Trumpeter 1/144 Sea Wolf Conversion

[joe]

First off I'd like to say hello! as I am a new member here. Subs are new for me as I have been involved mostly in R/C airplanes,helicopters,and rock crawlers.
I picked-up a r/c sub off ebay to get my feet wet in this uncharted territory.Modeled after a US Seawolf it is a dynamic diver,about 15inches long, and got it for only$19.99


For my first REAL submarine I decided to go with the Trumpeter 1/144 USS SSN-21 Seawolf and modify it for R/C use. I was also looking at the Dumas Akula, but something made me lean towards the Seawolf.After all who says we can only have 1 r/c sub! Maybe I will see the Akula down the road later.
I am in the process of ordering the WTC from Dave, I sketched up a drawing below...how does it look? Do you guys think Im on the right course? Any tips?

[crazy ivan]

Joe,

I'll make the assumption that

Joe,

I'll make the assumption that the mechanical speed control has a reverse function and that it is driving a reversable water pump. If this is the case, then so far so good. But you need to be sure that the pump is of the self sealing type when shut off so that no water (or very little water) leaks past it. Otherwise you would need to add another valve to the system.

Is the 500 ml container a soft bladder or a sealed hard tank? Putting a water filled bladder inside the WTC with the electronics has been done, but it is somewhat risky if it were to leak, and I believe this method is less commonly used.

On the other hand, if it is a rigid sealed tank, there are a couple of advantages. First, it can be mounted outside the WTC and pose no risk to the electronics. Second, as it fills up and compresses the air inside, the buildup of pressure will help blow out the water when you surface. You don't even need a reversable pump with this setup, you just need to provide a valve to let the water out and it will empty itself automatically. As a side benefit, if a little water is alowed to leak back through the pump, you have a built in failsafe that will eventually bring the boat back up if all power were to fail. I built such a system with a car windshield washer pump and it works fine. It helps to experiment a little with the components outside the WTC before committing them to a permanent location.

Does the ESC incorporate a BEC? If not you will need to add an external voltage regulator for the reciever and servos. And as long as your pump and motor have proper noise supression, you should be able to get by with a single battery.

Finally, you should seriously consider using an Automatic Pitch Contoller in line with the dive plane (what you fly-guys call the elevator ) servo. Some perfectly trimmed subs do operate OK without an APC, but it makes a world of difference in maintaining steady depth control.

Your choice of going with the Seawolf is probably a good one. I once built the Dumas Akula stock out-of-the-box, but ended up gutting it to put in my own system.

So welcome to our hobby and our forum, and keep asking those questions. From your sketch, it looks like you have all the essentials in place.

[Rogue Sub]

Dang George you beat me

Dang George you beat me to it. I first purchased the Dumas Akula like george did and have since totaly gutted the boat. It was a good place to start but it will leave you wanting much more.

The seawolf will give you longer lasting satisfaction. And the kit you ordered is really nice.

Make sure to ask lots of questions. Alot of these guys have already made the mistakes you can avoid. Im still learning.

[crazy ivan]

Heck Kevin, I've got mistakes

Heck Kevin, I've got mistakes I haven't even begun to make yet!
The day we stop learning is the day we go 6 feet under.

[joe]

Yep the mechanical speed control

Yep the mechanical speed control has forward and reverse, the pump is also a reversable pump. I don't know if the pump is a self sealing type. I will have to test it first and try to figure out different options for a valve that I can buy if needed. The tank is hard tank(plastic). I like your idea about having the tank outside of the WTC. The most confusing part of this whole thing for me is the pump and tank system. Im the type of person that needs to see how it works to completely understand.

"It helps to experiment a little with the components outside the WTC before committing them to a permanent location."......I agree with you 100%

I have seen someone on here(video) of a Seawolf with an air pump? It would fill up a bag with air....then release the air with a valve. There were also holes drilled in the WTC where the air bag was located.
The ESC has a BEC so thats good. Im happy to hear that I made a good choice with the Seawolf kit instead of the Akula, I still like the look of the Akula...but not worth it if Ill end up gutting it....I know I would because I love the static divers.
Heres my big question of the night.....which planes would the APC control? The ones in the front of the Sub or back. Or are the elevator looking things on the front just trim tabs? Im a bit confused because Im new to this but very eager to learn!

Thank You Crazy Ivan and Nuke Power

Also I just recieved my kit tonight, and Im so excited

[crazy ivan]

There are several ways to

There are several ways to handle the diving planes. The usual functionality is this: the bow planes (front) mainly affect depth, and the stern planes (rear) control the pitch angle. With a 4 channel radio, you can just fix the bow planes in the neutral position and control the stern planes with the stick. If an APC is used with this configuration, it also goes on the stern planes and it will tend to hold the boat at whatever pitch angle you set with your joy stick. I ran the Akula this way for years, and it is probably the most common arrangement for a basic sub.

