1/48 G7 Torpedos

[Bob Gato]

Heck, I really couldn't tell you how long until the charge gets unusable...but if it is any indication-I had one sitting in a magnetic cradle on the bench for a week and it ran when I picked it up off the magnet.
Yes lightweight...at 1/64 that was my issue, they were borderline bound for the abyss. I was saving weight by the composite body tube, removing the insulation on the ground wires, cutting the all component leads short, using an epoxy covered foam nose cone. Probably not a problem at your scale...I am very stoked about your gearbox-looking FWD to the next post!-Bob

[Monahan Steam Models]

BG, I like what you are suggesting! Definitely would be a much lighter setup. I will look into gathering up the components you mentioned and give it a try. How long would you say that the capacitors will store a charge?

Thanks!
Nick

[Bob Gato]

Hey Nick, congrats on the success of the gearbox-at the risk of being redundant-consider upping the voltage instead of changing the motor. With an 8mm 10uf 6.3volt or even a 10volt ultracapicator that little coreless motor would give you all the power you need. The park flyer guys do it all the time you could lose the timer BC the cap would run for about 30sec-1min depending on the charge and with only the motor, cap, and reed switch, it would be all waterproof and light weight I realize that you probably want to just reuse the torp over and over on the battery but you will have the torp in hand between loading anyway whats a quick 20 second charge from a battery pack before slipping it back into the sub?-BG

[Monahan Steam Models]

Test report for the G7E counter rotating torpedo transmission. Here is the good news and the not so good news. Good news is, it works and the counter rotating props appear to have completely stopped the torpedo body from torque spinning around its central axis. The travel trajectory is noticeably much more straight after repeated tests. (Almost perfectly straight. Outer prop was slipping on shaft)

The not so good news, the decision to swap the 15mm length 65,000rpm motor out for the lighter weight 9.3mm length 28,000rpm motor has proven to be a mistake and the torpedo’s speed has been significantly reduced. The shorter length motor lacks the rpm and torque that the longer motor produces. The picture of the disassembled torpedo show the original 15mm long motor used in past design test and the current 9.3mm long motor used in this current design.

In the next design revision, I plan to look at using the 15mm motor again or possibly sourcing and testing a new 12mm long motor. Future designs with either motor will either use the current 5:1 planetary reduction gear box or not. The counter rotating gearbox will stay. Thanks for following this developing build!

[Monahan Steam Models]

A small amount of soldering work tomorrow morning to get everything connected, then hopefully some wet testing in the pond to see how the counter rotating props affect the running characteristics of this torpedo

[Monahan Steam Models]

I’m back to work this week so I doubt I’ll be able to make any more progress until next weekend. Now that the experimental gearboxes prove to work, I’d like to look at comIng up with much more simplified design that is not so tolerance critical with so many tiny machined shaft bushings and hours of hand fitting parts. A much more simple production method basically. Have a couple ideas so far

[Monahan Steam Models]

Thanks H.W.S.N.B.N.!

[Monahan Steam Models]

Thanks BG!

This is designed to fit in the current 11mm or 7/16” OD torpedoes I built in 1/48th scale. The diameter of the black abs part holding the motor and gearboxes is .335”. That part slides into the tail cone just like the earlier designs I first posted. Looking forward to do a couple small design revisions, then assembling and testing this latest torpedo. Amazingly this latest design is the lightest weight torp yet

Nick

[Bob Gato]

That is Killer! Are you still trying for 8mm?

Oh and that response thing from post #41, Nick-they may call it the silent service! but they are listening!

[Monahan Steam Models]

Okay thanks guys for the reply’s of interest. I was starting to have doubts and wondering if I was just wasting storage space on a server somewhere.

Bob, yes sir you are absolutely correct about how it works. I’ve attached a screen shot of the basic idea. The pink gear is the input which drives the yellow gear as well as drives the inner prop shaft. The yellow gear drives the green gear. The green gear drives the blue gear that drives the outer counter rotating shaft. I chose this arrangement because it has a lower center of gravity and smaller packaging then using the more common miter gear approach.

Also, here’s a couple video from today testing the rough prototype for the very first time.

Nick

https://m.youtube.com/watch?v=DeVboWjDNrU

https://m.youtube.com/watch?v=UZ06B_8o_xA

[Bob Gato]

Nick- don't stop posting! please-
I can't quite get the layout.my guess is that there is an additional gear set that meshes with the input and coaxial output shaft gears-accessing those gears thru those housing holes? up coming episode?

[coryhenry]

With over 600 views it definitely has interest!!

[Monahan Steam Models]

Does this group even care about this project or am I wasting my time sharing this.

[Monahan Steam Models]

A little more progress on the second stage of the 1/48 scale G7E torpedo’s transmission. The counter rotating part. Going cross eyed making these tiny parts. Hope to finish the transmission soon then testing

[Monahan Steam Models]

Small progress update on the 1/48 G7E two stage counter rotating shaft transmission build. Here are some of the different length motors I’ve been testing to date in the miniature torpedo. The shortest motor is a new one that is yet to be tested but will be in the next couple of days. The black cylinder attached to the short motor is the first stage 5:1 planetary gear box. The black machined stepped part attached to the gears sitting on the Penny is the adapter to drive the second stage counter rotating gear box that I will begin making tomorrow. A .8mm carbon fiber shaft inserts into the end of the adapter (that the blade is pointing at) which drives the aft most propeller, while a custom machined bronze gear presses on over the lager diameter of the same shaft which drives the 2 stage counter rotating shaft transmission. Will post more as progress is made