Bomb fragmentation test

An interesting film from the Pathe archive shows a live bomb detonation to record bomb fragmentation and penetration. There is no sound (MUTE) and the film is unedited so clips are out of sequence.

Of note are the semi circle layouts of thick steel plates to record penetration and similar but higher layouts of fragmentation and velocity test panels. These seem to be thin metal strips similar to a slatted window blind and scenes show boffins with metal rulers 'shorting' the panel strips whilst a telephone talker relays information back to the control bunker housing the recording equipment.

Two of the bombs three tail fuzing pockets are shown having adapters with electric detonators installed. Of particular interest are the two men electrically connecting the detonators to the duplicated firing lines. Before connecting, they earth (ground) any static electricity in the landlines by pressing the bare ends of the wires to their tongues. I suspect that they have never encountered any significant static charge in a firing cable or they wouldn't do it! Once bitten twice shy!

There is one individual with unusually long hair for the period. A passing violinist?

www.britishpathe.com/record.php?id=74995

Fascinating video, though the description provided to go with it is dire. Always wondered why there were so many large bolts surrounding the fuzing pockets. The device doesn't have to stand the test of time - it only needs to function once. Wonder what all the other cables were for - and then that pendulum device - some sort of rapid sequencing ? I thought the long-haired individual was a woman!

Suspect licking the wires was to make sure that they were volt free rather than static discharge. A ground spike would perform the latter function more efficiently, where as a small DC / AC voltage is easily detected by the tongue.

Excellent find, Peter.

Graham

It was certainly a woman, two or three of them to be precise, But only one wearing trousers!

Does this look like Foulness Island/Shoeburyness? very flat marshy landscape, but then that could fit many locations.

I reckon it's either Orford Ness or Shoeberry Ness.

The mass of cables is because each 'slatted' panel (fragmentation recorder) has at least two wires (probably a dozen!) to relay a 'strike' signal back to a recorder in the control room. As you say Carnaby, the pendulum device could be a sequencing device and the boffins are shown examining a paper tape with recorder markings.

It is clear that the detonation just about destroys all the panels so it is a one off test where all the transducers need to be replaced for the next test.

I agree that touching the cable connections to the tongue will detect any voltage in the line including static. During my demolition training we were taught to ground (earth) the cable carefully by holding the bare ends to the ground for at least ten seconds but, of course, the other end had first been checked to ensure that it was not connected to the exploder. Dependent on atmospheric conditions, particularly humidity, a considerable charge could be build up in a couple of hundred metres of cable that had been dragged into position. Sticking the bare ends onto the tongue in that condition had a really electrifying effect especially if hung-over from the night before!

Just out of curiosity, what type of Bomb was that?
Apart from being a big bugger!

I think it has to be the body of a 12,000 bomb. It's about the right diameter but seems too short; nevertheless, the triple fuze pockets are an indicator. Given that this the film is of a trial, it is quite likely that it was a a prototype 8000 pound (ish) medium capacity bomb.

PETERTHEEATER;61196 wrote:

... a considerable charge could be build up in a couple of hundred metres of cable...

When I was very active in caving many years ago, I occasionally got involved in cave exploration using 'Dr Nobel's Linctus'! As much of this took place in the Mendip Hills, there was always concern about the 500kW being radiated from the Mendip TV transmitter often within view of the guy holding the detonator wires.

Graham

Carnaby;61248 wrote:

When I was very active in caving many years ago, I occasionally got involved in cave exploration using 'Dr Nobel's Linctus'! As much of this took place in the Mendip Hills, there was always concern about the 500kW being radiated from the Mendip TV transmitter often within view of the guy holding the detonator wires.

Graham

Yes, RADHAZ as it came to be known is a proven danger that resulted in the redesign and protection of electrical circuits intended to fire electrically inititiated cartridges and detonators.

norwichpaul;61269 wrote:

I dont think this is Orfordness despite there being much work done there on bomb effects to various types of reinforced concrete for the Air Ministry for example. There are pictures of this in Works.

I don't disagree with you Paul, not enough large shingle pebbles; the other likely option is Shoebury Ness. The crane lifting the bomb has a three letter 'ownership' abbreviation (which I've forgotten already!) but it relates to the experimental department rather than the site.