Revell Gato 1/72 scale build

[salmon]

Using a soldering tip at higher temperature (about 620 degrees Fahrenheit) soldered the wires to the deans connector and after it cooled, trimmed the ends, slid the red and white shrink tube up and used heat to tighten that. Finally slid the blue shrink tube up to keep the wires together.


On the aft end of the WTC wire I matched the ESC end with a Tamiya connector. Put it all together with shrink tube and powered it on. Using a multimeter I wanted to check that all the connectors were good. They are (yeah). Oh wait.... Were am I going to tie in the SNORT (LPB) and the LiPo guard? I was in a hurry that I forgot those....GRRRRR.
I will tackle that later, I have a Sombra Labs receiver and a WFly transmitter to get set up.


Plus this rats nest to get under control.

[salmon]

I removed the pins from the Tamiya and added wires to branch out. These wires will supply the power for the SNORT pumps and LiPo Guard. It was not difficult to back them out, with a pair of tweezers I squeezed the tabs that spring out to keep it from pulling out. Soldered the wires to attach the other devices and reinstalled. Metered the connection to verify that I was getting power to the new connections and I was. Issue solved.


Here is a photo of the additional connections that were added to the Tamiya connection. The wires that I added went to bullet connectors, then to the devices. The thinking is, if in the future I want to change or add equipment, it would be easier to work from the bullet connection.


Did a water displacement test. Without overdoing the exactness (measuring the compressed air tank, tube running from engine room to battery compartment, float, and misc items) I estimate about 45 cubic inches of volume or .75 of a liter (.198 of a gallon) in the ballast tank.
My first test was one pump to see how long it would take to empty if I inverted it in a pot. It took about 220 seconds to empty over 3/4 of a gallon. The jug lifted itself up and caused the tube to come out. So my output was close to a liter a minute.
Second test was two pumps connected to a single intake. I did not have a T or Y air fittings. so I made one.


Connected both pumps to the fitting on the intake and ran tubing from the output to the opening of the inverted milk carton and terminated it with a piece of 1/8” brass tubing matching the SNORT tubing.



Then started up the pumps. It cut the time in half and maybe even slightly better than half. It was hard to say for sure because like the first experiment the jug moved (even while holding it) and caused one output to come out.
So, the conclusion is, the additional pump will help without requiring a duplicate air intake and output. I suspect that if I minimize the silicon tubing and maximize the use of brass, I may get a performance boost because the brass tubing has smaller walls and will allow a higher volume through and the brass is less likely to get pinched or collapse by pressure.

[salmon]

Wiring and stuffing a sausage.... they both apply to the Gato.



I added the ADF2 and the LiPo to the madness and began attaching components to the engine room with zip ties and velcro.
The ESC (Electronic Speed Controller) was installed first. I slapped some velcro on it and set it up, but then I thought......I bet there is some heat generated by the ESC, maybe I won’t velcro it, but use a zip tie instead.


Added the LiPo Guard to the port side of the engine room using sticky velcro (has adhesive backing). Began running servo cables from the port side servos to the Sombra Labs receiver. In an effort to reduce the length I twisted the servo cables and thought that this might help reduce interference (nothing scientific to back that up it probably is as good as the aluminum hat I wear to prevent cosmic signals from controlling my brain - joking of course). It is interesting the weaving and testing to make sure there is no binding with the servos or the pushrods.


Moving to the starboard side the ADF2 is mounted with a piece of velcro to the servos. Again, tried to weave the wires in such a way as to not cause binding.


Then the transmitter is on the top between the servos. I did this because David recommended to someone not to put it below just in case water leaked in. You do not want it fried. Well I do not want to fry any of my electronics and so looking at other installs moved things higher up. The only thing that will be low are the mini pumps.


I checked to make sure it fit in the tube with this configuration (it did!) and tested servos. I am open to suggestions or if you have pictures that will help me make this nice and clean, I would love to see them.

I had some issues that randomly would happen. It was suggested I replace the ESC (Electronic Speed Controller) BEC (Battery Elimination Circuit) with a dedicated BEC because it is possible I was overtaxing the built in one.

Changing of the BEC.
Needed to cut the ties off and unraveled the tangle of wires packed in the engine room. What a mess!
I put in a bullet connector to tap into the main battery power earlier during the build just for this kind of thing.


Added the BEC to the bullet connector tap.


Then I needed to disconnect the red cable from the ESC. #3 is the connector from the mtroniks speed controller. I will apologize in advance for the cheesy contrast. It was to eliminate the clutter to make my point clearer (I hope).


