? on ANHEDRAL, DIHEDRAL, & conventional STABILIZERS usage.

[88SST56]

What are the determining factor that a designer uses to determine which tail configuration they use. I understand the reasons for the "T-tail configuration" when used with rear engined aircraft. Some examples of the different configurations in use are:

The Dassault FALCON 50, 90, 900, 2000 and FX all utilize the middle span ANHEDRAL style stabilizer, the FALCON 20, however, uses the slightly DIHEDRAL mid-span stabilizer. CITATION II, V, 500, and 550's all use a DIHEDRAL configuration. LEARJETS use the T-tail configuration exclusively, the HAWKER-SIDDELY 125 use a T-tail configurtion, and the anachronistic WESTWIND uses what looks like, a low conventional stabilizer. Any explaination on the positive and negatives of each configurations would be great. Thanks everyone.

 

[corgum]

A full answer is long and involved. It may help to shorten the answer if you would say why are you asking.

 

[88SST56]

No specific reasons really, I just want to know if there is a criteria that dictates a particular choice. Any links to books that could provide in-depth explanations would be great as well. Thanks

 

[Miper]

Usually the boss likes one configuration or another. The design always starts there. I remember a light twin design where the President of the company wanted the tail to look like the tail on the F-5. We just about never got that to work right.

The tail's vertical placement is a tradeoff between aesthetics, tail arm, and desired distance from the propwash or jet engine exhaust.

T-tails sometimes have anhedral because that was an early solution to dynamic cross-coupling in flutter problems. T-tails don’t seem to always have anhedral anymore.

Other than that, dihedral or anhedral is usually added to a tail after wind tunnel tests in order to tailor the roll/yaw characteristics of the airplane.

 

[88SST56]

Thanks Miper, that makes sense to me now. I appreciate your reply.