videns
Posts: 132
Joined: Thu Mar 18, 2004 3:28 pm

Stabilizers

Sun Oct 31, 2004 3:00 pm

Horizontal stabilizers are airfoils right?
Are vertical stabilizers airfoils? Their shape seem to indicate they are...

In large transport aircraft, there doesn't seem to be any designs to reduce drag on these airfoils (Like winglets, or wing fences, or whatever)...
Horizontal stabilizers move up or down to trim the aircraft, which makes the design of a drag-reducing device harder, because of the different regimes they have to work under...
What about vertical stabilizers? They do look like an upright wing, which would induce drag, but I haven't seen any drag-reducing measures for that...
Does reducing the drag on these devices have such a negligible effect that they don't use it?
Any thoughts, corrections, or links to look into?
Please don't mention the Beluga or the 747 space shuttle transport, as the added stabilizers were added for stability, not drag reduction....
Thanks;
Videns
Travel? Why would i travel if I can watch it on TV?
 
QantasA332
Posts: 1473
Joined: Sat Dec 13, 2003 5:47 pm

RE: Stabilizers

Sun Oct 31, 2004 4:31 pm

Horizontal stabilizers are airfoils right?

Yes, horizontal stabilizers are airfoils. More specifically, they're inverted airfoils (i.e. they produce downward lift - a nose-up moment - which counteracts the nose-down moment produced by most wings).

Are vertical stabilizers airfoils?

Yes, vertical stabilizers are airfoils as well. Unlike horizontal stabilizers, however, they're usually symmetrical.

As for control-surface drag reduction devices, they're basically not worth the added weight, parasite drag, and manufacturing costs. The amount of lift produced by vertical and horizontal stabilizers is relatively small (particularly in the case of vertical stab.'s, as under normal conditions almost no lift is produced at all) and the resulting induced drag is even smaller still, such that any winglet-like device would be more trouble than its worth for the reasons stated above.

Cheers,
QantasA332
 
747NUT
Posts: 77
Joined: Sun Sep 05, 2004 12:24 am

RE: Stabilizers

Sun Oct 31, 2004 6:40 pm

"What about vertical stabilizers? They do look like an upright wing, which would induce drag, but I haven't seen any drag-reducing measures for that..."

A vertical stabilizer is a symmetrical wing as mentioned before.
The purpose of a winglet is to prevent wing tip vortices that are produced by the different air pressures on either side of a wing.
With a vertical stabilizer being symmetrical you do not get the pressure differencial like on a wing, therefore there is no need for winglets.
If it's not broken, don't fix it !

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