Originally Posted by
chorner
Len what're you using to obtain the RPM figures in the air? Are you piping it back to your receiver through some sort of optical RPM gauge, or through the ignition...?
I use one of HH's optical RPM couplers pluged into the DLE ignition module's RPM output. They work great. Then the coupler goes to a TM1000 telemetry module. The Telemetry module sends a signal back to the transmitter with all the data that I am measuring. I usually monitor Head/cylinder Temps, RPM and Battery voltages. I have alarms set on various parameters including temps, voltage, frame losses and holds. When I get an alarm, my observer typically takes a quick look to see what is going on. On the Jet, it monitors all kinds of parameters. But I only have an alarm on flameouts and battery voltages. Once I get all the bugs shook out, then I don't monitor telemetry that closely. I just listen for alarms which I seldom get becuase I got all the bugs worked out and the thing is running cool and correctly. Once you try telemetry, you will never fly an expensive plane w/o it. It is an outstanding tuning tool. I also use it to find the right prop.
On the air dams in front of the exit holes: A 1/2" dam angled at a 45 degree angle back added 30-45 degrees of added cooling on the same exit hole. This was on one of giant Extras with DLE 111. The faster I went it seemed to have even more positive effect.