1/48 G7 Torpedos

[Bob Gato]

Hey Nick, things are looking very promising over there in torpedo land! Pardon my ignorance, You state that the motor shuts down as a result of current draw protection? are you using an auto reset fuse(current limiter) or are you talking about a lipo low voltage cutoff of some sort? within the runtime module?-BG

[Monahan Steam Models]

Latest design revision for the G7E torpedoes.

The torpedoes are running very straight now. Will start to increase the run time soon. The new scale propellers worked great. The internal chassis was reduced and redesigned to accommodate slight changes to the counter rotating transmission that reduced the last of the rotating friction. Weight needed to be reduced in the chassis to correct the ballast to make up for switching back to the more powerful 6mm X 15mm coreless motor and original sized LiPo. The next tests will be using the same sized LiPo but stepping up to a new 90mAh from the current 60mAh battery. The runtime module is set for 5 seconds but of all the tests done on each version so far running in the pond, the battery’s current draw protection shuts down before the timer. Hopefully the new battery pack will solve that. If it does the revisions following will be to make further improvements on the final design.

[Monahan Steam Models]

Okay, here is a prime example of the struggle to perfect the perfect 1/48 scale G7E torpedo. After hours of careful design work and machining the last of the parasitic drag in the counter rotating transmission has been removed. The main torpedo chassis design has been carefully worked out to mount each component in the lowest location while keeping the mid ships neutral Buoyancy point slightly aft.



The main parts being tested here is the new motor, the scale props and the new smaller battery. Normally each change would be isolated and tested individually.

The reworked counter rotating transmission an tail cone assembly rotate butter smooth now. The measured amp draw on the smaller motor is much less now compared to earlier tests. Overall weight of the torp is ideal. The torp runs great in mid air. As soon as the props are submerged the LiPo battery over current shut off kicks in.

And there you have it. Back to the drawing board to rob weight from here to make up for it there because everything has to change again



The size change in the battery size. Might add a small super capacitor to even out the amp draw if the weight allows

Nick

[Monahan Steam Models]

First off, what a wonderful little mechanism you've come up with. When you start using collets, you're deep into watchmaking stuff!

I first write the text, then use the 'Upload Attachments' button (below the text block here) to bring up the desired photos from your hard-drive, then plug them into the text as desired. You start with the text, then you plug in the photos -- that way you keep the text AND photos in your post.

David

Awesome, thank you David. That is most helpful and I will use that method going forward.

Having owned and used some large very precision commercial manual and multi axis cnc machine equipment in the past, I’m still amazed at the precision I get using that little jewelers lathe.

Nick

[Monahan Steam Models]

Very nice, any trials yet?

Not yet with the current design. There has been a half a dozen or more slight design revisions since the last sea trials. Each revision has required making many new parts. If the design didn’t pass the bench test goal then it has been onto the next revision from what was learned without doing any sea trials. Overall the torpedos have worked every time, but the quest has been mostly to perfect the running behaviors, weight, trim and production methods. The earlier designs used longer bodied more powerful motors. As the design has evolved, the length of the 6mm coreless motors has been reduced to save weight and improve running characteristics by not being so overpowered. However these shorter length motors are less forgiving of any resistance in the rotating assembly. Not a problem for the earlier simpler single propeller designs but a significant problem for the later counter rotating propeller designs.

The last video links I posted of the counter rotating torpedo sea trials went really well but that torpedo was using a slightly longer bodied more powerful motor that didn’t blink an eye at the very minimal resistance that was in that transmission. Also that torpedo’s speed through the water was way over scale. It worked out to be around 90 knots.

Most of the latest revisions have been focused on improving the precision of the transmission and torpedo tail housing assembly. Normally when I am trying to achieve absolute assembly precision, I would machine every part but I am trying to leverage using a mix of 3D printed parts and machined parts to cut down the labor required to make each torpedo. The problem has been that the 3D printed parts are close but not nearly precise enough to be used without needing additional work done to them.

[He Who Shall Not Be Named]

Quick update

Edit: I added a description to each photo but when viewing on a mobile device the full description is not visible. What is the best method for uploading photos to this forum? I’ve run out of curse words trying to sort it out myself

First off, what a wonderful little mechanism you've come up with. When you start using collets, you're deep into watchmaking stuff!

