Iskandar,
You are right about the CL engines now being tried in RC Combat. Several years ago we first tried Cyclon PC4's with Kalmykov's own design carb. That was before we were using bladders. The learning curve with the hipo FAI engines was too steep for us then. Now that we understand more about the metalurgy, the longer break in cycles, and the use of more head shims, plus the bladder pressure systems we are able to run them quite well.

George Cleveland lent me a Fora .15 for test on one of his Falcon 72 ARF RC Combat wings. I propped it with a MA 8X3 instead of the "meanie greenie" that George provided. The choice was to have low pitch, high thrust rather than high rpms. The engine is probably not its happiest at 19K to 20K but pulled the Falcon with authority. As a point of reference the OS LA with a mousse can, running on bladder will turn a MA 8X3 over 18K and close to 19.

I talked it over one long evening with Lee Liddle and his conclusion is that we are not yet seeing the performance advantages of the FAI CL Combat engines because our planes are not optimized to their power bands. He thinks lighter, smaller planes with thinner wings will be needed to effectively gain the performance that the engines offer.

For the balance of this year I will run a Cyclon in Open A as well as OS LAs on mousse cans. The RC combat Open A class has a bright future but if we start with pricey FAI engines requiring bladders we may be putting to high of a technical learning curve in front of fliers and possibly be impeding its development. The rules allow us to run anything we want in "Open" A but I think we have to be careful not to kill it in its infancy.