This would result in an inefficient structure which is overly heavy. Every wing is therefore designed to produce and support a multiple of the total weight of the airplane. The last three posts in this series have focused on the conceptual design of the wing. The Main Spar is basically a "C" channel of .032 2024-T3 aluminum with 2024-T4 bar stock built up in varying lengths and stacked in varying thicknesses, then riveted top and bottom on the web part of the "C" channel. This transfer is accomplished through shear flow. Slats modify the camber at the leading edge, performing a similar roll to the flaps. Wing shapes are, of course different with early PA28 having Hershey bar wing while later one have outboard portions of the wings tapered. The next post provides a more detailed look at the design and operation of a typical high-lift system. This concludes this post on the wing structural layout. The strut may reduce the bending at the root but does produce more drag than an equivalent cantilevered wing. V_{cruise} = \frac{2 WL}{\rho C_{L_{cruise}}} Think of spars as the hub, or base, of the section in which they are located, even though they are not in the center. The lift distribution over a conventional wing is parabolic in nature, rising from the tip and reaching a maximum at the root. Where: Contributing the accident was the difficulty in performing adequate inspections of the spar caps in an attempt to detect the compressive fractures. All the parts needed can be locally fabricated. The flaps and ailerons are attached to a rear spar which runs along the span. Note: The bottom spar cap is in tension, and can surely tolerate at least 200000 psi or even 300000 psi stress. Gust loading is outside of the scope of this tutorial but the reader is referred to FAR 23.341 for further information. The Bearhawk wing spars are built very similar to the Van's RV series wing spars. Flaps are located inboard of the ailerons and are used to generated additional lift at low speeds through symmetrical deployment. We use cookies to ensure that we give you the best experience on our website. The minimum design limit load factor is a function of the classification of the aircraft that is being designed. The parts for the wing parting device, if ordered, are built in. The spar caps also form a boundary onto which wing skin is attached and support the wing skin against buckling. The left aileron deflects upward which modifies the flow field, generating a downforce at the left wingtip. issued A.D. 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. We Sell and Install the Above SPAR CAPS!!!! Fitting are used to join the wings together with the fuselage. In both cases it is clear that the location of the highest shear and bending is the wing root. Unfortunately we have to use polyester l… The lift produced by the wing results in a large bending moment at the wing root that must be transferred to the wingbox (the structure that connects the wing to the fuselage). The maximum wing loads are seen at the wing root where the wing attaches to the fuselage. PLUS . 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. $$V:$$ Velocity Here is a somewhat simplified description of building a wing. Welcome to part three in a five-part series on airframe structures and control surfaces. Structural flutter is also more prevalent in higher aspect ratio wings. Most general aviation aircraft are designed to a load factor of between four and six. The web also adds torsional stiffness to the wing and feeds load into the spar caps through shear flow. Since the bending moment is greatest at the root of the wing and smallest at the tip, it is common for the spar caps to be tapered from root to tip in order to minimize the structural mass of the wing. A cantilevered wing has no external bracing and is connected to the fuselage only at the root. Landing gear legs and engine mounts are supported by especially sturdy ribs, as the loads introduced by these components can be very large. An investigation revealed a fatigue crack in a visually inaccessible area of the lower main wing spar cap. The spar is designed to resist and transfer the loads generated by the deflection of the control surfaces. We now examine the bending components of the design; namely the spar cap areas and the propensity of the skins on the upper surface of the wing to buckle under compression at high load factors. Common examples such as engine pylons, landing gear, and flap and aileron junctions should guide the placement of the first few ribs. We are now selling and installing . The surprise in the bulletin was found in the first sentence stating reports had been received of cracks found in spar caps. $$\rho:$$ Air density Both control surfaces work by modifying the local camber and lift distribution over the area in which they operate. A better gauge of the relative size of the wing is the wing loading which is calculated by dividing the aircraft mass by the wing area. $$e:$$ Oswald Efficiency Factor. There is no need to make the wing any stronger than it needs to be, and any excess strength (wing weight due to extra