Mine Warfare

[Velius]

Hey,

I've read in a few of my books about modifications done on certain aircraft where a circular de-gaussing ring was mounted on the airframe for mine warfare. Cables inside the ring would carry a high current to create a strong magnetic feild to explode magnetic mines during low fly-bys. So far, I've found such modifications were done on some PBY-4 and PBY-5's and on MS (Minensuche) BV-138.
Was this kind of warfare used often in WWII? What are "magnetic mines" and where where they usually deployed? What other information can y'all tell me? Any help is appereciated 8)

 

[DerAdlerIstGelandet]

I posted some pics of the Ju 52 Minesweeper a while back. I think they are on my home computer at home.

If no one else posts one before I will find them when I get home.

 

[Wildcat]

The RAF also did this with some of their Wellingtons.

 

[comiso90]

The RAF also did this with some of their Wellingtons.

View: https://www.youtube.com/watch?v=IAMIsP92EQo

8)

 

[Micdrow]

Here are a couple that I was able to dig up real fast.

 

[Velius]

Interesting Mcdrow, thanks! Did this meathod for mine warfare actually work?

 

[Micdrow]

Here are a couple of articles on magnetic mines and such. Should help with some of your questions.

German Mines
The Magnetic Mine

Hope it helps.

 

[DerAdlerIstGelandet]

Thanks micdrow those are the pics that I have as well.

 

[Velius]

This is EXACTLY the things I'm looking for!

Thanks everyone!

Oh, and one last thing: are magnetic mines still used? The principle of them sounds quite reliable.

 

[antoni]

Early in WW II the Luftwaffe had laid a new design of mine around the coast of Britain. They were detonated by a ship's magnetic field as it passed over the mine. Still on the secret list the Germans were confident that the mine was immune from detection and deliberate detonation. However, in late 1939 an unexploded mine was recovered intact and its secrets revealed. Work on developing a method to destroy the mines by using a magnetic field was instigated by the Admiralty in conjunction with the Royal Aircraft Establishment. As the mines were laid from the air it was thought that it aught to be possible to destroy them from the air. Dr C.S. Hudson of the RAE produced the required data for the task. To begin with it was planned to use an obsolete type of aircraft but it made more sense to use a more modern type and so the Wellington was chosen.
At Weybridge, George Evens was put in charge of the conversion work. On 20th November 1939 work commenced on a turntable for making the coil. 2 inch wide aluminium strip was wound on the turntable like a clock spring with paper insulation wound with it. The completed coil was enclosed in a balsa wood fairing bound with tape. Wind tunnel tests with a model showed the best location points for attaching the ring. Aerodynamic troubles were anticipated so arrangements were made to manufacture the casing in sections for transporting to Chester for assembling and testing. The first aerodynamic test flight was to be made with the casing empty, and then it was to be flown to Weybridge for the coil to be installed. It was considered unsafe to make the first flight from Brooklands. The coil was energised by a 26hp Maudesley generator driven by a Ford V8 petrol engine. Pierson preferred a solution using a Gypsy Six aero-engine driving a 120hp English Electric generator. The coil was cooled by air circulated in the casing from an intake in the front and outlets at the sides and rear. This first example was known as type 418 Wellington DWI Mk I. DWI was an abbreviation for Directional Wireless Installation, a ruse to confuse and mislead the enemy. Recently Detonation Without Impact has been given as the true meaning while in the factory it was known as Down With 'itler. It was required that every night photographs of progress made be taken and sent to Winston Churchill, then First Lord of the Admiralty, so that he could see how much progress had been made in the past 24 hours.
The Wellington installation was such that the magnetic field generated in the ring could be focused fore or aft of the midships line by adjusting the angle relative to the aircraft's fore-and-aft datum. The detonation of the mine would be caused at, or immediately following, the peak effect of the magnetic field, and the incidental effect, if any, on the aircraft then depended upon the height and speed. Height had to be low enough to ensure triggering the mine's mechanism but not low enough to detonate the mine in the path of the aircraft. Speed had to be not so fast that the magnetic field peaked for too short a period for the mechanism to operate, yet fast enough for the detonation and splash to miss the tail. Regarding the angle of incidence in level flight, the ring would contribute a significant amount of lift. The trim of the aircraft/ring combination required very careful attention to ensure level flight and the correct location of the magnetic field.
On 13th December, Air Marshals Tedder and Sholto Douglas agreed that three conversions of Wellington Ias should be made off the production line and subsequent conversions should be installed by Rollason at Croydon, the ring being made there by English Electric.
By 19th December the first ring the first coil had been finished at Weybridge. The casing had been proof-loaded and sent to Boscombe Down the same day. Wellington Ia P2516 was taken off the production line to be fitted with the ring. It was test flown and taken to Boscombe Down to have the casing fitted. At Farnborough on the 20th December it was proposed that Handley Page should make the ring cases for future conversions for fitting by Rollason. Some early Wellington Mk Is were available and a trial Gypsy Six/120hp generator combination was installed in one of these. A slightly smaller and lighter ring gave a 50% greater magnetic field saving 1,000lb. Next day P2516 was flown light to Boscombe Down and fitted with its ring casing. Tested by Mutt Summers it was pronounce satisfactory and flown by him back to Weybridge to have the ring installed. On 27 December the Wellington returned to Boscombe Down to have the Ford/generator fitted. The installation was completed the next day but bad weather precluded full-load tests on the 29th. On the 30th the Wellington was flown by Summers. Experiments were carried out in January 1940 over Salisbury Plain using the mechanism recovered from the German mine. The Wellington flew over at different heights and either side of it. Each time the device clicked. The Ford engine was not adequately cooled. January 1940 was the coldest winter for many years, with temperatures going as low as -20 C while inside the Wellington it was 120F with people working stripped to the waist.. Pilot Maurice Hare's expensive wristwatch was ruined because he was too close when the device was switched on in the works.
On 30th December 1939 the RAE advised Vickers that Tedder had agreed to four Mk Ias being converted at Weybridge. Obsolete aircraft were to be used for the conversions by Rollason using locally made English Electric coils. Design work for subsequent conversions with smaller more powerful rings was Vickers responsibility. These were known as DWI Mk II Type 419. Farnborough undertook the major modifications before flying the Wellingtons to Croydon for assembly of the rings and power plant. Vickers kept its own assembly rig until all four MK Ias had been completed.

By 15th January Weybridge's second Wellington was ready to fly from Boscombe Down to Manston for trials over the Thames Estuary. A week later No 3 had passed the flight test and the coil was being tested before being fitted to the casing, it being delivered to Boscombe Down on 25th January and completed two days later. The forth followed soon after. On 22nd February three DWI Wellingtons were flying and two mines were exploded safely. Early in March the DWI had become routine for Vickers. On 2nd March Summers tested the first Wellington Mk Is converted by Rollason. Ten more were modified in England to DWI Mk II standard, one of which was flown to the Middle East where several more were converted. There they cleared the Suez Canal and North African harbours of magnetic mines, The Weybridge Experimental Department had the satisfaction of sing photographs of their own 'baby' at work but also a German version clearing allied mines. With the availability of degaussing coils for ships the DWI was superseded in British coastal waters but continued to be used in the Middle East for a time.