Airframe with eight motors arranged as in a conventional octocopter, and scaled here to represent 18" propellers, a 20" centre-section and 48" airframe. Demonstrates how a quadcopter is the better choice for proof-of-concept, from the point of view that the swept area of eight 18" propellers improves upon four 22" propellers by only 25%. This has to be offset as well against a 25% increase in size, along with the added cost and weight of four additional motors.

In fact the two kilos of thrust which an extra four motors provide at 60% rpm using a smaller propeller is offset by the surplus weight. This is the curse of the multicopter: requiring ever more motors to approach the safety of the helicopter, whilst sacrificing aerodynamic efficiency at every stage of the game.

It provides a more stable platform and ample redundancy with as many as sixteen motors fitted over-and-under. It's filed under Creative Commons attribution 4.0 too, so fill your boots.