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80 PERFORMANCE, STABILITY, DYNAMfCS, AND CONTROL
The maximum range occurs when the glide angle is minimum
1
ynun - En
1
- 28 86
- 0.0346 rad
= 1.985 deg
The velocity and lift coefficient for the fiattest glide are given by
V : VR
.~ If4[F~
\1 .225~8 OV 0.015
- 23.328 m/s
CL = C:
- 0.866
Example 2.2
A glider weighing 5000 N and having an elliptical wing with an area of 10 m2 is
required to maintajn a glide angle of3 deg at a forward speed of 50 m/s. Assuming
CDO - 0.015, find the aspect ratio of the glider.
So/uOon. Because the glider has an elliptical wing, e - 1. Then,
CD
y- CL
3
= 5~30
-. 0.0524 rad
AIRCRAFT PERFORMANCE
C~ = p2S~
2 *5000
= ~25~0~502
- 0.3260
CD - CLy
- 0.326 * 0.0524
- 0.01708
kC~. = CD - CDO
k = O 01708 - 0.015
0 3262
- 0.0196 .
1
A--
k7te
1
=00~96 7r*l
- 16.20
81
2-4 LeveIFlight
The forces acting on an airplane in level :flight are shown in Fig. 2.7. In level
flight, the airplane is at a constant altitude so that h = y = 0. With this, Eqs. (2.7)
and (2.8) take the following form:
/- W _O
T-D-O
(2.61)
(2,62)
\
┏━━━━━━━━━━━━┳━━━━━━━━━━┓
┃ ┃. ┃
┃ -- o- -. ┃ ~ \ Rit ┃
┃ ┃--,- ┃
┃ ┃ ~} ' ┃
┣━━━━━━━━━━━━╋━━━━━━━━━━┫
┃ ┃ a l. ┃
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