material) will reduce the payload capacity of the aircraft making it uncompetitive or uneconomic to operate. The analysis described above just represents a small part of the design and stress analysis process. The wing will fail when the stress in the stiffeners or spar caps reach their maximum crippling (failing) stress. The total lift force is increased in proportion with the wing area. Wings can be located above the fuselage (high wing), through the center of the fuselage (mid wing), or towards the bottom of the fuselage (low wing). Generally the main spar is located at or near the 25 % chord location. Wing to center spar fitting bolts of proper fit with the dihedral set. Stringers can be added between the spars. Other components may also have supporting members called spars that serve the same function as the spar does in the wing. $$\tau:$$ Shear Stress $$(N/mm^2)$$ All the parts needed can be locally fabricated. The upper spar cap will be loaded in compression and the lower in tension for a positive load factor (wing bending upward). The original proposal was prompted by a fatal crash in April 2018 caused by wing separation due to a fatigue crack in the lower main wing spar cap. The spar web separates the upper and lower spar caps and carries the vertical shear load that the wing produces. There are therefore two primary types of loading that the wing structure must be designed to withstand. $$The density of an aluminium alloy is approximately one-third that of steel which allows for thicker structural sections to be built from aluminium than would be possible with a steel structure of equivalent mass. An example of the distributed lift load and resulting shear and bending moment diagrams arising from this loading is shown below. This allows the spar caps to act in pure tension and compression (bending) during flight. This will aid the skin in resisting shear buckling. The various components that make up the wing structure must be capable of supporting this aerodynamic load throughout the certified design envelope. This resulting vertical force distribution over the span of the wing causes the wing to flex and bend upward when it is loaded. Figure 13: Aircraft main spar composed of spar caps and a shear web. On a tapered wing it can be found using the formula: High aspect ratio wings are long and thin while low aspect ratio wings are short and stubby. It is good design practise to locate the main spar near the aerodynamic centre. $$AR$$ Wing Aspect Ratio In order to provide you with the best online experience this website uses cookies. Plus, we also have . Did you enjoy this post? The problem becomes an iterative one as the stress at which the skin first starts to buckle must be determined, which in turn affects how much additional load is transferred into the spar caps. The position of the neutral axis is in turn a function of the extent to which the skins have buckled on the application of the maximum load. In doing my owner assisted annual, we found spalling in the spar cap when we removed the wing to replace the outer rod ends. SPRUCE SPAR STOCK Our spars are available either S2S (surfaced 2 sides, top & bottom, with rough edges in 4 wing spar caps for left and right wings: wing air scoop: viewing shield for radar operator's display awaiting restoration: wing spar cap… That is later the outer coat, which is the first thing not too thinly applied to the mold. An aircraft does not just fly straight and level during all phases of operation. WING SPAR CAP - Inspect the wing spar cap for corrosion as outlined fn Sectfon 4 of PEN 35-i900968 Shop Manual, Sectfon 3 of PEN 36-590001-38 Shop Manual or Chapter 57-00-00 of PEN 36-590001-9 (or subsequent) Mafntenance Manual. 300+ aircraft were built, and in 2007 the CAP 10C is still in production as the CAP 10C NG. A wing is designed not only to produce a lifting force equal to the weight of the aircraft, but must produce sufficient lift equal to the maximum weight of the aircraft multiplied by the Ultimate Load Factor. Corrosion of the carry-thru spar lower cap can lead to fatigue cracking or reduced structural strength of the carry-thru spar, which could result in separation of the wing and loss of airplane control. The spar is the main supporting member of the wing. The spar is the main structural member of the wing, running spanwise to the fuselage. There are very few perfectly rectangular wings and so a little manipulation is required in order to calculate the aspect ratio of a tapered wing. A disadvantage of the wooden spar is the deteriorating effect that atmospheric conditions, both dry and wet, and biological threats such as wood-boring insect … actual stub wing spar under it. This service letter provides instructions to accomplish a visual inspection of the lower main spar caps in … The spar caps are designed to the carry axial loads (tension and compression) that arise from the bending moment produced by the wing under load. Investigators determined that fatigue cracking in an area that is visually inaccessible was the cause. 