Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[HS93 (RIP)]

They dont use reverse as the shaft unwinds  Peter

i cant see any electric motor unwinding them as they handle gas engines upto 46 cc ,even more!! ,one small 800 motor wont unwind it im sure!!.in any case you can weld it so it wont unwind using normal solder!!.

if you are going to solder the shaft so it wont unwind what is the use of it.?

[Colin Bishop]

I agree with Malcolm. The best solution would be to use either a double coupling or a cardan shaft with two couplings depending on the amount of room you have and the present degree of misalignment. The Ripmax Double coupling is shown below and is pretty free running at low angles of misalignment. It's a better engineering solution than a flexible drive which will inevitably try and wind up or unravel depending on which way you run it.

[flybobby]

I am using the cardan shaft method as want perfect (or near perfect) alignment.  Had to order some bits, hopefully they should arrive tomorrow.  Will post on how it goes

[cbr900]

Flybobby,

You have chosen the safest way and the best as it will allow you to line all up and make a better job of the whole thing.....



Roy

[Shipmate60]

The cardan Shaft is the method used on full size ships, usually on engine changes, etc.
You dont see it much on models as there is usually enough space to get the motor in.
Unusual for this problem to arise so quickly after posting my pics.
Anyway, just glad to help.

Bob

[flybobby]

Bingo, cardan shaft now in place, lines up a treat, very happy with that, however, a new problem to sort out;

I am running an 850 Torpedo motor (MFA) on 12v with a 50mm 3 bladed brass prop.  Going by the spec sheet and forum recommendation, this set-up shold be fine.  Power is excellent, with more than scale speed easily achieved, but the motor does get very hot after around 20 mins running ::).

It was during my sail today that I noticed that when the motor is hot (too hot to handle!) the motor becomes erratic and slow.  I am using an mtronic marine 40, and this apperas fine.  When the motor has cooled for a few mins, normal service is resumed until such a time that the motor is hot again!

I know by now that you are all screaming water cooling at the screen but I do like to run things by you guys before I jump the gun!!

It maybe relevent to mention that the lake was very choppy with a high winds, so the motor was working hard!

Does this motor usually require water cooling, and if so where could one purchase a jacket for such a fat body?

[martno1fan]

Bingo, cardan shaft now in place, lines up a treat, very happy with that, however, a new problem to sort out;

I am running an 850 Torpedo motor (MFA) on 12v with a 50mm 3 bladed brass prop.  Going by the spec sheet and forum recommendation, this set-up shold be fine.  Power is excellent, with more than scale speed easily achieved, but the motor does get very hot after around 20 mins running ::).

It was during my sail today that I noticed that when the motor is hot (too hot to handle!) the motor becomes erratic and slow.  I am using an mtronic marine 40, and this apperas fine.  When the motor has cooled for a few mins, normal service is resumed until such a time that the motor is hot again!

I know by now that you are all screaming water cooling at the screen but I do like to run things by you guys before I jump the gun!!

It maybe relevent to mention that the lake was very choppy with a high winds, so the motor was working hard!

Does this motor usually require water cooling, and if so where could one purchase a jacket for such a fat body?

hi mate make a cooling coil its dead easy all you need is some copper tubing or soft brass tubing 1/8 is ok tape up one end fill with sand or water let some out so its 1 inch off the top tape it up so its sealed then get your motor and wrap the tubing around it keep it tight then solder it to keep it tight .thats it job done just take off the tape and if youve used sand flush it out under the tap.ive used this method on a plane engine i put in a boat see pic!!i used zip ties to keep it tight while i soldered it keeps it nice and tight.

[flybobby]

Top Tip, thanks for that.

[Shipmate60]

flybobby,
Am MFA on 12 volts should swing the prop ok without getiing that hot, the recommended prop for those motor is a very coarse 2 bladed plastic prop, only cheap, you could try it and see if it is ok and keep brass prop for display.
But would let you see a difference in the heat generated by the motor.
Do you have any way of checking the current draw of the motor with an ammeter?
Not something most have I must admit.
But still useful.

Bob

[flybobby]

flybobby,
Am MFA on 12 volts should swing the prop ok without getiing that hot, the recommended prop for those motor is a very coarse 2 bladed plastic prop, only cheap, you could try it and see if it is ok and keep brass prop for display.
But would let you see a difference in the heat generated by the motor.
Do you have any way of checking the current draw of the motor with an ammeter?
Not something most have I must admit.
But still useful.

Bob

Hi Shipmate, the motor under load is pulling just over 12amps, which is slightly over what the spec sheet says.  Everything is lined up nicely, prp shafts lubed, it all turns free as a bird :-\  Seems a bit odd

[Shipmate60]

What does it pull in air or even disconnected.
Does seem a bit high, under heavy manouvering this will climb.

Bob

[cbr900]

Even so Bob with water cooling it should keep the temp under control....




Roy

[flybobby]

With no load it pulls less than 2amps.
On closer inspection with regards to cooling, there is not enough room between motor body and (supplied) mount to fit a cooling coil! :-\

[martno1fan]

With no load it pulls less than 2amps.
On closer inspection with regards to cooling, there is not enough room between motor body and (supplied) mount to fit a cooling coil! :-\

make anew mount? its simple enough you can use ply make a cradle with a half round shape to hold the motor one each end epoxy a peice of hardwood between the two ends and sit the motor in the mounts then bend some thin aluminium flat bar 1/2 by 1/16 or 1/8 then drill a hole in each end so its like a bracket and screw the bracket onto the hardwood on the mount it will hold the motor in place very well job done!!.

[Shipmate60]

flybobby,
What concerns me isnt the cooling of the motor, but WHY it is pulling so much current.
If the motor is that hot it is either being overworked or a small internal short. but as it only pulls less than 2 amps in air it shouldnt be this.
Do you have any pics of the hull and prop set up?
If she is overpowered do you have a smaller prop you can use, just to try out the consumption and performance.
My concern is the longevity of the motor, if you can get it running within its design paramaters it should go on for years, If you are having to water cool it you can cool the casing but not the brush gear, which will be subjected to high operating temperatures.
What is the effect of only using say 3/4 throttle?

Bob