1/72 HMAS Rankin (Collins Class)

[Slats]

Does the little rescue sub work on the Gotland?

No - but that would be cool.

[Subculture]

Does the little rescue sub work on the Gotland?

[Slats]

Here is Rankin (background), with David Hughes scratch built Gotland in the foreground at the 2010 Australian (ACT) Sub regatta.

[Slats]

Thanks Mike - much appreciate you loading the video.
Best

John

[Kazzer]

[Slats]

I have forwarded some very limited video of Rankin firing torpedoes at the Australian Sub Regatta to Mike, - Mike could you upload it into the thread, its the file with the bow shots?

I have pulled the torpedoes out of Rankin recently as I want to explore the mechanical side of launching the torpedoes a bit more.

In concluding this thread, I'll post some photos - when I get them of Rankin in her element. I am still awaiting pics taken by others as its hard to drive and photograph at the same time.
Best

John

[Subculture]

The best way to share video content is to upload it to one of the free on-line media providers like Youtube or Vimeo, photobucket is another choice, but I prefer the former two as they offer better quality (all the way up to 1080P if your camera is full HD).

It's quickest if your software enables you to save your edited film in an Mpeg 4 codec, as this is native for sites like Youtube.

[Slats]

And just back from the lake (fresh water dam).

Fresh water appears to have a marked improvement over the heavily chlorinated conditions of last weekends regatta.

More testing to come when I have time. Now to do some lawns that I have left over doing for a couple of months! I'd rather be sailing.

Mike and David, got to learn how this new software works between Video Camera and Mac. Might take a week or so to figure out, but will burn a DVD and post it. Anyway to upload it?

Best
J

[Slats]

John,

I've waited a few days before hitting you with specific questions and observations about your experience at the recent SubRegatta over there. You've needed the 'decompression time'. I know I do after a show ... sometimes takes a week before Ellie will talk to me again and let be back into bed.

First, thanks for putting in all those hectic, last minute modifications and fixes required to get the boat, the SD and the torpedo system ready for the event, John. I particularly appreciate your creation of the external test-display article for guys to play with and better be brought up to speed on how the torpedo and launcher sub-systems integrate into the complete system. Well done.

I've been working hit-and-miss on my version of a gas propelled torpedo and associated launcher for nearly 20 years now. I've always had a weapon stability problem -- every third or forth shot would go significantly astray from the tubes centerline. In order to get the weapon out of the destabilizing gas plume quicker I increased the launcher gas volume behind the weapon at time of launch, that fix incorporated in your Beta-test launchers. What was your experience as to weapon accuracy, at the SubRegatta?

What about weapon range?

What difficulties, if any, did you have recovering the weapons?

And please outline specific problems and suggested fixes regarding both the launcher and torpedo sub-systems.

I know that you had to go without a particulate filter to protect the little solenoid-valves from any garbage in the lines or on-board bottle. Any blockage problems relating to gas porting through the solenoid-valves?

Hang-fire: Where there any situations where the weapon failed to leave the tube when the tube was fired? And if so, what was the cause and your corrective action and/or recommendations to prevent/limit hang-fires.

Miss-fire/Cook-off: Did, at any time, a weapon self-launch, uncommanded? If so, why? Your recommendations.

Did you have the opportunity to engage any surface or subsurface targets? If so, did you nail 'em or not?

And, I assume you stayed well clear of Doctor Drake. Like they say, "Don't bring a knife to a gun-fight!".

David,

Thanks David,

appreciate the space - been a mad few weeks prior to the regatta - as you know. I was going to hold off on a report here on SD forum until I completed some further tests at my local freshwater dam tomorrow. But here is a preliminary report.

First - extensive test shots taken in the tank at home prior to the regatta revealled no major issues. A couple of hang fires, but these were exception rather than rule.

Next the regatta - a mixed success.
First the pool this year had high rate of signal drop outs and we suspected it might have been over cooked with Chlorine. The first salvo of 4 shots fired early on Sat am - went extremely well.
Range - around 20-30ft, speed is blink an you missed it initially-and for that reason - whilst I have limited video - which I'll send you, I have vast amounts of blank pool, where still photography of the shots needs better practice at actually getting the fish both in focus and in the picture.

