Photo Flash Bomb

Photo Flash Bomb

File:Mosquito photo-reconnaissance photoflash bomb loading WWII IWM C 4998.jpg

Photo Flash Bomb being loaded on to a Mosquito

Photoflash Bomb was used for night photography and developed so that planes engaged in night photography reconnaissance need not be limited to low altitude.  In appearance, the bomb resembled a conventional light case bomb.  It used an M111A2 fuse in the nose but was issued unfused.  It also had 2 suspension bands for rack and shackle suspension. The bomb had a box type tail with a square drag plate closing off the tail vane assembly.  When the bomb was dropped the arming wire was pulled, starting the mechanical time fuse.  When the time set on the fuse had elapsed, the fuse booster ignited the flashlight powder. The resulting flash of light lasted for about 1/5th of a second and had a peak intensity of approximately 500M candlepower.   They used the small F24 (5×5 image) and the derivative but much larger F52 (8.5×7) aerial cameras dominated, the former being used mostly for night photography with the aid of flash bombs. These cameras had shutter-in-focal-plane, whereas U.S. cameras standardised on shutter-between-lenses, claiming this reduced distortion.  The lens was mounted in front of the Bomb Bay.  Because of the brilliance of the flash, it would have been detrimental to the observer’s vision to watch the explosion of a photoflash bomb. Extreme care was also needed to be exercised in handling these volatile devices.

Bomb Aimers Instructions
The flash was designed to go off above the aiming point and the photo was of the flash, not of the bombs. The time between dropping the flash and it going off was set so that the camera was taking the photo when it pointing directly at the point the bombsight was set at when the bombs were released.   The shutter was open for about 8 seconds as the film wound through the camera. It produced one long photo and hopefully, somewhere along it, there would be the flash showing where the bomb aimer released the bombs.   Check with the photographer and armourer that the installation and setting of your camera and flash are correct before take-off.  Don’t forget to select the camera and flash before the bombing (if you aren’t lucky enough to have a type of aircraft where this is done automatically). Steady and level (fore and aft and laterally) your aircraft as quickly as possible after the 1st red light and keep it so until you are certain that your flash has exploded or the 2nd red light comes on. After that, get the hell out of there!

Operate the camera from the bomb firing key once as soon as possible after the 2nd warning light appears. This is to preserve that picture of the “Cookie Bomb” that may be in number 6 frame.  Give the photographer who removes the magazine all the gen you can about the operation of the camera and the weather conditions.  Also, don’t forget the camera shot when you are interrogated.

How does the camera work? – It’s as simple as ABC and pretty nearly foolproof, bearing in mind the 5 simple rules.
The flash and camera controls are set before take-off to the anticipated bombing height.  When you’ve selected the camera and flash and pressed the bomb release button, the flash bomb is released with rest of the bombs.  This also starts the control, which ticks over whilst the flash is falling, then switches on the camera mechanism 8 seconds before the flash is due to explode (at 60% of the aircraft height), just long enough to wind over 2 frames of film (taking about 4 seconds) – here the pilot gets the 1st red warning light to tell him to fly straight and level. When the flash explodes, the camera waits 4 seconds then turns over 2 more frames of film, then trips the 2nd red warning light the 8 seconds open frame allows for inaccuracies in fuse-burning times and changes in altitude. A few seconds later the bombs will reach the ground that you have just photographed.
‘Tee & Emm’, October 1944 – From Photos at Night Can Show if You’re Right

As the aircraft approaches the target the bomb-aimer presses the bomb release which releases not only the bombs but also a photo flash with a delay; in addition, it sets in motion the camera mechanism. This mechanism winds a fresh unexposed piece of film into place behind the open lens: and 2 seconds before the flash is due to explode another fresh piece of film is wound on and remains there in all for 4 seconds before the camera is again cleared, the whole business being timed for the aircraft to be over the point due to be bombed when the flash goes off.   However, in practice, the photo could be taken at any time during those 4 seconds, and the aircraft may have to bank, climb or dive present (shifts centre point by 600 yards per 5°).  At 20,000ft  the photo shows over 4,000 yards of ground.  The delay on the photo flash varies according to the height of the aircraft but is usually about 20 – 30 seconds.  The photo, therefore, is an accurate check on bombing only if the aircraft continues on the same course between the release of bombs and the taking of the picture.  When the wind is a factor, track and heading will vary, as will the direction of travel of the bombs and the heading of the camera.  Depending on the setting, the stick of bombs may stretch from 200 to 500 yards across the ground.

With all these disturbing factors playing a part, it is plumb foolish to think that a photograph plotted off the Aiming Point proves that the bomb aimer has boobed. Working from the known fact of where the photograph is plotted a good deal can be deduced about the probable position of the bombs, since it is possible to calculate how far the aircraft travelled per second, what the forward travel of the bombs was, and how much might be allowed for the tilt of the camera.  There would be a huge photo-flash as the bombing target photo was taken to show lighting up the ground below and the falling bombs.  his was a highly dangerous period of time as the bomber had had to fly straight and level to bomb, making itself a perfect target for gunners on the ground or enemy fighter pilots. The bomber pilot would typically then turn sharply and dive before heading on a course for home as a countermeasure to avoid predicted anti-aircraft fire or night fighter attack.    

BerlinPhotofLash.jpg

Vertical night aerial photograph was taken during a raid on Berlin on the night of 2/3 September 1941. , showing bombs exploding in the vicinity of the central cattle-market and railway yard (middle right), east of the city centre. The broad wavy lines are the tracks of German searchlights and anti-aircraft fire can also be seen. Also illuminated by the flash-bomb in the lower half of the photograph are the Friedrichshain Gardens and Sports Stadium, St Georgs Kirchhof and Balten Platz.

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