Thanks, Andy.
Its OK for trials - I just thought that it looked a little more "pukka" than my usual silicone-tube-and-tiewraps device.
Report on trials of 1/32nd PT boat with BL "bell motor"
The boat is my unfinished 1/32 Higgins PT boat
http://www.modelboatmayhem.co.uk/forum/index.php?topic=12272.0Original motor: Graupner S600, 7.2 Eco
Prop (?graupner) 2-blade - 35mm dia racing prop
This trial:
Brushless "bell" motor - 2508/21 1250KV - rated 100W
10A forward only speed controller, cheap, chinese - no identifying marks
Batteries used - 8X1000mah nicad pack , 6 x 2100 Nicad Buggy pack
I took the pt boat for a hurrl on a wet weekend morning just to see if the setup had promise. My aero ESCs wear 3mm gold plugs, so I made a tamiya-to-3mm adaptor to fit the batery packs
8 cells - (9.6) V
VERY sprightly performance - no measurements, but speed and "sit" on the plane appeared to be very similar to performance with S600 motor. I did the test in 3 or 4 very short bursts, checking the motor, ESC and battery pack for temperature with my digital thermosensory facilities (fingers)
At all times the motor was completely cool, ditto the ESC and the battery pack just a few degrees above ambient.
This set my mind at rest that the prop was NOT too big for the motor (it is essentially a low KV motor - very similar KV to the Eco 600)
6 cells - heavier, lower voltage but greater capacity
Still good speed and continuous planing. Less speed, but again comparable to the S600. No sign of heat in any component and I terminated the trial when the ESC started "stuttering" - presumably low voltage, so I brought her in.
I have read a post where a mayhem gent showed a picture of a bell motor, and asked "will this power a boat?"
Despite searching the I have not been able to find the post again - but the answer is a palpable YES!
For excitement more volts would be good - I was clearly nowhere near the 10A continuous of the ESC (still less the 15A burst) so I am crocheting some Li-ion packs for her.
These are made from reclaimed laptop battery packs, I am using 3S,2P to give good capacity
and more volts. I believe the capacity of a single cell is about 1500MAH so this pack is 12V, 3000 mAH
If I am drawing 7A I should get nearly 1/2 hr running with considerable velocity
I will mention that this bell motor gets its name from the shape (looks like a bicycle bell), the weight (weighs the same as Big Ben) and the NOISE - it is very noisy when running! This is a characteristic of this make and model of motor only - it is not true of any other BL motor!
more as it happens - with pics and video
andrew