At the reload all systems were functioning well. But upon entering the pool nothing doing on the fire control. Extracting the boat and checking everything pool side - (firing shots into a soft bag in front of the boat) everything working again. In the water zilch again.

I used silicon grease on the wet connectors to the solenoids but WE (I should point out I had lots of diagnostic help - including that of former RA N electrical tech), discovered that the fire control was working fine pool side (using a mutlimeter and actually firing shots), but immersion again in the pool, and nothing again.

After a considerable break and physically drying the connections and re applying silicon grease 3 more shots from 4 - these I have on video -nothing too spectacular as the bow was too close to the video camera, but you do get an idea of speed. One tube was a hang fire. Later on with some free sailing with no reloads (and this torpedo left in the tube) I was able to fire this by toggling Ch5. So all up 8 shots fired from the sub.

The big problem at the regatta seems to be "the water" with the electrical wet connections. Why it worked out of the pool, and selectively only worked on minimal occassions in the pool is suspect towards this.

The board I rigged up (shown in the previous photos), was a popular tester that a few of the guys played with. The interesting thing is that this baord (with zero electrical connections) being hand held in the pool - worked every time. It did not matter whether or not the valve was depressed (pnuematic firing) or the breech simply pulled back, it worked nonetheless. You do get a bigger run and more speed from the pnuematic release.

As far as I am concerned the issue has to be the pool water re the electrical connections, given my success in drinking water (tap water) that I have in my test tank. Tomorrow's test should hopefully provide a medium between heavy cholrination, tap water, and the fresh (but not advisable to drink) lake water.

OK so what other issues are there.
First loading the torpedoes. In this partciuclar boat reloading and charging tubes are a pain. There is simply no way of getting every time a consistent amount of propel fuel in each torpedo.
Range can be as much as 30ft but put less fuel in and you might find a shot that coughs and dies after just 5 or 6ft.
Allan Collins - one of the regatta organisers and long term RC submariner and I discussed the idea that there needs to be a better way of charging the torpedoes. The Schrader valves whilst they work seem to be hit and miss as to how much fuel is transferred. Allan has a unique way of charging his gas setup WTC, which involves in-line charging of propel (no schrader valve), but an in line valve (within a line like the clippard ones we use). He and I discussed the possibilty of charging the torpedoes this way, and possible doing so via a common manifoild so that you charge one line and in doing so charge all torpedoes with an equivalent and "right" amount of fuel.

The other problem with the Schrader valves for each torpedo fuel line is weight. Put 4 of these together and they are a few grams that need to be accounted for, and yes you do ballast the boat with these installed, but its where theses valves sit - after charging that is important for stability trim. A high speed turn I did shifted these to one side and the boat had a noticable list. Not a big problem to overcome, you can build in a rack to seat these but its another consideration.

Final consideration is that in a tight fitting boat, I found loading akward and time consuming. I think that a mechanical setup would greately improve speed of re-loading over what I currently have, (a bloody tight fit). This might have more to do with my particular boat.

Next do we need an electrical launcher? Sure if you want multiple shots (more than 2) from a single channel - its a great idea. In fact you can have up to ten, but I'd have to say I'd take mechanical simplicity over a electrical device and connection to the SD anyday. I have made no bones over electronics being something that I suck at - infact I thought the I-pad was femine hygeine product. I was initially thinking that if you wanted a pneumatic launcher that you would have to go the electrical route, but you could simply rig in a similar setup to the display board I rigged up and depress the valve (or valves) by a control horn linked to a servo. I like the idea of this so much David, you'll note I have included a couple of these valves in that shopping list I sent you and Mike. Most of the guys who saw the board and / or used it came to that conclusion and thought given the "displayed preciousness" of the electrical connections that this would be a good way to go. In fact you could probably rig up a cam connected to a single push rod that depressed say a whole bunch of valves in the wet area.

Seriously I run a brick of a speed control in my boats (an Electronize brand) - these are simply devices that I have never - and I mean NEVER had a single issue with in nearly 20 years in multiple vessels. Its not that I want to be an electrical ignoramus, but i have zero time for devices that I cannot repair myself. It probably does not suprise people therefore that I run a micro switch connected to a servo to turn my snort pump on /off. Sure there are electronics for this, but I'd rather have a device that I can understand and above all FIX. That is why I love the SD / gas / snort so much - mechanical simplicity and you can fix it yourself. Self sufficiency is a big factor in being in this hobby for the long hual.

