Power Guidelines

Courtesy of PhilipA on RCGroups:

• 50 watts/lb: Minimum required for flight.
• 70-90 watts/lb: Trainer and slow flying aerobatic models.
• 90-110 watts/lb: Sport aerobatic and fast flying scale models.
•  110-130 watts/lb: advanced aerobatic and high speed models

He notes:

• 80-100w/lb nice target for many planes.
• The Blue Wonder maxes out around 85 watts on a 3S lipo and GWS 9x5HD (straight blade) prop. 
• Sufficient for up to a 16oz AUW plane with decent performance including a 4ch aileron version.