I first write the text, then use the 'Upload Attachments' button (below the text block here) to bring up the desired photos from your hard-drive, then plug them into the text as desired. You start with the text, then you plug in the photos -- that way you keep the text AND photos in your post.

David

[coryhenry]

Very nice, any trials yet?

[Monahan Steam Models]

Quick update

Edit: I added a description to each photo but when viewing on a mobile device the full description is not visible. What is the best method for uploading photos to this forum? I’ve run out of curse words trying to sort it out myself

[Monahan Steam Models]

Hahahaha! What size ring are ya?!

The only thing I got done today was changing dirty diapers and getting stuff done around the house. I’ll try to get something about the torpedo progress posted tomorrow after my father in-laws restored WW2 jeep is dropped off here and unloaded to be stored in my shop for the winter.

[He Who Shall Not Be Named]

David, Your work and contributions are huge and very helpful to many! Your writings and sharing of your work have been very helpful to me! I am very relieved that I have not offended you. Speaking of Masters, I’ve lingered around this submarine hobby for many years and one of the great Masters that has been a constant over all those years has been you sir. Getting your input and feedback on this topic has been a treat so I was extra bummed to see that your past writings on this thread had been lost.

I’m humbled by your kind words and even more so to be considered a Craftsman by someone of your tremendous talent and track record of achievements

Nick

OK, OK... enough! Before we have to buy each other an Engagement ring, lets get on with the task at hand: what's the status of your torpedo work as of today?

[Monahan Steam Models]

David, Your work and contributions are huge and very helpful to many! Your writings and sharing of your work have been very helpful to me! I am very relieved that I have not offended you. Speaking of Masters, I’ve lingered around this submarine hobby for many years and one of the great Masters that has been a constant over all those years has been you sir. Getting your input and feedback on this topic has been a treat so I was extra bummed to see that your past writings on this thread had been lost.

I’m humbled by your kind words and even more so to be considered a Craftsman by someone of your tremendous talent and track record of achievements

Nick

[He Who Shall Not Be Named]

BG, I’m seeing the same pages 1-6 and 83 consecutive posts. Maybe there is something screwy going on with the forum software but there was more posts originally. From what I can tell, there was a post between what is now 44-45, another between 63-64. There was another between posts 22-23. Go back to post 34 I think it is. David has added technical wisdom when it came to prop walk. A reply you made quotes his post but his original post no longer shows up but the post numbers are consecutive.


David, I have huge respect for your work, knowledge, talents and everything you have contributed to the world of model subs . I hope I have not ruffled any feathers trying to figure out what is going on with the posts in this forum. If I have, then I apologize. That was never my intention.

Nick

No offense taken at all, sir. I'm in fact most flattered that a Craftsman of your demonstrated skills and accomplishments would regard my work useful. You brighten my day. Guys like you and me advance the Craft, Nick -- an obligation all Masters assume once they have availed themselves of the knowledge imparted by those who taught them. Keep the ball in play, sir. Our view is wide and clear only because today we stand on the shoulders of the Masters who came before us.

As you endeavor to unearth my previous writings, and hit the occasion brick-wall, don't hesitate for clarification on any point you think I can help you with -- I have hard-drives chock full of photos at hand.

David
humbled, for a change

[Monahan Steam Models]

BG, I’m seeing the same pages 1-6 and 83 consecutive posts. Maybe there is something screwy going on with the forum software but there was more posts originally. From what I can tell, there was a post between what is now 44-45, another between 63-64. There was another between posts 22-23. Go back to post 34 I think it is. David has added technical wisdom when it came to prop walk. A reply you made quotes his post but his original post no longer shows up but the post numbers are consecutive.


David, I have huge respect for your work, knowledge, talents and everything you have contributed to the world of model subs . I hope I have not ruffled any feathers trying to figure out what is going on with the posts in this forum. If I have, then I apologize. That was never my intention.

Nick

[He Who Shall Not Be Named]

Thanks for digging those out, Bob.

[Bob Gato]

Hey Nick-I see all from page 1 post 1 to page 6 post 81...consecutively all accounted for? could you mean these posts: https://forum.rc-sub.com/forum/torpe...edo-production from the Torpedo topic on home page?