The filter
To protect the manifold (with the solenoids) that ports gas to each pnuematic torpedo tube actuator is an in-line filter.
Before I went to the regatta, this started to leak infrequently. So I had to run at the regatta with this not in place.

Engaging targets -
The only targets deliberately engaged were guys with video camera's. The goal was to get as much film of the system as possible, but as discussed this was limited.

Dr Pat Drakes show
Was awesome - right up until I realised that I sailed Rankin into a mine field. Thankfully he was setting up at the time.
A flower class corvette is usually sacrificed and this regatta a mine blew it out of the water. Film on the official regatta DVD. Mike and David, I'll make sure I buy you guys a copy.

Accuracy of the torpedoes.
they tend to run dead straight for the first half of the run and gently taper off.

Recover of weapons
Easy in the pool - using a skimmer net.

Anyway - I'll report in with more over the w/end for the lake testing.
best
J

[He Who Shall Not Be Named]

John,

I've waited a few days before hitting you with specific questions and observations about your experience at the recent SubRegatta over there. You've needed the 'decompression time'. I know I do after a show ... sometimes takes a week before Ellie will talk to me again and let me back into bed.

First, thanks for putting in all those hectic, last minute modifications and fixes required to get the boat, the SD and the torpedo system ready for the event, John. I particularly appreciate your creation of the external test-display article for guys to play with and better be brought up to speed on how the torpedo and launcher sub-systems integrate into the complete system. Well done.

I've been working hit-and-miss on my version of a gas propelled torpedo and associated launcher for nearly 20 years now. I've always had a weapon stability problem -- every third or forth shot would go significantly astray from the tube's centerline. In order to get the weapon out of the destabilizing gas plume quicker, I increased the launcher gas volume behind the weapon at time of launch, that fix incorporated in your Beta-test launchers. What was your experience as to weapon accuracy, at the SubRegatta?

What about weapon range?

What difficulties, if any, did you have recovering the weapons?

And please outline specific problems and suggested fixes regarding both the launcher and torpedo sub-systems.

I know that you had to go without a particulate filter to protect the little solenoid-valves from any garbage in the lines or on-board bottle. Any blockage problems relating to gas porting through the solenoid-valves?

Hang-fire: Where there any situations where the weapon failed to leave the tube when the tube was fired? And if so, what was the cause and your corrective action and/or recommendations to prevent/limit hang-fires.

Miss-fire/Cook-off: Did, at any time, a weapon self-launch, uncommanded? If so, why? Your recommendations.

Did you have the opportunity to engage any surface or subsurface targets? If so, did you nail 'em or not?

And, I assume you stayed well clear of Doctor Drake. Like they say, "Don't bring a knife to a gun-fight!".

David,

[Slats]

You'll note that I have a nice test tank. This one is around 2.6m long a touch over 8.5ft, its around 80cm wide (about 2.5 ft), and its 19" or 50cm deep.
The benefits over a standard bath, aside from "domestic" bliss, is that you have a bit more length and remove to play with.

This setup is adjacent an undercover carport, allowing all weather trimming, and its well lit meaning I can do it at night too. Only draw back is the winter months when the water temp is around 5 degrees C. The tank itself sits outside, allowing rain water collection. There is a a central drain fitting which a hose connects to for filling and emptying on to the garden. The tank sits a full 1m of the ground (about 3ft) which means no stooping over.

If you are serious about the hobby - get or make a test tank. A childs blow up pool can be good too, providing its deep enough.
J

[Slats]

With the torpedo system installed its time to re-ballast the boat for both the new SD and the weight of the new torpedo system. Flick back a few pages and you will find where I located the C.p and ballasted the Cg on top of this point, being the centre of the ballast tank. Using one side of a boat stand I see-sawed the fully laden boat around with different small amounts of lead until she ballanced.

Final in water submerged and surface trim is done by adding foam - but first how well is you WTC balanced? - mine is shown here with a dunk in the tank. You'll note she floats very well in an upright position. The weight forward of the ballast tank is almost that aft of it, which aided the minimal weight readjustment I needed in ballasting the fully laden boat around the Cg.



Next final ballasting only involved slight amounts of foam and tiny bit of lead.

