Radio Control Model Planes and Indoor Flight
Miniature radios with foam RTF aircraft equal practical micro flight
The electric model plane has opened up a new world of flying for RC modelers. Thanks to advanced low cost fabrication processes, today’s micro RC gear and foam construction methods allow for incredibly affordable and well flying small model aircraft.
Employing techniques such as two channel infrared (IR) transmitters (as opposed to the longer range but more expensive radio frequency control system) with built in chargers it is possible to obtain a complete model airplane or micro helicopter flying ensemble for well under $50.
The variety of these micro RC flyers is amazing. One of the earliest of this new genre of ready to fly foam model plane was the Air Hogs Aero Ace. I have been flying RC model aircraft since 1972, but had seen nothing like the Aero Ace. Using two channels of RF radio control, the Aero Ace was unique in that it has no moving flight control surfaces.
Aero Ace control
Instead, the designers of the Aero Ace used differential throttle between the twin pusher props to make the model turn left or right. This control technique is transparent to the pilot, as the “rudder control” on the transmitter automatically adjusts the differential power setting between the two electric motors to produce a turn. The second channel on the Aero Ace transmitter is a fully proportional throttle.
With the Aero Ace electric model plane, the two control channels provide a surprisingly good response while flying. The Aero Ace pilot had to do a bit of thinking to properly fly this particular airplane. When airborne, increase throttle to gain altitude and reduce throttle to fly lower. As the Aero Ace does not have an elevator control for pitch, there is just one throttle setting that allows for level flight.
The differential thrust provides insight into another area of aeronautical knowledge for the Aero Ace pilot. When using the right stick on the transmitter to change heading, most models will have the rudder move to start the turn. The Aero Ace does not have a rudder. Instead you reduce the thrust on the motor in the direction in which you want to turn.
Differential thrust for turns
For example, if you plan for the Aero Ace to turn left, move the right side stick on the transmitter to the left. The Aero Ace’s on-board computer automatically increases the RPMs of the right motor a bit and simultaneously reduces the power of the left motor.
This action causes the Aero Ace to turn to the left. Note that in starting this turning maneuver the overall total power is decreased slightly due to the lower power of the motor inside the turn.
You quickly learn that when turning the Aero Ace, as there are no control surfaces, you need to increase power slightly to prevent the model from dropping in altitude.
One item of good news on small models such as the Aero Ace is that there is no penalty for failure. The model is so small and light weight that it is just about impossible to do any damage if you bump into a wall or suffer a crash. The tiny pusher props are protected from damage by being behind the wing’s leading edge.
Another interesting example of a two channel micro RC airplane is the Havoc Cyclone. The Cyclone is a flying wing using a pusher propeller.
The Cyclone uses two channels in the infrared (IR) spectrum. The Cyclone employs a proportional throttle and a tiny rudder for turns. The rudder uses a magnetic actuator, a common technique for smaller micro aircraft that bypasses the need for a servo.
The Cyclone’s geared motor allows for a larger propeller and provides plenty of thrust. The rudder is used for turns. The button arrangement on the transmitter uses either full left or full right rudder control. With practice, smooth flight is easily achieved.
Cyclone flying wing
The Cyclone’s flying wing layout has a unique airfoil section. The model flies at a very high angle of attack, close to 45 degrees nose high when in level flight. This all works well once in the air and the Cyclone has a very positive control feel when you are flying.
Note also that with the complex airfoil shape and embedded pusher propeller, it would be just about impossible to construct a micro model of this type as a home builder. This is a good example of the benefits provided by these precision built ready to fly RC airplanes, especially for the micro flyers.
Author: Gordon McKay