# Example 16.1 
IPS(deg, hp)    
 fn   =   20.0 deg
 y  =   30.0 deg
 f = atan(tan(fn) / cos(y))  ; deg 
 Pn   =   14.0 / in
 P1 = Pn * cos(y)  
 Np   =   18 
 dp = Np / P1 ; in 
 np   =   1800.0 rpm
 ng   =   600.0 rpm
 Ng = Np * (np / ng)   
 dg = Ng / P1 ; in 
 vp = np * dp / 2  ; ft/min 
 Wdot  =   0.5 hp
 Ft = Wdot / vp ; lbf 
 Fr = Ft * tan(f)  ; lbf 
 Fa = Ft * tan(y)  ; lbf 
 p = pi() / Pn  ; in 
 pa = p / tan(y)  ; in 
 b = 1.5 * pa  ; in 

# Example 16.2    
IPS(rpm, deg, hp) 
 nw   =   1200.0 rpm
 ng   =   60.0 rpm
 nw_over_ng   = 20.0 
 Ng = 2 * nw_over_ng  
 p  =   0.625 in 
 dg = p * Ng / pi()  ; in 
 c  =   5.000 in 
 dw = 2 * c - dg  ; in 
 L1  =   1.250 in 
 lam = atan(L1 / pi() / dw)  ; deg 
 vw = nw * dw / 2  ; ft/min 
 Wdot  =   2.0 hp 
 Fwt = Wdot / vw  ; lbf 
 Fga = Fwt
 vs = vw  / cos(lam)  ; ft/min 
 f  =   0.026  # Fig 16.23
 fn   =   14.5 deg 
 Fgt_over_Fwt = (cos(fn) * cos(lam) - f * sin(lam)) / \
     (cos(fn) * sin(lam) + f * cos(lam))  
 Fgt = Fwt * Fgt_over_Fwt ; lbf 
 Fwa = Fgt
 Fgr = Fgt * sin(fn) / (cos(fn) * cos(lam) - f * sin(lam)) ; lbf 
 Fgt = Fgr
 e = (cos(fn) - f * tan(lam)) / (cos(fn) + f * cot(lam))  
 Wout = Wdot * e ; hp 
 SL = cos(fn) * tan(lam)   
 f
 # SL > f => not self locking     

# Example 16.3  
 IPS(rpm, deg, hp)   
 nw   =   1200.0 rpm
 Ng_over_Nw =   11
 ng  =  nw / Ng_over_Nw
 Ng   =   44.0 
 Nw   =   Ng / Ng_over_Nw  
 fn   =   25.0 deg
 p  =   0.750 in
 dg = p * Ng / pi()  ; in 
 c  =   6.125 in
 dw = 2 * c - dg  ; in 
 L1 = Nw * p  ; in 
 lam = atan(L1 / pi() / dw)  ; deg 
 vg = ng * dg / 2  ; ft/min 
 vs = vg / cos(lam)  ; ft/min 
 f  =  0.027  # Fig 16.23
 e = (cos(fn) - f * tan(lam))/ (cos(fn) + f * cot(lam))   
 b  =   1.0 in 
 Fd_over_Fgt   =   1.25  
 Sn   =   24.00 ksi 
 y  =   0.15  
 Fs = Sn * b * p * y  ; lbf 
 Fd = Fs  ; lbf 
 Fgt = Fd / Fd_over_Fgt ; lbf 
 Wdotg = Fgt * vg  ; hp 
 Kw   =   180.00 lbf/in^2 
 Fw = dg * b * Kw  ; lbf 
 Fd = Fw  ; lbf 
 Fgt = Fd / Fd_over_Fgt ; lbf 
 Wdotg = Fgt * vg  ; hp 
 C1  =   45.00 lbf / ft / min / degFdiff # Fig 16.25
 a0   =   0.30 ft^2 / in^(1.7) 
 A1 = a0 * c^1.7  ; ft^2 
 DT   =   100.00 degFdiff 
 H1 = C1 * A1 *  DT  ; hp

# Homework Problems:

TBD