Shell shock: Japanese mortar fuzes revisited!

[ogreve]

Hi guys,

After extensive ploughing through documentation, and pictures of actual specimens, I have put together a debatable theory.

In my opinion, it cannot be dismissed too easily, and when doing true research at times one should step off the beaten track and ask critical questions, otherwise new facts and theories will never evolve.

Having made the above note, please consider a scrutinous dissertation of mine as to a theory I have been developing regarding valid usage of various different types of fuzes on Japanese mortar rounds (particularly on the 81mm mortar rounds).

I pose this at the risk of taking flak, or ridicule even, for it. Yet, I feel these questions need to be posed, and I am anxiously awaiting reactions from those knowledgeable in the area of Japanese ordnance, and/or fuzes. Particularly, I am hoping someone (Mr Fuze, perhaps?) to have sectioned one of (or more) of the Type 88 instantaneous or short delay fuzes that carry the 'Howitzer Mortar' markings on them.

I hope to have tempted all of you enough to indulge in reading the following illustrated dissertation of mine:
http://www.japaneseammunition.com/start.php?main_cat=26&sub_cat=197

Enjoy!
Olafo

 

[genkideskan]

Very interesting.
I wonder about that years ago. I dismantled a T 88 and a T 88 small fuze.
They both had the safety fork, the safety collar that was striped down by setback and the 4 segments that safe the striker.

The best would be to dismantle some fuzes and look what is inside.

We ve used several common fuzes on rockets - the problem was the lower setback and lower spin. So the fuzes where converted and work with these parameters.

The T88 mortar and howitzer fuze need a spring to remove the segments without rotation. May be there are no segments??.

May be the fins had an slight angle for a small rotation ?

 

[genkideskan]

Any news about this subject?- the mortar fuzes didnt use any collar or segments,bur simply a sheer wire.
The normal T88 could be converted by removing the segments and add an shear wire. Simply needs the dismantling of some "Mortar" marked fuzes.
They could be unscrewed easily.

 

[ogreve]

Hi,

Bougainville took one of the 'Howitzer Mortar' marked fuzes apart: it has all the safety mechanisms (i.e. a collar and the wedges) as the 'Field Mountain Cannon' marked ones has, but with the difference that the latch springs are weaker and hence require less set-back.

Now, you're last remark is an interesting thought: I wished someone had such a mortar and sufficient rounds and fuzes at hand to actually fire the bl**dy thing equipped with a Type 88 'Howitzer Mortar' fuze and see what would happen.
Really, it SHOULD result in a dud, yet it would be an interesting test nonetheless (even if only for seeing such a mortar getting fired once).

Anyway, make sure to read my revised theory on this fuze perhaps having been destined for the 70mm RIFLED mortar. That would certainly be more likely to give a working combination.

Also: Jim has some very, very interesting news (he'll elaborate later), as he has one of the improvised 58mm mortar rounds, and has two modified Type 88 fuzes for it. From what he describes it definitely sounds like field modifications.

Jim: feel free to chip in anytime you can.

Cheers,
Olafo

 

[JCB99]

improvised 58mm/60mm

Olaf,
I have that 58mm improvised mortar shell with a modified type 88 fuze. I will get some pictures posted in the next day or so. patience!

I also have a type 88 fuze modified for landmine use. Modified type 88 fuzes were used with improvised mines and the so called "Beehive" cast iron serrated AP mine.

I wish I had something to add about this ongoing Fuze discussion. The "mortar" character on some T88's was always a mystery for me.

Jim

JapaneseOrdnance(at)yahoo.com

 

[Nismosonic]

Theory... Any chance the designation "Howitzer Mortar" is a single meaning ? That is, that the fuze could be fixed onto a shell and fired from the howitzer gun, but with a barrel elevation that would make the shell behave like a mortar shell?

 

[genkideskan]

Here are some 70mm shells from a jpn. manual.

.

 

[Dronic69]

Theory... Any chance the designation "Howitzer Mortar" is a single meaning ? That is, that the fuze could be fixed onto a shell and fired from the howitzer gun, but with a barrel elevation that would make the shell behave like a mortar shell?

Olafo has researched and analyzed this to great details on both his website and on the other related thread started with Moondoggy (there's more on that one!)