[Slats]

So now some basics of how this system works:

First have a look at this board I assembled from components supplied by David.








In the top left hand corner is a gas bottle. In pneumatics and for that matter hydraulics this is called an accumulator. It stores energy to be injected into a line to activate a system. This gas storage bottle is charged in an upright fashion – the same way you charge a ballast tank with propel. Initially charge then vent (to chill down the bottle), and allow more quantity of liquid propel to fill it.

You can see a cilppard grey line leaving the top of the tank. This feeds gas into a manifold valve on the upper right hand side. This has a release valve on top of it. Pressing the valve down allows a flow of gas from the accumulator (gas tank) through the manifold and into an actuator (brass cylinder) on the lower side of the torpedo tube. The action of this forces the actuator to expand the clear section backward which moves the breech aft of the torpedo, unlocks the stopper ball forward and ejects the torpedo.

Charging the torpedo is done via
1- opening the breech (pull it back) to allow the torpedo to pass the forward stopper ball,
2- using a small piece of wooden dowel that is small enough to fit under the closed stop ball and contact the head of the torpedo, you then close the breech (move it forward). This seats the torpedo securely allow it to be charged and held in place.
3- Remove the dowel
4- Charge the torpedo line with propel liquid via inverting the can and holding the torpedo charge line vertically. So as to do this without freezing your figures hold the torpedo line with multigrips. I count 1 through 5 “one one thousands” (about 5 sec) charge for each torpedo line.
Releasing the torpedo involves activating the actuator, in this case on the board I rigged up by depressing the valve on the manifold.

In the boat with the electrical controller and solenoids rigged to the manifold, you simply toggle a 2 position switch channel back and forth to fire the torpedoes. In effect the controller board is providing a short burst of electric current to each solenoid valve- quickly opening it to allow gas to port down to the adjacent torpedo tubes actuator. In other words off just 1 channel you can control up to ten torpedo tube individual actuators.

Ok so some system performance reports.

Firing by simply mechanically pulling back the breach (no pnuematic activation) works remarkably well BUT you get a noticably bigger effect (more speed and longer run time), if you fire with the pnemuatic activation.

[Slats]

The mounting installed note the pins (bottom of the picture) for the solenoids - these go back to the SD and are the electrical connections to the controller board.


Here you see the forward endcap of the SD. This endcap seals off the battery compartment, has the main switch for the subdriver, holds the gas tank accumulator for the pneumatic torpedo release and has the 4 negative wires from the controller board to each solenoid (in this case 4 - for the 4 tubes) via through endcap bolts. The positives for each solenoid go back to a common positive (single end cap bolt). All these endcap bolts were covered in Silicon RTV prior to use.

[Slats]

Installing the new 1/72 torpedoes

I was very fortunate to be one of the beta testers of the torpedo system which is a great leap forward for the hobby on a number of fronts.

The first thing that is required for even contemplating having torpedoes in a RC sub, is working out if you have room. You need to allow around 5-6 inches of linear space for the length of the tubes and about 1/2 between tubes to allow for the pneumatic breech for each torpedo.

In Rankin, there are 6 tubes across the bow, but to allow also for room for the "plumbing", the gas lines leading to the charging tubes (these need to be stored somewhere after charging), and the tubes to the manifold that actuate pnuematic firing, I fitted 4.

To mount the tube I strongly suggest that you telescope the torpedo tubes inside a guid tube. The torpedo tubes OD is 5/16" so if you buy K&S brass in 11/32" tube - you will find that the torpedo tubes sleave fit inside.

Here you can see some 11/32" tube prepared as "sleaves" to fit the bow tubes for Rankin. Initially I made up 6 for her 6 tubes - but in the end I only had the two inner and two most outer tubes take torpedos. Note that these sleave or guide tubes are designed to accommodate the stop ball housing of each of the torpedo tubes. That housing abutts up against the completely round section of tube.


Loosely push fitted in place - these are then when squared up and true fixed in with a bit of green ZAP CA glue.


Next you can see the removable mounting I made for the 4 tubes I installed, I combined the manifold below this mounting, the whole unit telescopes inside the 4 corresponding sleave tubes, and a stainless bolt through the bottom of the hull and through the mounting with a nut holds it all in place.
View from above the mounting:


Mounting inverted showing the manifold connected by a couple of simple cable ties: