Etkin's book ( 3d.ed. ) contains two linearized models of the B747-100, one for the symmetrical and one for the asymmetrical motions. They both apply to cruising flight at ***** feet.
This section lists some of the geometrical and weight-and-balance data for these models.
Etkin get his data from : TBW. ( see page **** ).
Etkin's model values are for cruising flight at altitude :
TBW
Wikipedia B747-100, not in Etkin
lbs.ft SI
Lfuselage = 231 ft 10 in 70.7 m
lbs.ft SI
V (TAS) = 774 [ ft/s ] 235.9 [ m/s ]
W = 636,636 [lbs] 2.83176e6 [ N ] / 9.81
m = 288 760 [kg]
Iy = 0.449 e8 [ kg.m2 ] / m, √
Ry = 12.5 [ m ] TODO CHECK 25057_PL.doc
c (MAC) = 27.31 [ ft ] 8.324 [ m ]
For a standard Boeing 747 (most notably the widely used 747-400 variant), the official engineering values used for weight, balance, and flight computer calculations are:
• MAC Length (Chord Width): 327.8 inches (approx. 27.3 feet or 8.33 meters).
This represents the geometric average distance from the wing's leading edge to its trailing edge.
• LEMAC (Leading Edge of MAC): 1,257.0 inches aft of the aircraft's front reference datum line. [1, 2, 3]
How It Is Used
The airplane's Center of Gravity (CG) is always measured as a percentage of this 327.8-inch chord (%MAC). For instance: [1, 2] • 0% MAC represents the physical location exactly 1,257.0 inches from the nose datum. • 100% MAC (TEMAC / Trailing Edge) represents a position 1,584.8 inches from the datum (1,257.0 + 327.8). [1]
For safe flight operations, the flight control systems require the 747's actual weight distribution to rest within a safe operational envelope, typically between 13% and 33% MAC. [1]
This sort of data is incorporated in the aeroplane pre-design textbooks. The one I have is Synthesis of Subsonic Airplane Design by Torenbeek, which unfortunately predates the B747-400. But there is data available for the B747-100/200, in sections 9.5 9 Preliminary Design of the Horizontal Tailplane and 9.6 Design of the Vertical Tailplane.
Table 9-2 lists a.o. the following parameters for the B747 100/200 horizontal tailplane:
Area fraction Sh/S = 0.267
Aspect ratio Ah = 3.60
Taper ratio λh = 0.264
Sweep angle Λh = 37°
Tail volume fraction Shlh/(Sc¯) = 1.000
And from table 9-3 the data for the vertical tailplane:
Area fraction Sv/S = 0.196
Aspect ratio Av = 1.38
Sweep angle Λv = 44°
Tail volume fraction Svlv/(S⋅ b) = 0.0990
Airfoil sections for other aeroplanes of the era are listed in the table, also referenced in this answer, but not for the B747. Profile type must have been a closely guarded secret at the time already.
TBW