Game Development Reference
In-Depth Information
Exercise
1. Compute the liftoff velocity for the Cessna 172 Skyhawk that uses a NACA 2412 airfoil for its wing. Assume for
this problem that the incidence of the wing is zero. The weight of the plane is 10245
N
(2300
lb
), the reference wing
area is 16.2
m
2
, and the plane is taking off at sea level where the air density is 1.22
kg/m
3
. Assume that the flaps
are deflected at 20
o
during takeoff, resulting in an increase in lift coefficient of 0.25 over the nominal value, and that
the lift coefficient is increased by 0.25 due to ground effects.
Landing
If the lift generated by an airplane is less than its weight, the airplane will descend. The maximum
rate of descent for landing is limited by the ability of the landing gear to absorb the impact. The
pitch angle of the airplane at landing has maximum and minimum values as well. If the pitch
angle is negative, the nose of the airplane might strike the ground before the wheels do. If the
pitch angle is positive but at too high a value, the tail might scrape the ground.
The simplest way to evaluate a landing in an airplane simulator is to define a maximum
vertical velocity and pitch angle for a given airplane. If the plane hits the ground and is exceeding
these maximum values, the simulation can assume that the plane has crashed.
A Basic Flight Simulator
At long last all of the physical model development is complete, and we are ready to create
a basic flight simulator. If we know the geometrical and performance characteristics of an
airplane, the lift, drag, and thrust forces acting on the airplane can be evaluated using the
equations presented in this chapter. As with the other games developed in this topic, the flight
simulator will be displayed using a very simple Java GUI. The graphics aren't very sophisticated,
but the physics inside the Flight Simulator are real.
A lot of elements go into modeling an airplane in flight, but to make the Flight Simulator
a bit simpler to program, we will ignore some of them. Here is a list of some of the features,
assumptions, and simplifications in the Flight Simulator:
•
The engine thrust, lift, and drag are modeled according to the equations presented in
this chapter.
•
The lift coefficient will be modeled by straight-line curve fits to the experimental data for
the NACA 2412 airfoil shown in Figure 10-8.
•
The pilot will have control over the angle of attack, throttle, and bank angle of the airplane.
The plane will have the ability to pitch, yaw, and roll.
•
There is no wind in this simulation.
