What would be the ideal plane specs that minimizes consumption for 1000 kg of cargo payload (slow speed, wing span, whatever..)? Speaking of electric planes, I wonder what'd be the optimal specs if the only variable that we'd try to optimize was consumption (assuming a 1000 kg payload and 600 mile legs, unrestricted runway)?
The most fuel-efficient configuration would be one having a very high L/D. The best examples are modern sailplanes, aerodynamically clean, and with very long, slender wings.