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Similaire à Effects of Swept Wings on Supersonic Flight Performance
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Effects of Swept Wings on Supersonic Flight Performance
- 2. AIM INTRODUCTION Drag and mach number Comparison Variant of Design features CONCLUSION
- 3. Aim of this presentation is give brief idea about swept wing configuration and its applications on super sonic flight
- 4. A wing planform favoured for high subsonic jet speeds. To reduce the wave drag. first investigated in Germany from 1935 onwards. introduction of the MiG-15 and North American F-86 .
- 5. When aircraft enters the transonic speeds just below the speed of sound, an effect known as wave drag starts. Near the speed of sound oblique shock wave is generated. Shock waves require energy to form.
- 8. which characterizes a swept wing is conventionally measured along the 25% chord line.
- 10. forward sweep
- 11. Allowing more space in generally cramped corporate jet cabins Relatively expensive. Highly maneuverable at transonic speeds
- 13. Extra lateral stability. Longitudinally stable on its own. Delay the compressibility effect when flying at transonic speed.
- 14. Also known as swing wing. That may be swept back and then returned to its original position during flight.
- 15. Aeroelastically enhanced maneuverability Smaller basic lift distribution Increased trailing edge sweep for given structural sweep - lower CDc Unobstructed cabin Easy gear placement Good for turboprop placement
- 16. Aeroelastic divergence or penalty to avoid it Lower Cnβ (yaw stability) Bad for winglets Stall location (more difficult) Reduced pitch stability due to additional lift and fuse interference
Notes de l'éditeur
- Bell X-1 the first manned aircraft to fly at the speed of sound
- 1. a planform is the shape and layout of a fixed-wing aircraft's fuselage and wing.
- 2. at the point where the flow slows down back to subsonic speed3. This energy is taken out of the aircraft, which has to supply extra thrust to make up for this energy loss. Thus the shocks are seen as a form of drag. there is a certain "critical mach" speed (or drag divergence mach number) where this effect becomes noticeable.
- By swept wings we need to increase the Mach divergence number.
- If the 25% chord line varies in sweep angle, the leading edge is used; if that varies, the sweep is expressed in sections (e.g., 25 degrees from 0 to 50% span, 15 degrees from 50% to wingtip).
- Swept angle and its effect on drag coefficient with increase of mach number.
- Some unique characteristics of forward swept wing is shown below.1. the wing base to be placed behind the main cabin.2. Special composites may use to withstand on extra loads, high twisting resistance. wing stiffness needs to be increased.3. air flows over a forward-swept wing and toward the fuselage, rather than away from it.
- 2. without needing a horizontal tailplane as a straight wing does.3.
- This phenomena is important due to swept wings are may effect in negative, when airplane flies at subsonic spedes.
- aeroelastic phenomena arise when structural deformations induce changes on aerodynamic forces
- Winglets are to intended effect is always to reduce the aircraft's drag by partial recovery of the tip vortex energy
- when reach the Mach 0.8 or so there will be some supersonic flow on some parts of the airplane, This is called the transonic regime. Shock waves start at points where the local flow is supersonic and the shock waves propagate away at an angle called the Mach angle. It takes a lot of energy to make the shock waves in the first place and when a wave from one part of the plane hits another part it at least doubles the wave drag. The shock waves radiating from the nose form a cone and to keep the wave drag down it's necessary to keep all downwind parts behind that shock wave ( inside the Mach cone). Although technically the Mach cone only develops when the sound energy can't propagate forward because the plane is going faster than the sound can the the wave is mostly swept downwind and can be seen as a cone with a sweep angle of about 37 degrees. As you go faster the sweep angle of the shock waves gets steeper. To fly efficiently at wave inducing speeds means keeping as much of the airframe as possible inside the Mach cone and that's what actually sets the sweep angle of the wings on high speed airplanes.