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Micro_R/c.co.za
02-28-2008, 01:34 PM
I need some help please. I am new to innrunners as I have only used outrunners W/O Gearboxes. My motto Less components less chances of failure. I am wanting to buy an Inrunner for a Wing. But I see most of them have acurrent limitation of +-20A I see that the review on the RITEWING the motor Medusa 028-040-2500 drew +-60A. can some1 please explain how this is possible. I even went to MEDUSA's Website and the motor used is rated for 42A It also says the the max AMPS is rated for a MAX of 10s. Please Help....

DiveMasterPhil
03-17-2008, 06:22 PM
Try a Mega or Himax

Mega

http://www.megamotorsusa.com/BrushlessNew/Newbrushless.htm

Himax

http://www.maxxprod.com/mpi/mpi-2601.html

Dr Kiwi
03-18-2008, 02:43 AM
What is important is that the Medusa 28-40-2500 is rated at 302W max - I think it was CK who was using this one at 60A (on 3s I suppose, but maybe even 4s) - waaay beyond the specs!

Of course he admits to having toasted at least 4 Medusa motors (and their ESC's) in the last few months - but we owe him no sympathy. It's his money.

Reputable motor manufacturers can generally be relied on to set realistic upper limits for their motors - I follow them and don't have motor failures - others abuse them, then complain when they burn 'em up!

bajinuk
03-18-2008, 08:07 PM
What is important is that the Medusa 28-40-2500 is rated at 302W max - I think it was CK who was using this one at 60A (on 3s I suppose, but maybe even 4s) - waaay beyond the specs!

Of course he admits to having toasted at least 4 Medusa motors (and their ESC's) in the last few months - but we owe him no sympathy. It's his money.

Reputable motor manufacturers can generally be relied on to set realistic upper limits for their motors - I follow them and don't have motor failures - others abuse them, then complain when they burn 'em up!

i am glad you said that Dr Kiwi. I have a 86g 2900Kv motor rated for 25A continuously and 30A max. I use it with 4.7x4.2 prop on 3 cells; draws 26A static. I was tempted to prop up to 5.4x4.5 as i see others pushing similar spec motors way over the manufactures recommended amperage. Would greatly appreciate your knowledge on the following question.

Are heavier motors more efficient that light ones?.

I was looking at a 141g 3600Kv motor; continuous current 25A and max 30A. Suggested prop size 4x4 - 5.5x4.5. With my current setup rpm is about 25000 and efficiency is about 62% as calc by http://adamone.rchomepage.com/calc_thrust.htm . So lets say i use this prop on the 141g motor, then rpm must be more that 25000; im guessing 30000. Problem is that at 30000rpm, 30A and 10.5V efficiency is 93%. Is this really possible?


Nicholas

Dr Kiwi
03-22-2008, 11:00 PM
Well, Badcock reckons you'd need a motor at 120% efficiency to get a 4.75x4.25 up to 30,000rpm on just 10.5v/30A!

http://www.badcock.net/cgi-bin/powertrain/propconst.cgi?C_prop=6&RPM=++++30000&Volts=10.5&Current=30.00&Watts=0.00&Height=+++0&Temp=20.0