December 1st, 2008


Book meme

Via melissasutton:

* Grab the nearest book.
* Open the book to page 56.
* Find the fifth sentence.
* Post the text of the next seven sentences in your journal along with these instructions.
* Don't dig for your favourite book, the cool book, or the intellectual one: pick the CLOSEST.

From the Pilot's Handbook of Aeronautical Knowledge:

Since the weight of the horizontal surfaces is at the top of the vertical stabilizer, the moment arm created causes high loads on the vertical stabilizer which can result in flutter. Engineers must compensate for this by increasing the design stiffness of the vertical stabilizer, usually resulting in a weight penalty over conventional tail designs.

When flying at a very high angle of attack with a low airspeed and an aft CG, the T-tail airplane may be susceptible to a deep stall. In a deep stall, the airflow over the horizontal tail is blanketed by the disturbed airflow from the wings and fuselage. In these circumstances, elevator or stabilator control could be diminished, making it difficult to recover from the stall. It should be noted that an aft CG could be a contributing factor in these incidents since similar recovery problems are also found with conventional-tail aircraft with an aft CG.

Since flight at a high angle of attack with a low airspeed and an aft CG position can be dangerous, many airplanes have systems to compensate for this situation.
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