Another 4 channel option, which I now use, is to connect the stern plane servo to just the APC, but not to a channel. It will tend to keep the sub level at all times by itself. The freed-up channel can then be used to run the bow planes from the stick for depth control. This configuration makes it much easier to run stedily at periscope depth without "porpoising".

The next level is to have 5 channels so you can control both bow and stern planes independantly with the transmitter. You still want an APC at the stern. Then the ultimate thing is to add an Automatic Depth Controller to the bow planes. But this is rarely done. It is not advisable to try to couple the bow and stern planes together to run them both from a single channel.

If your pump does not self-seal, you can put an electric valve in series with it. Some guys have set up a pinch roller device on the servo to clamp off the hose to the tank when the pump is off.

The air bag system you mention is known around here as RCABS (for Recirculating Compressed Air Ballast System). It has become quite popular, and many of us have switched over to it, or its Reverse variant.

Oh, and as an experienced aircraft driver, you may or may not know]must not[/i] use your aircraft band radio (72mHz in the U.S.) for surface (or SUB-surface) vehicles. It is both dangerous and illegal. 75mHz is the proper U.S. ground frequency band (and in Canada too I believe).

[joe]

Hey Crazy Ivan I really

Hey Crazy Ivan I really like the second option you gave using an APC. I don't want my sub to start "porpoising"

"Another 4 channel option, which I now use, is to connect the stern plane servo to just the APC, but not to a channel. It will tend to keep the sub level at all times by itself. The freed-up channel can then be used to run the bow planes from the stick for depth control. This configuration makes it much easier to run stedily at periscope depth without "porpoising"."

Would you happen to have any pictures of how a servo is positioned within the WTC to control the bow planes on your sub? Any recomendations for an APC that would be good for the Seawolf?
As far as a radio, I have a Spektrum DX6 laying around here, it is a 6 channel 2.4GHz spread spectrum technology. Although it is a Airplane/Heli radio...I think the car/truck/boat pistol grip radio versions use the exact same technology. Im not sure if your familiar with these radios, but they don't use crystals for channels. I wonder if it would be legal to use it? What radios are popular with you sub guys? My radios throttle stick does not return to center postion
Im going to look up that pinch roller device and start playing around with my pump system

[KevinMC]

Hi Joe,

Welcome aboard!

Although a 2.4GHz

Hi Joe,

Welcome aboard!

Although a 2.4GHz radio is technically legal to use for surface and aircraft alike, I'd suggest that it's probably not a good fit for a submarine. (2.4GHz doesn't penetrate water very far.)

Do you have a module-based radio for any of your aircraft? If so, it's a no-brainer to drop in a 75MHz (surface) Tx module and pick up receiver to match. And don't worry about not having a centering spring on the throttle- just think of it as cruise control! (I drive my boat from an aircraft radio with a 75MHz module and it's been a great setup for me.)

[chuck chesney]

Hi Joe,
Crazy Ivan mentioned the

Hi Joe,
Crazy Ivan mentioned the RCABS ballast system. You might want to give it a real close look. It was invented by Dr. Art Broder, and is simple, RELIABLE, and inexpensive to build and operate. It is also very flexible in terms of space requirements within the hull, and is largely foolproof, particularly in it's Reverse RCABS variant. The battery drain is also very small, which might not be the case with your current scheme, the "pump boat".
I've run subs with piston tanks, gas (Freon), pumps, and RCABS. The RCABS wins , hands down. I am currently running with the Reverse RCABS variant which grew from the original RCABS, even though it is slightly more complex and marginally more space demanding in terms of space within a WTC.

For a first (or second or third, or fourth) boat, RCABS might be a way to eliminate a whole series of worries, both while building and running.

Just my two cents worth.

[warpatroller]

Crazy Ivan,

Could you please explain

Crazy Ivan,

Could you please explain why you made the following statement:

"It is not advisable to try to couple the bow and stern planes together to run them both from a single channel."

I have seen Steve Neill on Subpirates setup a small, 19" long Type 23 so that BOTH bow and stern planes are controlled by one servo from a single channel. The planes rotate in opposite directions. The Bow planes pushes the bow down and the stern planes raise the stern up (to submerge), or just the opposite, bow goes up, stern goes down (to surface). This sub was built as a dynamic diver and does NOT use an APC.

A linkage runs from the servo to the stern planes, then another linkage is attached to that stern plane linkage that runs to the bow planes. His bow linkage runs parallel and underneath his WTC.

I would like to know why you don't advise setting up dive plane controls like this? Especially why you might not advise it on such a small model like this.

