus, we slowly learned the way bombing errors are split into certain definite categories. The first major item that was tackled was bombsight maintenance, which had contributed no small percentage of the bombing error. By the end of November, bombing errors directly attributable to bombsight were almost eliminated.

    We learned next that the main error, called Crew Error, had two main components: the errors caused by the failings of pilot and bomb aimer, and the Vector Error, which is caused by the use of faulty wind velocities.
    We tackled the errors due to pilots and air bombers with a will, getting them down to a very small proportion by the end of December. 106 Squadron, for example, dropped 182 bombs at high level with an average pilot/air bomber error of 78 yards, an astonishingly good achievement. 619 with 101 yards, 467 with 115, 50 with 116 and 463 with 117 yards were close behind.

    However, and now we come to the major bombing problem, our Crew Errors were still too large because our average Vector Errors were much too high.
    The Group’s average Vector Error for November was 169 yards at 10,000’, and 162 yards in December. These figures convert to roughly 13 m.p.h. A good Vector Error is considered to be 5 m.p.h. and that is our target for all crews.
    When this is achieved, and it can only come with the greatest flying care by the pilots and the most accurate plotting, timing and computing by the navigators, then a crew will be able to drop 6 bombs in a close group of less than 50 yards radius with the m.p.i. less than 70 yards from the target. Then, and not until then, we can call ourselves BOMBER CREWS.

    A navigator of 619 Squadron looked into why such large Vector Errors occur. He back-plotted his bombing wind, to a much larger scale, and found that a 15 seconds error in timing over 6-7 minutes gave a Vector Error of 10 m.p.h., that is 130 yards at 10,000’. The wind found, he says, ‘brought us from Nottingham to Base on E.T.A.’

    This makes sense, because an error up to 3-400 yards in track and 1/2 to 1 second in time is almost unnoticeable, but it is such small and apparently insignificant navigation errors that cause displacement of bombs from the target to distances up to 200-250 yards away.

  5. #5
    Join Date
    Feb 2010
    Posts
    85
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Default

    Thanks Richard, also very interesting (to get within 70 yards of the target as standard seems ambitious, but I guess that would be in non-operational conditions. Even so, quite a big ask I'd think). My uncle's war service mostly involved pinpoint dropping, but from low level: I think he must've had a good navigator and air bomber with him at Hassani!

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •