A flight-dynamic helicopter mathematical model with a single flap-lag-torsion main rotor

Original publisher: Moffett Field, Calif. : NASA Ames Research Center : US Army Aviation Systems Command, Aviation Research and Technology Activity, [1990] OCLC Number: (OCoLC)62929975 Excerpt: ... TFW, which is defined in figure 4. The which canbeconvertedto the F framevia thetransformation force and moment coefficients are functions of af and _f, but the default fuselage-aerodynamics sets all force coefficients to zero except CDI, which is set to unity, making the fuselage reference area Sf the equivalent drag area. The fuselage mount moments are modeled as linear nonorthogonal springs, and the mount forces are treated as given quantities. These forces can be used during trim to satisfy a constraint condition, such as setting a certain amount of thrust. The parameters defining the mount effects can be set to zero for free-flight analysis. The force and moment expressions for the mount are given by ( 35 ) where ( 36 ) Mx =-KF_ ( Oz-Ozo )-CF_Oz ( 37 ) ( 38 ). Mz =-KF z ( Oz-Ozo )-CFzbz ( 39 ) QM = + Fyg + The nAlus The measurement outputs from the fuselage are acceleration, velocity, and angular rates. accelerometer outputs are expressed as ( 40 ) Y ( j ) = ( r-iuj-g_I ) " l ' 2 " ' " nAl_ = I1 11 j = ( 41 ) fj = fzjYCF + fyj_lF + fzjz'F where the direction of the measurement is selected through the components of. _. The velocity of the fuselage center of mass is resolved in the fuselage fixed frame and is available as a measurement, as are the fuselage angular rates. The components of the velocity and angular rate vectors are stored in y according to ( 42 ) = ric. 3cF y ( nAl_ + l ) = " ( 43 ) ( )-y nAlus + 2 = ric • _IF ( 44 ) ric " ZF y ( nAy_s + 3 ) =: " ( 45 ) y ( hA.f,., s + 4 ) = CSF / I " 3CF ( 46 ) y ( nAyus + 5 )--_F / I " _IF ( 47 ) y ( nAyus + 6 ) = gF / I " ZF 5