Boy, they do look different! They almost look like the props used on submarines.

Yes, I am aware that the turbine runs at a constant RPM and that only the pitch changes to increase or decrease thrust.
But, the question remains: Are the old or the new prop shapes quieter than what we are using on models and if so, has anyone experimented with that shape? By that shape, I mean a broader blade at the tip. I can see a lot of questions would come up as for example what RPM would a wide tip prop blade need to operate at and could we achieve that with a model?
This could get into some real Reynolds Numbers equations.

Anyone have any thoughts on this subject.

3dbob