I am trying to figure out why is the more vertical leading edge of the tail fin less draggy then the swept one. For example older Cessna vs post 60's swept tail one. Is it to do with larger size and corresponding thickness?
Thanks
Aerodynamic clarification -> Vertical Fin
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[quote author=Fendermandan link=topic=655.msg2470#msg2470 date=1439563138]
I am trying to figure out why is the more vertical leading edge of the tail fin less draggy then the swept one.
[/quote]
Because of 3 dimensional flow effects at the wingtip, swept wings have a shallower slope on the C[sub]L[/sub] v. AOA curve. So they gain lift slower as angle of attack is increased. A vertical fin is just a wing turned on it's side, and it's impact on directional stability is tied to how well it produces "lift". To compensate for the slower growth in C[sub]L[/sub], the area has to be increased, resulting in more skin friction and more weight.
The opposite effect shows up in forward-swept wings, which is why Mooney's have forward-swept tails.
I am trying to figure out why is the more vertical leading edge of the tail fin less draggy then the swept one.
[/quote]
Because of 3 dimensional flow effects at the wingtip, swept wings have a shallower slope on the C[sub]L[/sub] v. AOA curve. So they gain lift slower as angle of attack is increased. A vertical fin is just a wing turned on it's side, and it's impact on directional stability is tied to how well it produces "lift". To compensate for the slower growth in C[sub]L[/sub], the area has to be increased, resulting in more skin friction and more weight.
The opposite effect shows up in forward-swept wings, which is why Mooney's have forward-swept tails.