Ok I was kinda cheating when I tested them an had them clipped inside each other to made it look like 1 engine. So I suppose it's fine if the 2x engine groups are made to have clearly defined rules on their placing. (IE no rotors clipping into other rotors) But still, even with the extra weight of structure the 2x Aerosports have a very BIG energy advantage. They max out their thrust (which is ~40 kNt btw) at mach .1. This is the speed where the turning, banking dog fights happen. O my cheaty set up I was able to pull 5G sustained turns (no loss in airspeed, no loss is altitude) with the 2x aerosports. While when I use a single radial on the same design I'm only able to pull 3G sustained turns at the same altitude.