PFR - Aerospace Engineering Sciences Senior Design Projects ...

Project Final Report – CUDBF April 30 th , 2009
ASEN 4028: Aerospace Senior Projects
Table 21: Speed Controllers Options
Speed Controller Maximum Maximum Weight (g)
Voltage Amps
Phoenix 45 19.2 45 30
Phoenix HV-45 50 45 60
Phoenix 60 35.0 60 58
Because of the high voltage requirement, the Phoenix 60 speed controller was chosen. The
Phoenix 60 was chosen over the Phoenix HV-45 speed controller because it was 2g lighter and is
rated for higher current. The higher current rating means the speed controller will run cooler and
will run less risk of overheating. An image of the speed controller is shown in Figure 79.
Figure 79: Speed Controller
9.1.4 Wire Gauge
In order to connect the battery pack at the center of the aircraft to each motor, approximately 1ft
of wire must be run in each direction. This wire must be able to sustain the amount of current
flowing without overheating or causing a significant voltage drop, while keeping weight down.
The wire gauge sizes considered were 16AWG, 14AWG, and 12AWG. The higher the wire
gauge, the lighter the wire. However, the lower the wire gauge, the more amps the wire is rated
to handle. This means the wire will not get as hot, and there will be less voltage drop across the
wire at a given voltage.
The wire gauge was chosen based upon current rating, voltage drop, and weight. 16AWG wire is
rated for 22 amps, while 14AWG wire is rated for 32 amps, and 12AWG wire is rated for 41
amps. These ratings are for continuous current, and can be exceeded for short power surges.
Each motor may draw up to 20 amps of continuous current and up to 40 amps in short bursts for
takeoff.
Next, the weight of one foot of wire and the voltage drop over that span were calculated for each
wire. The voltage drop was multiplied by the average current in order to get the average power
lost in the wire. This value was compared to the equivalent weight of a battery required to
provide that amount of power. The extra weight of the wire was compared to the equivalent
weight of the extra batteries required to provide that power.
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