<DOC>
<DOCNO>
624
</DOCNO>
<TITLE>
cruise performance of channel-flow ground effect machines .
</TITLE>
<AUTHOR>
strand,t.
</AUTHOR>
<BIBLIO>
j. ae. scs. 29, 1962, 702.
</BIBLIO>
<TEXT>
  the performance theory for high-speed air-cushion vehicles
operating in close proximity to the ground is developed .  the
analysis is restricted to cruise flight of vehicles of rectangular
planform employing an air pressure seal between the ground and
the vehicle along the two streamwise sides .  the variation of
the optimum rearward deflection angle of the side jet pressure
seal with speed for minimum overall power expenditure and
maximum range is found .  it is concluded that a mixed propulsion
system (jet deflection plus propeller(s)) is required .
volume flow and the corresponding fan pressure rise needed are
also calculated .  the maximum lift drag ratio is determined .
  the maximum thickness ratios of the vehicles are considered
to be large compared with the ground-height vehicle-length
ratio .  two-dimensional airfoil theory is employed to show that
close to stagnation conditions exist below the vehicles .  the
lower-surface lift, pitching moment, and aerodynamic-center
location are determined .
  the flow over the upper surface is identified with flow over
mounds .  upper-surface lift coefficients are determined for
typical mound shapes .
  it is shown that high total lift coefficients are theoretically
obtainable with almost zero induced drag .  the conventional
induced-drag power penalty is replaced by a sealing-air power
expenditure, which is shown not to be excessive .
</TEXT>
</DOC>
