In aeronautics, the thickness-to-chord ratio, sometimes simply chord ratio or thickness ratio, compares the maximum vertical thickness of a wing to its chord. It is a key measure of the performance of a wing planform when it is operating at transonic speeds.
a=chord, b=thickness, thickness-to-chord ratio = b/aThe F-104 wing has a very low thickness-to-chord ratio of 3.36%
At speeds approaching the speed of sound, the effects of Bernoulli's principle over curves on the wing and fuselage can accelerate the local flow to supersonic speeds. This creates a shock wave that produces a powerful form of drag known as wave drag, and gives rise to the concept of the sound barrier. The speed at which these shocks first form, critical mach, is a function of the amount of curvature. In order to reduce wave drag, wings should have the minimum curvature possible while still generating the required amount of lift. So, the main reason for decreasing the blade section thickness to chord ratio is to delay the compressibility effect related to higher Mach numbers, delaying the onset of a shock wave formation.
The natural outcome of this requirement is a wing design that is thin and wide, which has a low thickness-to-chord ratio. At lower speeds, undesirable parasitic drag is largely a function of the total surface area, which suggests using a wing with minimum chord, leading to the high aspect ratios seen on light aircraft and regional airliners. Such designs naturally have high thickness-to-chord ratios. Designing an aircraft that operates across a wide range of speeds, like a modern airliner, requires these competing needs to be carefully balanced for every aircraft design.
Swept wings are a practical outcome of the desire to have a low thickness-to-chord ratio at high speeds and a lower one at lower speeds during takeoff and landing. The sweep stretches the chord as seen by the airflow, while still keeping the wetted area of the wing to a minimum. For practical reasons, wings tend to be thickest at the root, where they meet the fuselage. For this reason, it is common for wings to taper their chord towards the tips, keeping the thickness-to-chord ratio close to constant, this also reduces induced drag at lower speeds. The crescent wing is another solution to the design to keep a relatively constant thickness-to-chord ratio.
^"Aircraft Data File". Civil Jet Aircraft Design. Elsevier. July 1999.
^ abSimona Ciornei (31 May 2005). "Mach number, relative thickness, sweep and lift coefficient of the wing - An empirical investigation of parameters and equations" (PDF). Hamburg University of Applied Sciences.
Further readingedit
Andrianne, T. (2016). "Aerodynamics" (PDF). Université de Liège. pp. 49–50.
This aviation-related article is a stub. You can help Wikipedia by expanding it.
thickness, chord, ratio, aeronautics, thickness, chord, ratio, sometimes, simply, chord, ratio, thickness, ratio, compares, maximum, vertical, thickness, wing, chord, measure, performance, wing, planform, when, operating, transonic, speeds, chord, thickness, t. In aeronautics the thickness to chord ratio sometimes simply chord ratio or thickness ratio compares the maximum vertical thickness of a wing to its chord It is a key measure of the performance of a wing planform when it is operating at transonic speeds a chord b thickness thickness to chord ratio b a The F 104 wing has a very low thickness to chord ratio of 3 36 At speeds approaching the speed of sound the effects of Bernoulli s principle over curves on the wing and fuselage can accelerate the local flow to supersonic speeds This creates a shock wave that produces a powerful form of drag known as wave drag and gives rise to the concept of the sound barrier The speed at which these shocks first form critical mach is a function of the amount of curvature In order to reduce wave drag wings should have the minimum curvature possible while still generating the required amount of lift So the main reason for decreasing the blade section thickness to chord ratio is to delay the compressibility effect related to higher Mach numbers delaying the onset of a shock wave formation The natural outcome of this requirement is a wing design that is thin and wide which has a low thickness to chord ratio At lower speeds undesirable parasitic drag is largely a function of the total surface area which suggests using a wing with minimum chord leading to the high aspect ratios seen on light aircraft and regional airliners Such designs naturally have high thickness to chord ratios Designing an aircraft that operates across a wide range of speeds like a modern airliner requires these competing needs to be carefully balanced for every aircraft design Swept wings are a practical outcome of the desire to have a low thickness to chord ratio at high speeds and a lower one at lower speeds during takeoff and landing The sweep stretches the chord as seen by the airflow while still keeping the wetted area of the wing to a minimum For practical reasons wings tend to be thickest at the root where they meet the fuselage For this reason it is common for wings to taper their chord towards the tips keeping the thickness to chord ratio close to constant this also reduces induced drag at lower speeds The crescent wing is another solution to the design to keep a relatively constant thickness to chord ratio Airliners 1 Area m2 Span m AspectRatio TaperRatio Average t c 1 4 ChordSweep ERJ 145 51 18 20 04 7 85 0 231 11 00 22 73 CRJ100 54 54 20 52 7 72 0 288 10 83 24 75 Avro RJ 77 30 26 21 8 89 0 356 12 98 15 00 737 Original Classic 91 04 28 35 8 83 0 266 12 89 25 00 DC 9 92 97 28 47 8 72 0 206 11 60 24 00 Boeing 717 92 97 28 40 8 68 0 196 11 60 24 50 Fokker 100 70 93 50 28 08 8 43 0 235 10 28 17 45 MD 80 90 112 30 32 87 9 62 0 195 11 00 24 50 A320 122 40 33 91 9 39 0 240 11 92 2 25 00 737 NG 124 60 34 30 9 44 0 278 25 00 Boeing 727 157 90 32 92 6 86 0 309 11 00 32 00 Boeing 757 185 25 38 05 7 82 0 243 25 00 A310 219 00 43 89 8 80 0 283 11 80 28 00 A300 260 00 44 84 7 73 0 300 10 50 28 00 DC 8 271 90 45 23 7 52 0 181 11 00 30 00 Boeing 767 283 30 47 57 7 99 0 207 11 50 31 50 Boeing 707 283 40 44 42 6 96 0 259 10 00 35 00 MD 11 338 90 51 77 7 91 0 239 9 35 35 00 A330 A340 200 300 363 10 58 00 9 26 0 251 11 80 2 29 70 DC 10 367 70 50 40 6 91 0 220 11 00 35 00 Boeing 777 427 80 60 90 8 67 0 149 31 60 A340 500 600 437 30 61 20 8 56 0 220 31 10 747 Classic 511 00 59 64 6 96 0 284 9 40 37 50 747 400 525 00 62 30 7 39 0 275 9 40 37 50 MD 12 543 00 64 92 7 76 0 215 35 00 A3XX 817 00 79 80 7 79 0 213 30 00 regional narrowbody widebody double deckReferences edit Aircraft Data File Civil Jet Aircraft Design Elsevier July 1999 a b Simona Ciornei 31 May 2005 Mach number relative thickness sweep and lift coefficient of the wing An empirical investigation of parameters and equations PDF Hamburg University of Applied Sciences Further reading editAndrianne T 2016 Aerodynamics PDF Universite de Liege pp 49 50 nbsp This aviation related article is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title Thickness to chord ratio amp oldid 1218644523, wikipedia, wiki, book, books, library,
