system compatibility

[Ethan Heywood]

I'm looking to build a ft versa wing as a pusher, but need help determining whether or not my prop, motor and esc, would be compatible with a battery i want to use.
I’m going to use:
8x6 prop
EMAX GT2215 1100KV MOTOR: https://store.flitetest.com/emax-gt2215-1100kv-motor/
BLHELI SERIES 30A ESC: https://store.flitetest.com/blheli-series-30a-esc-xt60/

for the battery I’m interested in using a lithium ion 3 cell from titan flight because the enable longer flight time, but you can’t draw as much from them at one given time.
here is a 7.5 ah with 15ah constant draw: https://www.titanflight.com/collections/endurance/products/7-0ah-11-1v-120w-endurance
or...
here is a 5.2 ah with 22ah constant draw: https://www.titanflight.com/collections/11-1v-batteries/products/5-2ah-11-1v-225w-fast-discharge

tell me what you think of this idea and if it will work.
Thanks!

 

[pressalltheknobs]

A issue may be weight...it weighs 312g

Also the triangular shape may not suit the Versawing without some adaptation.

If I remember correctly a typical battery for the Versawing is a 2200mAH 3S which weigh about half that. Doesn't mean it won't work but from what I've heard getting the CG right on the Versawing is a bit tricky in any case without adding a heavier than normal odd shaped battery.

You may want research what the usual battery is - if it is the 2200mAH 3S they are only around $10 http://www.hobbyking.com/hobbyking/store/__21346__ZIPPY_Compact_2200mAh_3S_25C_Lipo_Pack.html I'm not sure so you need to check the build videos - or maybe someone with successful build can say.

Then get it flying with that before you try the expensive battery.

 

[Ethan Heywood]

my problem isn't weight or shape, it is necessary to have large weight in the nose in order to properly balance it and the shape won’t be a problem either. What I’m unsure of is whether or not the battery can provide adequate constant current to the motor without damaging it. Could you help me out with that?

 

[pressalltheknobs]

Well I can't tell you for sure if it will work but...going by the numbers

It looks like FT sell the GT2215-09 which has numbers for a 10X4.7 and 10X6 and can draw up to 26 amps full throttle.

The Endurance battery has a continuous C rating of 2 and is 7000mAH giving a continuous claimed current draw of 15amps - numbers say 14 but I guess they are rounding somewhere - but it also has a max amp draw of 40 amps for short periods.

It's hard to tell without a more data but on the face of it, it seems like an ok match for that motor assuming half throttle is around half max amps, about 12 or 13 amps, and your application is mostly cruising. You don't have a lot of room to spare though so this is definitely for gentle flying. It probably would not be good if you had acrobatics in mind but should be ok for occasional high throttle to get out of trouble.

The high discharge version gives you a little more room if the cruising amps turn out to be higher than expected. 22 amps continuous gives you nearly full throttle continuous but you lose nearly a quarter of your capacity. It's probably the safer choice given the unknowns but it depends what you are really after.

The ESC should be fine for that motor and prop.

I'm not sure why you want to use the smaller prop. It will have less thrust for the throttle position and you may need to run it at higher rpm to get the thrust you need. It should draw less amps but if you have to run a higher throttle it may not on average. Still props are relatively easy to change out and are not that expensive so you can try different ones. A pusher configuration could make that a bit more difficult.

The best way to determine all this is to get a watt meter, buy the motor and ESC and cheap 20C 300mAH Lipo and test the amp draw of the motor over its throttle range. Then fly it how you intend to see how much throttle you need. You can add weight to simulate the heavier battery for the test.

This http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=39148 goes to 30A so for $5 you can probably get the data you need. You will need to solder on some connectors though.