What You Need to Know for First-Flight Success
The first flight on any new giant-scale aircraft is always exciting and stressful. All models exhibit different behaviors that the pilot must understand and not abuse. With a lightweight, high-wing Pilatus Porter, for example, you can extend flaps and perform slow passes and turns over the runway with ease. If it’s a heavier airplane, however, its stall may be somewhat unpredictable when it’s flown in a similar way. You must be capable of adjusting to the flying style required by any giant plane you’re flying.
BACKGROUND BASICS
Assuming your airplane has been properly built, balanced, ground-tested, and charged, the first flight should be a fun experience. Pick a calm day, and if you feel that the winds are too high, simply cancel the flight. While experienced giant-scale enthusiasts may feel comfortable flying in winds higher than 15mph, select the appropriate day based on your piloting ability and the type of model you’re flying.
Larger flying sites are better in case of an in-flight failure. If the engine quits and you can’t return to the runway, for instance, you’ll need to identify an emergency landing area. If you’re at a new flying site, be sure to observe and become familiar with the surroundings. Note any obstacles, and identify a few potential alternate landing areas. For the actual flight, I recommend having only two people, at most, help you with the flight. One assistant should act as a spotter and watch for other aircraft to prevent a midair collision. The second person should assist you if the airplane is severely out of trim. Having a second set of hands for trim changes is helpful as it allows you to focus on the controls.
Having more than two helpers is not recommended. Far too often, I have seen pilots become distracted and nervous when there are too many people are present during the flight. They talk to the pilot, ask questions, and make the pilot more anxious. During the first flight, your full attention needs to be on the aircraft.
TAXI TESTS
Taxi tests help you become familiar with the ground behavior of the aircraft as well as how the throttle will respond at different settings.
For steering, point the airplane into the wind and increase throttle until the plane is moving at a fast walk. If tracking isn’t perfectly straight, adjust the steering mechanically or add trim to the rudder/steering servo. Then, increase throttle to explore even higher speeds on the ground while staying aligned in the wind. If the steering is too sensitive, decrease the steering servo or rudder servo travel and/or increase the exponential amount. Ground handling for WW I tail-draggers can be somewhat challenging with a nonsteerable skid, so proper alignment into the wind is important as corrections aren’t possible until the rudder becomes effective.
Pay attention to the throttle response.
The engine should respond in a linear manner and return to the same idle position. If the idle appears to fluctuate, examine your throttle linkage, carburetor settings, and the fuel tank plumbing and/or tank installation. After everything is sorted out, set an audible timer to keep track of your flight time.
IN THE AIR
Start the timer and slowly increase throttle. Apply small corrective commands as needed to keep the airplane tracking down the centerline of the runway. If you notice that the aircraft is not tracking well and is difficult to control, abort the takeoff by reducing throttle and examine the airframe. If you try to continue and make large rudder or steering corrections, you can quickly get behind the commands required and the situation will only worsen. Key areas for poorly tracking models typically include loose steering
linkages or friction on one of the main wheels. Throughout the takeoff roll, allow the aircraft to achieve the speed required for takeoff and, if a tail-dragger, allow the tail to rise. Slowly pull back on elevator until you’re in the air. If your model becomes airborne too quickly or remains on the ground for an extended period, the elevator alignment or the center of gravity (CG) may be incorrect. Focus on maintaining a relatively shallow climb angle and then turn 180 degrees away from the flightline to establish straight and level flight on the downwind leg. Remember: Use only small and smooth stick movements until you’re familiar with the aircraft’s response. Too often pilots become aggressive and overcompensate, which is the main cause of crashes. The goal at this point is to apply any trim for the aircraft to fly in straight and level flight, while at a high throttle setting, without any corrections. Some radios allow adjustment of the trim step values, which determines how many “clicks” of trim are applied when you press the trim button. I prefer fine adjustments, so I typically decrease the trim steps accordingly. If the airplane yaws in one direction or another, the cause could be any trim in the aileron and possibly too much or not enough engine side thrust. For the first flight, though, simply apply rudder trim to correct. Before you change any control surface deflections, exponential settings, or programmable mixing to correct certain undesired tendencies, make sure the CG is correct. Changes in the CG will have an impact on the feel of the aircraft. Coordinated turns are typically required, especially with high-wing models, so aileron differential is extremely helpful. If turns appear to require a lot of deflection, add some rudder.
I recommend that you explore slow-speed flight and practice a few stalls to become familiar with the behavior of the aircraft. I like to climb to a safe altitude, turn directly into the wind, and slowly reduce power while applying various corrective inputs to maintain altitude. At some point, the nose (or both the nose and one wingtip) will drop. When that happens, release inputs and establish downward flight while also increasing power to gain speed and return to upright level flight.
FLYING WITH FLAPS
If your model has flaps, you should test to see how the model responds to different flap deflections. Some modelers prefer not to use flaps on the first flight, and I have done it both ways. Many pilots assign the flaps to a slider switch, but I find it difficult to know exactly how much deflection exists with this method. I prefer to use a three-position switch: where the first position has no flap deflection, the second position is for half flaps, and the last position gives full-flap deflection. Light airplanes, like the Pilatus Porter, may require some down-elevator correction as the model pitches up slightly when flaps are deployed. Other aircraft may require little to no corrective elevator input. Add downelevator trim as needed for each flap position so that the aircraft maintains altitude when the flaps are deployed. It is important to become familiar with the response of the aircraft with flaps as it will change compared to flight without the flaps deployed. Being able to detect when the aircraft is approaching a stall is mandatory for safe flights.
LANDINGS
When the time has come for the first approach, your spotter should check the wind direction and let you know the correct landing direction. Slowly reduce throttle to about 30% as you turn onto the base leg. If high enough, you can reduce power to a just above idle and begin a descending turn to final, and become aligned with the runway. Giant models must be flown all the way to the runway, so with a typical approach, about 25% throttle is used until your airplane gets close to the runway. To prepare for a possible flameout, I start at a slightly higher altitude and keep the engine at idle in an effort to make the approach a little steeper. Control the descent rate with elevator, and throttle and make small aileron and rudder corrections to keep the airplane lined up with the runway. Add throttle, as needed, to keep the airspeed safe, and balance elevator input and throttle until the aircraft touches down.
Different models will require different flying techniques. While some prefer to land on the main landing gear (for tail-draggers), others may bounce. If that is the case, make a three-point landing. If you are going to overshoot your landing, don’t force the plane onto the ground. This will lead, at best, to a bent landing gear or a broken prop. Advance the throttle smoothly for a shallow climb and go around for another try. Don’t be in a rush to make that first landing.
Once on the ground, taxi back and shut the engine down. Shut off the ignition switch, check the fuel level in the tank, then adjust your transmitter timer.
FINAL THOUGHTS
With your first flight, time must be spent to become familiar with the response of your model. Take advantage of the programming functions of your radio systems to decrease your workload. Seek the advice of experienced modelers, both during the build and before the first few flights.