Go Back  RCU Forums > RC Boats > RC Scale Boating
Reload this Page >

LT Army tug power train

Notices
RC Scale Boating Enjoy rc scale boating? Talk about it here.

LT Army tug power train

Old 02-23-2024, 12:56 PM
  #1  
Greenyonline
Junior Member
Thread Starter
 
Join Date: Apr 2022
Posts: 1
Received 0 Likes on 0 Posts
Default LT Army tug power train

Iíve resurrected a project that was shelved decades ago. Planking is about 1/4 done. Itís being built as a 1/24th scale of WWII Army tug, LT5 (NY) or LT4 (CA) for example. Itís 56Ē long, 12 1/2Ē beam. Plans show a 4Ē, 4 blade prop. I have decided not to use a single direct drive brush motor so I can increase run time and make it more adjustable. I have a number of reduction drives and want to use a brushless motor and fully proportional esc. I could go anywhere from 1.5:1 to 4:1 reduction. Any suggestions as to what motor/esc combo might be appropriate? It doesnít need the big power or tremendous rpm of direct drive speedboats. I think Iím targeting 2500 to 3000 shaft rpm. Anyone with experience please correct me if Iím wrong. Any help/input will be appreciated.
Old 02-27-2024, 12:59 AM
  #2  
1967brutus
Senior Member
 
Join Date: Oct 2021
Posts: 1,234
Received 76 Likes on 71 Posts
Default

I cannot guide you directly to a motor... What I CAN do is first of all point out that there are motors that are wound to spin 2500~3000 rpm and that would save you the hassle of a reduction drive, as well as the possible gear-noise. For 12V you would be looking for motors with a kV rating of about 250, give or take.

But if I may be so frank: 2500~3000 rpm on a 4"fourbladed prop, you're talking about very roughly 250~400 Watt (power calculations on ships propellers are notoriously tricky), and that is an awful lot of power, even for a 56" boat. You're easily going to pull a rowboat with two adults in it around with decent authority. 250 Watt with certainty is more than a single oarsman in a rowboat can sustain for reasonable duration, so your boat will win in a tug-of-war, that kind of authority... Careful estimation it's something like 10 or 15 lbs bollardpull, probably more,

Anyway, whichever motor you choose (high RPM with gearing or direct drive) you'regoing to take into account that for example on 12V it is going to draw at least 20 Amps, probably significantly more, for a geared drive you would be looking for about kV1000 and rated for miminmum 20 amp, for direct drive kV250 and 20 amps (I think the 20 Amps is the bare minimum you should look for).

Just for frame of reference: A Sullivan starter as used for glow engines (planes) is about kV250 but only rated for approx 10 Amp... So that is a fairly big motor you would be looking for.

I myself am currently working on a 44" boat with a 4" prop, and I am targetting 1500 RPM, which should be about 80~100 Watt, and theoretically result in at least 6 lbs bollardpull. In-water tests in the bathtub it was quite a handful to hold in place by hand...

Last edited by 1967brutus; 02-27-2024 at 01:12 AM.

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.