Learning to Fly RC
Field inspections and trim flights
Text, photos and video by Tom Hintz
For our purposes here we will assume that you nearing completion of your airplane and have hopefully already been in contact with an instructor pilot from your flying club. There is lots of guidance available at club meetings and the field during the building process. See our story “Buying and Building Your First Plane”. Our story here focuses on taking the finished plane to the field for the first time.
Finishing the Plane
Part of completing the building process is making sure that the radio and plane understand each other. Today this “understanding” is accomplished by a process called binding. Today’s radios are computer-based and have the ability to focus on one receiver once they are acquainted with each other. The radio comes with a binding plug that goes into a special binding socket on the receiver. Your instruction manual for the radio will describe the sequence in which you turn things on and if a switch must be held during the binding process. Later in this story we will want to go through this binding process again to lock in “failsafe” settings.
You also want to check the CG (center of gravity) as described in your instruction manual for the plane. It is a good idea to mark the CG location on the plane with a magic marker or even a piece of masking tape. On high wing planes place these marks under the wing. On low wing configurations put the marks on top of the wing so they are easier to use at the field. Having the CG in the correct spot is crucial to how the plane flies, too far forward and the controls an get sluggish, too far back and the controls can be so sensitive a plane can be uncontrollable. When checking CG the plane has to be “flight ready” with fuel in gas or glow-powered planes and fight batteries in electric-powered aircraft.
You also should have prepared a few props to carry along with you. Snapping a prop is not uncommon during the early flights and can kill the whole day if you have no spares. Besides, we want the props to be prepared correctly and that is best done before you bring them to the field.
Sand the edges of most non-wood props to get rid of the often razor-like flashing left by molding processes. You don’t have to get carried away, just blunt the edges. You also need to balance the props (after sanding the edges) to protect your engine (gas or electric) and plane from vibrations that can damage bearings and cause them to operate below their capability. Vibrations can also impact receivers, especially those with gyro capabilities.
What to Bring
Of course you bring the plane to the field but it is also important to bring the manuals for the plane itself and your radio. If you have installed a separate ESC (electronic speed control) in an electric plane, that manual should come along as well. These manuals could provide important information if your instructor pilot finds a problem. Lastly, if you have a trainer cord, always bring that to the field. Instructors generally have them but bring it if you have it!
Also, bring your binding plug that came with your radio. Once the plane gets trimmed out it is important to re bind it to the transmitter to establish “failsafe” points. This is the configuration most radios go to if they lose signal from the transmitter. We want the controls to stay level and the throttle to go to idle so the plane doesn’t keep on going if something happens.
If your plane came with special tools or you found they were needed, bring them along in your field box. If your plane has a fuel engine make sure that you have enough of that and the means to fill the tank and start the engine it safely. Don’t count on the instructor having these items. If you have an electric plane be sure to have a few battery packs and/or a way to charge them so you can get in a few flights if everything else works out the first day.
The first few times your plane flies the instructor will probably be at the controls to get it trimmed out. The instructor will have gone over the controls before taking off to be sure that the controls move in the right directions when commands are issued from the radio and range check the radio.
During the first trim flight the instructor will adjust the planes control surfaces using the trim tabs on your radio. If the plane can be trimmed to fly normally the instructor may put it through some maneuvers to get a feel for what it likes, what it is capable of and to see if it has any bad tendencies. This also gives the instructor the opportunity to see how the power plant is working. Finally, the plane has to be landed and the instructor will learn a lot about how your plane handles then o better help you later.
After each trim flight the instructor will probably list changes you need to make to the control linkages. Ideally we want to get the plane adjusted so that it flies normally with all of the trims left at zero. After you make those adjustments and the plane is checked the instructor will fly it again to see if any further trims need to be made. This trimming out process may need just one flight or several. It depends on how close it was at first and how it responds to the adjustments.
I know that by now you are more anxious than ever to fly your new plane but this process of getting it ready for you has saved many good airplanes that probably would have crashed if we just tried to get you flying right away. Spending the time to go over the plane on the ground and then going through the trim process produces a plane that you can learn on more easily and quickly because it flies correctly. You also get to just watch your new creation fly a little.
I have had a number of student pilots remark after their first flights that they could not recall what the plane looked like in the air. They were so engrossed in flying it that the image of the plane itself sort of gets lost. That goes away soon enough, sooner if you have an instructor who did the trim flights first.