Torpedo system specs

[lotharbucheim]

Hi to all. First a huge thank you to Mr Merriman and Mr Caswell for designing and producing a system that so many of us have dreamed of putting in our boats for so long !

I just wondered if anybody who has bought the 1/72 scale torpedo system can give me an idea of what range you get out of a typical "war shot" ? I'm going to buy a system whatever the performance is; my OTW Trafalgar kit has been sitting half-finished for over two years while I tried to work out how to make a viable torpedo system ( I couldn't ! ). I would just like to get an idea of how the system performs.

Thanks in advance for any answers.

[Kazzer]

The Wizard has said that on average, the 1:72 torpedo will travel approx 30-60 feet. You should have plenty of space in that boat for the mechanical system which is being delivered to us right now. You can order it/them on the web page www.caswellplating.com/models

[Merriman]

Hi to all. First a huge thank you to Mr Merriman and Mr Caswell for designing and producing a system that so many of us have dreamed of putting in our boats for so long !

I just wondered if anybody who has bought the 1/72 scale torpedo system can give me an idea of what range you get out of a typical "war shot" ? I'm going to buy a system whatever the performance is; my OTW Trafalgar kit has been sitting half-finished for over two years while I tried to work out how to make a viable torpedo system ( I couldn't ! ). I would just like to get an idea of how the system performs.

Thanks in advance for any answers.

Lothar,

Good to hear from you.

Range is typically between 20 and 30-feet. Near the end of the run the weapon will assume a left-hand turn and will circle tightly in this pattern until the last of the propellant is consumed. This end-of-run circling a result of the slowed torpedo not rolling and the in water stabilizer (all four of which are angled to produce a counter-clockwise rotation of the fish during the high-speed portion of the run to improve the weapons stability) acting then as a rudder to turn the weapon to port. The circling weapon does not get too far away from you, easing your recovery effort.

Below is a shot of three typical 1/72 weapons. The two at the top are identical, differing only in the paint job. The green weapon represents a 'modern' homing type weapon, the lower, silver weapon represent a WW2 era, steam powered torpedo. The torpedo at the bottom has been cut away to show how the hollow interior serves as a propellant (air-brush propellant, comprising a mixture of liquefied Butane and Methane) reservoir; the centrally running pick-up tube and nozzle; and how the front end is capped to make the weapon gas tight. The O-ring equipped launcher breech-block engages and makes gas tight the weapons nozzle when it's in the tube and ready for launch.

A safety feature of the system is that the weapon can only be charged when it's secured in the launcher. A weapon cook-off/explosion can only occur with it securely confined within the brass tube of the launcher! I've been shooting these things for nearly 15 years now and have had only one weapon cook-off -- thought the weapon was toast, the launcher was undamaged by the 'event'.

DSCN0144.jpg

Here I'm showing off the first lot of 20 mechanical launchers, and 100 weapons ready to be sent to Caswell Inc. Note that the purchase of a launcher also gives you three weapons to play with. All weapons and launchers are qualified here before being packaged up and sent to Caswell.

DSCN0126.jpg

This is the contents of a mechanical launcher package. Spare fasteners, O-rings, flexible tube, loading ram (not pictured), stop bolt ball, and three weapons are provided.

DSCN0150.jpg

To ease repair and adjustment most of the mechanical launchers items can be disassembled through the loosening of two 4-40 set-screws. The exceptions are the breech-block, stop-bolt housing, interlink guide, internal torpedo stop, and trigger wire, which are all soldered items. The picture shows a disassembled launcher atop, and a ready-for-use launcher below.

DSCN0138.jpg

[Slats]

Lothar,
I had the privileged of being involved in the testing of these great little fish, you will find these a nice feature for your OTW 1/72 Trafalgar. I concur 100% with David's specifications. The only thing I would add is after a nice initial whoosh out of the tube the fish decelerate a bit and leave nice trail of bubbles in their wake.

Best
John

[lotharbucheim]

Guys, many thanks indeed for all the advice, it is much appreciated. I wonder if you would answer a few more questions so that I can decide the best system for my boat. I am not a complete newby to subs, having built and run a dynamic diver and then one of David’s Skipjacks which I bought un-built and second hand. But I have never come close to the build quality I see on this forum. I will try my best with the Trafalgar.

First of all the launch system ; I am not sure which system ( electrical or mechanical ) to go for. I have thought of a few pros and cons for each system, but perhaps I am thinking wrongly, and would appreciate your advice. Let’s assume that cost is not a factor.

Mechanical : Pros : reliable, relatively easy to adjust and keep working.
Cons : Each pair of tubes ( and I have already made provision for 4 tubes ).
Will need a linkage..which means potential leakage through the
rubber bellows.

Electrical : Pros : Less likely to cause leaks, as the connections are easier to make
watertight.
Few moving parts.

Cons : Not sure about the reliability.

Could you give me your honest opinions about each system ?

The next question is about the trim of a model submarine when firing torpedos. I have read lots of the Wizard’s articles over the years about his work to develop a viable and reliable system. As far as I remember there are several problems which can be created. Let’s assume that I have managed to trim my boat perfectly, so that when she is loaded with torpedos she dives at a perfect static trim ( I wish ! ). When I fire the torpedo one of two things can happen .

(i). The gas which vents from the torpedo as it launches can form a bubble of gas in the tube, causing a bow-up out-of-trim situation. Or

(ii).The volume of the torpedo is replaced by a similar but heavier volume of water, causing a bow-down trim.

Either way, after firing its ‘war shot” my submarine is now out of trim. Is there anyway that I could stop this happening, and which of the two situations is more likely to happen?

