I have a Badass 2814 870, apc 10X5.8 F2B prop going on a  RD-1 (think Twister), looking at battery options I like Thunder Power 2800 4s as they are only 234 grams but don't know if 2800mah is enough, please anyone know?
Thanks

Dwayne,

I currently have a Brodak Vector electric ARF that I fly with a Cobra 2820/14-840Kv motor using a Roaring Top 4s 2700 mAh battery on an APC 11x5.5 prop.  My Vector weighs 47 oz (with battery).  I check my batteries after each flight and consistently have 15-20% left.

The power loading on my Vector works out to about 140 Watts/lb.  Looking at the prop data chart for your Bad Ass motor and the wattage for a 10x5.8 F2B prop, if you can keep the weight of your RD-1 under 41-42 oz, you should get similar battery results.

Kermit