Gentlemen,

Thanks to you all...good information. Even tired old man's comment - I appreciate nice dry wit. Sorry, I'm just tuning back in - I was away from web access for a bit. I will do a search and look at both Pe's charts and the info on Boucher' formula.

Regarding the formula posted, what does the ^ mean - raise to the power of?

Also, how does the constant play into it all? Is there a different constant for 3 and 4 blade props? If so how are they derived?

Lastly, the relationship of all up weight to power in watts? What is the ideal ratio? Or better what is the minimum to sustain flight? Though I'm sure this depends on the lift of the wing as well. Maybe then power to wing loading?

Rick