However after reading the excellent reference that Robert (bougainville) mentioned prior {Nose Percussion Fuzes Type 88 for Gun Ammunition with 24mm Fuze Hole}, I'm also of the impression that it could simply be interpreted for any low velocity high angle weapon (i.e. a howitzer or mortar, perhaps more specifically "rifled mortar"). That certainly seems to be the British viewpoint:

From page 2 (ii):
"The other fuse is marked with the Japanese characters "88 Type Pomegranate Mortar" This marking, by inference refers to howitzer, i.e. a low velocity weapon. The stirrup spring in this fuse is comparatively weak and will arm with a much lower velocity"

..and from the previous page:

"One fuse is marked with the Japanese characters "88 Type Field Mountain Gun" as shown in the plates. It indicates that the fuze has a comparatively strong stirrup spring restricting its use to guns with a relatively high velocity"

Since the two Type 88 Instantaneous could have been marked "88 Type high velocity" and ""88 Type Low Velocity", then I would assume it to be much easier for the ground troops to ID by the more granular inference of "GUN" "Howizter" and "Mortar" - well IMO anyway!

...and as the Japanese supply ships had something like 4,000 miles to transport equipment which were always under attack by the Allies, then I'm sure desperate times required desperate measures with supplies dwindling with the potential modification of the Type 88 fuses for smooth-bore usage - how widespread is yet to be determined.

Cheers
Drew

 

[BOUGAINVILLE]

Very well said Dronic69.

As always it is always good practice to look at all sources of information as where some omit an important point others will pick it up. The British were very Teutonic in their investigations of captured ordnance and this is what makes the Kirkee publications so invaluable.

A point worth mentioning is that it was normal military practice to ship fuzes and ordnance together in the same shipment. Mortars were no different and in fact I can produce photos of packing boxes for the Type 94 90mm & the Type 100 81mm mortars packed with two mortar shells along with two fuzes individually packaged in fuze tins for assembly as required. Their artillery ammunition was also likewise packed. This then discounts the supposition that they could've had situations where they had to improvise with type of fuze being used.

You will find the said photos on pages 158 & 167 of "Japanese Infantry Weapons Vol. 1" which is a reproduction of "Special Series No. 19 Military intelligence Division 31 December 1943"

Surely it is about time people stop trying to legitimise the erroneous matching of the Type 88 fuzes with either the 81mm or 90mm mortars.

Cheers,
BOUGAINVILLE

 

[JCB99]

Modified Japanese Type 88 fuzes for Improvised Mortar shell/AP Beehive mine

Olafo,

Sorry for the delay. Here are photos of two field modified Japanese Type 88 fuzes.

The one is attached to a rare Japanese 58mm Improvised mortar shell. This fuze has two crude wrench flats ground into the sides with a shear wire hole (?) through the plunger. I am unable to unscrew the fuze from the adapter ring and I am also unable to take the fuze apart.

The other is a Type 88 Modified fuze for landmine use. This steel fuze also has two wrench flats with a safety pin through the nose. It is shown with a Beehive AP mine fuze adapter ring. I am unable to take this fuze apart to examine the interior parts. I am absolutely sure this is a Beehive mine adapter ring. The safety pin is either a Type 3 ceramic mine fuze pin or Type 99 magnetic mine safety pin. The pullcord might be a collector replacement.

Both items came from large Japanese militaria collections from people who are respected. I do not doubt the authenticity of these. I don't often see modified fuzes of any type. I'm Glad to have these.

Interesting stuff.
Jim
JapaneseOrdnance(at)yahoo.com


Link to Japanese Ordnance page: http://www.castle-thunder.com/wforum/viewtopic.php?t=976

I

 

[Dronic69]

Jim,

Very interesting - first time I have seen "modified Japanese fuses"!

Is the steel one also a "Howitzer-Mortar" or "Mountain Gun" Type 88? (can't quite read it?)

Must have been "desperate times" - I'm now curious to how many "modified fuses" (or lack of them today) resulted in premature ignition once the bore-safe mechanism was also removed???

Thank you for sharing.

Cheers
Drew

BTW - fantastic collection you have!

 

[ogreve]

Hi,

Jim: thanks for posting these pictures and explanations: great stuff!
I wonder if it would be possible to get them X-rayed or so, so the inner construction can be seen. I also wonder if only the wedges have been removed, or if the set-back mechanism has also been removed.

Drew: the brass one for the 58mm mortar round is the 'Howitzer Mortar' one and the steel one for the mine is the 'Field Mountain Cannon' one (I could make out the markings in the last image). Interestingly enough the steel one does not seem to have the column that states 'Type 88'.

Cheers,
Olafo