Torpedos and Bismarck

hampten98. Nothing gets my goat more, or annoys me, when these film makers get simple things like we have both spotted wrong. When I was an apprentice, my mentor told me always pay attention to detail, and how right he was.
Like an Ad I saw recently on T.V. where a man was fly fishing with the reel, “Wrong handed” and back to front. Also a film, where a Sea Angler had a rod that was about 200lbs Test, and he was fishing for Mackerel, which he could have used a hand line to do.
I wonder what other things members have seen likewise?.
Jim.

Lincoln. 7

I noticed the other day when watching the filme Cruel Sea the word “INERT” stamped quite clearly on the side of the Depth Charges in the scene where they fire them off to attack a sub. Funny but I’ve watched that film so many times and never spotted it. It’s so obvious! A bit like the Star Wars stormtrooper head on door frame gaf.

Hi dogsbody… Many, many thanks for the link, it’s just what C.D. and I have been looking for.
We have one, for roughly £1,000.00 we can actualy buy one:D, however, we want the “Guts” from one who’es tail has been cut off and made into a table.
Now into the waiting game.
Jim.
Lincoln .7

A little info:

http://www.navweaps.com/Weapons/WTBR_WWII.htm

[QUOTE=cabbage;1834135]Hi Jim,
Sorry if my previous post doesn’t help. I was trying to justify my belief that the torps in the film were dummies.

I’m probably wrong, but I imagine that WW2 torpedoes used a similar drive system, without the “fancy” electrickery.

Hi Cabbage. I am still awaiting a call from the guy who has them, and who cuts the tails off them to make tables.I would say your most likely right in your assumption.
One lives in hope;)
Jim.
Lincoln .7

My dear chap, we are talking the British Royal Navy, how else would they wind up the big rubber band, but to use the airflow over them, that way they had enough twists on them to propel them through the water… 😀

These Navy lads, if they read this, just may FORCE you to find the “Golden rivett”:D
Jim.

Lincoln .7

Hi Jim,
Sorry if my previous post doesn’t help. I was trying to justify my belief that the torps in the film were dummies.

Incidently, the Mk.44’s I worked on used an electro-mechanical drive to contra-rotating propellers. This consisted of a seawater activated battery, powering an electric motor, that drove the propellers through a mechanical gearbox. The props could just be turned by hand, with the appropriate noises from the gearbox. It also used valves and associated vintage technology to carry out all the operational functions required.

I’m probably wrong, but I imagine that WW2 torpedoes used a similar drive system, without the “fancy” electrickery.

Cabbage

for the first time, I noticed that the props on the torpedoes were turning quite freeley.

My dear chap, we are talking the British Royal Navy, how else would they wind up the big rubber band, but to use the airflow over them, that way they had enough twists on them to propel them through the water… 😀

Should not spin, cause it can’t spin when hot.

… Mechanical fuzes are activated by means of an arming wire or lanyard, or by electrical energy transferred from the aircraft-carried equipment to the fuze as the weapon is released from the aircraft. When the mechanically fuzed weapon is released and falls away from the aircraft, the arming wire is pulled from the arming vane. This allows the arming vane to rotate in the airstream, arming the fuze. For emergency or other tactical reasons, the pilot has the option of permitting the arming wire to fall with the weapon. When the pilot uses this option, the arming vane can’t rotate. Therefore, the weapon remains in an unarmed condition …

Hi Jim,
I suspect it was an error by the film makers. As the propellers are usually connected to the drive mechanism, they shouldn’t be able to freewheel, I would have thought.

Modern air launched torpedoes have have various means of preventing their propellers turning until after water entry. I know as I was trained on the preparation for use, and loading of Mk.44, Mk.46 and Stingray torpedoes on Nimrod aircraft.

Hope this is of some help.

Cabbage

Hi Cabbage, Yes, it does, but we are talking WW11 torps, and I guess things have changed since you worked on them, but the principal of how they are propelled would be nice to know.
Jim.
Lincoln .7

C.D. Warren, thanks for the drawing. It suddenly hit me there is a Company, family run, with whome I have had very many dealings with over the years, and who deal with all nauticle thingeys,, and I mean all. I phoned them up today and they have the very Brit 21″ Mk V111 torpedoes kicking around somewhere in one of their MANY very large warehouses.
They cut the tails off the torps, and folk use the tails as tables:confused: weird.
They take the guts out and sling them, to reduce the postage rate.
They are going to have a look see to see if they can find me one. It would seem, the propellant is the same as you stated.
The name of the Company is Trinity Marine, and I am sure if any forum member needs anything nautical, or even aircraft bits I have seen on their site, they would be most helpfull.
Jim.
Lincoln .7

Hi Jim,
I suspect it was an error by the film makers. As the propellers are usually connected to the drive mechanism, they shouldn’t be able to freewheel, I would have thought.

