- Contributed by
- Frank Yates
- People in story:
- Frank Yates, Buster Bell
- Location of story:
- Background to story:
- Article ID:
- Contributed on:
- 19 November 2005
Bofors 40mm/L60 fitted with the Stiffkey Sight (Stick) being operated by the aimer No.1 standing behind the left-hand layer No.2. Further information on the history of the gun and Colonel Kerrison’s Director (Predictor) see Wikipedia, the free encyclopaedia on http://en.wikipedia.org/wiki/Bofors_40_mm_gun. Photograph reproduced with permission from Wikipedia.
Memories of Frank Yates CHAPTER 4
Buster Bell and I set off on our predictor course, entraining at Lincoln, on our short journey to Derby, where we were met by a vehicle belonging to an RASC unit and taken to their HQ, a Victorian mansion in a Derby suburb, situated in a part of a ring road, called Broadway. We were attached to this unit, just for accommodation and rations, being transported in a 15 cwt truck, each morning, to Carlton, Nottingham, to a drill hall belonging to the Sherwood Foresters, the Regimental insignia being carved in stone on the façade of the modern building. Whatever the ownership, the course was run by Artillery men.
After formalities, the 10 members of the course were taken out onto the parade ground, at the rear of the building and there stood the first Bofors gun that I had ever seen. It was one of the original Swedish types, now being produced in Britain, under licence. Although, subsequently, this design was substituted by a simpler and cheaper weapon, with a different chassis, I will try to describe the original “Bofors, Quick Firing, 40 mm Light Anti Aircraft Gun”
The gun was mounted on a beautifully designed chassis for towing. A long, box girder, with a screw jack at each end, was fitted with two outrigger girders, similarly provided with jacks, which could be swung out and locked in place. A pair of car type wheels and axles, at each end, could be raised off the ground, with an easily operated lever system, leaving the four jack pads on the ground, ready for levelling.
The gun, proper, was attached to the chassis by its turntable and could be moved round, “traversed” by No 2, a gunner sitting on the left side, turning a crank handle. It was pointed up and down, “elevated and depressed” by No 3, who sat on the right hand side, operating a similar handle. These two “layers” could smoothly follow a target and had the help of open sights, calibrated in 50 mph. rings, to point the gun barrel in advance of the target, so that, by the time that the shell arrived, it, and the aircraft, would hopefully occupy the same bit of space. This ideal situation depended, obviously on the skill, experience and intelligence of the layers, who were helped by the No 1 who, from a detached viewpoint, could better observe the flight of the tracer- lit shell and order corrections accordingly. It was, of course, the purpose of the predictor to cut out these human frailties, but in the end, the shot still had to be observed and corrections made.
A platform, behind No 2’s seat was provided for No 4, who loaded the gun and fired it. He put a clip of 4 rounds into the “Autoloader” and fired by pressing his foot on a pedal. If he had set the selector lever to “Auto” the shells would fire at a rate of two a second. Two gunners, Nos. 5 & 6, were responsible for keeping No 4 supplied with ammunition. This meant that they each had to run to the “ready” ammunition racks, bring back a clip and hand it to No 4, every four seconds, a salutary experience, the first time!
We were arranged into groups of six, to practice bringing the gun into action and manning it and then we changed round, so that we all had a go at every job, and we followed every aircraft, in the Nottingham skies, enjoying the exercise.
The worst part of week one was the journey, sitting in the back of a truck, from Derby to Nottingham and return, every day. We were relieved to be told, that, with effect from the next Monday we would be in civilian billets, in Carlton.
We had a relaxing weekend, having a look at Derby, walking along the banks of the Derwent, a very popular promenade for the locals, especially those of the younger female variety. Then it was back to the truck for its last journey, via Spondon and Long Eaton, to Carlton, where Buster and I were taken to our “digs”. We stayed with a widow and her two daughters who were 18 and 19. I suppose that the good lady could do with the extra money and the girls found the presence of two young men a welcome diversion. Anyway, they polished our boots!
Now the predictor; The sergeant instructor told us that a large number of them had been landed in Norway in the disastrous invasion, and had been thrown into the sea, still in their wooden packing cases, in the equally disastrous evacuation. A predictor was useful only in a static situation with a power supply laid on. They were far too heavy to be carted about in action, as we were about to find out!
