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• Geometry and Balance

Starting from basic inputs such as the wing area, aspect ratio, fuselage size etc, Piano calculates all other necessary geometric data, wetted areas and volumes. The user can specify arbitrary shapes for the front and rear fuselage and nacelles. This is done through a 'shape editor' at several longitudinal stations. Typical predefined shapes are available and can be 'rubberised' (i.e. scaled to any dimensions).

The basic wing specification can include a spanwise planform break (kink or 'yehudi') and a thickness break. A variety of common wing area definitions can be used (basic trapezoidal, gross, Airbus, ESDU or Boeing 'Wimpress' reference areas). Internal fuel capacity is calculated and can be adjusted to fit known values.

Given no additional information, Piano will automatically balance the design (locating the wing along the fuselage and sizing the tail areas) so as to match a required static margin and using statistically derived equations for the horizontal and vertical tail volume coefficients (V-bars). The user can move the wing by altering the fixed-equipment C.G. assumptions or by specifying a location directly. Tail areas can also be input to override internal calculations and match known aircraft geometries. Fuselage 'stretching' exercises can then be carried out with a fixed tail geometry.

3-view sketches are created dynamically from the current definition.

The following is a sample geometry report:

 GEOMETRY REPORT
 _______________
                                Wing    Stabiliser   Fin 
                                ----    ----------   --- 
 Area, trapezoidal reference   3568.38   836.87    427.80    sq.feet
 Area, piano gross             4057.75   836.87    427.80    sq.feet
 Area, airbus gross            4000.49                       sq.feet
 Area, boeing wimpress         3900.00                       sq.feet
 Area, esdu                    3892.76                       sq.feet
 Area, exposed                 3273.34   640.00    427.80    sq.feet
 Area, wetted                  6662.91   1300.25   869.13    sq.feet

 Aspect Ratio, trapezoidal      10.38      5.00      1.70    
 Aspect Ratio, piano gross       9.13      5.00      1.70   
 Aspect Ratio, airbus gross      9.26
 Aspect Ratio, boeing wimpress   9.50
 Aspect Ratio, esdu              9.52

 Span (excluding winglets)     192.50     64.69     26.97    feet

 Sweepback at 1/4-chord         32.00     36.00     40.00    degrees

 Taper Ratio (trapezoidal)       0.20      0.22      0.33   

 t/c at root                    0.134     0.100     0.100   
 t/c at thickness break         0.094
 t/c at tip                     0.088     0.100     0.100   

 Volume Coefficient (V-bar)               0.900     0.048   
 Mean Aerodynamic Chord         21.28     14.70     17.19    feet
 Arm between MAC 1/4 chords               81.68     76.91    feet

 Wing chord at tip                                6.18       feet
 Wing chord at planform break                    21.79       feet
 Wing chord at root (gross)                      38.61       feet
 Wing chord at c/line (gross)                    44.69       feet
 Wing chord at c/line (notional trapezoidal)     30.90       feet

 Planform break location        0.300  (fraction of exposed semispan)
 Thickness break location       0.333  (fraction of exposed semispan)

 Wing location (station of extended leading edge at c/line):
 55.05 feet    (30.0 % of fuse.length)

 Spar locations (fractions of local trapez.chord):
 Wing root: 0.15, 0.75       Wing tip: 0.15, 0.65

 Fuel capacity  (avail/reqrd = 1.151)
 -------------
 (US.gal.: wing 27519.6, centre 10760.1, tail 0.0, adjust -5339.7)

 Total Available: 32940.00 US.gal. (geometric capacity)
 Total Required : 28620.90 US.gal. (at mtow & design payload)

 Fuselage geometry
 -----------------
 fuselage max. width            18.83    feet
 fuselage max. depth            19.77    feet

 length, total fuselage        183.50    feet
 length, front section          37.00    feet
 length, mid section            81.50    feet
 length, rear section           65.00    feet
 
 wetted area, total fuselage   9480.31   sq.feet
 wetted area, front section    1785.58   sq.feet
 wetted area, mid section      4939.96   sq.feet
 wetted area, rear section     2754.77   sq.feet

 Nacelle geometry
 ----------------
 nacelle length                 18.60    feet
 nacelle max. width             12.00    feet
 nacelle max. depth             12.00    feet
 wetted area per nac.          661.75    sq.feet

 Overall dimensions
 ------------------
 Span over winglets            197.31    feet
 Overall aircraft length       185.59    feet
 Height at top of fin          55.14     feet
 Overall aircraft wetted area  19677.73   sq.feet 


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