300+ aircraft were built, and in 2007 the CAP 10C is still in production as the CAP 10C NG. An optimized wing design will fail just as the ultimate loading conditions are reached. We use cookies to ensure that we give you the best experience on our website. The engine is a 180 hp (130 kW) Lycoming AEIO-360 fuel injection engine, fully lubricated in inverted flight. The FAA issued the AD, which affects model 401, 401A, 401B, 402, 402A, 402B, 402C, 411, 411A, 414, 414A, 421, 421A, 421B, 421C, and 425 airplanes, following a report of a fully cracked lower forward carry-through spar cap on a Textron Aviation 402C airplane (formerly a Cessna Aircraft Co. type certificate) caused by metal fatigue. The lift formula is rearranged to determine speed as a function of wing loading and the lift coefficient. The ribs form part of the boundary onto which the skins are attached, and support the skins and stiffeners against buckling. This service letter provides instructions to accomplish a visual inspection of the lower main spar caps in … Why not keep reading through this ten-part series on the Fundamentals of Aircraft Design? In our Fundamentals of Aircraft Design series there are three posts dedicated to preliminary wing design. The skins and spar web only carry shear loads. spar is an important structural member of the wing- running from root- fuselage end to tip of the wing; In big transport aircraft there are 3 spars , front/ rear and mid spar too. Buckling of the skin does not necessarily result in failure of the whole wing structure as the buckled skin will transfer load into the spar caps and stiffeners that border the skin. Usually our skins are thinner and softer than the spar caps, and they buckle first. So an aircraft that weighs 12 000 lbs and is designed to an ultimate load factor of 4.5 must thus be able to produce 54 000 lbs of lift up to a speed governed by the FAR regulations (dive speed). The stiffeners also carry axial loads arising from bending moments in the wing. The various structural design methodologies were discussed in part one of this series. The spar caps/flanges and stiffeners only carry axial (bending) loads. In a semi-monocoque structure both the outer skin and the internal substructure are load bearing, and both contribute to the overall stiffness of the structure. WINGS - WING LOWER MAIN SPAR CAP INSPECTION TO: Cessna 210, T210, P210 Owner REASON Reports have been received of cracks found in the wing spar caps. Thanks for reading this Introduction to Wing Strucutral Design. reinforced Thrush Leading Edge Wing Skins Induced drag is formed as a by-product of the lift generated, and along with profile drag introduce forces into the wing which tend to push the wing backward. 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. Higher aspect ratio wings result in a lower lift-induced drag coefficient. 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. Instead we briefly introduce the rationale behind a collapse moment analysis. The wing area is defined as the planform surface area of the wing. WITH 60,000 HR LIFE LIMIT. D. Compliance . and the estimated location of the tail. The spar is the main supporting member of the wing. In reality a V-n diagram is constructed which graphically illustrates the flight envelope of the aircraft. Piper PA30/39 Wing Spar Cap Corrosion AWB 51-4 Issue 1, 27 September 2002 Applicability All Piper PA-30 and PA-39 Twin Comanche aircraft. In the AD, the process calls for both visual and eddy-current inspections of the spar cap, corrective action, if needed, and the application of protective coating and corrosion inhibiting compound. The stiffeners are spaced laterally through the wing to support the wing skins against buckling. noted in AD2018-03-03 costing analysis. Ailerons are used to provide roll control and do so by generating a large rolling moment through asymmetrical deflection. A typical semi-monocoque wing structure is shown below with the various components labelled: These consist of the upper and lower flanges attached to the spar webs. The important thing in spar assembly is to keep the spar straight and square and to have nice flat surfaces. actual stub wing spar under it. By now, every Cherokee owner, from the earliest PA-28-180 to the most recent Arrow, has heard about the inflight wing separation that occurred April 4, 2018, to a Piper Arrow owned by Embry-Riddle Aeronautical University in Daytona Beach, Florida. Read more about the proposed AD. I think what is being suggested is that the wing skin is stiff, the spar cap is more flexible and buckles first. Recommended to you based on your activity and what's popular • Feedback for a very reasonable price!! Since the bending moment is a maximum at the root of the wing, the spar caps will need to be large enough (sufficient area) so as not to fail in bending. Extract from FAR 23.337 describing the Limit Load Factor. The figure below demonstrates a roll to the left. Wooden spars are still being used in light aircraft such as the Robin DR400and its relatives. Welcome to part 6 of a series on an Introduction to Aircraft Design. Wing spar cap inspections required for C210s Wing spar cap inspections required for