Super. Around 1400, then. Will call when I'm on my way
1/72 688 class
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Some small progress this morning between other tasks.. yes, it's a MSD, but the sharp eyed among you may note that the ballast tank is wet. On the inside.. yes, it's officially a submarine. No observed leaks while I pressurized and moved servos/motor, and the flood/blow worked like a champ. The foward dry space (let's call it the battery compartment) held way to much buoyance to sink, so it really didn't exactaly submerge all the way, but that's not surprising, given how light Lipo batteries are. Will have to take that into account when I ballast the boat.
Met with David yesterday, and the hull got an ass-lift. Well, more of an ass-sculpt. The prop hub didn't match the hull, so with a few deft applications of the screeding tool and bondo, we wind up with an exact match.. and some filling/sanding to do. Hopefully get on that today while the weather is nice before it gets hot later on. Starting to look like something now...
Nothing else takes me back to high school like the smell of bondo. Ah, the magical things it can do...
"It does not take so many words to speak the truth" Chief JosephComment
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So. Before I go out and wrestle with a non-conformist finish mower, let's do some work on the boat. I've groused and groused and whined and complained, time to pick up the saw and get to work. Let's cut a chunk out of the hull to get better access to the linkages. I took a few minutes and miked a couple of different cutting tools. Turns out my Zona saw and X-acto fine blades produce the narrowest cut.. so they are the tools of choice. First step is to mark off cut lines and ensure that they look straight:
I realize it's really dark.. that's a tough exposure, even for a good camera. It took a few lifts and replacments until the lines looked straight.. yeah, I eyeballed it. The join line is going to be below the waterline anyway, so once it's in the water nobody will notice. So it's time.....
I had to do some acrobatics while cutting, and I finished the cuts with the exacto saw mounted in my handle. When all was said and done:
Lots of room now... Yeah, I know, 1/72, plenty of room to start with. Good thing I have a big van. Next step is to join the two cut pieces together. I thought on this for a while, as the hatch has guide pieces that would keep it from sitting flat on the table. My first thought was to do it on the boat with the pieces taped to the hull. That seemed to work fine, until I picked it up... didn't wait quite long enough for the thick CA to cure. Well hell. Let's try it again. This time, more powder and some accelerator. Success!
Fairly tight joint, ran another bead of thick along it. Then.. a piece of glass over the top just to be sure, as it's going to need some serious filling.
Of course I didn't take a picture of teh glass. Well, we've all seen glass work before... nothing special necessary. I ran a piece around the inside, and then ran 2 pieces fwd and aft along the edges, just for some extra reinforcement.
Since I have so much room now, let's fit the WTC. I measured to find the geometric center of the hull (fwd and aft) and placed the WTC so the ballast chamber was directly over it. The support directly forward of the ballast chamber is going to be the thrust support, so it will be tight up on the bulkhead. The other 3 supports are, well, just supports. Actually, I'm being overly cautions here, all thrust from the prop is going to be taken by the stern tube and oillite bearings, not like we're gonna be pushing any barges here.
So question time. When I tested the WTC in the tub, it would not submerge completly on its own. The battery compartment held enough buoyancy to hold the front of the cylinder out of the water. No real surprise there. Is this going to create a real issue when it comes to trimming? Obviously I'm going to need to hold the front of the cylinder down in the boat, but I think a velcro strap will take care of that, or perhaps I can do it with flotation foam if necessary.
WRT the location of the cylinder in the boat. I'm about dead center in the hull. is there an advantage to having the WTC located lower or higher? I believe the instructions state to place the cylinder as low as possible in the hull, but having it centered simplifies design of the supports, as well as providing ample room for fixed ballast, and centers the prop shaft."It does not take so many words to speak the truth" Chief JosephComment
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The buoyancy of the MSD itself does not make a tinkers damn to anything. It's when it's integrated with the boat that buoyancy is an issue. You trim the MSD as an element of the submarine. You don't trim the MSD itself.
YOU PEOPLE!!!
