Problem 12.29

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Problem 12.29 [Difficulty: 2]
Given: Scramjet-powered missile traveling at fixed Mach number and altitude
Find: Time necessary to cover specified range
Solution:
Basic equation: c k R T M
V
c

Available data R 286.9
J
kg K
 k 1.4 M 7 Δx 600 nmi 3.65 10
6
 ft
At z 85000 ft z 25908 m interpolating from Table A.3 T 220.6 K 222.5 K 220.6 K( )
25908 24000
26000 24000

T 222 K
Hence c k R T c 299
m
s
 c 981
ft
s
 and we have V M c 6864
ft
s

The time needed to cover the range is: Δt
Δx
V
531 s Δt 8.85 min This is about ten times as fast as the Tomahawk!