Moebius (Revell) Skipjack Build

[trout]

To fix, I am guessing by adjusting the wheel collars inside the ballast tank?

[greenman407]

Thatll do it but also you can adjust the trim on the radio, if there is room.

[trout]

What a dummy I am, that did not even cross my mind......Mark thank you for that suggestion! So obvious. (Hope M does not read this - he will have choice words for me)

[Peter W]

Tom, That is looking really good.

Peter

[trout]

Added a small bracket to catch a disconnected magnet. I will try this because I am out of magnets to replace all of the connectors (and they do not need to be replaced). The one I am most worried about is the rudder, at extreme end of the swing, it will stick every so often. Before this bracket was installed there was zero chance of it reconnecting. Now, hopefully, the magnet connector will fall into the indentation which is close enough that the next time the pieces come close together they might re-engage.

I will run a bead of baking soda and CA to firm up the points that contact the hull.
This is light enough that I do not think it will make a big impact on the trim, so I will pool test and see!

Final checks are being done. I will use silicon on pushrods, o-rings, and motor shaft. Batteries are all charged.
I wonder what grandma is doing right now?

Peter, Thank you! I really appreciate that!

[greenman407]

Lookin Good. Im still working on getting where you are now. It appears that the pushrods, at the klikon, are not in a straight line because the hookups are near the prop centerline. If the droop is not too much you could put a light weight sleeve over the klikons at the connection point, capturing them that way as well. You could also add an additional magnet to both sides and CA them in place.

[trout]

Mark, those are good ideas. A soft silicon tube would work as a sleeve, but I do already have some solid magnets that I could use too. We will see how it goes at the pool. Should be leaving to go there within the hour......I am so excited!

[greenman407]

AS the Klingons would say: "KAHBLAH! (success) Putting your first submarine in the water for the first time is thrilling to say the least! Its a mix of emotions, from sheer Terror to giddy elation. A high that will keep you going. And more than that. If you are in clear water where you can see the sub well as she maneuvers,down 20 or 30 feet, well then you take it to the next level. Its a certain "je na sais qua" if you catch my meaning. I remember well taking my 52" Seaview out with those eight front windows lit up like broadway, to a local pond at 10:00 at night. Now that was a sight to behold. As she came out of the turns heading straight for you with the Headlight beam on her nose showing as well, needless to say I was very pleased!

[trout]

Yes it was stressful, but it was amazing! This sub is fantastic! What a great system David put together! This test was done in a pool (and a recently repaired one - hence the cloudy conditions), more to report later with video.
Right now here are some teaser photos from the video:

[trout]

I will not be able to throw enough adjectives to describe how amazingly fun this sub was to drive.
At the pool I could not get my sail plane to engage. So I thought I would just see what I could do with the sub. I don't need no stink'n sail plane! Using speed and leveler adjustments I had a blast.
So much so that I did not take one picture. The only footage taken was by Sam while swimming in the pool. So pardon the shaky footage, but here you go:

[alad61]

Nice video and manoeuvring Tom. All it needs is a Russian bogie sub in the shadows and some torpedos skimming past for that Hollywood Cold War epic...

Once you get the sail planes working you'll hardly ever need totouch the rear planes.

[trout]

Alec, Sam wants me to get a 1/72 Typhoon (because of Hunt for Red October), so someday that battle might occur. :-)

Post Mission Check
Not everything is perfect with the sub, not horrible either.
The engine room had water in it about a tablespoon. When I took the hull apart there were water droplets over the SAS float valve. I am going to assume it was from some of the snap turns I did as I got used to sailing the sub. On more than one time it banked pretty hard. Those could have jarred the sail's float seal enough to let the water in.
How to prevent it? not sure I can, but I can try to manage the water coming in. Since the SAS draws air from the inside of the sub-driver to expel the water in the ballast tank, I am thinking of using that to purge out some of the excess water. I could take a hose and run that from the nipple on the float tank to the bottom of the wtc to a tank that would collect water that comes in and vacuum water out. I chose to build a tray to hold water.
Here is a crayon drawing to help visualize what I think may work:

As water comes in, it will settled to the bottom of the tray and once the order to blow the tanks is given, the suction will draw the water out of the tray and expel it into the ballast tank.

