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OK, here's the start of my first RC sub build thread. This will be a conversion of the Moebius 1:72 Skipjack kit. This is going to be unconventional in that I don't plan on using a water tight cylinder (WTC). The plan is for a free flooding model that will use parts from my warship combat parts bin to fabricate a CO2 ballast system. Electronics, servo's, and everything else will be individually waterproofed. Propulsion will be a 755 brushed motor direct driving the prop. The motor may or may not be waterproofed (haven't decided yet). Lets get started.
Bonding the bottom sections:
It's common knowledge that the hull sections of this kit are anything but round when they come out of the box. I wanted to address this before gluing the two bottom sections together. I temporally hot glued a 124mm diameter half frame into the aft section to get this section into the correct shape. I didn't permanently bond this frame in place because I haven't decided on the final frame design yet.
When I placed the aft section flat on a flat surface, and then placed the front section over it. I figured out that pressing down on the front section draws the piece into shape. To hold it in shape, I hot glued bits of scrap onto the bench. Here we see the bits holding the bow section tight and flat to the bench and giving a nice snug fit to the aft section at the mid point.
The aft section is taped to the bench to hold it in position for the glue-up.
Testor's red is spread on the inside of the joint of the bow piece...
... and then the bow is lowered over the aft piece and snapped into the holding pieces on the bench. A clamp is used to draw the sides in tight and a lead weight to gravity assist the clamping from above. This is left to cure overnight.
The next morning, a single bottom piece. At this point I decided to see how accurate the glue-up was. I strung a line from bow to stern ...
... and found out the mid point is almost 1/8" off center, bummer.
Investigating further, I marked lines on the bench and determined that the stern is almost 1/4" from where it should be. The red lines on this pic are where the hull sits naturally if the lead weight wasn't there.
Checking further, I determined that the aft sections are relatively straight. It's actually the bow section that is skewed to starboard.
I can live with a bit of error in the bow section. The framing system I'm melding into the hull requires straight sections in the aft two thirds of the model. Speaking of framing, since I won't have a WTC to mount the systems to, I need something else instead.
Frame System:
What I came up with is three frames cut on my CNC that precisly mounts a section of aluminum angle into the hull. The systems will be mounted to the angle.
In the warship combat hobby, I originated the use of 24v power systems. Not just 24v though, but 24v from power tool batteries. I power all my surface models with them and I figure I'd give it a go with the sub.
In the center of the hull, will be mounted a 4oz paintball CO2 tank. Attached to the tank is a 145psi pressure regulator and solenoid valve commonly used in warship combat for powering bb cannons. There will be a removable 500ml (or so) ballast tank that will fit over the CO2 tank and valving.
Behind the ballast section will be the drive motor and servo's.
That's it for now...
Bonding the bottom sections:
It's common knowledge that the hull sections of this kit are anything but round when they come out of the box. I wanted to address this before gluing the two bottom sections together. I temporally hot glued a 124mm diameter half frame into the aft section to get this section into the correct shape. I didn't permanently bond this frame in place because I haven't decided on the final frame design yet.
When I placed the aft section flat on a flat surface, and then placed the front section over it. I figured out that pressing down on the front section draws the piece into shape. To hold it in shape, I hot glued bits of scrap onto the bench. Here we see the bits holding the bow section tight and flat to the bench and giving a nice snug fit to the aft section at the mid point.
The aft section is taped to the bench to hold it in position for the glue-up.
Testor's red is spread on the inside of the joint of the bow piece...
... and then the bow is lowered over the aft piece and snapped into the holding pieces on the bench. A clamp is used to draw the sides in tight and a lead weight to gravity assist the clamping from above. This is left to cure overnight.
The next morning, a single bottom piece. At this point I decided to see how accurate the glue-up was. I strung a line from bow to stern ...
... and found out the mid point is almost 1/8" off center, bummer.
Investigating further, I marked lines on the bench and determined that the stern is almost 1/4" from where it should be. The red lines on this pic are where the hull sits naturally if the lead weight wasn't there.
Checking further, I determined that the aft sections are relatively straight. It's actually the bow section that is skewed to starboard.
I can live with a bit of error in the bow section. The framing system I'm melding into the hull requires straight sections in the aft two thirds of the model. Speaking of framing, since I won't have a WTC to mount the systems to, I need something else instead.
Frame System:
What I came up with is three frames cut on my CNC that precisly mounts a section of aluminum angle into the hull. The systems will be mounted to the angle.
In the warship combat hobby, I originated the use of 24v power systems. Not just 24v though, but 24v from power tool batteries. I power all my surface models with them and I figure I'd give it a go with the sub.
In the center of the hull, will be mounted a 4oz paintball CO2 tank. Attached to the tank is a 145psi pressure regulator and solenoid valve commonly used in warship combat for powering bb cannons. There will be a removable 500ml (or so) ballast tank that will fit over the CO2 tank and valving.
Behind the ballast section will be the drive motor and servo's.
That's it for now...
Attached Files
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