A heavy duty steel tripod stand, fitted with plate sized feet was put in position, the top having three mounting “pinkles”, each of which could be raised and lowered, by turning a screw operated handwheel, allowing the predictor to be accurately levelled.
Our friend, the instructor, before giving us the pleasure of lifting the thing, told us about the inventor, Colonel Kerrison and his team who had demonstrated their prototype to the powers that be, by hitting the towed drogue target, with astonishing accuracy, and then bringing down the house by deliberately severing the tow cable. Be that as it may, during the next two or three years, I saw many predictor hits, but nothing approaching that level of skill. I suppose that the 3 scientists responsible for the design and building of the instrument had the edge, both in intelligence and know how
A large, dark green, steel box, about 30 inches square, and 24 inches high, standing on four tubular, spring loaded feet, protecting it from shock, was equipped with 4 hefty rings, through which long steel porter bars were threaded. Then four gunners, facing each other, gripped the ends of the bars, and at the command “Lift” raised the bars up to chest height in the weight lifters’ “Snatch” position. Then No 1, by cajoling, with verbal instructions and tactical pushing and shoving, manoeuvred the base of the box over the tripod and, not too soon for the lifters, had it lowered, securely, onto its mounting points. Once in position it was a fixture, weighing about a quarter of a ton.
High up, on opposite sides, were two, right angled, telescopes, the rubber cupped eye pieces at a convenient height for most people. These telescopes could be elevated and depressed, by means of a six inch diameter hand wheel, mounted low down below the left hand telescope. Similarly, another wheel on the other side caused the box to traverse. Once the two layers could see the target in their ’scopes, they could, by inserting their fingers in convenient finger holes in the hand wheels, keep the target smoothly and instinctively in their crosshairs.
The predictor would then accurately follow the flight of the target, and thus constantly measure its angle of velocity, both in azimuth and elevation. When an estimated range was set into the machine, by means of a calibrated hand wheel, operated by No.1, a mechanical device multiplied the angles by the time of flight of the shell, thus giving the “lead” needed for the hopeful meeting of shell and target.
A mains junction box, containing a 50 volt transformer and rectifier was connected, with hefty rubber covered cables, both to the gun and the predictor. I well remember the 4 plugs, being 10in. long, and 2in in diameter, “D” shaped in section, and having 15 beautiful copper rings. When inserted into the sockets, they were turned through 90 degrees and locked. The gun, itself, was fitted with two electro-hydraulic motors, one to traverse it, and the other taking care of the vertical movement.
This then was the sequence of events;
1. The No 1 grasped a clutch handle, conveniently positioned near his right hand, and bodily turned the box, using an open sight on one of the telescopes, instructing the No 3 to elevate until both layers yelled “ON.ON”, where upon the No 1 released the clutch and the predictor followed the target. He then “wound in” the estimated range. With a competent crew all this took about two seconds.
2. Meanwhile, the detachment commander (sergeant) grasped a large handle, on the rear of the gun and swung it round, until the barrel pointed roughly at the target, slamming down the handle when in the right direction. This re-established the electrical drive, and accurately co-ordinated the movements of predictor and gun. Later, the gun was equipped with a visual device, which ensured that the gun and predictor were in phase, before the connection was made.
3. The loader, firer, No 4, was the only person on the gun, ready to put his foot on the firing pedal on orders to “FIRE; after the detachment commander, who; apart from being responsible for the welfare and efficiency of the whole detachment, had to identify the target and give the “simple” order “ENGAGE”.
4. The No 1, observing the path of the tracer, adjusted the range accordingly, hoping that the shell and the target would occupy the same bit of airspace!
The course finished, at the end of the second week and, full of new knowledge, we were sent home, on leave, with the necessary railway warrant to return to the Unit in Lincoln. The date was May 10 and the day when Hitler walked round the end of the vaunted Maginot line, and his Panzers smashed their way to the coast, dividing the French and British forces and, eventually, trapping our forces with their backs to the sea.
A feeling of gloom, almost panic seized the Nation, which could see no future, or any way out of its difficulties, the very best scenario being that the Island might be able to hold out against the obvious threat of an invasion, and wait for “something to turn up”! The position of the inept Government became untenable and the Prime Minister tendered his resignation to the King.
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