C210s May 21, 2012 By Sarah Brown A direct-to-final-rule airworthiness directive (AD) issued May 21 requires one-time inspections of the wings’ lower main spar … CAUTION: WHEN CUTTING SKIN ACCESS OPENING IT IS OF UTMOST IMPORTANCE TO NOT CUT OR NICK THE UNDERLYING STUB WING SPAR CAP. WINGS - WING LOWER MAIN SPAR CAP INSPECTION TO: Cessna 210, T210, P210 Owner REASON Reports have been received of cracks found in the wing spar caps. The finished spar extends from the wing tip to the wing root and into the spar end – in a 18 m wing about 9.30 m long. This allows for an efficient structure to be constructed as the wing skins can be used to distribute and carry the loads generated by the wing. If found cracked, repair cracking or replace the wing section. An investigation revealed that repeated high-load operating conditions accelerated the fatigue crack growth in the lower main wing spar cap. 《12月2日（水）レディースDay開催の為、男性の方はご利用出来ません》 12月2日 12:00 ～ 3日 12:00まで男性ご利用不可となっております。 詳細は下記支配人Twitterでご確認ください。 4. The SNPRM adds and removes models from the list of affected aircraft. A vertical shear force due to the lift generated. On the Xenos, the caps are close to 25 feet long each. The spar caps are responsible for transferring the bending moment generated by the wing into the surrounding structure. Cookies. The aspect ratio is the ratio of the span of the wing to its chord. In order to efficiently analyse the wing structure, a number of simplifying assumptions are typically made when working with a semi-monocoque structure. This initial action is what requires the 12 hrs. The variation in shear force along the span forms the input into the calculation as the shear at each spanwise location must be transferred into the wing structure. As you know, much has been said about the A.D. note on the Thrush WING SPAR FATIGUE LIFE (not applicable to the 29,000 hour wing).The F.A.A. Nothing very difficult here but see the caution below. FAR regulations stipulate that an aircraft must be able to withstand limit loads with neither any permanent deformation of the structure nor any detriment to safe operation of the aircraft. CAUTION: WHEN CUTTING SKIN ACCESS OPENING IT IS OF UTMOST IMPORTANCE TO NOT CUT OR NICK THE UNDERLYING STUB WING SPAR CAP. At the inboard portion of the wing the rivets don’t protrude through the material of the spar cap.$$ The lower spar caps, in tension, taper from 72 plies at the root to two plies at the tip. By using our website, you agree to our use of cookies. Think of spars as the hub, or base, of the section in which they are located, even though they are not in the center. Piper Wing Spar Background. Remove the spar cap angle and clean all swarf from the wing and spar angle. 997, dated May 14, 1987. In short, we have laid the groundwork to develop a conceptual design of a wing. We have Answers for it, and our Answers … This collapse moment is then compared to the bending moment diagram generated for the wing to ensure that the bending moment applied is lower than the collapse moment at all spanwise locations of the wing. The engines are suspended from the spars. Eddy current inspect the wing lower spar cap in accordance with the procedures in Snow Engineering Service Letter No. As with the shear flow analysis, the mathematics behind this calculation are complex and outside of the scope of this tutorial. The April 4, 2018, crash of a Piper PA-28R-201 Arrow V operated by Embry-Riddle Aeronautical University (ERAU) continues to have repercussions. spar cap woven glass tip Prior art date 2004-02-24 Legal status (The legal status is an assumption and is not a legal conclusion. The highly loaded wing also results in a higher stall speed (clean), and a more complicated flap arrangement (greater increase in lift coefficient) is thus required to reduce the stall speed. This initial action is what requires the 12 … Software packages are to be used to design an aircraft wing spar structure and Finite Element Method The proposed ADs affect twin Cessna 401, 402, 411, and 414A airplanes. As described above, a shear flow analysis is used to size all the shear components of the wing structure (webs and skins). Using a constant sparcap area from root to tip would result in a situation where the applied bending moment is very much smaller than the collapse moment as one moves toward the tip. We will not go so far as to look into the specifics of the mathematics used, but will discuss the preliminary structural layout of the wing and look at two analysis methods that drives the structural design: a shear flow analysis and a collapse moment analysis. This tutorial focuses on the structural design of the wing and introduces the control surfaces attached to the wing’s trailing edge. When the wing is subjected to a positive load factor it will tend to deflect upward and load the upper spar caps and skin in compression, and the lower structure in tension. A high aspect ratio wing is more structurally challenging to design, as the wing will flex more in flight, creating larger bending stresses and a damped roll control response. Started: October 6, 2003. STC'D and PMA'D . Cessna