To remove the red cable, use a sharp point to lift the tab that is behind the brass tip and pull out the red cable.


Here is a closer look with the tab pointed out.


It will slide out and be able to re-insert if later you want to use the ESC in a different model.


I folded the red cable back and used electricians tape to hold it down and protect it from touching anything. Bound up all the loose cables and stuffed it into the WTC. Tested it on the bench and all worked well.

[salmon]

Here is my general crayon drawing of the electronics used in the Gato.


Please let me know if I made a mistake or not clear.

[salmon]

Once the sausage is packed with electronics, I tested the tube for water tightness just to see if there were any leaks (I bought this tube off eBay or second hand). Removed the valve center. Bought a 3’ length of vinyl tubing. Heated the end over an open flame (stove) just enough to get it soft. Then pushed it up onto the end of the needle nose pliers to stretch it. I did this a couple of times until it fit on the valve threading.


Partially filled the bath tub and placed the WTC in. Blew gently into the vinyl tube and........

got bubbles. That is not good. It is coming out of the rudder push rod bearing. It needs to be replaced and I might as well do the difficult bearing that seems to get tighter after it sits awhile.

I could not slide my old seal off the pushrod because I had a soldered end, but once it was out it was a simple matter to loosen the end off and re-solder it back on


Placed the RTV on the seal outer edge and slipped it into place. Gave it a few hours to set and did the water test. I had to blow a lot harder, but I had bubbles.....dun dun dunnnnnn (for that dramatic touch). The good news is it came from the seals edge (near a bubble in the casting).


and near the motor shaft also from a subsurface bubble.


So for the seal I placed some additional RTV


and same for the Motor shaft area


Once the RTV was placed on the areas I created a negative pressure in the WTC to suck in some of the RTV into the leaks. Let this dry.
My son and I both tested the WTC - NO LEAKS!


Now I will replace the one that is so tight.

[salmon]

Replacing a seal.
The seal that I am replacing is the one that is really tight - the rudder pushrod seal.


Just push the seal out with a spare piece of rod. I had to push from both directions, but it comes loose.


I had soldered my threaded end for the Kli-cons (which I saw a posting by David Merriman you could just CA them in place) and needed to remove it.


Put a generous amount of RTV silicon on.


Push the seal in until it is flush or slightly out with the WTC end cap.


Clean up, let it set up, install pushrod, and pressure test your hull.

[salmon]

Conning Tower.
I wanted to extend the SNORT tube on my Gato and looking at the periscope, I thought why not use it for air intake? So let's chase that rabbit.
I drilled out the molded in periscope shaft. Slowly and with a much smaller drill I worked it down the frame.



I somehow thought I could drill a 1/8” hole through rear periscope shaft to add a brass riser to it. So carefully and in tiny bits I was able to complete the drilling.




Slid in the brass tube to see fit and what areas I need to clean up.



Then using an Xacto Blade, trimmed the edges and thinned walls.


Slid in the brass tube to see fit and what areas I need to clean up.




The tube coming down will be connected to the tubing from the pumps by way of a magnetic connector.
The joys in small accomplishments. The brass tube did not slide in nice and easy. I had to take a 1/8" brass tube and file/cut teeth into the end and I roughed up the outside with 120 grit sandpaper. Then spinning the rod as it went through helped bore out the path and open it up enough to allow the inserting of the tube.
Now, the real reason I did the additional tube. I wanted to add it as an air vent for diving, but if my testing of the SNORT system did not accurately measure air demands, I was piped and ready.

[salmon]

With the conning tower being open underneath


and the doors cut out, I did not like how I could see the light coming in from below the deck. At certain angles it is fine it looks satisfactorily dark.


So, I built a quick floor from styrene, I traced the outside of the ridge on the deck meant to hold the conning tower. Transferred the pattern to some sheet styrene and did some scribing of lines (not for scale, but effect). Then shot it with a quick coat of black paint.


Putting the conning tower over it, I got the look I was going for. The only light coming in or showing up was from the light coming in from the other door.


Wait, that is not the end of the story. Once I placed the new deck in, I then realized that the ridge built for the conning tower is really high and with the door cut out it stands higher than the threshold. Add a deck and now you are obnoxiously obvious.


So, the only solution that came to mind is cut out the raised ridge and have the floor in the conning tower for strength.
Marked area needing to cut out and verified the placement on the conning tower.



Using the deep throat jewelers saw and the wax blade (twisted blade that can cut in any direction) the area marked for removal was excavated.


