A Skipjack in Ireland

[The Boattrainman]

Nice video, going to be a while before I get to that stage, but very encourging to press on with the work.

The method in my madness is to solve all the engineering challenges one by one, and move on only when that piece of the puzzle is solved. It's a boring method but it ensures you don't get swamped with problems and the 'fun' of the build becomes work.

I've made a point of not ordering the Subdriver until the Revell kit and Caswell fittings are fully sorted, if I had the SD I'd be too excited to work on it and then maybe miss something at this stage of the build. The model world is full of failed projects because the maker got carried away (as per David's previous post), I'm as impatient as the next guy (and usually make errors when rushed), so steady as she goes.............one step at a time.............onwards.....................zzzzZ ZZZZZZ (sorry fell asleep there!).

Rob

[He Who Shall Not Be Named]

https://youtu.be/7aaAVtlnbVM

[trout]

Ahhh, a method to your madness! Excellent, I will sit in my corner and watch :-)

[The Boattrainman]

Whn I have the snorkel and induction fitting, I'll be making that section look like Swiss cheese!

[trout]

Open up the openings to the sail, let that air out!

[The Boattrainman]

I've decided the 'break' point for the linkage to the sail plane mechanism will be at the rear of the sub, where the screw holding both halves together is located. I'm going to fabricate a mechanical linkage here and I'll use the KlikOn at this location.

So I've made a 'throw' extender for the sail plane yoke as I won't e using the KikOn here, instead a clevis will suffice, plus given there is a bit of room (see above), there's now no need for the long cut in the upper hull to take the plastic magnet holder.



The shape of the yoke was transferred to a piece of 2mm Plasticard and then a projection drawn, and when cut out and sanded gives this shape.




The extender is drilled for the existing pivot hole in the yoke to take the brass pivot bar ,plus two bolt holes, and then three clevis point attachment holes. Note, the threads for the bolts are in the extender NOT the yoke, the resin is strong but the Plasticard stronger, the brass bolts go through the yoke and screw to the extender.




This is the extender coming out of the sail into the hull, it's 3/4 of inch into the hull but too long and will need to be cut back to fit, but I've include the extra length so I can experiment with the next phase which will be the linkage to the rear of the sub.

The Boattrainman

[The Boattrainman]

Just a quick question.

What is the headroom between the top of the Subdriver and the subs hull at the point where the sail plane yoke mechanism comes through the hull?



I made a mock up, and I'm getting approx 3/4 of an inch, I know the headroom decreases as you move aft, till it's quite tight at the end of the Subdriver.

Rob

[He Who Shall Not Be Named]

[QUOTE=The Boattrainman;n113745]I'm only going to use one KlikOn magnet, it will be on the linkage to the sail planes, not sure which end of the linkage yet, but I want a quick break as the clevis linkages are hard to open.

[ATTACH=CONFIG]n113746[/ATTACH] [ATTACH=CONFIG]n113747[/ATTACH]


However, I want security, so this has been achieved with a small washer, soldered to a short brass wire, plus two very small split pins which have been pushed through holes in the plastic housing and glued in place and the ends opened and spread around the housing. The brass wire is pushed through the two holes in the split pins and soldered, all brass parts that won't rot in water and very strong, but will pull off.[/QUOTE

[The Boattrainman]

Here is a partial solution.

The two holes are 2.5mm wide, and under the upper rudder, when heeled over to 40 degrees they are still hidden, at least some air will escape at these holes as the rudder is held off the hull by 0.3mm and I have sanded a concave shape in the rudder base at the hole points to give more room. Other than a great big un-prototypical hole in the upper hull, that's the best I can come up with.




Ok, so I cheated a bit with the deck mounted PE parts (ballast vents etc.), I sanded the mounting points down a bit and then hard sanded the metal parts when glued on to get them (almost) flush. I can't use that dodge on the sail PE parts.




Instead, the locations are completely drilled out, and a backing of 0.5mm Plasticard is stuck inside the hull, and disc of 1mm card drop into the hole, which brings the depth back to just under the lip, with the PE part pushed into the shallow hole.




The two vents on either side of the sail get the same treatment, they will have their edges filled with putty and sanded into the hull.

The Boattrainman

[trout]

Being hidden means being restricted. You may want to reconsider that. If it is under your rudder, is it getting the 3mm space to allow the air out or water in?

[The Boattrainman]

I've been scratching my head about the rear section.

For a full 12 inches to the prop, there is no flood/drain/air route out of the top of the hull, and given it's going to pitch forward I can see what you have explained happening.

I've holes in the rear dive plane supports, but I was considering a 2/3mm hole very tight to the pivot point under the top rudder, between the the rudder and the prop, it will be hidden as long as the rudder doesn't swing more than around 35/40 degrees each side.

Rob

[trout]

You will not need to in the exhaust with a good path for air to escape, the only place you may need to is at the aft end of the sub. As the Skipjack initially dives the air gets pushed to the rear. Once under, the leveler allows air to once again travel out the sail. I am really excited for you, it is a fun sub to run!

[The Boattrainman]

Roger that.

I've ground out a path in the ribbing under the exhaust as per other threads, plus I've not used the rear resin screw holder in the sail, as the top has to be ground out anyway as an air path.

Would really prefer to not have to put a 3mm hole (scale 21cm/9 inch) in here, would look bad, so hopefully the air path will work.

Rob

[trout]

In our mind, it would make sense those tiny holes would let air out, but they won't work much on the first time diving. Once water gets to them, the surface tension of water is too great. The effective hole needs to be 3-4mm (1/8 inch) or larger. The best thing you can do is grind out a path on the underside of the exhaust so the air will travel to the sail.
Your whole sub will need to be inspected to see if there are areas that will prevent air from leaving. Those pockets of air will make it very difficult to trim or if trimmed with the air pockets, in the wild can cause your boat to run incorrectly. So removing mold marks, ribs, and other obstacles is important. You may know and have done this, if so I apologize for being redundant.

[The Boattrainman]

Some of the Photo-etched (PE) parts are now attached, the ballast tank surrounds are slid down a cocktail stick jammed in the hole so that they centre correctly.




The two deck hatches have their indents accentuated by using a small drill bit in a pin vice.




I'm not going to use all the PE parts, just where I think they make a visible improvement, the quality of the Revell kit is good enough for some hatches etc.

There is a series of indents along the spine of the exhaust aft of the sail, these are drilled all the way through (72 thou bit), to accentuate the feature and more importantly to let the air out when filling with water when submerging. That seam will eventually be filled and sanded which will fill some of those holes, they will be re-drilled from the inside, their position is set by drilling through now.



The Boattrainman