Steve

[anonymous]

On my seawolf I didn't

On my seawolf I didn't even use the bow planes.

http://sneill.com/seawolf/seawolf_2.wmv

If your gong to RC the Seawolf follow what BigDave did. It works in fact, perfect!

http://www.frontiernet.net/~bwelch/

Best of luck and welcome aboard.

steve

[Rogue Sub]

That build will take you

That build will take you all the way through completion. I do believe the the kit you ordered also comes with a bunch of pictures and a list of all equipment he used to get his running.

Matching the hull up will prob end up being your biggest pain in the rear.

[joe]

Thanks guys for the help!

Thanks guys for the help! Looks like I have to shop for a radio. I was looking at the Futaba 7C. The 7C can be ordered as a surface or air frequencies. I think if I buy another module for the radio then I can pop out the surface module and slap in an air module and use it for my aircraft.(Please correct me if Im wrong)
Im going to research more on that RCABS system and learn as much as I can. I dont think I can do much more than that until the WTC arrives so back to the "drydock" for me

[crazy ivan]

OK, let's see now:
Could you

OK, let's see now:
[quote]Could you please explain why you made the following statement]

Short answer: My own experiences and the sage advice of those who came before me. Longwinded technical dissertation: Well, let me see if I can articulate this clearly. As I previously posted, the bow and stern planes act in distinctly different ways, at least on the military subs we typically model, be they of the Seawolf, Gato or U-Boat type. There is a reason for this, and it starts with the center of gravity and its location.

Any forces applied to a submerged hull by the rudder or dive planes will cause it to rotate around the center of gravity. If the center is too far forward, there is extreme stability and the turning response becomes very sluggish due to an effect known as weathercocking. Too far back and the hull becomes dynamically unstable, making control difficult. Anyone who has built and flown model rockets will recall the importance of properly locating the center of gravity relative to the center of dynamic pressure.

The balance between stability and control response is generally achieved in model subs by locating the center of gravity somewhat forward of the middle of the boat, maybe in the area of around a third or more of the way back from the bow, depending on the boat. This means that the the bow planes are relatively close to the center of gravity, so they "tend to change the vertical position of the submarine on an even keel. There is a certain rotational moment, but it is counteracted to a great extent by the longer after body which acts somewhat as a stabilizing rudder, resisting angular displacement." (All quotations are from The Fleet Type Submarine training manual)

The stern planes, on the other hand, will have a relatively large rotational moment arm which will result in a change of pitch, and "their effect is much greater than that of the bow planes." In addition, when the submarine "is inclined, the hull presents planing surfaces. The resultant upward or downward thrust is added to that of the diving planes." The upshot of all this is that, in our scale, when the stern planes are used to angle the boat for diving or surfacing, the effect of the bow planes is probably negligible. The bow planes may as well be fixed in position, avoiding all the extra linkage. A lot of boats run successfully this way (although sometimes at the risk of finding your tail in the air, with the prop sucking wind because you gave her too much throttle, too soon, with too much down angle on the sternplanes!). It's happened to my Akula and other boats I've seen at the subregattas.

So then why can't the bow and stern planes be coupled together? Won't the boat still dive and surface? Absolutely! Steve's Type XXIII is a case in point. Knock yourself out. But after the novelty of going up and down wears off, it becomes a matter of control... very precise control. Many of us derive great satisfaction when we can get our boats to run steady at periscope depth, particularly with hands-off on the joy stick. If the bow planes are to be used at all, de-coupling the functions of the bow and stern planes enhances the likelyhood of success, with the boat running on an even keel.

There is one circumstance where hooking the two together might be beneficial, and that is the case of a boat like the Seaview. Dave Merriman has noted that the bow planes in this case (NOT the Sail Planes!) are far enough ahead of the center of gravity that they would impart a rotational force that would enhance the effect of the otherwise poorly performing stern planes. Maybe this is also the case with Steve's little Type XXIII, depending on how far back he located his COG. The Trumpeter Seawolf that started this discussion, at 29 inches long by 4.5 inches beam, I would expect to fall more in line with the conditions stated above.

[crazy ivan]

Joe,

To answer your questions; I

Joe,

To answer your questions; I use a SubTech APC-4 from http://www.mikessubworks.com. It works great (as long as your radio isn't an Airtronics VG600 with mini-servos... compatibility issues).

I can show you my bow plane control hook-up, but it may not help much because I designed my WTC with rotary outputs out the top rather than the usual linear push rods out the rear endcap.

Well here it is in my Gato. You can see a long pushrod heading up the right side along the top of the WTC.



I think a lot of guys mount the servo right behind the forward WTC endcap, i.e. Nuke Power's Akula. Is that right, Kevin?