MK10 MOD 0 DEPTH CHARGE / MINE Hydrostatic Arming Device Pistol 1967

[apfsds]

Just added this unusual MK10 MOD 0 Depth Charge or Mine arming device / pistol, dated 1967 to my inert underwater warfare collection. On its transport can it says, " FIRST ARTICLE APPROVAL ITEM." I was told that this means it was still in its experimental stage out for approval.

I sent these photos to a good friend who is Ex US NAVY and currently runs a Naval Ordnance Museum for his opinion on it and he wrote this,

"I have done some reading about hydrostatic fuzes, and heres how it kinda works: I think ! water (fresh water) exerts a pressure of .433 psi per foot of depth (saltwater is slightly different) They set the depth where this will reside until show time but they have to take into consideration the out of water temp of the mine itself, as there is a spring in the mechanism, and when it get colder it will shrink and cause premature detonation. So,anyway, this mine is in the water and the fuze is set to a known psi of the water pressure and taking into account the spring, so everything is in equalibrium. When a heavy ship comes plowing thru the water, it exerts pressure on the water (to stay afloat) and that pressure gradient is transmitted thru the water, down to your fuze. Now the equalibrium is upset, causing the fuze to detonate.. Of course, this could also be set off by any other large hydraulic disturbance, (torpedos, artillery shells exploding underwater, etc."



Jason

 

[weberoed]

The Mk 8, 9, and 10 pistols are usedwith the Mk 10 depth charge.

The Mk 8 pistol is of thehand-grenade type, and may have one of two settings, 50 and 100-feet dependingon the length of time fuze is installed in the assembly. The pistol is 10 inches long, protrudes 5inches from the case, and has a hand-grenade type of release handle and cotterpin on top. Its preset depth is painted on the outside by the numeral"50" or "100" as appropriate, and two or four blackstripes.

The Mk 9 pistol operateshydrostatically at one of four possible depths, which are preset duringassembly; 25, 50, 75, or 100 feet. It is 11 inches long, protrudes 6 inchesfrom the case, and has its basic elements two small switches with hydrostatic
diaphragms, which are connected inseries with a battery and detonator. Spring tension on the diaphragm, whichcontrols the firing depth, is preset during assembly.

The preset depth of the pistol ispainted on the outside body with the appropriate numeral and white stripes. Forexample, a 75-foot setting would be indicated by the numeral "75" andthree white stripes indicating depth setting No.3.

The Mk 10 pistol is similar inoperation to the Mk 9, the main difference being that it can be adjusted tofire at depths from 30 to 100 feet in 10- feet steps by a hand dial on the faceof the pistol. It is about the size of the Mk 9, but may be
distinguished by the depth settingdial and the absence of the stripes and figures which indicate the depthsetting on the Mk 9.


The depth charge is armed as soonas the pistol is locked in the well.

When using the Mk 8 pistol, thecotter pin is removed from the handle just prior to dropping. Upon dropping,the handle flies home from the cocked position, igniting the
firing train consisting of aprimer, black-powder delay, "quick match", fuze and a detonator.

The Mk 9 and 10 pistols operateafter water pressure becomes sufficient to depress the diaphragms, closing thehydrostatic switches and completing the circuit from the battery to thedetonator.

 

[apfsds]

Thank you so much for this great information, Weberoed! I really appreciate it a lot. This is a super fascinating subject to me but detailed info like that is hard to find. I have an inert (I think MK9) Depth Charge fuze also that is definitely designed a lot different then this MK10. It has a outer ring with settings at SAFE, 30, 50, 75, 100, 150, 200, 250, 300 and an inner setting dial with 350, 400, 500, 600, 0 to 300. I'll take some pics. Again, thanks big time!

Jason

 

[weberoed]

No problem, a few years ago I got a load of docs on underwater ordnance from a fellow EOD tech (Navy). I'm not so much interested in all the UW stuff except for limpets mines.

 

[eodda]

Hi apfds
Just small point. 'FIRST ARTICLE APROVAL' means what it says: the first item to come off a production line, or from a new Lot batch that is tested to make sure that it conforms to the specification. It's not a Development or experimental item - it's a fully developed Production item at a defined build standard.

Regards

eodda

 

[apfsds]

Thank you for the clarification, Eodda!

Jason

 

[TimG]

Would MRC be Marlin-Rockwell Corporation, 402 Chandler Street, Jamestown, NY 14701 a division of TRW INC.?

TimG

 

[apfsds]

Tim, on the transport can it says, "Miller Research Corp."

Jason

 

[TimG]

Jason,

Thanks

Tim

 

[apfsds]

Any time, Tim!