Model Boat Mayhem - Forum

Technical, Techniques, Hints, and Tips => BRUSHLESS Motors and Speed Controllers => Topic started by: kurriedkat on March 08, 2009, 09:12:13 PM

Title: What Brushless Motors to use ?
Post by: kurriedkat on March 08, 2009, 09:12:13 PM
Fairly new to the RC scene (I normally sail a 22ft river boat!)

So for a toy to use while afloat I have purchased an old Graupner Commodore (28") - Should be delivered tomorrow !!! From the pics the motors & elec gear need replacing , have i mate into RC copters who has recommended the use of brushless motors

What sort of power / size should I be looking at ? Boat is twin screwed

Cheers

Adi
Title: Re: What Brushless Motors to use ?
Post by: andrewh on March 17, 2009, 01:12:47 PM
Adi,

One way to look at this is to work away from what you might have done if it was brushed motors, etc.

Not familiar with the commodore (pause to have a look)  OK, nice little cabin cruiser :}
What do you want it to do?  cruise, plane or terrify the locals and impress Stavros?

For fair performance  - good planing and appearance a pair of S400s would do a good job if they were modestly propped - around 30 mm max and they would run on 6, 7 or 8 cells buggy pack (S400 7.2V have a kv of 2300 from memory)

I run my pt boat on a single prop - 35mm 2-blade and either a S600 7.2 eco or a single brushless "bell motor" with 10A ESC which gives the same performance with vastly less weight

SO:  I would suggest a pair of fairly small brushelesses with KV around 1500 to 2000, props which would suit S400s (25 to 30mm dia) and 2 cheap aero ESCs, or you might try one ESC if you like a challenge :}
By small I am thinking of something with numbers like 2215-10 or similar - appearance like
(http://i222.photobucket.com/albums/dd159/andrewh_photo/Metal_Outrunner_Brushless_Motor__17.jpg)
http://www.giantcod.co.uk/epower-2215-1700kv-brushless-outrunner-motor-p-403200.html?osCsid=8auev3nv3no6085tiike3385v7
and the price looks reasonable , too

Please tell us how you think, and what you do  - and show us the pics :}
andrew

Title: Re: What Brushless Motors to use ?
Post by: andrewh on March 17, 2009, 01:17:10 PM
Adi,

I forgot to say - look out for your Heli mates  - they are wonderful people :}

But

Have you seen the size of their main gears? 
There is such a huge reduction (about 12:1) that heli brushlesses have extremely high KV  - 3000 to 5000!  (AND the fins go the wrong way round the motor cases)(for us)
Helis are a very special form of BL use - just be aware. :}
andrew