Ernie,


Master Airscrew regular props (black) may be quiet, but this may be a result of the blade 'flattening' as RPM rises, reducing its pitch.
This also allows the engine to gain RPM.

Anyway, changing to a prop with similar diameter and pitch, form APC, Bolly, or the MA Scimitar series; although RPM is reduced somewhat, invariably results in the model flying visibly better; faster and with a much better vertical performance.

I use my remaining remaining black MA props (11x6) in trainers and in slower flying models.