For higher than 30 minutes you really want to look into planes instead of quadcopters. Running 4/6/8 heavy duty motors forces battery life to be an issue.
A plane has significantly less than that which lets them go for longer.
A plane has significantly less than that which lets them go for longer.
Depending on the exact motor+prop setup, peak draw of between 200-400W is pretty common for fixed wings in the 1.5-2M wingspan range, and cruise is often around half of that.