1/48 3D Printed USS Jimmy Carter

[SubDude]

Careful, Steve. If the coefficients of expansion between your WAA substrates are at any significant variance between themselves and your printed hull, the WAA's will evidence cracking as you quench your noon-day sun heated model into the cool waters of Red Clay Resort.

David

ABS is 40-60% Styrene which helps and I try to keep a very close eye on sun exposure to my boats no matter what material they are printed out of. It's a left over habit that was developed with flying foamy airplanes. I will certainly be watching out for it.

[He Who Shall Not Be Named]

Careful, Steve. If the coefficients of expansion between your WAA substrates are at any significant variance between themselves and your printed hull, the WAA's will evidence cracking as you quench your noon-day sun heated model into the cool waters of Red Clay Resort.

David

[SubDude]

I decided to change the appearance of the WAA's to be closer to scale. The two most aft ones have convex edges as is proper whereas the remaining four have concave edges. A simple reshaping of the edges with a Dremel sanding drum would be in most cases sufficient but the shapes of the WAA's is also off a bit for me. Having the Trumpeter 1/144 model as an example of what they should look like is a big help. After translating some measurements to the scale of my boat I cut some 0.020 thick Styrene sheet to the proper size and shape for the aft Port WAA. Because the aft most arrays have more of a contoured shape I knew they would be more a challenge to adhere the Styrene properly. I cut some blue foam camping mat to the same shape as the Styrene and using a couple small pieces of plywood clamped the foam tight to help shape the Styrene to the intended surface after applying black Starbond CA to glue it down. Worked like a charm. Once set I did a little grinding work around the edge with the Dremel to clean it up. The new array shape was smaller than the old array which left a large area to remove and was just too much to tackle with the Dremel so I got one of those vibrating saws and used it to cut the remaining array loose. Then it was a simple matter of some Rage Evercoat bondo, sanding, Nitro Stan, sanding and now it is proper. After I do the Starboard side the four remaining WAA's will be a snap. There is also some rework I am going to do regarding the torpedo doors that will come later.

The Trumpeter WAA I am trying to achieve.


Before... (Starboard side)


After... (Port side)


Close enough for me.

[He Who Shall Not Be Named]

Well done, Steve!

[SubDude]

Added control horns to the rudders and stern planes. I have a plan for how I am going to set up the linkages. Here is a short video of how the stern planes work.

And some pics of the inside of the tail cone. I haven't added set screws yet to the control horns. So far everything moves freely and the entire tail section can be easily disassembled.

[He Who Shall Not Be Named]

I sense more Tribute is in order at Subfest.

Cold this time... damnit!

[He Who Shall Not Be Named]

I sense more Tribute is in order at Subfest.

To ensure uniform fillet shape around the perimeter of the WAA 'blisters' make and employ a screeding-blade which you'll use to give form to the still wet Bondo. Makes the filleting go much quicker and with better uniformity than if you winged it with spatula and fingers.

[SubDude]

Those six (three on each side) stand-off structures contain arrays of hydrophones that are electronically scanned. They are Wide Aperture Arrays (WAA). Passive sonar that, because of the geometry of their positions on the hull, can derive useful bearing AND range of local noise sources; lets you work up a useful solution without pinging yourself. This is the current offspring of the old PUFFS. Pretty slick. As the exterior structure of all modern American submarines are about 70% pressure hull you can't inlay the WAA hydrophones, that's why the arrays stand proud of the hull. Ugly, but serviceable.

Break out the Bondo and soften the edges between WAA structure and hull. A convex, not concave transition.

https://youtu.be/2O8gTIr4lys

David
Task Master

I sense more Tribute is in order at Subfest.

[SubDude]

Here is the link to the thread on the Thresher PUFFS arrays for reference

https://forum.rc-sub.com/forum/gener...one-end-plates

Yes. Thank you again for the information on the Thresher PUFFS. I could not rember where your thread was but my rendition is based entirely on your find and documentation. I wish there was similar photo evidence for the prop but I know the Navy's stance on that. My gut feel is that it had the 7-blade but I have not been able to determine that for sure.

[He Who Shall Not Be Named]

Here is the link to the thread on the Thresher PUFFS arrays for reference

https://forum.rc-sub.com/forum/gener...one-end-plates

Excellent! Thank you so much for your careful work and sharing it with us. I'll start hacking away at a 1/72 and 1/96 PUFF array masters this morning.

Most appreciated.

David

[jphatton]

Here is the link to the thread on the Thresher PUFFS arrays for reference

https://forum.rc-sub.com/forum/gener...one-end-plates

[jphatton]

David, Steve,

For reference attached are plan and side view projections of the Thresher PUFF's array with dimensions from the Thresher CAD model I made a while back. These were based on photo interpretation / measurement from the Thresher wreck photo's so there is some uncertainty in the actual dimensions, so don't take the 1/4" resolution on the measurements as an indication of accuracy... I need to check my notes again to see if I made some better refinement of the measurements - also I made a post on the forum a few months back with some more details and assessment, I just need to find it again for cross reference (Steve, if I recall correctly this is what you used as reference for your model?).

The Thresher wreck photo's show that the PUFF's arrays were installed on Thresher at the time of her loss. Also there is a drydock photo of USS Barb showing the PUFF's installed, but no other photographic evidence they were installed on other boats of the class.

[He Who Shall Not Be Named]

One more top section came off the printer. Just three more to go and the hull parts will be done. Lots of sanding, fitting, filling and sanding to do.



What are the raised areas on the lower hull? As modeled they have very rounded corners. What images I can find they appear to be less rounded.

Those six (three on each side) stand-off structures contain arrays of hydrophones that are electronically scanned. They are Wide Aperture Arrays (WAA). Passive sonar that, because of the geometry of their positions on the hull, can derive useful bearing AND range of local noise sources; lets you work up a useful solution without pinging yourself. This is the current offspring of the old PUFFS. Pretty slick. As the exterior structure of all modern American submarines are about 70% pressure hull you can't inlay the WAA hydrophones, that's why the arrays stand proud of the hull. Ugly, but serviceable.

Break out the Bondo and soften the edges between WAA structure and hull. A convex, not concave transition.

https://youtu.be/2O8gTIr4lys

David
Task Master

[SubDude]

One more top section came off the printer. Just three more to go and the hull parts will be done. Lots of sanding, fitting, filling and sanding to do.



What are the raised areas on the lower hull? As modeled they have very rounded corners. What images I can find they appear to be less rounded.

[He Who Shall Not Be Named]

You are a frig'n Machine!