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delta wing incidence?

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Old 03-12-2002, 08:58 PM
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gsoav8r
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Default delta wing incidence?

Hi all,
Is there a such thing as wing incidence with repect to a delta? Most of the time when I here talk about incidence, the person is talking about a conventional aircraft and comparing the wing angle to the horizontal stab or vise versa.
Anyway. With a delta wing I am wondering what the pros and cons are to building in +2-3 degrees of wing incidence in respect to the thrust line.
Would the delta wing require more reflex or less?
Would the plane have a tendency to balloon like a trainer does when speed is increased?
Would I even notice it?
Any input is appreciated.
Thanks.
James
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Old 03-13-2002, 03:22 AM
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gubbs3
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Default delta wing incidence?

If you think about it you won't really be building in incindence but only adjusting thrust angles. Without the horizontal stab the main wing incindence will have nothing to do with how it will fly unless there is a thrust issue. I suggest building the wing straight (or with washout) and adjust thrust angles as needed.
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Old 03-13-2002, 10:36 AM
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Ollie
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Default Up or Down Thrust

The purpose of up or down thrust is to minimize pitch attitude changes with throttle variation. If the thrust line falls above the center of drag of the aircraft, then up thrust is required to compensate for the thrust-drag couple which tends to pitch the nose down. If the thrust line falls below the center of drag then down thrust is required. If the thrust line is aimed through the center of drag then the moment arm of the thrust-drag couple is zero and the pitch attitude is unaffected.

A low aspect ratio delta flies with a lot of induced drag caused by the vortices at the wing tips. Induced drag tends to dominate the drag budget of the whole aircraft. Running the thrust line through the wing center is a reasonable starting point for adjusting the thrust line on a delta which has no dihedral or anhedral.
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Old 03-13-2002, 02:07 PM
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gsoav8r
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Default delta wing incidence?

Thanks for the info gentlemen.
I think I get it. So by pointing the wing leading egde up 2-3 degress I would in effect actually be building in 2-3 degress of down thrust. Definitely not what I want to do.
Straight it is.
Cheers,
James
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