1/48 scale Type VIIC U-201 build

[Monahan Steam Models]

Nick,
would offsetting the shaft of the magnetic coupler to one side work, something like on a countergear? M is the motor P is the propeller, instead of intermeshing teeth you use magnets.
.

Yes that would work. The motion at slow speed would experience a bit of cogging motion. Not sure off the top of my head what the work transfer efficiency would be between the two parts

[redboat219]

https://vbn.aau.dk/en/publications/design-and-construction-of-permanent-magnetic-gears

[Monahan Steam Models]

Thanks for sharing this Romel. I may explore something like that just to see first hand how well it works.

For now I was able to test the magnetic coupler this morning. It works really well. With the motor at almost full throttle and grabbing the coupler with my hand to stop it, the motor kept spinning while the coupler remained stopped. Amperage draw from the motor only climbed about 1 to 1.5 amps while the coupler was stalled. That was using all four magnets in each part, so eight total. The number of magnets could probably be reduced by half. I did a live demonstration of the magnetic coupler during today’s Dive-Tribe video meeting.

A problem that I discovered this morning is the outrunner brushless motor casing (the part that spins) was not running true to the axle centerline. They wobble fairly bad. I’m guessing the center shafts are bent. Bummer because I really liked how well the 350kv motors performed. The wobble was more noticeable once the longer magnetic shaft coupler assembly was bolted up to the motors. I know the mag shaft coupler runs true because I tested in the lathe.

I’ve since swapped out the 350kv outrunners for the 500kv motors I had on hand and the wobble problem was solved. The initial tests for the mag coupler has gone well so I’ve revised the design so that the overall length was about 3/8” shorter. Doesn’t sound like much but this will allow me to gain a better angle with the double universal joints which will further improve the shaft connection smoothness. I like quite and smooth running gear.

[neitosub]

Glad the wobble problem got solved! Was really surprised at how smooth those brushless motors ran when you showed them at the Dive Tribe meeting yesterday. Might go with a brushless setup myself in a future build.

Nate

[Sam Victory]

Very good idea to avoid overloading the motor. The magnets can also be replaced in time if they fail magnetically. I have had this idea before, using magnetic coupling to complete the connection between the motor and the propeller, and the number of magnets at each end of the connector to achieve the right reduction ratio. I also designed a radar rotation device for the I-400 submarine (for dry hull submarines), also using magnetic coupling, which is easy to disassemble.

[Monahan Steam Models]

After a number of successful tests with the first design of the magnetic coupler, I redesigned it to be 3/8” shorter in length. This helped reduce the offset angle of the double universal joints from 30 degrees to 18 degrees.



Here is the little brother version next to the original. It can still hold 4 magnets per half, so eight total but I find four total to be a good starting point. The connection is strong enough not to slip under full power with some drag applied to the shafts but still able to slip easy enough if the shaft is stopped by lightly pinching the spinning shaft. With the current magnet set up, the amps only jump .200 when the shaft is stalled. Work great at low rpm as well.




The double universal joints have a much friendlier angle now.



Space is starting to fill up in the aft section but it is easier to see how everything fits together and has it’s own space. The aft trim tank extends over and above the servo/motor module.



Another view of the same.


It looks s getting there. Still lots more to do still. At this point the port and starboard lower stern hull halves can be permanently bonded together. I will probably do that very soon.

Nick

[Monahan Steam Models]

Not a lot to report today. Spent most of the day doing one last final leaf and pine needles clean up on the property before the big snow storm begins tonight through next week. Stacked another half cord of hard wood on the back porch so we can stay toasty.

Still managed to get a couple small mechanical tasks done on the build today. Also thanks to the trouble shooting help of David and Ken, I was able to finally solve the servo travel issue for the forward planes using the Depth Cruiser module.



After figuring out where I went wrong with the DC module set up, I decided to design and build a set of telescoping double universal joints similar to the solid versions that I made the other day. Simple, quick and dirty.



Nothing fancy.



Set made and finished. Time to install.



Fit just like the solid non telescoping versions did. These were probably not necessary but it gives some freedom of play in the driveline.

Here’s a link to a short video of the motors running with the new universals.

https://youtu.be/v2oeXsjbrhQ

Nick

[rwtdiver]

Nick,

I have a question about the Arkmodel Vll C that you are building? I am thinking about building this boat, and I am wondering about the WTC system that can be purchased with this kit! Can you give me any input on this system? Also, how come you decided to split the hull rather than build it as per it's original design?

After seeing Das Boot three times (great movie) I am hooked on that submarine. I do not have any working models of any U-boats. I did look at the 3D STL files that Nautilus Drydocks has, and they looked a little rough to me, or I may have tried to build a U-boat with those files, plus the fact it is not the Type Vll C.

Any advice would be appreciated. Thank you! (By-the-way, your build is looking great!!)

Rob
"Firemen can stand the heat"

[Monahan Steam Models]

Nick,

I have a question about the Arkmodel Vll C that you are building? I am thinking about building this boat, and I am wondering about the WTC system that can be purchased with this kit! Can you give me any input on this system? Also, how come you decided to split the hull rather than build it as per it's original design?

