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ť Forum Name: PT Boats - General
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ť Topic: Query, Stopping a Hot Run in the Tube?
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Hi there.

Just wondering about how a hot running torpedo was stopped whilst it was still in the tube. I read in 'They Were Expendable' that one crewman stuffed some rags into the torpedo propellers. What I am wondering is how he accessed the propellers? Was there some way to open the rear of the torpedo tube?

Thanks once again from PeterTareBuilder

"Give me a faster PT boat for I'd like to get out of harm's way!"

Posted By: PeterTareBuilder | Posted on: Aug 25, 2008 - 10:15pm
Total Posts: 494 | Joined: Jun 24, 2008 - 5:59pm

Torpedo had access panels, but in an emergency such as a hot torpedo which has not left its tube, it would be a most difficult thing to do to remove any panels. The torpedos were set to arm themselfs after a short distance, so the props turning while stuck, would do the same thing as if in the water. One slap of a wave, would cause the boat and crew to be destroyed. You must somehow stop the props from turning, so jamming something into them would be the logical thing to do. Stuffing rags, or anything else handy would do the trick. I don't think this happened to many times while usng the roll of rack system, but I have heard of this in the older torpedo tube.

Greese was used to line the inside of the tube, so if the vains of the torpedo hit the sides, or the black powder charge was wet, or not enough used, it could cause the torpedo to lodge part way out of the tube. Not sure how they wuld reach the props, if this happened with the torpedo stuck half way out. I do not think the tube itself had any way to reach in so you could stop the props. The only open end was the front, and of course you could remove the back, but in combat conditions, this would be pretty tough............

Posted By: Frank J Andruss Sr | Posted on: Aug 26, 2008 - 6:39am
Total Posts: 3497 | Joined: Oct 9, 2006 - 6:09am

I'd have to go pull the account, but there is a fairly famous Ron 15 story about getting a friendly torpedo in the stern...I'm at work now, so I'll stumble through it and hopefully someone will clean it up...

...the end of the story involved a Motor Mac jumping down into the Lazerette and stuffed a rag into the arming impeller so that the torpedo warhead would not arm itself. I would imagine this would be near the front of the torpedo...so this would work on a hot running torp as well?

Of course, I'm a third generation kid passing along someone else's account...so hopefully the vets could shed some light!

Grandson of James J Stanton
RON 15 PT 209 and RON 23 PT 243
Check out: www.pistolpackinmama.net

Posted By: newsnerd99 | Posted on: Aug 26, 2008 - 8:18am
Total Posts: | Joined: Unregistered

We never had a hot run torpedo on our boat but I have seen and heard other boats while tied at the dock. They make a tremendous noise. I always got as far away as possible to avoid any flying objects and let it burn itself out.
The Mark 13 had a lock that fit on the propellers so if a hot run the engine would not be turning which made it much safer.
CJ Willis TM/3c

C. J. Willis

Posted By: CJ Willis | Posted on: Aug 27, 2008 - 7:38am
Total Posts: 464 | Joined: Nov 5, 2006 - 5:02pm

Frank,
I think you may have a misconception about the operation of the torpedo engine as it relates to the arming mechanism - exploder. The engine, which burns compressed air and alcohol with a water spray mixed in, cause the torpedo turbines to spin and this in turn spins the two counter rotating propellers. The turning of the propellers has nothing to do with arming the torpedo. A separated mechanism, (the Mark 4 exploder) located on the underside of the warhead, has a little paddle wheel that is turned by the sea water as the torpedo goes forward through the water. After the torpedo travels 2-300 yards, the motion of the paddle wheel will do 3 things, 1. Extend the detonator (dime sized mercury fulminate) out of the protective safety chamber into the tetryl Booster charge cavity. 2 Cock the spring loaded firing pin holder (hammer mechanism). 3. Allow the Firing Ring to be unlocked by releasing the fingers

When the torpedo hits the side of the target, the Firing Ring (aka Flop Ring) will contact the tilting Firing Plate, which releases the spring loaded firing pin holder (hammer mechanism), and sets off the Detonator. The detonator sets off the booster which sets off the main charge of Torpex.

The part about stuffing rags up inside the tube was done in order to block the water from flowing over the arming impeller (paddle wheel) on the underside of the warhead. If the torpedo was hanging partly out of the tube, passing water spray could theoretically turn the arming impeller inside the exploder assembly thus arming it and then any sudden shock or big wave hitting the warhead could set it off if the firing ring tilted the firing plate.

Also, I know the greatest danger from having a "Hot Run" in the tube was the danger from pieces flying off of the turbine since it would overspeed due to no resistance from the water against the propellers, which normally would prevent overspeeding the turbine wheels. It was important to stop a hot run before the out of control turbine flew to pieces, and became a fragmentation hazard. On the Mark 13 torpedo (and I think on the Mark 8 as well) there is a Stop Valve, which shuts off air flow to the combustion pot on the engine. This valve is a 1/4 turn quick acting valve and is located right next to the Starting Lever. I am pretty sure the TM was able to turn this "Stop Valve" at a moments notice using a special wrench in case there was a hot run in the tube.

Here is a photo explaining the Mark 4 exploder operations. Jerry PT658 Portland

[image]http://i130.photobucket.com/albums/p249/ptboats/00000017.jpg[/image]

[image]http://i130.photobucket.com/albums/p249/ptboats/00000018.jpg[/image]

Jerry Gilmartin

Posted By: Jerry Gilmartin | Posted on: Aug 27, 2008 - 11:53am
Total Posts: 1473 | Joined: Oct 8, 2006 - 11:16pm

Jerry

Thanks very much for the lesson on the torpedo and the arming system. Appreciate the help..........

Posted By: Frank J Andruss Sr | Posted on: Aug 27, 2008 - 10:05pm
Total Posts: 3497 | Joined: Oct 9, 2006 - 6:09am

Jerry,

Thanks for the great info on torpedo operation, you answered a question I always had regarding arming.

Nerd,

Check out Action Report No. 41 for the torpedo in 204's lazarette.

Steve Nugent

Posted By: Nuge210 | Posted on: Aug 29, 2008 - 12:04pm
Total Posts: 323 | Joined: Jun 4, 2008 - 7:50am

Thanks Steve for a pic I hadn't seen before of the 204 with a torpedo in her! Enjoy:

[IMaGe]http://i43.photobucket.com/albums/e362/newsnerd99/204torp.jpg[/IMaGe]

Grandson of James J Stanton
RON 15 PT 209 and RON 23 PT 243
Check out: www.pistolpackinmama.net

Posted By: newsnerd99 | Posted on: Sep 3, 2008 - 1:04am
Total Posts: | Joined: Unregistered