What Steph says is true, we can run the YS with no nitro with the CDI, but what is the point then? we still use 30%, now 25% on the 175, the manual says 25%max on the 170, and we have been running 30% in them since day one with no problems at all, I only got a bad pump during training once on the 170CDI version(that was the pump with problems), but that is it. Even thoug we know it can work with less nitro,there is a difference of $12 in price per gallons, wich is alot,but there have been situations where full power was needed at least one or two times during a schedulle, a high power output is a must, we use the highes nitro content possible anyway. Anyone who flies at sea level should be ok whith 15% I think.

MVVS, ZDZ are engines designed from the ground up for RC use, and also Desert Aircraft engines are, so the DLE, Turnigy etc are copicats realy,I hve a Turnigy 55 and is almost identical to my DA's, the OS it is indeed RC all in it's own, but one of the most important factors during the design in the case of th the DA was what they called the aerobatic power curve, so raw power will not do good if it can not effectively be controlled, we all know two clicks on the throttle control can change a lot in a maneuver, so the presicion needs to be there.

One important thing as Timble says is, the UAV world can have the resources for this, DA was selling only 50% of it's production to the RC industry, the rest was going to drones and UAV's, that was about 4 years I think, last time at was at their factory, but their designs are tweeked to the max but nothing really new on the cilinder/piston combination.

What I see is, if ZDZ who really developed and engine specifically for F3A and then abandoned the development, then who else will pick up the proyect? that is the big question, maybe someone should ask ZDZ to find out what happened, maybe they did not get enough orders and dumped the proyect? I wonder because I think DA has sold more than 7000 DA 50's alone, I wonder how many ZDZ40F3A were produced and sold.

Regards