In WW2, when and aircraft, flying straight and level and releases, say, a 250lb GP bomb would the bomb always impact on the target directly blow the aircaft irrespective of height or speed? I have been puzzling over this for some days now, on and off as photos seem to imply this is the case. I have no idea of the maths involved as it is a curved trajectory. I am trying to understand how some of the training devices would have worked if this wasn't the case.
Please show any workings in the margin
No Amount Of Evidence Will Ever Persuade An Idiot (probably not Mark Twain)
No it wouldn't. Once the bomb is released, as it isn't under power it's forward velocity would reduce as it fell. As the aircraft maintains constant speed the bomb would gradually fall behind so the higher the aircraft the more the bomb's forward velocity would be retarded by the time it hit the ground. The amount it falls behind will depend on the size and shape of the bomb.
'The distance bombs will move forward while they fall is a function of the ground speed (the sum of the aircraft's speed and the wind speed). During the 60 secs that it took bombs to reach the ground, a 20 mph wind would typically blow the bombs 570 yd from their aim point.
One can see why bombsights were / are complex devices.
Plan A is always more effective when the problem you are working on understands that Plan B will involve the use of dynamite
The 'bombing solution' is complex and the theory would fill a book! Training diagrams often present an object falling in a vacuum. Bigbear is correct, the external forces acting on the bomb after release will cause it to deviate from the 'perfect trajectory'. The distance that the bomb falls behind the aircraft (as related to the target) is known as TRAIL.
The margins are not big enough to include my working so here are a couple of diagrams showing the basics:
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Thanks for all the info. I thought things sounded to simple and when I tried to draw a simple diagram to explain things it didn't quite work - hence the question.
No Amount Of Evidence Will Ever Persuade An Idiot (probably not Mark Twain)
Great info Peter, what is the reference that you took these from? Would love to get my hands on a copy.
Dietmar
The definitive history of the Norden bombsight used by the USAAF during WW2 is 'The Legendary Norden Bombsight' by Albert L Pardini (who was deeply involved in design and manufacture) ISBN 0-7643-0723-1 first edition 1999. This tome is not for the faint hearted since it is very technical but then, so was the problem and the sight! Due to the secrecy prevailing at that time, few photographs of the sight in its various mod states survive and the reproductions in the book are poor reflecting the quality of records found in US archives. Of course, many examples of the sight exist from post-war sell off and photographs can be found on the web.
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