Paul Williams Posted June 27, 2008 Share Posted June 27, 2008 Ok now I am confused, just finshed my multiplex twister and as per instruction book extended the battery wires to reach the esc parked in front of fan. Just read the article on electric flight and he says never extend batt wires if any thing extend wires from esc to motor. Which one is right? Using 2.4gh some not much worried about spikes and noise.while I'm here the twister does not have cut out for front ring on fan, so fitted it without some one said this is a big no-no any advice on this oneCheers guysPaul Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted June 28, 2008 Share Posted June 28, 2008 By "he" I presume you mean me Common practice is indeed to avoid long wires from the ESC to the battery. A phenomenon known as BEMF ( back electromotive force ) can produce very high voltage spikes in any rapidly switching device - which is basically what an ESC is. These spikes are normally "damped out" by the battery itself, but if the leads to the battery are very long this damping effect is reduced, so leaving the spikes to possibly destroy the input capacitors on the ESC with bad things happening ! Using 2.4Ghz will, of course, offer no protection against thisAn inlet lip has a dramatic effect on thrust and efficiency of an EDF unit - see the test results I published in my thread " fan testing"HTH Quote Link to comment Share on other sites More sharing options...
David Ashby - Moderator Posted June 28, 2008 Share Posted June 28, 2008 Paul, I extended the wires as per instn's on my Twister and didn't have a problem - I was using 2.4 though. Again, I didn't use the front ring and it's just fine without. Quote Link to comment Share on other sites More sharing options...
Paul Williams Posted June 28, 2008 Author Share Posted June 28, 2008 Thanks guys,I agree the jet works well, but if its capable of being 30% better with no extra cost !!!!!looking at the model its seems to me maybe the front inlet is not fitted due to the position of the esc. It would be difficuilt to fit the ring without seating the esc lower into the foam will this then disrupt the airflow and counteract the effect? Or worse still make the construction to weak. I could mill a slot into the ring so it fits around the esc without seating it deeper. I will email Multiplex for their views anyone know the address?Timbo, do your think your tests showing inprovement with ring fitted would still come to the same result if the fan was tested installed in model? Am I trying to inprove whats best anyway? While your not doing any thing just adapt your rig to hold the jet mate HA HA. Wil expect the result before fly time tomorrow.Seriously keep up the good work I am looking to design a twin unit with large wing span so I can see the b******* thing with my eye sight. Your testing is helping my thinking one large fan or two small ones?? Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted June 28, 2008 Share Posted June 28, 2008 1 large fan gets my vote - twin fans means more weight for equal power as you will need two ESCs and associated wiring harnesses and so on. however appearnace may be very important to you too, in which case if its twin jet unit, then - well you get the drift........ addy Quote Link to comment Share on other sites More sharing options...
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