Banner Ad 1

12V for Robbe U-47

R/C Submarine modelers

Postby preveze » Tue Nov 18, 2003 8:25 am

Robbe U-47 is my first sub kit.I had no marine modelling and building experience and there are some some faults on my kit.I filled the shafts with gress and rpm decreased considerabally.Sub seems too slow for me so I decided to power it with two serial connected 6V4AH batterries totalling 12V.I did not test it but can the stock motors handle this power?I changed the wiring with thicker wires and replaced the speed control with a switch.
preveze
Registered User
 
Posts: 7
Joined: Tue Nov 18, 2003 8:07 am

Postby Sub culture » Wed Nov 19, 2003 7:05 am

Right. If you run the stock motors at 12 volts there is a good chance the motors will overheat and hence have a short life span.

The supplied motors (Speed 500) should have more than adequate power to submerge the boat at 6 volts.

In fact they tend to be a little juicy, so a lot of folk have replaced the stock motors with Speed 400's reduced with a toothed belt drive. These are sold ready to fit by one of the sub vendors, I think it's 'Ships and things', but I could be mistaken.

What grease are you using in the shafts?

Packing the shafts fully with grease will load the motor considerably.

I'm not that familiar with the Robbe kit, but I'm sure the shafts must have some sort of rubber seal/stuffing box to prevent water ingress.

If not consider uprading the shafts, Subtech do a good range of sealing devices.

Also use a good quality electronic speed control with your sub. A switch is bad way of controlling a model sub, crude and too many nasty things can happen to a switch which could easily result in the loss of your boat (i.e. it gets stuck on).

Cheers

Andy
'Why are you staring at an empty pond?'

Want to dive your boat in crystal clear water? Then you had better Dive-in- http://www.diveintomodelsubmarines.co.uk
User avatar
Sub culture
SubCommittee Member
 
Posts: 2851
Joined: Fri Feb 21, 2003 6:55 am
Location: London, UK

Postby preveze » Thu Nov 20, 2003 9:16 am

I used Shell water resistant gress.Friction in the sahts is terrible Can you suggest me a heavy duty speed control that can handle 12V and hi amps that I can use in my further projects?
preveze
Registered User
 
Posts: 7
Joined: Tue Nov 18, 2003 8:07 am

Postby Sub culture » Thu Nov 20, 2003 11:58 am

The controllers I use can be found at this site-

http://www.modelcontrollers.co.uk

Up to 27 volt working- they work great on 12 volts.

I see no reason to use anything else.

Keenly priced too!

Silicone based grease is best for your shafts.

Cheers

Andy




Edited By Sub culture on 1070564474
'Why are you staring at an empty pond?'

Want to dive your boat in crystal clear water? Then you had better Dive-in- http://www.diveintomodelsubmarines.co.uk
User avatar
Sub culture
SubCommittee Member
 
Posts: 2851
Joined: Fri Feb 21, 2003 6:55 am
Location: London, UK

Postby safrole » Thu Nov 20, 2003 1:14 pm

I converted to shaft seals with some 11mm seals from www.subconcepts.com. Here is the page showing the process.

--Jason

http://www.3rdgendecals.com/submarine.htm
User avatar
safrole
Registered User
 
Posts: 274
Joined: Wed Aug 06, 2003 9:22 am
Location: Elkhart, Indiana

Postby boatbuilder1 » Thu Dec 04, 2003 12:54 am

shaft grease I have always used prathers cable grease it is 100% manmade silicone grease blue in color and doesn't thin or melt with temps up to 500 degrees
I inject the tube before gluing in the boat and then insert shaft and and catch the excess grease as the shaft fills the cavity so none is lost this stuff is nice and you get a 1/2 pint for around 6 bucks one can lasts me thru at least a dozen boats

don't use this to stop leaks on flat surfaces though it just promotes the leak even faster




Edited By boatbuilder1 on 1070513738
charlie



Time is a fleeting idea of man's invention.
its all relative
User avatar
boatbuilder1
Registered User
 
Posts: 392
Joined: Sun Mar 02, 2003 5:56 pm
Location: mid west

Postby MIT » Thu Dec 11, 2003 10:40 pm

Having over 20 years in RC airplanes and Helis and the last 5 in electrics I can say this:

a 6V rated 400 / 500 / 600 motor can take 9.6 to 10 V with low loss in longevity. Above that value, you will be "chewing up" the commutator pickups and brushes BIG TIME.

If you are haveing so much resitance in your drive shafts, all you are doing by raising the voltage is spending energy to overcome a problem.

Its best you re-look at your setup and try an minimize friction and assure efficient transmission of enegry along the couplers and shafts before raising any voltages.

By the way. The best volatge for a 400 class 6V motor is approx 8 Vdc.

Nick
User avatar
MIT
Registered User
 
Posts: 99
Joined: Wed Dec 03, 2003 10:49 am
Location: Milford CT


Return to R/C Modeler

Who is online

Users browsing this forum: No registered users