Is there a minimum prop speed?

Ok,
in another thread we've been talking about 2 blade vs. 3 blade props, maximum tip speed and so forth. Someone posted a comment about needing really long landing gear to handle the 2 blade prop for a 1350 SHP turbine. That got me to thinking about the prop chord length and what a minimum prop speed might be. So then comes the question, why not just go to a longer-chord 2 blade prop rather than a 3 blade to handle the higher power?

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Jim Carter