When demonstrating my Raptor last week, I noticed some resonance in the body just before reaching my normal flying RPM. I only noticed it briefly during the spool-up, once the rotor reached its normal speed of ~1700rpm the vibrations where gone. This called for a checkup of the rotor balance, which is what I’ve done this weekend. I used the page over at Raptor Technique to guide me through the process.
The blades seemed to be fine; their Center of gravity matches almost perfectly (less than 3mm difference). Their weight also looks fairly identical, as I could balance them on the (blunt) edge of a knife (1.5mm wide).
All that’s left is give it a test-flight and see if it’s better; but with the current weather, it will have to wait a few days.