How are the velocity equations from Appendix 2 converted into rectangular coordinates?

The conversion is described in Appendix 3 to ETSO-C117b, which defines intermediate variables to simplify the written equations and provides the horizontal and vertical velocities, partial derivatives, and other relationships from TASS.

What is the definition of z* in the wind field model?

z* is the altitude where wx is half the value of wx max, expressed in feet.

What does the variable ε represent in the coordinate system transformation?

ε is the characteristic height of boundary layer effects, expressed in feet.

What is the meaning of zh in the wind field model?

zh is the depth of outflow, expressed in feet.

What does zm represent in the wind field model?

zm is the altitude of maximum outflow, expressed in feet.

What is the scaling parameter λ in the wind field model?

λ is the scaling parameter, expressed in s⁻¹, and is determined from the above relationships.

How is the radial distance from the aeroplane to the downburst defined?

r is the radial distance from the aeroplane to the downburst, expressed in feet.

What does R represent in the wind field model?

R is the radius of the downdraft, expressed in feet.

What are xad and yad in the coordinate system transformation?

xad and yad are the x and y coordinates from the aeroplane to the microburst, expressed in feet.

What do wx max, wy max, and wh max represent?

wx max, wy max, and wh max are the maximum winds in the x, y, and h directions, respectively.

Appendix 3 to ETSO-C117b - Wind Field Model Coordinate System Transformation

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Appendix 3 to ETSO-C117b – Wind Field Model Coordinate System Transformation

ED Decision 2020/011/R

This Appendix describes the conversion of the velocity equations in Appendix 2 to rectangular coordinates.

Define intermediate variables to simplify written equations:

Horizontal and Vertical Velocities

Partial Derivatives

Other Relationships

From TASS

Maximums

(λ is determined from the above relationships)

Variable List

z* = altitude where w_x is half the value of w_x _max (ft)

ε = characteristic height of boundary layer effects (ft)

z_h = depth of outflow (ft)

z_m = altitude of maximum outflow (ft)

λ = scaling parameter (s^-1)

r = radial distance from aeroplane to downburst (ft)

h = altitude of aeroplane (ft)

R = radius of downdraft (ft)

x_ad, y_ad = x, y coordinates, aeroplane to microburst (ft)

w_x
max, w_{y max}, w_{h max}maximum winds, x, y, and h directions

[Amdt ETSO/16]

Details

Source-Title: Appendix 3 to ETSO-C117b - Wind Field Model Coordinate System Transformation View latest amendments

Erulesid: ERULES-1963177438-18080 Compare versions

Domain: Initial airworthiness

Amendedby: Amendment 16

Applicabilitydate: 25 July, 2020

Entryintoforcedate: 25 July, 2020

Regulatorysource: ED Decision 2020/011/R Navigate

Regulatorysubject: CS-ETSO

Typeofcontent: CS (Certification specification)

Parentir: ETSO-C117b

Origin: EASA

Category: EAR