After seeing Das Boot three times (great movie) I am hooked on that submarine. I do not have any working models of any U-boats. I did look at the 3D STL files that Nautilus Drydocks has, and they looked a little rough to me, or I may have tried to build a U-boat with those files, plus the fact it is not the Type Vll C.

Any advice would be appreciated. Thank you! (By-the-way, your build is looking great!!)

Rob
"Firemen can stand the heat"

Rob, good morning and Merry Christmas!

The Arkmodel type VIIC is a great kit by itself. Especially for the price it is available for. The instructions aren’t great but not terrible either. I haven’t had any real difficulties assembling the model as it was designed.

As far as the WTC that is available for this kit from Arkmodels goes, I have it and the design and quality of it suffers from multiple issues that are not easily resolved. On top of that the piston tank volume seems to be under sized by about 200ml or more if I recall correctly (it has been awhile since I attempted to work with it before ultimately abandoning it).

Bob’s new 3” WTC would be absolutely perfect for this boat if you plan on building it in the future.

The reason I split the hull the way I have is personal preference. Using the kit’s original split sections, is perfectly fine. The choices that I have made on how I’m going about building this boat have added a lot of complexity and having the hull split the way that I have helps gain additional and much quicker access to the complete hull. There was other factors in choosing to split the hull this way. Such as being able to reduce the final number of parting line seems visible once the build is completed. Also with all the small parts that can easily be broken off a WW2 boat such as this one, I felt making the hull sections separate the way that I have would help reduce the inevitable chances of parts being knocked loose during routine access to inside of the hull.

In my pre and early teen years growing up, I spent a lot of my time watching WW2 movies. I’d almost always have one playing in the background will I was assembling plastic ship or submarine models from that background or while I was building RC boats also from that era. After many unsuccessful attempts in the early nineties, my first successful submarine build was a dry hull dynamic diving 1/125 scale Revel type VII. Around the same time of that build Das Boot had become one of my all time favorite movies along with a handful of others.

Fast forward to present day, building this type VII for me is somewhat of a nostalgic throwback to the much smaller one I built all those years ago. The big difference is, in the years since, I’ve continued to learn and refine my skill sets and now get to apply a lot of that to this build.

Nick

[redboat219]

Nick,
Do you still have that 1/125 dynamic diving Type VII U-boat? If not, can you describe how you made it. Was it RC?

Romel

[Monahan Steam Models]

Nick,
Do you still have that 1/125 dynamic diving Type VII U-boat? If not, can you describe how you made it. Was it RC?

Romel

Romel, good morning and Merry Christmas!

I still have the RC 1/125 dynamic diving Type VII U-boat. It is in a box, stored in my shop currently and was taken apart many years ago to repair it. My build of it was inspired by and was a direct copy of how a gentleman built his 1/125 revel type VII U-boat and his build was featured in a RC model boat magazine back in 1989 or so.

At the time these sort of miniature builds was pushing the limits of the available RC gear of the time. I’ll try my best to explain how it was built. The twin prop shafts were driven by the single motor and guts of a modified standard servo. Old servo gears were used to drive the counter rotating props. Two micro servos placed inline in the hull under the conning tower. One controlled the rudders. The other controlled the forward and aft dive planes. NiCad C-cell batteries were placed ahead and behind the micro servos. A on/off switch was glued under the conning tower hatch. Two 1/8” brass charging pins protruded out of the bottom of the keel. A three channel AM receiver taken out of its plastic case was also stuffed into the hull. The very forward and aft ends of the boat had styrene bulkheads and were filled with petroleum jelly to try to keep water out. The antenna from the receiver was used as the cable running from the bow to the stern. The whole hull was permanently glued and sealed up creating the dry hull. The boat would sit in the water with the decks almost awash. It took 5 attempts with 5 model kits before I finally had a successful working build. The model lasted for a few years of a couple dozen runs before corrosion from water ingress finally took its toll and the deck was cut back open and the guts of the sub were removed. Lost interest in repairing it and it now sits in a box along with the other 4 previous build attempts as well as 3 fresh kits that were for future builds. Maybe some day I will build another but use the experience that I’ve gained since.

Nick

[rwtdiver]

Rob, good morning and Merry Christmas!

The Arkmodel type VIIC is a great kit by itself. Especially for the price it is available for. The instructions aren’t great but not terrible either. I haven’t had any real difficulties assembling the model as it was designed.

As far as the WTC that is available for this kit from Arkmodels goes, I have it and the design and quality of it suffers from multiple issues that are not easily resolved. On top of that the piston tank volume seems to be under sized by about 200ml or more if I recall correctly (it has been awhile since I attempted to work with it before ultimately abandoning it).

Bob’s new 3” WTC would be absolutely perfect for this boat if you plan on building it in the future.

The reason I split the hull the way I have is personal preference. Using the kit’s original split sections, is perfectly fine. The choices that I have made on how I’m going about building this boat have added a lot of complexity and having the hull split the way that I have helps gain additional and much quicker access to the complete hull. There was other factors in choosing to split the hull this way. Such as being able to reduce the final number of parting line seems visible once the build is completed. Also with all the small parts that can easily be broken off a WW2 boat such as this one, I felt making the hull sections separate the way that I have would help reduce the inevitable chances of parts being knocked loose during routine access to inside of the hull.