And there are no filleted unions on an LA between stabilizers and hull. File that Bondo induced radius to a near right angle.
I buy you books, I send you to school, and what do you do???... you eat the ****ing teacher!
David
Who is John Galt?Comment
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We had that conversation.. I don't think the fillets are bondo, I think they may be molded into the hull. Haven't gotten down there with a file yet to check. I base that on the fact that when the fin broke off the hull, it left a raised boss behind that wasn't resin. Either way, I'll do something with it, at some point.
I guess my boat can't be the USS Norfolk... no VLS tubes."It does not take so many words to speak the truth" Chief JosephComment
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We had that conversation.. I don't think the fillets are bondo, I think they may be molded into the hull. Haven't gotten down there with a file yet to check. I base that on the fact that when the fin broke off the hull, it left a raised boss behind that wasn't resin. Either way, I'll do something with it, at some point.
I guess my boat can't be the USS Norfolk... no VLS tubes.
It's a Flight-1, start with that. Hell, make it the LOS ANGELES itself! (post towed array upgrade).
DavidWho is John Galt?Comment
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Bondo and filler time! The mower was less of an ordeal than I thought. Amazing how much easier old fasteners come off with air tools. Anyhoo... after some bondo, and some glazing putty, and finally some primer...
Not a terrible cut line, or awful kerf. Will address that down the road. I thought there was a thread here on filling the kerf, but cant' find it, and the link clicked on took me to the home page. I guess I'm ready to install planes and make linkages... then it's into the tub (if it fits!) and start with the trimming."It does not take so many words to speak the truth" Chief JosephComment
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Let's get some surfaces connected. Due to a lack of foresight, I attached one of my magnet halves to the pushrod coming out of the cylinder. Not a terrible gaffe, or so I thought, but it does create a few issues. So, some linkage to the fairwater planes:
Allowing for some minor adjustability.... and then installed.
No lack of room in that hull huh. Looks like a decent straight setup, dosen't it? Well... disconnecting the magnetic coupler is a pita. No idea if I'm going to have to put some floatation foam in there... if so, then there's gonna be no room. Also, a small issue with the servo horn.. it cracked at the outer hole. I put a little too much force on it pulling the magnets apart. Luckily, I have a large assortment of servo horns, and I'll source something similar and make a more solid horn. Minor inconveniences.
On the success front, made a locater pin and block.... ez peezey japaneesey.... sorry that's non politically correct. But it was in a movie...
"It does not take so many words to speak the truth" Chief JosephComment
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Now, we need some connections to the back end. I'm wondering if the 1/8" rods are sufficiently stiff for the length... I did add a section of larger tubing in for adjustment, if necessary... the horns are very close in the tail, had to set the rudder yoke low in the hull to clear. Full range of motion on both wiht no interference issues, other than at the ends of travel as expected.
"It does not take so many words to speak the truth" Chief JosephComment
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Not much time these last couple days.. but I did come up with a solution to a problem that bothered me. The sail.. it wasn't quite rock solid when screwed down, didn't help that there was no real base for it. So, I drew up some internal supports and printed them... nice and solid now. Not that I'm really worried about hydrodynamic forces, etc etc.. I'm more concerned about hangar rash. I also got the rudders connected to the cylinder.. not much throw there! This beast is not gonna be quick turning... hopefully it backs quickly. Anyhoo. pictures...
"It does not take so many words to speak the truth" Chief JosephComment
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I love the creativity on making a stable sail, well done. I would make some modification to it., mainly air passage. You made a dam for air travel as your boat is diving. The air will collect and sit there with nowhere to go. Either have an escape out the top of the hull or into the sail (it might be there already and I just missed it) Or make some passage through your stabilizer. Anyways my < $.02 suggestion.
Looking over your build, looks like there is escape routes for air. Excellent solution sir!Last edited by trout; 05-27-2020, 09:19 AM.If you can cut, drill, saw, hit things and swear a lot, you're well on the way to building a working model sub.Comment
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