question regarding leading slat
oliver
(sealed),and flap usually 11 or 15 degrees; during landing, slat is
full extended(unsealed) and flap is set to 40 degrees.
My question is: why slat is sealed when taking off and unsealed duing
landing?
thanks!
matt weber
During takeoff you want maximum lift, and minimum drag, as the
aircraft tends to be quite heavy, and at high weight, MD80's and D9's
often didn't have especially good short field characteristics. Put as
much of the engine performance as you can into lift, and as little as
possible into drag. You want to maximize L/D. Keep the open spaces
between the control surface to an absolute minimum for minimum drag.
On landing, the aircraft is much lighter, the unsealing causes a
signficiant increase in drag. Increasing the drag allows you to
increase the rate of descent, and to bleed off excess speed more
easily. The full extension of the leading slats provides more lift,
but with a hefty drag penalty, reducing L/D. On approach and after
touchdown, the hefty drag penalty tends to be a useful.
Boeing is in fact in the process of sealing many control surfaces and
altering the Kreuger flaps schedule on the 737-900ER to improve the
short field performance! Since CFM isn't building a bigger engine for
the -900ER, but MGTOW is going up about 13,000 pounds, there is a need
to improve the takeoff performance.
tomst...@gmail.com
thin, black hair was stuck eagerly forward, and all his motions
and evolutions expressed a dry, cautious acuteness. The great man
poured out a big tumbler half full of raw spirits, and gulped it
down without a word. The little man stood tiptoe, and putting his
head first to one side and then the other, and snuffing considerately
in the directions of the various bottles, ordered at last a mint
julep, in a thin and quivering voice, and with an air of great
circumspection. When poured out, he took it and looked at it with
a sharp, complacent air, like,a man who thinks he has done about
^^^
the right thing, and hit the nail on the head, and proceeded to
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"Wal, now, who'd a thought this yer luck 'ad come to me?
Why, Loker, how are ye?" said Haley, coming forward, and
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"The devil!" was the civil reply. "What brought you here, Haley?"
The mousing man, who bore the name of Marks, instantly stopped
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I'm in a devil of a hobble, and you must help me out."
"Ugh? aw! like enough!" grunted his complacent acquaintance.
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"You've got a friend here?" said Haley, lookin
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nostrils, she drew herself up, and fixed a glance, blazing with
rage and scorn, on the driver.
"Dog!" she said, "touch _me_, if you dare! I've power enough,
yet, to have you torn by the dogs, burnt alive, cut to inches!
I've only to say the word!"
"What de devil you here for, den?" said the man, evidently
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"Keep your distance, then!" said the woman. And, in truth, the
man seemed greatly inclined to attend to something at the other
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The woman suddenly turned to her work, and labored with a
despatch that was perfectly astonishing to Tom. She seemed to
^^^^^^^^ -?
work by magic. Before the day was through, her basket was filled,
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"Dat ar Tom's gwine to make a powerful deal o' trouble; kept
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said Sambo.
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Both negroes grinned a horrid grin, at this intimation.
"Ay, ay! Let Mas'r Legree alone, for breakin' in! De debil
heself