In my pre and early teen years growing up, I spent a lot of my time watching WW2 movies. I’d almost always have one playing in the background will I was assembling plastic ship or submarine models from that background or while I was building RC boats also from that era. After many unsuccessful attempts in the early nineties, my first successful submarine build was a dry hull dynamic diving 1/125 scale Revel type VII. Around the same time of that build Das Boot had become one of my all time favorite movies along with a handful of others.

Fast forward to present day, building this type VII for me is somewhat of a nostalgic throwback to the much smaller one I built all those years ago. The big difference is, in the years since, I’ve continued to learn and refine my skill sets and now get to apply a lot of that to this build.

Nick

Good morning Nick, Thank you, and a very "Merry Christmas" to you and your family.

Thank you for the input on the Arkmodel Vll. It is appreciated and very helpful in my possible jumping into a German type submarine build. Speaking of Das Boot, my wife down loaded the film last night and we watched it. Needless to say, it certainly opened her eyes!

I think the history behind a lot of our submarine building is the history itself that makes it such a great hobby!

Thank you again Nick, for taking the time to answer my questions!

Rob
"Firemen can stand the heat"

[Monahan Steam Models]

It’s 32 degrees out and dumping snow. Thankfully the Irish whiskey keeps me warm and salty during these times. I haven’t been sitting on my hand since the last post.

With the aft assembly almost there, I needed to focus on the forward section again with all its junk crammed up there.

Since we’re going one piece hull with the cut at waterline, all the work I did last year needed to be redone.



This is what I came up with for the forward planes using the original model part lines



The torpedo launchers were made to drop right in to the original cast abs molds.



A sneak preview of the new junk that will fill that area.



More to come

[rwtdiver]

Rob, good morning and Merry Christmas!

The Arkmodel type VIIC is a great kit by itself. Especially for the price it is available for. The instructions aren’t great but not terrible either. I haven’t had any real difficulties assembling the model as it was designed.

As far as the WTC that is available for this kit from Arkmodels goes, I have it and the design and quality of it suffers from multiple issues that are not easily resolved. On top of that the piston tank volume seems to be under sized by about 200ml or more if I recall correctly (it has been awhile since I attempted to work with it before ultimately abandoning it).

Bob’s new 3” WTC would be absolutely perfect for this boat if you plan on building it in the future.

The reason I split the hull the way I have is personal preference. Using the kit’s original split sections, is perfectly fine. The choices that I have made on how I’m going about building this boat have added a lot of complexity and having the hull split the way that I have helps gain additional and much quicker access to the complete hull. There was other factors in choosing to split the hull this way. Such as being able to reduce the final number of parting line seems visible once the build is completed. Also with all the small parts that can easily be broken off a WW2 boat such as this one, I felt making the hull sections separate the way that I have would help reduce the inevitable chances of parts being knocked loose during routine access to inside of the hull.

In my pre and early teen years growing up, I spent a lot of my time watching WW2 movies. I’d almost always have one playing in the background will I was assembling plastic ship or submarine models from that background or while I was building RC boats also from that era. After many unsuccessful attempts in the early nineties, my first successful submarine build was a dry hull dynamic diving 1/125 scale Revel type VII. Around the same time of that build Das Boot had become one of my all time favorite movies along with a handful of others.

Fast forward to present day, building this type VII for me is somewhat of a nostalgic throwback to the much smaller one I built all those years ago. The big difference is, in the years since, I’ve continued to learn and refine my skill sets and now get to apply a lot of that to this build.

Nick

Hi Nick,

Can I pester you again?



I took a screen shot of Bobs (Nautilus Drydocks) new line of WTC. (I do hope Bob will not be angry with me for taking the screen shot) But buy chance is this the WTC you are suggesting would be a good set up for my Arkmodel Vll?

I really appreciate all the help and great information you give me!

Rob
"Firemen can stand the heat"

SPECIAL NOTE 12/27/2021: I sent Bob an email asking the same question, and he verified what you said. His new 80mm double shaft WTC would be perfect for the Arkmaodel Vll Boat!

Thanks again for all your great advice Nick!

Rob

[Monahan Steam Models]

Rob,

Not that one. That’s the R&R WTC that Bob also stocks. The one I am referring to is his new 3” sub driver. The 80mm one. It’s available as a early release to dive tribe members.

We got walloped last night by a heavy snow storm. Trees and power lines down every where. Snowed in for the next few days at least. Can’t use the 10’s of thousands of dollars in back up power gear we just installed because the county hasn’t done their final inspection on it yet. Was scheduled for this coming Friday but that ain’t gonna happen now. A number of the local neighbors and I spend all day with chainsaws and 4 wheelers and winches trying to cut access and re open up the roads for repair crews and emergency vehicles to get through.

Had to break out the smaller back up generators for the time being and of course they didn’t want to behave. Spent hours troubleshooting and rebuilding the main one. Got it running just in time as the sun set. More storms inbound. Oh the joys of living in the mountains.

Nick