Forward Swept Wing Advantages And Disadvantages PdfBy Togesheaho In and pdf 24.03.2021 at 00:51 6 min read
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A B Stratofortress showing wing with a large sweepback angle.
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Aviation Stack Exchange is a question and answer site for aircraft pilots, mechanics, and enthusiasts. It only takes a minute to sign up. What are the advantages of a forward-swept wing vs. Image credit: NASA. There have only been a few aircraft built with forward-swept wings. Most notably was the X, which you have pictured above. One of the biggest claims as to the superiority or an advantage of a forward-swept wing was increased maneuverability. The high pitch instability of the airframe led to wide predictions of extreme maneuverability.
This perception has held up in the years following the end of flight tests. Air Force tests did not support this expectation. For the flight control system to keep the whole system stable, the ability to initiate a maneuver easily needed to be moderated. This was programmed into the flight control system to preserve the ability to stop the pitching rotation and keep the aircraft from departing out of control.
As a result, the whole system as flown with the flight control system in the loop as well could not be characterized as having any special increased agility. The Su was indeed a highly maneuverable aircraft, capable of pulling 9 Gs, however, its immediate predecessor, the Sukhoi Su, was capable of pulling 10 Gs. So it's not clear whether a forward swept wing has any real positive impact on maneuverability.
However, stall characteristics are very different. Air tends to travel towards the rearmost end of the wing. On a standard configuration Rear-swept wing , this of course moves from the wing root to the wingtip. On a forward-swept wing, however, this moves from the wingtip to the wing root. As a result, the dangerous tip stall condition of a backwards-swept design becomes a safer and more controllable root stall on a forward swept design.
This allows full aileron control despite loss of lift, and also means that drag-inducing leading edge slots or other devices are not required. With the air flowing inwards, wingtip vortices and the accompanying drag are reduced, instead the fuselage acts as a very large wing fence and, since wings are generally larger at the root, this improves lift allowing a smaller wing. As a result maneuverability is improved, especially at high angles of attack.
At transonic speeds, shockwaves build up first at the root rather than the tip, again helping to ensure effective aileron control. Because of the capability of the X to have the tips of its wings bend down when at high angles of attack, the X remained controllable at an angle of attack of 67 degrees. However, thanks to modern advances in thrust vectoring, the F Raptor is capable of sustaining an angle of attack over 60 degrees.
With inherent instability and problems with extra stresses on the airplane for only moderate or supposed but not observed gains in instability, it is unlikely we will see combat aircraft with forward swept wings any time in the near future. Other technologies have enabled similar or enhanced performance without the need for novel concepts. These two disadvantages easily outweigh the advantages for most designs. The first forward swept design, the Junkers , needed a massive, wrought wing carry-through for stiffness.
Handling was great, but performance overall was poor. Ju with tufted wings and rockets below the wing engines. The tripod ahead of the vertical holds a faired camera for in-flight observation of the tufts. If combined with a T-tail, the aft position of the root of a forward swept wing will ensure that the tail is in the wake of the wing root at a high angle of attack, which can result in a deep stall. The best forward-swept wings can be found in nature: Birds will sweep their wing tips forward if they want to pitch up and create lots of lift.
Especially for short landings the forward-swept wing is ideal when the legs are on the ground at the time of wing stall. Note that the Hansa Jet actually was a production airliner using the forward swept wing, and 2 glider types that i regulalrly flew also had forward swept wings for visibility reasons: Schleicher Ka7 and Ka Not for aerodynamic reasons, but to place the pilots at the center of gravity and the spar behind them.
Blanik L and Scheibe Bergfalke sailplanes had swept-forward wings, it seems it helps in adding freedom in setting center of gravity respect to the pressure center and pilots placement. Advantages of forward swept wings may be mainly in the low speed range, takeoff and landing. Sign up to join this community. The best answers are voted up and rise to the top. What are the advantages of a forward-swept wing over a rearward-swept wing?
Ask Question. Asked 6 years, 11 months ago. Active 4 years, 2 months ago. Viewed 51k times. Improve this question. You can fight nature, but only to some extent. This is a good related read from a control system perspective: "Respect the unstable", G.