Modern air launched torpedoes have have various means of preventing their propellers turning until after water entry. I know as I was trained on the preparation for use, and loading of Mk.44, Mk.46 and Stingray torpedoes on Nimrod aircraft.

Hope this is of some help.

Cabbage

dogsbody… Hi Chris. The props I was refering to were the ones on the TAIL, not the nose of the torpedo, still bugging me!!;)
Jim.

Lincoln .7

I know some will groan, and say, not again, but I watched for the umpteenth time, “Sink the Bismark”
When a flight of Swordfish were about to take off from H.M.S. Ark Royal, for the first time, I noticed that the props on the torpedoes were turning quite freeley.
Was this an error on the film makers part, or did they turn freely whilst in flight, but engage when dropped from the aircraft,

I know some of you lads were in the Royal Navy and may be able to answer a question that’s been bugging me since I saw it.
Jim.

Lincoln .7

Though you said ” propellors “, do you mean the twin props on the rear end of the torpedo, or the arming vanes on the nose-mounted fuse?

Chris

Warren, your wealth of knowledge never ceases to amaze me…

You know me Jim…..anything with pistons in, and the stranger, the better! 😀

Actually the ‘radial engine’ in certain British torpedoes is more like a four-cylinder radial air-motor really, the difference being that fuel is added to the compressed air and this burns (with water added to produce steam?) to increase the pressure on the pistons in the cylinders. Honestly I’d love to know how it really works; and, yes, if anybody has a torpedo engine, or a piston from one, I’d love to hear from them!

The diagram below comes from an excellent book called ‘Graphic War’ by Donald Nijboer and is part of a series of five Air Ministry posters that when hung side-by-side show, life-sized, an 18-inch Mark XII Aircraft Torpedo. Unfortunately they are reproduced rather small in the book.

Another poster, Air Diagram 2384, detailing before take-off checks on an Aircraft Torpedo states ‘propellers set to starting position and clamps removed’. That doesn’t sound like the propellers would be free to rotate in flight since they seem to be being used to turn the torpedo (air) motor to the most favourable starting position. More information is available in AP2495A (according to the poster).

I’ve also found an internet reference (for an American aircraft torpedo) that states there was an ‘immersion’ device so that the torpedo motor didn’t start until after the torpedo was under water.

I reckon empty shells for the Movie.

Or, like a free fall bomb, the prop has to spin a few dozen times to engage the detonator? It screws it up in place. This is why, back in Falklands 1, a lot of Argie Bombs bounced not banged….the prop hadn’t spun enough because of the very low level attacks giving not enough air-time for the bomb. Had they had more experience, you can manually set it very close before take-off.

Tornado64. O.K. I see where your coming from, so lets forget all about the film, the making of said film, Bismark etc, etc, and just stick to the pertinant question I ased in the 1st place, and follow Warren, C.D.s reply, and take it from there,
It’s one of those things that makes one not settle until the answer is found.
And found it WILL be, there is a Forumite out there who knows, it’s just that they havn’t picked up on the question.

Warren, your wealth of knowledge never ceases to amaze me;)

Jim.

Lincoln .7

the main thing we have to remmember is that in film making directors do what is visualy appealing for an audience ( often authenticity is sacrificed ).

plus for filming it was probably a prop (scuse the pun ) if many takes were being filmed with a film crew around the last thing you would want would be a live.

it may even have been a genuine but deactivated so possibly no internals with a prop either free to or made to spin

It is an interesting question and I suppose it depends exactly what you mean by ‘in flight’; I think the original question was are the propellers of a torpedo free to rotate in the airflow in flight (or even from the prop-wash while on deck)?

For the propellers to be free to rotate there would have to be some mechanism to disconnect them from the torpedo engine as the airflow alone would be unlikely to rotate the engine. That would introduce another complexity to the, already complex and expensive, torpedo, even if it was a relatively simple ‘free-wheel’ affair, and I do not see what advantage there would be to it. I suppose there could be the need to reduce shock-loading when the torpedo entered the water but at that point the propellers would be rotating (fast) under engine power anyway.

The only torpedo I know anything about is the British 21 inch Mark VIII. This was driven by a radial piston engine (or motor) running on compressed air and fuel (diesel or alcohol I think). Air-dropped torpedoes were smaller 18 inch versions but I guess they operated in a similar way. I’m pretty sure the engine (and propellers) would be started as they were dropped.

My understanding is that WWII torpedoes did have the propellers turning in flight and before they entered the water, is this incorrect then?