Nathan K. Hammond
I'm New Here
Long time listener, first time caller.
Chasing a vibration that I can’t seam to null out.
3 blade MT on an angle valve AEIO540, mounted on a Chipmunk.
Installed the O/H’d prop on an O/H’d engine, dynamic balanced from .75ips down to .03ips but it still has a noticeable vibration. My running theory (and it’s a SWAG for sure) maybe a blade is out of profile. With the sun at my back, I have 3 distinct reflections at the blade tips. 2 are slightly overlapping, but the third is not tracking with the others. (Aft 4” of the blade tips are painted white for formation work.) That makes me think something internal is off, or the blades are profiled slightly differently.
Trying to eliminate as many possibilities (aerodynamic, resonance, or ___?___) before pulling the prop. Dan Horton mentioned the Resonance App in a previous thread, which I downloaded, but I don’t know how to interpret the data.
So, for the collective knowledge…. What am I looking at here?
2600rpm
2500rpm
2400rpm
nkh
Chasing a vibration that I can’t seam to null out.
3 blade MT on an angle valve AEIO540, mounted on a Chipmunk.
Installed the O/H’d prop on an O/H’d engine, dynamic balanced from .75ips down to .03ips but it still has a noticeable vibration. My running theory (and it’s a SWAG for sure) maybe a blade is out of profile. With the sun at my back, I have 3 distinct reflections at the blade tips. 2 are slightly overlapping, but the third is not tracking with the others. (Aft 4” of the blade tips are painted white for formation work.) That makes me think something internal is off, or the blades are profiled slightly differently.
Trying to eliminate as many possibilities (aerodynamic, resonance, or ___?___) before pulling the prop. Dan Horton mentioned the Resonance App in a previous thread, which I downloaded, but I don’t know how to interpret the data.
So, for the collective knowledge…. What am I looking at here?
2600rpm
2500rpm
2400rpm
nkh