I was thinking that , if the bubble of gas is the problem, then a tube soldered to the torpedo tube, allowing it to vent through a deck-vent could be the anser. But I also remember David drilling holes in some of his launch tubes..was this to stop the gas problem ?

At the end of the day I would happily exchange an out-of-trim boat for the chance to shoot off torpedos. But it would be great to hear from David and from you guys who have used the system, about any ideas that you might have. Thanks again for all the advice, and best regards.

[Slats]

Guys, many thanks indeed for all the advice, it is much appreciated. I wonder if you would answer a few more questions so that I can decide the best system for my boat. I am not a complete newby to subs, having built and run a dynamic diver and then one of David’s Skipjacks which I bought un-built and second hand. But I have never come close to the build quality I see on this forum. I will try my best with the Trafalgar.

First of all the launch system ; I am not sure which system ( electrical or mechanical ) to go for. I have thought of a few pros and cons for each system, but perhaps I am thinking wrongly, and would appreciate your advice. Let’s assume that cost is not a factor.

Mechanical : Pros : reliable, relatively easy to adjust and keep working.
Cons : Each pair of tubes ( and I have already made provision for 4 tubes ).
Will need a linkage..which means potential leakage through the
rubber bellows.

Electrical : Pros : Less likely to cause leaks, as the connections are easier to make
watertight.
Few moving parts.

Cons : Not sure about the reliability.

Could you give me your honest opinions about each system ?

The next question is about the trim of a model submarine when firing torpedos. I have read lots of the Wizard’s articles over the years about his work to develop a viable and reliable system. As far as I remember there are several problems which can be created. Let’s assume that I have managed to trim my boat perfectly, so that when she is loaded with torpedos she dives at a perfect static trim ( I wish ! ). When I fire the torpedo one of two things can happen .

(i). The gas which vents from the torpedo as it launches can form a bubble of gas in the tube, causing a bow-up out-of-trim situation. Or

(ii).The volume of the torpedo is replaced by a similar but heavier volume of water, causing a bow-down trim.

Either way, after firing its ‘war shot” my submarine is now out of trim. Is there anyway that I could stop this happening, and which of the two situations is more likely to happen?

I was thinking that , if the bubble of gas is the problem, then a tube soldered to the torpedo tube, allowing it to vent through a deck-vent could be the anser. But I also remember David drilling holes in some of his launch tubes..was this to stop the gas problem ?

At the end of the day I would happily exchange an out-of-trim boat for the chance to shoot off torpedos. But it would be great to hear from David and from you guys who have used the system, about any ideas that you might have. Thanks again for all the advice, and best regards.

Hi Lothar,

first don't be intimated by more skilled people on this site, the website here promotes and encourages improvements in all skill levels. We all started somewhere. We are all still learning.

Before we talk about the system - do you have a set of plans with the OTW boat you have? I know the 1/72 Trafalagar boat very well. I have assembled one myself without torpedoes. The boat has 5 tubes (the fifth one is a chin mounted one under the bow). If you want to detail it up I would strongly recommend buying the Jecobin plans http://jecobinplans.com/estore/index.php?cPath=22_24 if you have not already done so.

Next the system - its fair to say in Beta testing I had some electrical glitches BUT it would be unfair to comment on the reliability of the in-production electrical setup which features a different board to what I was experimenting and testing. My test situation was also compromised to some degree by some now known bad pool chemistry.

You have provided some sensible thinking of pros and cons above to mechanical versus electrical, however, I have to say that if you are using the standard 1/16" push rod seal manufactured by David under the Caswell brand banner, the risk of of leaking is pretty much zero (if installed and maintained correctly) for push rods controlling moving parts (mechanical torpedo releases mechanisms) through these seals . The quality control of the product is exceptional - so forget rubber bellows and get the best push rod seals money can buy. You should IMO be using these seals for all push rods on board your WTC, regardless of whether its a Sub Driver or other brand or home built setup. Logically the more moving parts through WT seals, you would conclude that there are more potential leak points, indeed I always had this thinking in mind for years prior to using the Caswell product. Now I don't worry about potential leak points in seals (yes I do regularly check them) -But I haven't had a problem with these yet, and we are talking around 100 hours use to date thus far.

To me which system for your torpedoes (mechanical vs electrical) really comes down to not only a question of reliability but a question of personal preference. I for one like mechanical linkages - primarily as I like understanding completely what is occurring so I can apply maintenance, care and repair myself. I really lean to this side as electronics are not my strong point, but having said that -(and that is just my view), the electronics that Kevin Mcleod produces that are part n parcel of the electrical system are top shelf gear and my experience is that the products are fully backed by Mike, David and Kevin. One of the benefits of buying through Caswell, is you aren't left out in the cold should some defect or part failure occur. The key here is quality control and partnership with the customer are highly valued by Mike, David, and Kevin. I have had but a few parts problems, and these were all promptly and professionally resolved.

Trim issues - a good question.
You trim the boat with the tubes installed. Given the volume of water displaced in each tube is equivalent to a fully charged torpedo, firing torpedoes does not effect trim. There is as you pointed out a slight bow up reaction upon firing each shot, and you do need a few holes in the bow top to let an excess gas escape so that an air bubble does not cause a bow up trim situation. You also need to install some locating positions for the each torpedo tubes fuel line and charging valve. there is some weight in the charge valves and if these valves move whilst the sub is underway it can cause a list to either port or starboard. Have these effectively stored for sea solves the problem.

I hope this helps
Best

John