help

[neverending123]

im finishing my cap project. i have a rimfire 42-50-800kv and a electricfly 60 ecs, using a ar6100 rx. do i have to use a seperate rx bat? a what batt should i use to power my motor? thanks for all help jusitn

[nate428]

more info would be helpful, we need to know all equipment drawing power from rx to figure out how much power is needed... number and names of servos? also the battery used to power the motor?

to what i can tell, your ESC has no bec? it supplies no power to the rx? if this is the case you can use an external bec such as one from castle creation: they offer two versions, the 10amp version might be enough to power your gear.
http://www.castlecreations.com/products/ccbec.html

[neverending123]

ok i figured out i do have to use a bec . im using hitech hs-81 on all surfaces and a hs-86mg on rudder. my biggest problem now is figuring out what batt to use (keep in mind) my motor and esc is the same one they use on the nexstar ep and calls for two 9.6 3600mah but im looking to run lipos

[nate428]

sounds like that 10amp bec will be more than enough for those servos.
what esc do you have exactly? what plane is it exaclty?
what kind of performance are you looking for, sport? aerobatic? extreme 3d?
if you are new to lipo's make sure you have a balancing charger, to keep each cell fully charged and avoid damaging the battery or causing a fire on a bad battery.

[neverending123]

cap 232, unknown make, manual says with a .32 engine flying weight is 56-59oz, so i used that weight to figure motor. electrifly recomended the 42-50-800kv. its the same motor that comes in the nexstar trainer ep, and they call to use 2--9.6 volt 3000 mah nihm in series. i am looking for aerobatics/extreme 3d want to be able to fly it like i hate it
so far i think im going to need a 18.5 2200mah 5s 30c lipo i can get two of them for $58.68

[nate428]

that motor is rated for a 6+ pound plane for extreme 3d... where your plane is supposedly under 4lbs. it might not be a good match to the plane if its too heavy.

for that kinda power, you want around 175-200+ watts per pound. your plane is around 4lbs, thats 700-900 watts. i would aim for around 200 watts per pound myself so 800 watts. the cell count of the battery and the prop will determine how many watts are being pulled. so we need to consider prop clearance for a bouncy landing. whats the biggest you can fly with and feel good about landing? if the clearance is really low you will need a higher cell count lipo to reduce the size of the prop.

an example i found for your motor showed 12x6e APC on a 4cell pack getting around 740 watts @ 50amps. a four cell and 13x4e or 13x6.5e apc might get 800+ watts. i think the batt for this would be a 4cell 2500-3500, not sure what the flight times would be. a 5cell battery would swing a smaller prop to make the same 800 watts, and a 3cell battery would swing a bigger prop to make 800 watts.

if your plane is fully assembled minus the battery, you may want to test the cg by finding something to mimic the weight of a battery. if you try to use too heavy or light of a battery it will be very difficult to get the cg right without adding extra weight.