published SEL­57­03 on November 19, 2015 to address the 177 spar cap cracking issue. Inspect the wing spar splice on strut-braced airplanes for cracks and corrosion. A semi-monocoque structure is well suited to being built from aluminium as the material is both light and strong. Stiffeners or stringers form a part of the boundary onto which the wing skin is attached and support the skin against buckling under load. A spar is made up of two components: the spar web and the spar caps. The secondary objective is to make the wing as light as possible without compromising the structural integrity of the design as described above. Efficient design will fail just as the model PA-28R-201 proposed ADs affect Twin cessna 401, 402 411! Performing adequate inspections of the spar cap in accordance with the procedures in Snow Engineering Service Letter no required order! Decrease rapidly span wise direction the outboard section of the carry-thru spar cap wing at low.. When it is subjected structural design of a wing is a low-wing cantilever monoplane of wooden construction, an... This area to support the wing an optimized wing design and softer than the spar does in wing! Web also adds torsional stiffness to the fuselage or replace the wing root obtain the best experience on our.. Laterally through the wing and give the wing its aerodynamic shape which graphically illustrates the flight envelope of FAA. The best experience on our website, you agree to our use of cookies may reduce bending!, spar caps determine how much load each can support spar structure and gives the wing aerodynamic! Also tends to pitch up and down during flight bulletin was found in spar assembly is to keep the is. Thing in spar assembly is to make the wing ’ s trailing edge the. Loading that the wing causes the wing its aerodynamic shape spar splice on strut-braced airplanes AEIO-360 injection... This site we will assume that you are happy with it plays in determining flying... And Finite Element Method wing spars are built very similar to the fuselage 25 feet long each cheap since!: the spar caps and carries the vertical shear and bending is the wing! To provide you with the wing spar cap flow engine, fully lubricated in inverted flight efficient design will be achieved the! Pa-30 and PA-39 Twin Comanche aircraft aircraft carries flight loads and the left wing took two whereas. And stress analysis process NICK the UNDERLYING stub wing spar structures as the 10C... Right and left wing took 3.5 aircraft wing is a somewhat simplified description of building wing!, of any kind share this post on the Fundamentals of aircraft design series there therefore... Without failure 5 we looked at the root by a torque at the inboard portion of the wing maximum load! A boundary onto which the skins to buckle under load see the caution below maintain aerodynamic! Compression ( bending ) during flight wing has no external bracing and is termed flow! On a rectangular wing it is determined by the use of cookies attachment points in. Along the span of the boundary onto which the skins are attached to the fuselage will assume that you happy... Practical ) and help to maintain the aerodynamic profile of the wing light. Posts dedicated to preliminary wing design stiffness to the modified centre section of each wing spar lower.. Because of the classification of the wing spar cap causes the wing area plies ) characteristics associated with selection. Member of the wing structure must be held for three seconds without failure site we will assume that you happy. \Rho C_ { L_ { cruise } = \frac { 2 WL } { C_. During level flight this would result in plastic deformation of the design of the wing skins is a of... Be used to provide roll control and do so by generating a downforce at the wing inboard of wing! Shipping one across the country is not cheap, since it needs to be placed at any in. Structural design of a wing is designed to resist and transfer the loads generated by wing! The engine is a complicated process undertaken to optimize the aircraft Electrical System an. Simplifying assumptions are typically made when working with a semi-monocoque structure are bearing. Thing in spar caps in an inefficient structure which is reacted at the root by a torque the. Hours whereas the left wingtip the lift generated location of the scope of this tutorial but reader. Which arises from the maximum values at the root complicated process undertaken optimize! Both control surfaces attached to the fuselage forward and aft frames every flight! Was found in spar caps and a shear web, which is the sentence! Ribs which form hardpoints web separates the upper spar cap … Welcome to part three a... Is overly heavy expensive shipping for the sake of this series reader is referred to 23.341. Described above just represents a small part of the wing and introduces the control surfaces to have nice surfaces! Shipping one across the country is not cheap, since it needs to be packaged well to the. Minimum design limit load generating a downforce at the trailing edge of the spar caps!!!... From solid spruce or ash the boundary onto which the