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Appendix 4 to ETSO-C117b - Dryden Turbulence and Discrete Gust Model
Available versions for ERULES-1963177438-18027
ED Decision 2020/011/R
found in: CS-ETSO Amdt 17 - European Technical Standard Orders (Oct 2026)
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CS-ETSO Amdt 17 - ... (Oct 2026)
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###### Appendix 4 to ETSO-C117b – Dryden Turbulence and Discrete Gust Model *ED Decision 2020/011/R* This Appendix contains data that defines the Dryden turbulence and discrete gust model to be used in conducting the tests specified in paragraphs 4(d)(7)(ii), 4(d)(7)(iii), 4(d)(8)(ii), and 4(d)(8)(iii) of Appendix 1 to this ETSO. Dryden Turbulence Model where: SIGMAu, SIGMAv, SIGMAw are the RMS intensities; TAUu = Lu/VA; TAUv = Lv/VA; TAUw = Lw/VA; Lu, Lv, Lw are the turbulence scale lengths; VA is the aircraft’s true airspeed (ft/sec); PI = 3.1415926535; PI2 = 6.2831853070 (2 times PI); SQRT3 = 1.732050808 (square root of 3); and S is the Laplace transform variable. The following table lists SIGMAu, SIGMAv, SIGMAw, Lu, Lv, and Lw versus altitude. Extrapolation will not be used, and simulator altitudes outside the bounds of the turbulence list will use the data at the boundary. <table bgcolor="#d9d9d9" cellpadding="7" cellspacing="0"> <col/> <col/> <col/> <col/> <col/> <col/> <col/> <thead> <tr valign="top"> <td bgcolor="#808080" rowspan="2"><p align="left"> <b>Altitude (feet)</b></p> </td> <td bgcolor="#808080" colspan="3"><p align="center"> <b>RMS Intensities (ft/sec)</b></p> </td> <td bgcolor="#808080" colspan="3"><p align="center"> <b>Scale Lengths (feet)</b></p> </td> </tr> <tr valign="top"> <td bgcolor="#808080"><p align="center"> <b>Long</b></p> </td> <td bgcolor="#808080"><p align="center"> <b>Lat</b></p> </td> <td bgcolor="#808080"><p align="center"> <b>Vert</b></p> </td> <td bgcolor="#808080"><p align="center"> <b>Long</b></p> </td> <td bgcolor="#808080"><p align="center"> <b>Lat</b></p> </td> <td bgcolor="#808080"><p align="center"> <b>Vert</b></p> </td> </tr> </thead> <tbody> <tr valign="top"> <td bgcolor="#d9d9d9"><p align="left"> 100</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 5.6</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 5.6</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 3.5</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 260</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 260</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 100</p> </td> </tr> <tr valign="top"> <td bgcolor="#d9d9d9"><p align="left"> 300</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 5.15</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 5.15</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 3.85</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 540</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 540</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 300</p> </td> </tr> <tr valign="top"> <td bgcolor="#d9d9d9"><p align="left"> 700</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 5.0</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 5.0</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 4.3</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 950</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 950</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 700</p> </td> </tr> <tr valign="top"> <td bgcolor="#d9d9d9"><p align="left"> 900</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 5.0</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 5.0</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 4.45</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 1123</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 1123</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 900</p> </td> </tr> <tr valign="top"> <td bgcolor="#d9d9d9"><p align="left"> 1500</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 4.85</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 4.85</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 4.7</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 1579</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 1579</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 1500</p> </td> </tr> </tbody> </table> The applicant shall demonstrate that the variance of their turbulence implementation is adequate. Discrete Gust Rejection Discrete gusts (in the horizontal axis) with ranges of amplitude and frequency (A and OMEGA) of the form [A(1 − cos OMEGAt)] shall be used. The following table lists the values of A and OMEGA to be used (this simulates an approximate 15-knot gust condition): <table bgcolor="#d9d9d9" cellpadding="7" cellspacing="0"> <col/> <col/> <col/> <thead> <tr valign="top"> <td bgcolor="#808080"><p align="center"> <b>A</b></p> </td> <td bgcolor="#808080"><p align="center"> <b>OMEGA (rad/sec)</b></p> </td> <td bgcolor="#808080"><p align="center"> <b>Approx. Gust Duration (sec)</b></p> </td> </tr> </thead> <tbody> <tr valign="top"> <td bgcolor="#d9d9d9"><p align="center"> 7.5</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 2.10</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 3</p> </td> </tr> <tr valign="top"> <td bgcolor="#d9d9d9"><p align="center"> 7.5</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 1.26</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 5</p> </td> </tr> <tr valign="top"> <td bgcolor="#d9d9d9"><p align="center"> 7.5</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 0.78</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 8</p> </td> </tr> <tr valign="top"> <td bgcolor="#d9d9d9"><p align="center"> 7.5</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 0.63</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 10</p> </td> </tr> <tr valign="top"> <td bgcolor="#d9d9d9"><p align="center"> 7.5</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 0.52</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 12</p> </td> </tr> <tr valign="top"> <td bgcolor="#d9d9d9"><p align="center"> 7.5</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 0.42</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 15</p> </td> </tr> <tr valign="top"> <td bgcolor="#d9d9d9"><p align="center"> 7.5</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 0.31</p> </td> <td bgcolor="#d9d9d9"><p align="center"> 20</p> </td> </tr> </tbody> </table> [Amdt ETSO/16]
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