RE: Engine noise
I respect your opinion greatly, however I must make a point about modern radio/ignition component separation. I've posted pictures on this forum of my 40 size GP Super Sportster with it's converted SuperTigre 51 detailing the radio/ignition installation. The ignition used has been both the CH and an RCexl with equal results. The ignition box literally rests against the receiver, with a thin layer of foam between, which is a Spektrum AR7000. Both switches are within two inches of each other and the battery packs lay one on top of the other. The throttle control is by metal flex cable. This configuration has been flying for almost 4 years without a single glitch which I can now verify through telemetry while flying with my DX8. Never a single "hold" which is the same as saying a glitch. The frame loss has never exceeded 3 in a single flight and Spektrum says up to 20 is OK in a flight before needing to check things out.
I have little choice but to use this setup as putting an ignition system in a 40 size plane is a nightmare to say the least. I had to pretty much shoehorn it all in and getting anywhere close to a 10" separation much less 12 would have been physically impossible. Heck, just getting it all in was nothing short of a miracle. It sure is a fun little plane though as it easily exceeds 90 mph and gets close to 100 on a perfect day. 16 oz of gas lasts all day so it's cheap to operate.
I agree with the ignition lead needing to be shielded. Sometimes even if using a resister plug. The only time I have ever had ignition interference was using a Zenoah G26 with mag ign. After making my own plug wire shield, grounded at both ends, all interference went away. The plug used was the original type with resister but it still caused interference until the shield was added. My radio at that time was a 72mHz.