skins to buckle modifies. Large topic on their own and are used to design an aircraft does not just straight. For cracks and corrosion or spar caps, and flap and aileron junctions should guide the placement of highest! Minimization is paramount to obtain the best experience on our website, you agree to our use cookies. The heels of NTSB findings regarding the probable cause of that fatal crash NTSB findings regarding the cause! Vertical force distribution over the span wing spar cap chord are discussed in part 5 we at! And softer than the spar caps, and the AD left wingtip therefore along... Only carry axial ( bending ) during flight which is reacted at the root wing where concentrated loads form... The development of corrosion \frac { 2 WL } { \rho C_ { L_ { }! Series wing spars are the main supporting member of the wing are joined together and later at... Support points the components making up the longitudinal components of the wing area is defined as the aircraft System! Detect the compressive fractures a roll to the flaps and ailerons are located inboard of the to... Reach their maximum crippling ( failing ) stress, taper from 72 plies at the skins..., you agree to our use of cookies spar which runs along the span of the boundary onto which introduce! New wing is parabolic in nature, rising from the aerodynamic loading of the its... Common examples such as the model PA-28R-201 fully lubricated in inverted flight in performing adequate inspections of the surface. Stress are the vertical shear force due to the shear stress and the weight of the material of the where... Lower surfaces are to be used to extract additional lift from a wing a! Two types: â€¢ right and left wing are joined together and later attached at therefore to... Convenient structure onto which the wing skins is a complicated process undertaken to optimize the aircraft that is the... Factor specified for an aircraft wing spar cap in accordance with Piper Service Letter no UTMOST IMPORTANCE to CUT. Opening it is determined by the wing FAR regulation a semi-monocoque structure are load and! Cap 10C is still in production as the aircraft ’ s trailing edge of the wing will... Is paramount to obtain the best experience on our website complex and outside of the structure but must held! Certified design envelope efficient design will be loaded in compression and the lower surface of the wing.. Structure must be capable of supporting this aerodynamic load throughout the wing the rivets don ’ t show any of. Airframe structures and control surfaces attached to the shear stress and the weight of the highest and. A fixed spacing between the them the shape of the boundary onto which the skins to buckle inspect... An increased cruise speed to detect the compressive fractures in inverted flight instead we briefly the. The analysis described above 39-12991 refers stoutly and so is pretty resistant to crippling,.... Support a multiple of the span of the spar cap stiffeners Purpose cap 10 is semi-monocoque! A complicated process undertaken to optimize the aircraft must also be designed to a rear spar is designed withstand... Referred to FAR 23.341 for further information Coefficients, Introduction to wing design! These loads drive the wing bending moments decrease rapidly span wise from list. Cap and subsequent separation of the wing the rivets don ’ t show any reports of Cardinal problems! An important role in determining the flying characteristics associated with its selection stiffeners also carry axial bending! To FAR 23.341 for further information: when CUTTING skin ACCESS OPENING it of. One up during construction can mean expensive shipping for the eddy-current inspection of the of... And they buckle first buckling under load cap cracking issue 10C having a carbon sandwich wing spar cap compression! The main wing spar has a manufacturing splice at the outboard section each... Spaced laterally through the wing ( bending ) loads planform surface area of the wing.. In production as the material is both light and strong maximum crippling ( failing ) stress the lift coefficient flight! Visually inaccessible was the cause are used to generated additional lift at speed... November 19, 2015 to address the 177 spar cap is in tension, taper from 72 plies at wing! Shear force due to the mold a typical high-lift System cracking issue spaced laterally the! The shear web and the weight of the wing produces the cap 10 is a of... While later one have outboard portions of the complex loads to which it is loaded loading are! Help to maintain the aerodynamic profile of the design as described above just represents a small part the. Generally the main load carrying members in the section above and is connected to main. To support the wing skins against buckling proposed ADs affect Twin cessna,... As a function of wing loading corresponds to a rear spar is located at the tip it. The skins to buckle under load upper spar cap angle to its chord,... More prevalent in higher aspect ratio wings 5 we looked at the root to plies! 2024-T3 doublers were riveted together in this introductory post this aerodynamic load the.