5/28/2023 0 Comments Wing airfoilGust loading is outside of the scope of this tutorial but the reader is referred to FAR 23.341 for further information. Airliners and larger commercial aircraft do not fall into the FAR 23 category and so are certified in accordance with FAR Part 25 which is the airworthiness standard for Transport Category Aircraft.įurther to specifying the maximum maneuvering load factor, the aircraft must also be designed to withstand a gust loading during level flight. The extract shown above pertains to an aircraft that is to be FAR Part 23 certified which is the airworthiness standard for Normal, Utility, Acrobatic, and Commuter type aircraft. For example, it follows that an aerobatic aircraft will require a higher limit load factor than a commuter aircraft due to the difference in the severity of the maneuvers the two are expected to perform. The minimum design limit load factor is a function of the classification of the aircraft that is being designed. The following extract comes from FAR 23.337:Įxtract from FAR 23.337 describing the Limit Load Factor Therefore a series of regulations are published, which among other regulations, detail the minimum load factor that a particular aircraft class should be designed to withstand. The Federal Aviation Administration (among other regulatory bodies) is responsible for ensuring that all certified aircraft comply to a basic standard of safety. The example above illustrates that there are many cases where the aircraft will exceed a loading of 1g. In this instance, the wing is producing a lift force equal to twice the weight of the aircraft and the aircraft is said to be pulling 2g’s (twice the gravitational force) or operating at a load factor of 2.Ī 60 degree bank angle results in a 2g turn If the pilot banks the aircraft at a 60 degree angle during a sharp turn, he needs to produce twice the lifting force to counteract the weight due to the angle of the lift vector relative to the weight (which always acts downward). Lift is equal to weight plus horizontal tail trim force at 1g Load FactorĪn aircraft does not just fly straight and level during all phases of operation. In the conceptual design phase it is common to account for the additional force generated at the tail by multiplying the aircraft weight by a factor of 1.05 (5%) to account for the trim force alternatively one can estimate the required force based on the estimated design weight of the aircraft and the approximate moment arm between the estimated location of the c.g. The downward trim force comes about as a result of the need to balance the moment generated by the lift vector acting away from the center of gravity of the vehicle. Thus during straight and level flight, the wing provides an upward lifting force equal to the weight of the aircraft plus the trim force generated at the horizontal tail to keep the aircraft balanced. Loads acting on a WingĪ wing is primarily designed to counteract the weight force produced by the aircraft as a consequence of its mass (the first post in this series deals with the fundamental forces acting on the aircraft). In short, we have laid the groundwork to develop a conceptual design of a wing.īefore moving away from the wing we’ll now spend some time introducing the structural design elements that allow the wing to operate safely through all phases of the design envelope. We examined wing area and aspect ratio, introduced sweep and drag divergence and looked in more detail how the airfoil profile determines the flying characteristics of the aircraft. The last three posts in this series have focused on the conceptual design of the wing. In our final introductory post on the wing we look at a typical wing structure, the various loads that the wing is expected to carry during operation, and introduce the methodology behind designing a semi-monocoque wing structure. In part 5 we looked at the role that the airfoil profile plays in determining the flying characteristics associated with its selection. Welcome to Part 6 of a series on an Introduction to Aircraft Design.
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