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Wing Twist - posts deleted after this

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This was the last content before Posky stated to `wipe' my posts..[h2]Wing twist[/h2]Personally I think the wing angles are backwards. The Wing incidence is normally POSITIVE and the tips twist DOWN or NEGATIVE.http://www.edwinn.com/flightsim/wing_twist.pngUse settings such as thesewing_incidence = 1.251wing_twist = -1.50wing_incidence = 1.00wing_twist = -1.250wing_incidence = 1.00wing_twist = -1.000p.s. sender agrees that wing incidence and wing twist effect cruise pitch, but the cruise lift scalar and apex_lon should be used to tune for pitch angle, not wing twist..!!

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Hi,I'm not quite sure what you are getting at, but most aircraft have what we call "wash in" at the wing tip. That means the angle of incoidence at the tip is less than at the root. The purpose for this is to cause the tip to stall last. You want the stall to begin at the wing root and work outboard. Thus, as the aircraft stalls, the tips are still providing lift, and thus a more stable aircraft. An aircraft with "wash out" at the tip is mean machine during a stall, and will in most cases enter a snap roll. Hope this helps.Regards,Bob I

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>>I'm not quite sure what you are getting at, but most >aircraft have what we call "wash in" at the wing tip. That >means the angle of incoidence at the tip is less than at the >root. The purpose for this is to cause the tip to stall >last. You want the stall to begin at the wing root and work >outboard. Thus, as the aircraft stalls, the tips are still >providing lift, and thus a more stable aircraft. An aircraft >with "wash out" at the tip is mean machine during a stall, >and will in most cases enter a snap roll. Hope this helps. >>Regards, >Bob I Wash In - Wash Out[/font size]Hi Bob..I think we are saying the same thing .. only the 767's that I edited had a NEG wing root angle and a POS wing tip angle .. which I believe would cause the tips to stall first. Not to mention the effect it has on cruise pitch!!Would not want to start tuning for cruise_lift_scalar before the wing twist is `in the ballpark' .. and likewise I would not use the `twist' to tune for pitch (my own technique - yours may differ).Note: content is for development purposes and subject to change.[/font size]Gregory Abbey - Edwinnengineering

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Hmm, Well i don't know what you mean by the tips of the Wing's twisting Down in Flight??? Off all the PIC's i seen of a real 747-400 in flight the wing tip sure does not look like it bends down!!? I see the wing tips on a fully loaded 747-400 bending upward and above the fusealge!!! So maybe it's a limitation of FS2002 to make that effect happen, so Please don't go bashing POSKY in here for wrong modeling technic's!! If you don't like the Model just Delete it or don't download it! Since this subject might turn into a POSKY Bashing thread, I apprecite al of Posky work and it's free! So unless you are a real Pilot or an ANircraft engineer Please Don't post Negative comments till the plane actually comes out! Thank's MIKE-:)

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>Hmm, Well i don't know what you mean by the tips of the >Wing's twisting Down in Flight??? Off all the PIC's i seen >of a real 747-400 in flight the wing tip sure does not look >like it bends down!!? I see the wing tips on a fully loaded >747-400 bending upward and above the fusealge!!! Hi Mike..You are describing the wings `flexing upward' due to loading (weight). I've not mentioned wing-flex here. Look again at the figure in the post above. See how the tip of the wing is `twisted' such that the leading edge is lower that the training edge (NEG angle)!!Likewise.. the wing `root' has an incident angle with the leading edge higher than the trailing edge (POS angle). The wing at the root starts off with a POS incidence angle and then transitions NEGATIVELY out to the tip, where it's now a NEG angle.Hope this helps clarify..!!Gregory Abbey - Edwinnengineering

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I'm confused about much of what is being written here... but I'm not confused about aerodynamics and aircraft design.The picture shown in Edwinn's post is the correct way for a wing to be built. The wing root almost always (there are exceptions... such as a radical wing design) has more incidence than the wing tip. And for the reasons outlined by Bob. A wing constructed this way has "wash-out", while a wing with more incidence at the tip than the root has "wash-in" (sorry, Bob, you switched the terms). Personally, I wouldn't want to fly a standard configuration (i.e. one that doesn't use a radical wing design) airplane that uses wash-in. The stall characteristics Bob rightfully described are outside my "fun zone". :-eek BS Cal-Poly, Aeronautical Engineering

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Hi Greg,I sure did switch em. Sorry, been a long time since I used those terms.Bob

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>I'm confused about much of what is being written here, but >I'm not confused about aerodynamics and aircraft design. >>The picture shown in Edwinn's post is the correct way for a >wing to be built. The wing root almost always (there are >exceptions, such as a radical wing design) has more >incidence than the wing tip. And for the reasons outlined >by Bob. A wing constructed this way has "wash-out", while a >wing with more incidence at the tip than the root has "wash-in". >>BS Cal-Poly, Aeronautical Engineering Wing designThanks Mr. GregI yield the floor to the Aero Engineer. My background in dynamics comes from Beer and Johnson, circa 1979 and the study of physics. Before creating that figure on wing twist, I did a number of web searches on `wing twist'. The main reason for this was to adjust for incorrect `pitch angle' during flight. It was logical to start pitch tuning with a `known' +1.0 incidence and a -1.0 twist. Adjustments from there focused on the Apex_lon and the cruise_lift_scalar numbers (amongst other things) to get just the right `flight attitude' while ranging weights from really light to almost full.Please comment on typical pitch angles vs IAS for a number of aircraft.Cheers..!!Gregory Abbey - Edwinnengineering

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