rapo
Posts: 383
Joined: Fri Sep 17, 1999 12:04 pm

Tall Tails/Short Tails

Fri Jun 22, 2001 2:42 am

The Boeing 747SP has a taller tail than that of other 747's. The A330-200 has a taller tail than an A330-300. What is the effect of having a taller tail on a shorter plane? One would think that to obtain the same turn rate in a longer plane (ingnoring the ailerons), more surface area would be needed at the tail. But, exactly the opposite seems to be true. Can anyone explain these "tall tales"?
 
A320FO
Posts: 209
Joined: Wed Oct 25, 2000 12:28 am

RE: Tall Tails/Short Tails

Fri Jun 22, 2001 3:43 am

The size of the tail has a different reason. It has to do with the controllability of an airplane during a one-sided thrust loss (engine failure case). A longer fuselage needs a greater turning moment, increasing directional stability. Now the same plane with a shorter fuselage has to compensate this loss in stability. That is done with the larger tail surface. On the A321-A319 a one-sized tail is sufficient, but on the A318 it will be heightened by several feet.
Just a basic explanation.

A320FO
 
rapo
Posts: 383
Joined: Fri Sep 17, 1999 12:04 pm

RE: Tall Tails/Short Tails

Fri Jun 22, 2001 4:09 am

Ahh, I didn't even think of that. Thanks for the explanation.

Rapo

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