There isn't anything really wrong with the Queen Bee engines. Cox needed to have a engine with RC throttle capability and a muffler on it for the current rules where mufflers are required at the flying fields. But a muffler on a 1/2a engine robs a fair amount of power from it. So they had to increase the displacement to compensate. Also going with a glow plug hurt performance slightly which also meant the displacement had to be larger too. So the engine wound up being .074 cubic inch displacement to compensate. The reed valve intake is actually not a bad thing either as you can run the engine forward or in reverse, like for using in a pusher application. Yes the engine's performance is more like a regular .049 engine but if you put a muffler on a regular .049 engine then it doesn't perform as well as the .074 engine does. Unfortunately the Cox Queen Bee wasn't popular and it wound up being discontinued after a while.