PrfctChaos wrote: ↑Wed Feb 24, 2021 1:09 amfluidity wrote: ↑Thu Feb 04, 2021 9:37 am
I can tell you the characteristics that will make a poor foil to control in unifoiling mode:
characteristics that will make the foil want to dive:
Concave rear underside profile.
High assymetry including wings with a very flat underside.
For performance I believe you need a foil with around 2:1 top:bottom curvature profile.
Are these statements backed up by any calculations Fluidity? Showing that those changes cause less "dive" with increased speed.
I think we both know that you are the gun on here for general hydrofoil calculations as attested to by your very popular thread in gearbuilder.
However its over complicating matters to require mathematically proof that a curved surface likes to ride over a fluid pivoting around the projected centre of the curve. Simple, right?
The curves of an assymetric foil can be cancelled against each other to leave a remainder assymetric curvature which is the significant factor in built in pitching moment of the foil independent of external pitching considerations.
As for my comment "2:1 top:bottom curvature profile", this is ball park but is based on requirement for pumping and net lift with stable characteristics over use-case angles of positive and negative attack.
You could also put it another way and say I just fluked it with my first non naca design that rides "real sweet" and break down its possible weaknesses based on a direct link to my lack of certification in the field!
(kind of like faulting a dog based on poor pedigree documentation)