<html><head></head><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px"><div id="yui_3_16_0_1_1454791197583_3086"><span></span></div><div class="qtdSeparateBR" id="yui_3_16_0_1_1454791197583_3250"><br><br></div><div class="yahoo_quoted" id="yui_3_16_0_1_1454791197583_3249" style="display: block;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;" id="yui_3_16_0_1_1454791197583_3248"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;" id="yui_3_16_0_1_1454791197583_3247"> <div dir="ltr" id="yui_3_16_0_1_1454791197583_3246"> <font size="2" face="Arial" id="yui_3_16_0_1_1454791197583_3245"> <hr size="1" id="yui_3_16_0_1_1454791197583_3244"> <b><span style="font-weight:bold;">From:</span></b> Alan James <alanlindsayjames@yahoo.com><br> <b><span style="font-weight: bold;">To:</span></b> Personal Submersibles General Discussion <seaquestor@gmail.com> <br> <b><span style="font-weight: bold;">Sent:</span></b> Saturday, February 6, 2016 11:18 PM<br> <b><span style="font-weight: bold;">Subject:</span></b> Brushless thruster test 2<br> </font> </div> <div class="y_msg_container" id="yui_3_16_0_1_1454791197583_3279"><br><div id="yiv1584632493"><div id="yui_3_16_0_1_1454791197583_3281"><div style="color:#000;background-color:#fff;font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px;" id="yui_3_16_0_1_1454791197583_3280"><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822">This is mainly for Cliff's benefit, as he is going to be doing some</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">thrust testing.</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">Tested 2 different props out. One being the same as the first test, the yamaha 7&1/4" x 4" pitch </div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">& the second was a Vetus 6 blade 108 mm ( 4") for 25kg bow thruster. No stats on the pitch but it</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">looks about 180mm or 7".</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">My watts measurement is done off the battery whereas other people quote their output at the motor.</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">I am comparing my motors performance to statistics from commercial thruster brands but not sure</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">where they are measuring there power from.</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">Had some wacky results from the yamaha prop again. It was the more powerful & I think I am getting what</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">is called a "short circuit" effect through having the motor about 28" out from the pool edge & in about 3ft</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">of water. Short circuit is where an edi is formed & the water moves from the output to the input in a semi</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">circle around the thruster. This is caused by water bouncing off a pool wall, or in my case the inlet flow </div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">bouncing off the wall or pool bottom.</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">I was running off a 40V 5 amp Lipo battery & the voltage dropped a bit during the tests.</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">Ist test was 10 kg (22 lb ) at 500 W </div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">2nd 11 kg at 1000 W & 39 V</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">3rd 15 kg at a huge 3,400 W</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">4th 37 kg at 3,800 W & 85 amps.</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">As you can see some inconsistent results there, and some missing figures like amp draw, as I needed</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">an assistant to read the figures.</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">Next is the Vetus prop.</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">1st 10kg 547 W 39 V</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">2nd 11 kg 634 W 11 amps 37.81 V</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">3rd 15 kg 998 W 27 amps</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">4th 20 kg 1700 W 39 V</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">5th 24 kg 2500 W</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">It's amazing what a difference a prop makes.</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">In conclusion, I need to ditch this rig & buy a longer plank of wood to do tests in the middle of the deep end.</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">I have a more sophisticated volt / amp meter that stores results & plots on a computer & I need to employ that.</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">I need to buy a similar motor but a sensored version, as there was too much cogging at low speed.</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">Sensoreless motors read the back emf produced by the motor to ascertain the position of the rotors & can stop /start<br></div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">& rotate backwards on low speed where there isn't enough back emf produced.</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">I need to replace my motor controller with a sensored controller, probably Kelly & buy a bigger life po4 battery.<br></div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr"> I also want to wire the motor to a WYE configuration which will give me .73 less rpm. So will gear it down a bit.</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">Some good news is I have found people on boating forums adapting these RC brushless motors & an absolute</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">guru who uses these motors for traction vehicles & has posted pages of information on them.</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr">Cheers Alan</div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr"><br></div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr"><br></div><div id="yiv1584632493yui_3_16_0_1_1454723982197_14822" dir="ltr"><br></div></div></div></div><br><br></div> </div> </div> </div></div></body></html>