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4 Answers

Type of wing designs?

Asked by: 4187 views Aerodynamics, Commercial Pilot, Flight Instructor, General Aviation

Not that I am trying to become an instructor but this was always a curiosity to me when I would see a Dassault Falcon with negative dihedral, a Challenger with about a zero dihedral and the king airs with positive dihedral. I understand that this has to do with the lateral stability of the aircraft to return to wings level, but what does the negative/zero dihedral do as far as stability? Also the kinds of wing designs that manufacturers implement is a foggy topic I fully have not grasped. Your input is appreciated!

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4 Answers



  1. Ernest Ortner on Oct 08, 2014

    I am not an instructor but I’m trying to get there so I will take a stab at this one. Like you pointed out dihedral gives the aircraft stability, stability directly affects two things; maneuverability and controllability. The negative dihedral is commonly referred to as “anhedral.” The more dihedral an aircraft has the more difficult it will be to disturb its lateral stability. When you also add in swept wings, which also positively affect lateral stability, you begin to make an aircraft so stable you can’t bank. For aircraft that fly at faster speeds you do not want to sacrifice the positive effects of swept wings so you reduce your dihedral to gain more maneuverability, sometimes to the point it is anhedral, a great example is the AV-8. Aircraft with high mounted wings also add to lateral stability from keel effect, large aircraft like C-5s have anhedral. As you pointed out this would typically lead to lessened stability. To try and put dihedral into perspective you can look at it as “dihedral effect,” mounting a wing higher on the aircraft adds dihedral effect, sweeping the wings back adds dihedral effect as well. So you can adjust the design of your aircraft to account for these to give the aircraft the stability you are looking for depending on the intended mission of the aircraft. Wings are designed to perform different jobs there is not one airfoil that does them all perfectly. Manufacturers must look at what the aircraft is going to be used for and then determine the best wing design.

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  2. Ernest Ortner on Oct 08, 2014

    Also, take a look at the Pilot’s Handbook of Aeronautical Knowledge (PHAK), FAA-H-8083-25A, Chapters 3 and 4.

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  3. nyc_pilot on Oct 08, 2014

    Thanks Ernest I will read into that. Also my friend was explaining to me that in a swept wing a/c in straight and level flight if it is disturbed and banked/tilted to the right in this case that the left wing is more exposed to the relative wind while the right wing is less exposed and and increase/decrease in slipstream on both wings is what returns the a/c back to wings level. How does this apply to an aircraft like a single engine archer or a falcon that has anhedral, and is this theory of mine on the right track?

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  4. Ernest Ortner on Oct 08, 2014

    Archers have a very slight swept back wing and dihedral for stability. The falcons have swept back wings which will give the aircraft stability as well. If you look at all the factors as giving you an overall stability represented as a number then it clears it up a little bit. If you want positive stability you will want a positive number so you have to put the pieces together properly; dihedral (positive), swept wings (adds lateral stability), and keel effect (high wings add to lateral stability). The explanation of why swept wings give lateral stability is close or I do not understand what you are saying. When you bank the aircraft without turning it will cause a sideslip condition the lower wing will become perpendicular to the relative wind which will increase the lift on that wing and thusly the drag, bringing the wing up and back to wings level. The archer has a slight sweepback to the wing and dihedral giving it good stability for a light single engine aircraft. The falcon flies faster so the sweepback is more pronounced adding to the stability. The manufacturer gave it some anhedral only to improve its maneuverability. I can’t explain exactly why but it met standards to certificate the aircraft so it did not sacrifice stability to the point of it being unsafe.

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