This preview shows pages 1–2. Sign up to view the full content.
Practice Exam 1
Fa 2009
Solution
This exam is for your practice only.
1. On a summer day, the temperature in the stratosphere above Edwards Air Force Base
in southern California is constant, and equal to
T
1
= 236
.
65 K
for altitudes in the range 11
,
000 m
≤
h
≤
25
,
000 m. A test pilot ﬂying there wants
to make some performance measurements of her aircraft at a
density altitude
h
d
=
20
,
000 m.
(a) What must be the local (ambient) density at the altitude of her test?
(b) At what
pressure altitude
h
p
should she ﬂy for the test?
Note: the distribution of temperature
T
in the
Standard Atmosphere
, up to 32,000
meters, is given by
0
≤
h
≤
11
,
000 m:
T
= 288
.
15 K

(
.
0065 K/m)
h
11
,
000 m
≤
h
≤
20
,
000 m:
T
= 216
.
65 K
20
,
000 m
≤
h
≤
32
,
000 m:
T
= 216
.
65 K + (
.
0010 K/m)
h
Solution
If the
density altitude
is given by
h
d
= 20, 000 m, then from Appendix A in Anderson
we have that the density is
ρ
= 8
.
8909
×
10

2
kg/m
3
. The temperature is
T
1
= 236.65
K
(a) From above
ρ
= 8
.
8909
×
10

2
kg/m
3
(b) From the ideal gas law
∴
p
=
ρRT
= (8
.
8909
×
10

2
)(287
.
05)(236
.
65) = 6039
.
6 Pa
From Appendix A we have
p
1
= 6074.4 Pa at
h
G
1
= 19, 400 m,
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview. Sign up
to
access the rest of the document.
 Fall '08
 CAUGHEY

Click to edit the document details