Checked fit with deck. Added some small pieces of styrene as tabs or stops for the deck so it would set at the right depth. placed deck in and used cohesive glue to attach deck to tabs and conning tower. Once set, filled edges with CA and baking powder.

[salmon]

Now the deck sets lower and is less obnoxious.

[salmon]

The model is based off of the USS Cobia

I have read that it is originally from Dutch Admiral Maarten Tromp, who legend held, placed a broom at the masthead to show he had swept the sea clean of the foe--the English in his case. There is an old song called "The Admiral's Broom."

what is in the conning tower inside where the open doors are?


David Merriman said "You step through that opening and you have, to the left, a huge concave circular 'dish'. That's the after end of the conning tower proper (cylindrical, pressure proof structure where the boat is conned while submerged). To the left are the forward ends of those long gun/ammo storage lockers you see projecting out the after end of the fairing. Above, a lot of truss work under the cigarette deck -- re-enforcing members to harden the gun platform. In the center of the fairing, to the right of the door, is the big main-induction valve (kinda looks like the upper end of a dance-club 'smoke eater'). And within the superstructure fairing itself you'll will see stringers and frames. Very busy looking in there. And smelly."

Good info to maybe do a little detailing out later. Remember get the sub running first, then chase details!

[salmon]

Ballast and trimming.
I wanted to be smart and pre-build my ballast so I could add as I needed.
I got some potters clay (the kind they put in a kiln) and built a simple wood frame with the edges at the height, short of the distance, to the bottom of the wtc. Rolled the clay into the frame and laid the ballast pattern on top, Using an xacto knife, cut around the pattern.


Removed all the areas that I wanted filled with lead. Anywhere there is clay, that was an area that water would come in from.


Melted the lead (time to insert disclaimer - lead is know to be dangerous to your health, use at your own risk - I am not recommending you use lead and will not be held liable for any injury or harm to yourself or others or to property damaged by molten lead, handling lead, and usage of lead) If you are worried use BBs or Zinc. Poured the lead into the mold and presto, I have ballast........or DO I?


It de-molded great, but I used a flat bottom mold and my hull is curved. Which if I thought about it first, I should have seen that. The outside edges meet the hull before the center of the ballast keeping it raised too high. I would have to further modify the casting to fit the hull and not inhibit the WTC from mounting properly.


Try number two.......
I laid a strip of clay in the hull pressing it into all the recesses.
Trimmed the edges to keep the mold height right and pushed out all the flood holes. Also cut out channels on each hole to allow a path for water to come in once the ballast is installed.




Then let the clay dry. Hoping it would not stick because if it can go wrong (I seem to attract the go wrong) it will. The clay came out, for the most part O.K. - a couple of narrow pieces broke off.
Then I purchased come craft plaster. This was not like standard plaster of paris, soft and gouges easily, it was more like the harder plaster used in special effects (a dental plaster or Die Plaster) or in jewelry (casting investment). Mixed the batch a little thicker and ladled it into the mold frame, then I placed the hardened clay pieces in. Made sure that they were oriented the correct way (keel facing down). Let it set until it firmed up. Using a putty knife carefully leveled everything to the top of the mold frame.


I had some left over plaster and two pieces of ballast castings. These two pieces were from the extreme bow end and extreme aft end. I laid these two into the leftover plaster. The instructions say it can be microwaved to speed the hardening process once the initial set occurred. Hmmmm, I’ll try that with the extra molded pieces (not the core pieces). About 40 seconds on defrost, I heard a pop and a raining sound....that is not good quickly went through my head. I stopped the microwave and opened the door. One corner of the mold blew out. The microwave door was plastered with, well, plaster. Being the quick thinker, I better clean this up before my wife discovers what I did.
The mold was still salvageable, but I think I will just let the molds dry on their own. The instructions said it can take 24 hours to fully cure. I do not have 24 hours.
Being too impatient I turned the oven on to 195 degrees fahrenheit and I placed the main mold in there. Once the oven reached 195, I turned off the oven, left the door closed, and worked on other things. I came back later and everything had hardened. The next question is how do I get the clay out....since it is potters clay, adding water will get the clay soft again. I placed the cooled mold into a bucket of water and let it sit for a while. When I came back to it, the clay had softened. Using a old toothbrush and a toothpick cleaned out the clay.


