Game Development Reference
In-Depth Information
Example: Computing the Thrust of the Cessna 172 Skyhawk
Let's apply what we've learned about propeller engine thrust to compute the thrust profiles
of the Cessna 172 Skyhawk airplane. The Skyhawk, shown in Figure 10-15, is a small, single-
engine airplane that has been flying for many years and is still quite popular in the world of
private aviation.
Figure 10-15.
The Cessna 172 Skyhawk (Photo courtesy of Steve Ashley)
According to the manufacturer specifications,
4
the Skyhawk engine delivers 160
hp
at
2400
rpm
. The propeller diameter is 75
in
. We'll assume the Skyhawk is using a McCauley 7557
propeller, so we can use the curve-fit relation shown in Equation (10.9) for the propeller efficiency.
In order to compute the thrust profiles, the engine and propeller specifications will be converted
to SI units.
P
e
= 160
hp
= 119310
Watts
rev
s
n
= 2400
rpm
= 40
--------
d
= 75
in
= 1.905
m
a
=
1.83
b
=−
1.32
The thrust profiles will be computed at several altitudes so the power drop-off factor will
be computed for each altitude. Table 10-1 shows the atmospheric density and power drop-off
factor for four altitudes.