Here is the tray installed.
Next, I had water in the battery compartment (maybe a teaspoon). It had been dry in my other tests, so something was marginally working, but failed with the additional depth. There are only 3 ways water is getting in. That would be from the o-rings, the switch, or the power conduit going between the bulkheads through the ballast tank.


A visual looking over the end cap, I did not see any clues.


Even the bulkhead conduit looked O.K. On the Gato I sealed the tube with RTV rubber, I may do that here too.

Next I inspected the o-ring seal on the bulkheads and end caps.

You can see in the above photo the area being squished against the polycarbonate tube, it is a dark black line.
Rotating the end cap I found this:

A small piece of o-ring was damaged and a sliver of the rubber is torn. And near it is a gap where no contact is happening between the tube and o-ring. This will need to be replaced even if the leak is not coming in from here. I will run the sub again and see if water is in there again.
The sail plane magnet was tweaked, probably from the pull off the counter top. The aluminum tube in the upper hull was also bent.

I did not get a chance to work on the sail connecting issue.

The last issue I had was the rudder and making a hard port turn. It would get stuck enough that the Klik-on did disengage and did not have enough pull to reengage even with the bracket holding it. At the poolside I wrapped a rubber band between the magnets and that solved the problem temporarily.
Tomorrow Sam is walking with his Scouts in the Veteran's Day parade. If there is time, I will try to get the sub in the water again.

[He Who Shall Not Be Named]

I so appreciate a thorough postmortem followed by a reasoned course of corrective actions presented in a WIP. So many guys just post the pretty pictures with little or no critical comments and fixes. Thank you, Tom, for using the sharp knife. Smiley-faces do me no good; pointed observations followed by informed analysis is what I need!

You deliver!

I like that moisture separator you came up with. A neat idea. But would it not be simpler (as you pointed out as an alternative) to simply run a flexible hose down from the safety float-valve nipple to the bottom of the dry space? That way you not only strip away any water that got past the valve during the next 'blow from depth' evolution, you also scavenge out any water that got into the after dry space from another route.

Early production bulkheads feature an installed plug in the center of the forward ballast bulkhead and forward bulkhead -- these were secured with CA and sometimes leak. Check those as possible routes of water intrusion into your forward space, Tom.

Well done, sir!

M

[He Who Shall Not Be Named]

I so appreciate a thorough postmortem followed by a reasoned course of corrective actions presented in a WIP. So many guys just post the pretty pictures with little or no critical comments and fixes. Thank you, Tom, for using the sharp knife. Smiley-faces do me no good; pointed observations followed by informed analysis is what I need!

You deliver!

I like that moisture separator you came up with. A neat idea. But would it not be simpler (as you pointed out as an alternative) to simply run a flexible hose down from the safety float-valve nipple to the bottom of the dry space? That way you not only strip away any water that got past the valve during the next 'blow from depth' evolution, you also scavenge out any water that got into the after dry space from another route.

Early production bulkheads feature an installed plug in the center of the forward ballast bulkhead and forward bulkhead -- these were secured with CA and sometimes leak. Check those as possible routes of water intrusion into your forward space, Tom.

Well done, sir!

M

[alad61]

Tom I can confir re the quick movements causing the float to shift letting water in the system. The first days sailing at the regatta I recently went to saw the skipjack porpoising and doing very sharp banking turns like a jet fighter. Both of which I handled badly on the tx and I believe these greatly contributed to water in the rear compartment. Once I dialed back the speed as David suggested and feathered my tx commands with better control the water issue was virtually nullified. Yes there will be droplets above the sas internal safety valve which I believe comes from water droplets being drawn in when the boat surfaces and the snorkel float falls away. Every now and then I have the rudder klick-ons disengage which only happens when I do an emergency all back on the throttle. I am seriously contemplating Marks double klick-on system for that. But I also like your glued in guide too. I have been driving my boat for many months and voyages now with great enjoyment but it can be a rocket if the speed is up over the 50 - 55% mark. I know this because even at 80 - 90% on the epa I generally had the throttle stick at ahead two thirds. Also throttle back a bit when turning. It helps eliminate the banking effect. Also whilst turning is when the sail planes show there value at keeping the keel level.

That said I like the flexible tube idea to suck back any water in the rear dry space something I might have a go at that...