Then it was time to melt the lead. And I had a thought......Scary isn’t it? Why am I doing all this? I do not even know if I need all these and I am delaying the inevitable, getting the sub in water (and in the back of my head I can hear the voice of David saying "get her in the water doggone it" Well not the doggone it part). I have enough ballast from my first attempt to use. Then I can pour only the pieces I need. The master tub is too small (who designed these tubs?) and the guest one might work.
Did the pre-sail checklist. I filled the tub and put my Gato in. The excitement was high. My son came in and wanted to help. I set the sub gently into the water, holding it as water filled the free space, and let her go. She promptly, unceremoniously, flopped over on her side like a dead fish in an aquarium. I was not expecting that, but knew that is why I was making the ballast.
Released air out of her tank and lovingly held her upright, the aft end sank and the bow was high. Placing a piece of lead (from the first batch of ballast- 140grams) on the deck towards the bow, it began to level out, but it quickly was stopped by the curve of the tub. RATS...this tub will not work.


So, my son and I played (err - verified the procedure) with filling the tank using SNORT and emptying her and repeating the process. I will need to build a tank to trim the Gato. We also played with the propulsion. There is a TON of power in these props! I am so excited to get to the point of sea trials!
Once we were done playing/testing, checked the wtc and it was wet where it is supposed to be and dry where it is supposed to be dry! YESSSS!

[salmon]

Inflated the mini-pool and filled it with water...in the garage..... and began testing....my son's Rain Gutter Boat for Cub Scouts. Yep, that was the priority. However, last night after Sam went to bed, I began the trimming of the Gato!

With lots of rubber bands and just under 1 lb of lead I began the process. The first order was to stop the sub from laying over and playing dead. I added most of the lead to stop that. Placing some in the front and majority in the middle. When I filled the ballast tank (this sub is first trimmed submerged) the Gato gracefully sunk - upright!. Good start, Then I added foam to either side in the middle and some in the stern. This lifted her back up to decks awash. I placed the remaining weight on the deck and it got to the point where if I put the last chunk on, she would sink. Took it all out and the Gato is drying. The lead is affixed with RTV rubber.

Then I will repeat this process for more refining of the trim (this time I will take pictures).
Bought a kiddie pool (or test tank) from Target. It was cheap about $25 -$35.

Placed the Gato in the pool. It sat proud and really close to the proper waterline. The aft end was a little high. Then flooded the ballast tank. She sank, slowly. That was O.K. I knew it needed another round of adjustments. A light tug on the periscope moved the sub and it had a little resistance. I had two pieces of pink foam left over and strapped it to the deck just forward of the conning tower. It did not raise her. Then I moved to the blue foam and cut a thicker piece. The Gato began to raise. The aft end was above the surface, but the bow hovered below. There were only a few smaller pieces of lead. I tried each one and it would cause the sub to go to negative buoyancy. Then I had a piece of lead that was more of a overflow, scrap, flat piece. Placed it on and at first I thought it was too heavy, but she settled to a very nice level below the surface.


It may be hard to see where she stopped at, so here is an enhanced image.


and full view. The sub is about 4” off the bottom, nice and level.


Emptied the tanks and she sat at the proper waterline. That told me the foam will need to be placed on the underside of the deck, above the waterline.


And here is an enhanced view.


More views.


Not everything is smooth sailing, I noticed I can tip her to starboard side and she will list. Tipping her to the port side would correct herself upright.


I think I now what that is about, in the first round of trimming, the Gato listed to the port. I moved a keel weight to compensate, I will move that back. As I played with buoyancy, I went ahead and added a piece of my pink foam aft of the conning tower where the rubber band is (no picture due to...well...read on). This additional amount raised the sub to about 1/4 of conning tower decks under water. I felt the additional buoyancy was needed.
Since things went relatively smooth, I had to apply the power to the props.... Wow! No really WOW! Tried reverse and still great performance.

Anyway the test in the inflatable pool was FUN. I still had another adjustment to make (add a little more weight), but that SNORT really works great! And in the short distance going forward, I could get her to begin the dive! There are trapped air bubbles, need to see what I can do to fix that - There was some water that entered the battery compartment.

It turned out that the o-ring in the bulkhead between the dry space and the ballast tank was not getting enough squish to seal properly. I ended up removing the bulkhead and wrapping the o-ring channel with a couple of wraps of teflon pipe thread.

