Calculate maximum flight time

If you know your average cruise current you can estimate maximum flight time from any battery.

Assuming you only want to use 80% of the battery capacity the equation is:

Battery mAH divided by Cruise Current Amps multiplied by 0.048 = Flight Time Minutes

Example using 2200mAH Lipo and 3Amp cruise current 

2200mAH / 3A X 0.048 = 35min

Note that battery cell count is not required for the calculation

Typical power to weight ratios for RC planes

Typical power to weight ratios for RC models.

11-15 watts/100g Minimum level of power for decent performance

15-20 watts/100g Trainer and slow flying scale models

20-24 watts/100g sport aerobatic and fast flying scale models

24-29 watts/100g Advanced aerobatic and high-speed models

29-33 watts/100g Lightly loaded 3D models and ducted fans

33-44 watts/100g Unlimited performance 3D models