Originally Posted by
Shaun Evans
Hi,
That makes it a little trickier. Should we assume that the manufacturer is always referring to 'unloaded' RPM as max? If so, how would one know if you weren't using telemetry? I always knew there was a little bit of unloading in the sky, but I'd have never guessed it would be that much. Frankly, it was a little alarming when I saw the telemetry reading. I don't have any reason to doubt the reading, either, because it's matching the on-board tach and a handheld tach for the ground readings.
Well telemetry is fairly new, it has only been commercially sold in the past couple of years. I do not think any manufacture has collected any data . It was always done by ear for me. You can usually tell if an engine is overreving." A guessing game"
The MAX RPM is what is considered a safe number for continuous running at the highest power level on the curve. I have had engines that were taken beyond the safe number a few times weather it be in a dive or underpropped. I have also overpropped engines but that loss of energy has to go somewhere =(heat).
My philosophy is to stay about 12-1500 under the max while being on the ground.