View Full Version : Electric newbie converting a Uravich Extra 3.25

01-30-2006, 11:21 PM

I am pretty new to electrics. I have been in R/C for about 17 years. I am looking at building the Extra 3.25 published in MAN a number of years back and powering it with brushless electric. Any thoughts as to how to set it up? What motor recommended, etc. Just looking for good aerobatics, not necessarily any 3D.

01-31-2006, 06:34 AM
The beat way to get the right set up is to start with what you think the all up weight will be.
For good sports flying (not 3D) about 100 watts per pound will do.
Let's say the all up weight will be 3 1/2 pounds so we will need about 350 watts for good sports flying.
Now what is watts, Watts are the amp draw X the volts used, So let say we want to use a 3S battery (called a 11.1 volt battery) A good 3S will hold about 3.4 volts under a load.
Now we have our volts so we will see what amp motor we need.
For 350 watts with 3S at 3.4 volts per cell = 10.2 volts X 35 amps = 357 watts. From what we have put together so far we need a motor that is good up to 35 amps and a good battery that will do 35 amp draw so it will have to be about 3500 mAh at 10C discharge.
Now if we want to cut down the amp draw we can go with a 4S battery X 3.4 volts = 13.6 volts with 26 amp draw = 353 watts.
With this set up you can use a smaller mAh battery a 4S 2600 mAh at 10C discharge.
Hope this helps