Part V - Airworthiness Manual Chapter 549 - Amateur-Built Aircraft

Canadian Aviation Regulations (CARs) 2017-2

Appendix A
Maximum Allowable Wing Loading For A Fixed-Wing Aircraft With Flaps

A549.1 General

This Appendix details the methods of calculating the maximum allowable wing loading and hence the maximum allowable take-off mass for a fixed-wing aircraft with flaps. The maximum allowable wing loading is calculated from the flap span ratio, flap chord ratio and flap deflection

Information Note:

(Ref. section 549.103).

A549.3 Flap Span Ratio, Flap Chord Ratio and Flap Deflection

The Flap Span Ratio (Rfs), Flap Chord Ratio (Rfc) and Flap Deflection (df) are calculated as follows:

  1. (a) Flap Span Ratio :

    1. The Flap Span Ratio (Rfs) is given by:

    2. R fs = 2 x b f / b

    3. where:

    4. bf = Span of One Flap, m (ft)

    5. b = Wing Span, m (ft)

    6. The value of the Flap Span Ratio shall not exceed: 0.75

  2. (b) Flap Chord Ratio:

    1. The Flap Chord Ratio (Rfc) is given by:

    2. R fc= C f / C w

    3. where:

    4. Cf = Mean Flap Chord = (Sf / bf),m (ft);

    5. Sf = Area of One Flap, m2 (ft2); and

    6. Cw = Mean Wing Chord = (S / b), m (ft);

    7. S = Wing Area, m2 (ft2).

    8. The value of the Flap Chord Ratio shall not exceed: 0.25

  3. (c) Flap Deflection:

    1. The Flap Deflection (df) = number of degrees (o) of flap rotation from fully retracted position to fully extended position. The value of the Flap Deflection shall not exceed = 45o.

A549.5 Maximum Allowable Wing Loading

Using the Flap Span Ratio (Rfs), the Flap Chord Ratio (Rfc) and the Flap Deflection(df) determined in A549.3, the maximum allowable wing loading is given by the equation (a) or (b), as applicable:

  1. (a) For Use with S.I. (Metric) Units, the lesser of:

    1. M/S = 65.0 + (4.66 x (Rfs) x (Rfc) x (df)) kg/m2; or

    2. M/S = 100 kg/m2.

  2. (b) For Use with Imperial Units (fps), the lesser of:

    1. W/S = 13.3 + (0.96 x (Rfs) x (Rfc) x (df)) lb/ft2; or

    2. W/S = 20.4 lb/ft2.

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