This pushed the o-ring a little tighter against the wall. However, if it continues to leak I might put a little silicon against the bulkhead and create a little negative vacuum to suck some into the weak area. Although this seems like a sloppy or lazy way to two it.
*/Digression moment
When I was a kid and installed alarm systems, too many installers were silicon crazy. Instead of taking the time to do it right, they would slop silicon to attach a contact and leave a mess.
End of Digression */
So, I am reluctant to use silicon as my fix, although it may be perfectly O.K. here. I just have to get over myself. LOL

[salmon]

My son wanted to assist in the testing, and I thought sure. He was thrilled to see it sitting in the water so proud. Looked at me and said It floats (like there was any doubt I thought). Time to dive.
As she began to sit low .... there was that list again. Sealing the torque tube did not solve the issue. I also thought that trapped air could cause this and possibly the snort tubes were trapping bubbles. So inspired by David, raised the snort plumbing. This was done prior to this test. So problem not fixed.


There is also the issue with trapped air in the bow and stern, that I have not addressed yet. I could do a Manfred and make the hatches open or raise as the sub submerges, but that would delay the open sea test and I do not want to do that yet. So I will have to ponder more.
I showed Sam the bubbles and he played, err tested, the systems. The emergency ballast did not work, but the releasing of air to dive does, so note, adjustment needed. Snort worked great, but again the Gato would list to one side????? What in the world? The only difference, as far as balance goes, was the filling of the gas saver. We could manually upright her, but each time we surfaced the same thing happened. After a many minutes of testing, time to take the sub out and check things over.

First, the battery area was dry!!!! Huge relief. Conclusion on listing.... I need to add more weight to the keel and re-trim her. The more weight I put in the keel and foam for balance, the less likely or lessen amount the sub will list.

[salmon]

Pool day......
Did a preliminary check.


There was a funny glitch initially, the system would not turn on, after fiddling with it for awhile, it started up......


all systems checked out (or so I thought)
It was time to launch.


She sat in the water with a list again. So I took her for a drive anyways. If I installed hydrofoils, I think I could get her keel off the water. This is fast and the sticks seem a little hot (can be adjusted on the transmitter). A small bump and she wants to RUN! Turn radius is not too bad, but what do I know?
Well let's take her down..........down.........I said take her down.......funny she would not do that. So, time to bring her in.

Yep, that is my emergency crew ready to dive just in case there was a need. (Child labor laws? He was paid according to his experience)
Monday will be the next test.
When I opened up the sub there were a lot of red LEDs. So, I am guessing the sub would not dive because it was receiving a low battery alert. I did find one solder joint loose and re-soldered it, but in my tests my LiPo guard still does not show all cells charged (I have talked to Kevin and I need to take some voltage measurements - have not done that yet). The listing was most likely from the battery being on the WTC port side and not centered.


THE SOLUTION TO MY PROBLEMS (and it does not involve switching hobbies)

I plugged the LiPo that was swollen into the Caswell charger.......it is a dumb charger (no offense intended). When it showed green....Magically the battery was not swollen (what goes on in that fireproof bag?)...I have been charging my batteries on a Sigma II charger (supposedly intelligent). The battery that was charged on the Caswell charger when placed in the sub showed up on my LiPo Guard as a 3S and I took the sub to the inflatable pool to test it out. Ran the sub through the paces and then after a while let the motor run on high. It was over 6 minutes of running and and no problems. So, I must have a setting wrong on my Sigma where it is not charging the LiPo completely. I do not know that I am out of the water, but I see light at the end of the tunnel.As far as it not starting right away, I will go component by component, and meter along the way. The throttle on the transmitter was set back to 50% forward and 80% reverse (I just want a little extra just in case there is an emergency collision about to happen).

Ordered some parts and I am bored. So I thought I would make a detail for the conning tower. The conning tower barrel, not the whole barrel just enough to give the illusion of one being there. Checking out references.

[salmon]

Conning Tower



Cut out a pattern from Garolite (brandname - it is phenolic sheet) or any stiff sheet would work.


shaped some clay using the pattern from above and let it dry.


The last time I vacuum formed was when I was 7. It was a time when toys were good and dangerous. I have not vacuum formed since, so this was a fun first.
I glued a couple of oak scrap blocks together. I took some of that stuff I made my hull bulkheads out of (Garolite) and drilled holes on a grid I drew out. Cut out two different size holes. One for the hose on the bottom and a larger hole for under the plate. Glued that perforated plate to the oak that I drilled out with a hole saw.


Heated the plastic in a make-shift frame. Turned on the vacuum and allowed the suction to bring the plastic around my clay plug. Then used the heat gun to bring in the edges more.



Trimmed out the conning tower proper end piece. It came out nice enough.


It looks good in there.