Add a comment. Active Oldest Votes. However, in the case of the X, as noted in the Flying Qualities Evaluation of the XA Research Aircraft , The high pitch instability of the airframe led to wide predictions of extreme maneuverability.
Improve this answer. SSumner SSumner 5, 1 1 gold badge 24 24 silver badges 38 38 bronze badges. It is caused simply by aft centre of gravity irrespective of wing design the forward-swept wings just helped to put the centre of lift forward in this case. But that shifts the control problem now to stopping the pitching motion. Seems to me that if it requires a computer to stabilize the plane, the benefits of extended maneuverability could actually be reaped if the plane were fully computer-controlled.
Show 2 more comments. This is important for business-jet sized aircraft. The boundary layer at the tips is not affected by the inner wing. Controllability can be maintained up to stall. Aeroelastic effects will increase control commands. This makes for a very responsive airframe. However, they are directly connected to these disadvantages: Stall will happen inboard first, which will result in a pitch-up.
If the tail cannot compensate, the stall is unrecoverable. The aeroelastic effects will encourage flutter. If flutter speed is found to be too low, the wing needs to be made stiffer, resulting in a weight increase. Read all about it here. Robert Robert 49 1 1 bronze badge. Better visibility is just a pleasant side effect. Urquiola Urquiola 1, 12 12 silver badges 18 18 bronze badges. Sign up or log in Sign up using Google.
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Last month we began our discussion of the structural layout of the wing with a look at externally braced wings. We now turn our attention to cantilever wings. The majority of modern airplanes have cantilever wings because the drag penalty of external wing bracing is excessive for their mission. On a cantilever wing, all of the loads are borne on structural elements that fit entirely within the airfoil contour of the wing. The wing will incorporate one or more full-span spars that carry the primary bending load.
Keywords: forward-swept wing, FSW, aerodynamics, instability, Grumman X Nomenclature some of its benefits and shortcomings presented. 2 General.
With the tips located forward of the point where the wings connect to the fuselage, the plane almost looks as if it is travelling backwards in flight. They maintain airflow over their surfaces at steeper climb angles than conventional planes, which means the nose can point higher without the aircraft going into a dangerous stall. Forward-swept wings are unusual, but one of the better-known recent designs is the Russian experimental fighter, the Sukhoi Su Berkut.
A swept wing is a wing that angles either backward or occasionally forward from its root rather As the pressure waves converge the air in front of the aircraft begins to compress. This creates a
By Collimatrix , March 9, in Aviation. Every so often someone asks a question about the advantages of forward-swept wings, and usually they get a shitty half-assed answer about how they somehow improve maneuverability and stuff. I will attempt to provide a fully-assed answer. The short version is that forward swept wings do roughly the same thing as conventional aft swept wings; they increase critical mach number. Typically, a straight wing starts experiencing shock wave buildup at around mach.
Within the frame of the NLF path a short and medium range transport aircraft with forward swept laminar wing was designed. The present paper is focused on the aerodynamic design of the forward swept wing in cruise flight. The resulting wing was assessed on overall aircraft level with respect to its fuel reduction potential, whereby the CSR configuration, essentially a re-design of the Airbus A, was used as a reference. Laminarization of boundary layers on wing, empennage and engine nacelles of transport aircraft has undoubtedly the highest potential for improving the aerodynamic performance.
Forward-swept wings make an aircraft harder to fly, but the advantages are mainly down to manoeuvrability. They maintain airflow over their surfaces at steeper climb angles than conventional planes, which means the nose can point higher without the aircraft going into a dangerous stall.
Over the years, countless wing configurations have been tried and tested. Few have been successful. Learn about the different types of aircraft wing configurations and see how each wing type differs from the other, as well as the pros and cons of each. Aircraft wings are airfoils that create lift when moved rapidly through the air.
A forward-swept wing is an aircraft wing configuration in which the quarter-chord line of the wing has a forward sweep. Typically, the leading edge also sweeps forward. The forward-swept configuration has a number of characteristics which increase as the angle of sweep increases. The rearward location of the main wing spar would lead to a more efficient interior arrangement with more usable space. Air flowing over any swept wing tends to move spanwise towards the rearmost end of the wing.
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