Re: Fillets rule

David J. Gall


Without surveying the literature:

According to Hoerner's "Fluid Dynamic Drag" page 8-12, there's a chart that
appears to show best drag reduction for fillet radii between 4% and 8% of
the chord. The drag reduction in this range of fillet radii is on the order
of 20% for a fillet on a profiled end plate, not a fuselage, as that seems
to be how the tests were conducted.

"Your mileage may vary."

David J. Gall

-----Original Message-----
From: Sam Hoskins [mailto:shoskins@...]
Sent: Monday, February 07, 2005 7:35 PM
To: Q-LIST@...
Subject: [Q-LIST] Fillets rule

I'm looking for a general rule of thumb regarding fillets. I
know if the angle between two surfaces is less than 90
degrees, a fillet should be used.
My question is how much?

I remember seeing a rule regarding the required size of the
radius. Maybe it had something to do with the chord of the surface?

Can anyone help me out here?



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