Skipjack 1/72

[greenman407]

Thanks Bruce. Yep, I read you there. Already done. Also, the trim is completed.
Next up, I ,as Ive said before, dont care for the way my sail planes are working. Too much delay to control inputs and lack of general control due to flexing of servo pushrod. Solution? Home made bellcrank assm. Already installed and ready for fine tuning tomorrow. Ill get some pictures up tomorrow. Wont be long now. Ill take it out and see if I can sink it....er....sail it.

[HvyCGN9]

G'day Mate,

I was re reading your build and had an idea for your battery moving dramas.....ditch the foam and make up a cradle out of styrene (Plasticard) to hold battery in fixed position, that way you retain the air volume with minimal loss.

Cheers Bruce

[greenman407]

For a week or so Ive been down with the flu. Its amazing how a Virus can change your mindset and the things you like to do. For this whole week, I couldnt have cared less about this submarine. I was miserable............Im not miserable anymore and I seek resolution to this waterline thing. With all this testing and moving foam and weight and re-floating...........Ive come to the conclusion that I was right all along.
You cant change the laws of Physics. You set your Submerged trim First. Once that is good and proper your surfaced trim............. "is what it is". With one notable exception. You can at times insert additional foam above the waterline if you have room for it to delay a slowly sinking stern for instance. Because its high above the waterline, it doesnt change your surface trim.
In this boat Ive already got the above waterline space filled with foam, there isnt room for any more in the stern where the problem exists. It
floats perfect. When you submerge, the stern drops like a brick. The only solution is to install foam to displace the weight of the water thats coming in in the stern. If you could put the foam at the waterline you could help the matter but since the foam at the waterline is already full, you have to put it below that. Which then causes it to sit higher in the water that you want to.
You could try moving the Subdriver but then there a far worse consequences for doing that....a Unstable submarine. So as she stands She sits a little low in the front but goes down flat and even.

[crazygary]

Great build going on here, gentlemen!! Thanks much!

Also, ya gotta have provisions on board!
Never know when ya might get stuck in 10' thick ice at the bottom of the world!!
( A miscue at the hands of Al Gore and global warming?? ) Hah!!

[trout]

I am sorry Mark for not comprehending what you were saying, when you were saying float valve my mind was translating that to the SAS valve on top of the sub. Now that I put two and two together, I get it. The foam in the copper pipe container was stuck in the up position (as if water had flooded it) preventing the air to go through.

[He Who Shall Not Be Named]

It hung-up because of a heavy wad of silicon grease between the nipple and rubber element atop the float -- the gooy stuff stuck the float in the 'flooded' position. You're shot of air shoved the wad out of the way so it would not 'glue' the float in the 'up' position with no water in the unit. All fixi-poo!

Damn, boy ... easy on the snacks, you'll start looking like me soon.

M

[greenman407]

Dave recommended that I use air pressure to blow into the subdriver to free up a sticky float valve. Well, since I lost my job, I no longer had access to air pressure. I then went out and bought a Craftsman 1.5 HP x 20 gal. compressor that was on sale. But then, i didnt have a nozzle. But I bought it because I knew I would eventually need it for other chores. My testing continued and eventually it started working and has been ever since. It just needed to get broke in.

[trout]

So Mark, what was it that made the SAS work? This is excellent news!

[greenman407]

Thanks for that Alec. Now on to the update. In our last episode, as youll recall, we find our bumbling hero struggling with various issues. Well, Im proud to announce(drum roll please) that I just got my first WHOOSH! Yes , the SAS decided to cooperate. I like it a lot. Ive got the radio set up to allow me to turn on the SAS pump at the stroke of a key and it stays on till I turn it off, using the trim lever and the stick in concert. The rest of the sticks throw allows me to engage the gas progressively, all the way up to full emergency blow. I am aware of the drawbacks to this but we will leave it that way for now. Im also happy to announce that we still have no water leakage since the o ring modification, despite much testing. Testing what? Im trying to get the waterline right. The nose sits a little low and the stern sits too high. I have been progressively installing foam above the waterline a third of the way forward at the rear of the Subdriver area. At the same time reducing foam inside the tail cone. Little bit by little bit. In the picture you can see green oxidation on the brass push rods and drive tube. I believe it was caused by the toxic fumes from the curing silicone seal behind the foam. The next time I dunked it, it disappeared. Also, an absolute necessity is plenty of snacking materials on hand. Im out of chocolate, otherwise you would have seen a picture of a Cadbary bar in there.

[alad61]

Great stuff on the emergancy blow system Mark. Re the battery try using Velcro tabs at the end of the battery and the bulkhead. Seems to work for me and I have done some serious hook turns with no noticeable listing from the battery shifting.

[greenman407]

To hold the gas valve in place there are two set screws, one on top and one on the bottom. The bottom one can be accessed via a predrilled hole in the bottom. The top one you have to drill your own hole. This makes sence, since most people are not going to use it. I drilled a 1/8" hole, set the adjustment and then forgot to cover it. If you dont cover it, your air will leak out and your ballast tank wont work. Needless to tell you, I got it into the bathtub to re-trim the sub and I couldnt figure out why it was going straight to Davy Jones Locker. So , I took the top off of the sub and lowered the rest of the sub down into the water and then it became obvious. OOOPPPSSS! Dryed and cleaned off the area around the hole and then covered it with a piece of high quality Electrical Tape. That fixed it. Dont tell anyone.

[greenman407]

Gas valve in place. The function of the gas system is excellent! Also I stopped the waterleaks from the orings using four wraps of 3/32" vinyl trim tape. Watch it. The 3/32" Tape is really a strong 1/16". If I had bought 1/16" trim tape it would have been less in width. The resistance of the oring fit to pushing on of the end cap is now much stiffer. Perfect. In the process of re-trimming. To keep the battery from shifting I put some foam in there to hold it in place. Bad thing about it is that it reduces internal volume of air for the SAS. Ill come up with sumpin else.

[greenman407]

Tom, thanks for the advice. In the picture I dont have the gas valve shown installed yet in its rightful place, in its own cubby hole on the inside face of the ballast tank bulkhead. Today itll be there.

[greenman407]

Since these Gas valves seem to be in short supply I decided to make my own for next time.

[trout]

Mark, if you attached a plate to the end of the pipe the schrader valve could be attached there so it will line up with the vent pushrod. Then set the servo on radio loss to go to say 120% and have that hit the valve.