Print

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

[Number 6]

Hello there all, I've got Robbe U2540 and she's fitted with 2 x 12v Graupner 500e motors as recommended by Robbe in the instructions. They get way too hot though, on last outing the stickers on them have melted and the esc kept cutting out!  Any advice would be appreciated. There isn't enough room really to fit a fan and they'll still be overheating. I am thinking of changing the motors for a pair of 12v 700bb turbos with the built in internal fan, they're slightly larger dimension wise but should fit in ok. Other solutions I've considered are going with brushless motors (expensive) and/or fitting larger props so motors don't have to work so hard to move her along. Any advice would be much appreciated, thanks, Dave. 

[6705russell]

Dave,

Fitting larger props will make the motors work harder especially on a 1.9mtr sub, fit the Graupner speed 600,s with internal cooling and you should be ok...

Russ

[Number 6]

Hi Russ, 600s haven't got internal fans as I can see, nothing in the spec about them? That why looking at the 700s as they've got fans?? Dave. 

[6705russell]

I will check mine in the Brede later, i should of said the 600 eco,s , i am sure they have an internal fan?

[bonehead]

Just a thought but check the prop shafts aren't binding in any way as any load will cause the motors todraw ore current a n consequently get hotter than normal.I had a Robbe U47 but found they ran ok. Fan wise I have seen some VERY small fans as used in computers.... they could fit??
Just a thought! 
Regards
Jim

[Number 6]

Hi there Jim, the shafts seem fine but I'll have a another good look. I've got to go Maplins soon so I'll have a look at the computer fans and see what's what, though there's not much room to fit one. Thanks for the info, Dave. 

[Sub driver]

are you still using the black plastic props that come with the kit ?


you would get far more thrust and efficiency from a pair of prop shop props with less drag on the motors too..  i would definately ensure the motors are aligned correctly and also the shafts run free too. what have you lubricated the shafts with. as normal grease can be too thick and you have long shafts in the xx1




regards sub

[Subculture]

Don't need fans, you need to cut the RPM, as the motors are clearly overloaded with the prop size you are running. Try inline planetary gearboxes e.g MFA/como maybe 2:1 reduction.

What size prop and pitch are you running currently?

[Andy_k]

Hi I will be building a type xxi in the new year and I think that gear that gearboxes are the the way to go reduce draw on the motors and give increased battery life
and defo stay away from the 700s unless you what the boat to plane would defo be a talking point at the waters edge lol

[funtimefrankie]

Thinking about fitting computer type fans, wouldn't you need a supply of cold fresh air? not available in a sub?

[Number 6]

Hi guys, sorry not to get back sooner but my laptop died and have had to get another one. I didn't build this one but everything seems to be in line and running as it should be, props aren't ones that were with kit as these are brass, don't look oversized. I'll check it all out again anyway. I've run fans in plenty of boats without a fresh supply of air and they definitely helped to keep things cooler. I'm fairly new to the sub world as you can tell but am getting there slowly, cheers, Dave. 

[gantu]

Hi dave

best motors for her are the bühler  motors long life. Ask norbert brüggen he have a lot of them ther fit very good.