Initial Glider Setup
Trimming and setting up your glider should be a repeatable task. Here is our basic procedure for setting up our own gliders to be competition ready, hope it helps! If you have any questions, please feel free to email us.
Basic Setup Pre-Maiden
- Flaperons: ~15-20 mm up and down deflection (make sure it is symmetrical on both sides).
- Rudder: ~10-15 mm left and right deflection (make sure it is symmetrical on both sides).
- Elevator: ~10 mm up, max down deflection.
- Brakes: ~45 - 60 degrees down deflection.
- Center of Gravity (CG): as per plane guidelines.
- Flight modes: as per glider guidelines.
- Make sure all the deflections are moving in the correct direction.
Level Hand Toss
- Every new glider should first the trimmed to fly straight and level from overhand tosses.
- Trim for your speed, cruise, and float flight modes.
- Once the glider is trimmed to be level and stable with the overhand tosses, add the launch preset flight mode, with around 3 mm of up elevator trim. The launch preset is a momentary flight mode used to pitch the glider upwards during a discus launch, and is let go after a fraction of a second, as soon as it reaches the angle that you would like the glider to climb.
- Softly test the launch preset and add power gradually to ensure the plane is trimmed safely.
Center of Gravity (CG)
- Personally, I prefer a forward CG, why? Because with a forward CG, the glider is always in a positive stability condition, with the ability to auto-correct small inefficiencies in flying attitude without constant pilot input, thus increasing the overall flying efficiency while reducing pilot workload. Trimmed to fly itself in stable conditions, you can pay attention to how it reacts with the air surrounding the glider, for a more accurate 'feel' of any air activities around the glider. As the pilot workload is decreased, you will also have more time and energy to be aware of other glider in the air, flying strategies, etc.
- First set your glider to fly in speed mode, in level flight. The glider will need to be high enough to perform the following maneuver, say, roughly 25 meters or above.
- While in speed mode, push your glider to enter a roughly 45 degree dive. If the glider pulls up by itself, it is nose heavy; if the dive steepens by itself, it is tail heavy. Add or remove nose weight and retry.
- My goal is to have the glider dive at a constant angle while in speed mode, this way, it will result in a slightly nose-heavy condition, lending itself to a forward CG preference.
- After this quick setup, the CG is in the general location that suits my flying. I will continue to test the CG with actual flying, but typically it will be within 1 or 2 mm of this location.
Flight Mode Optimization
- The actual flight modes will be pilot dependent. For example, I have the following flight modes: Launch Preset (for plane attitude rotation after release), Zoom (for the climb phase), Speed (for glider acceleration), Cruise 1 (for best L/D when coming home), Cruise 2 (slightly lower L/D but higher lift), Float 1 (for situations requiring higher lift), and Float 2 (for best hang-time in dead calm conditions). Typically, the minimum you will need is the 4 basic flight modes: Launch Preset, Speed (used for climb phase, glider acceleration, and best L/D), Cruise (for general flying), and Float (or, Thermal mode, for when you want the most lift). Below, I will talk about the setup and functions of these 4 basic flight modes:
- Launch Preset is a momentary flight mode used for a fraction of a second after the release of the glider. It rotates the glider's attitude to the angle of your choice, and upon release going into Speed (or Zoom) mode, allows the glider to continue straight up at that angle to reach the highest height. Setup with 3 mm or so of up elevator deflection for the main rotation power, 2 or 3 mm of right rudder deflection (in case of right-hander) to compensate for any slight give in the rudder linkage (it is normal), and 2 or 3 mm of down flaperon deflection to assist in rotating the plane efficiently, and perhaps a few clicks of right aileron trim (for a right hander) to compensate for some yaw-induced roll from launch. All these values need to be tested and refined until you have the best setup to reach your highest heights. The use of an altimeter (telemetry will be best, logging works but is not as good since you can't have instant feedback) is priceless in this application.
- Speed mode in general will serve several functions. It is typically the mode with lowest drag and lowest lift. In a basic setup, the speed mode is used for the climb phase, for accelerating, and for coming back home from downwind. The camber setting is a pre-determined value that will be available from the manufacturer or vendor of your model. Occasionally, you may tweak this value slightly to achieve the effect you want. Trim the elevator so that the glider tracks nice and straight during the climb phase.
- Cruise mode is a very pilot-dependent mode that is a fine balance between the low-drag speed more, and the high-lift float mode. I use this mode to fly around looking for lift quite often, and the camber setting is very personal. There is no 'best' value. Try different settings and stick with something you like and fits your flying style. Trim the elevator so that glider can fly hands-off the sticks straight, level, and stable.
- Float (or Thermal) mode is the setting you use when you need the wing to generate massive amounts of lift, and/or fly slowly. While many reference it as the thermal mode, I find that it is not a very suitable name because often times the best mode to use in a thermal might not be the float mode, it could very well be cruise if the air is active. The more camber you use in this mode, the more lift the wing generates, as well as an increase in wing sensitivity to error and turbulence, and an increase in drag. Typically the max value is provided by the manufacturer or vendor. As a general rule, the more forward your CG, the more camber you can use due to the increased stability; going the other way, the further back your CG is, the less camber you can use due to the inherent instability of an aft CG. A simple way to test what is the maximum amount of camber you want for your model is to find a very calm morning or evening, and do repeated flight time testing. Launch, push over, and allow the glider to fly in big circles around the field with as little pilot input as possible in float mode. With each adjustment in camber, make sure you trim the elevator so that the glider can fly hands-off the sticks straight, level, and stable. Record all data, and find the best combination and settings.
- Brakes are used to increase drag and slow down your glider during landing
- On DLG's the brake is setup on the throttle stick with fully proportional control to accurately control the drag and speed of the glider during approach
- Elevator compensation must be used to stabilize the glider's attitude
- To achieve proper elevator compensation, a minimum of 3 points must be used on a brake to elevator mixing curve. For example: 0% brakes > 0% down elevator; 50% brakes > 25% down elevator; 100% brakes > 35% down elevator.
- If possible, aim for 5 or 7 points to fully smooth out the operation.
- The compensation at every single point of the brakes application must be so that the more brakes are applied, the lower the nose points.
- The ailerons are used to control the glider's bank, therefore at its most basic form, aileron deflection must be isolated from any yaw or pitch changes.
- Launch and level off in speed mode and fly straight. Once you are in a stable, straight, and level flight patch, rock to aileron sticks (be careful to not affect other control surfaces) left, right, left, right, left, right, at around 1 second intervals. If the plane exhibits a pitch up tendency, add reverse differential (more down, less up); if the plane exhibits a pitch down tendency, add positive differential (more up, less down). Do this test on all flight modes, and independently trim the differential values for each flight mode.
- For a rudderless glider, after the above test, you will want to add a little more reverse differential, because there is no rudder control to push the nose down into the turn.
Aileron to Rudder Mix
- By adding aileron to rudder mixing, when trimmed properly, it is easier to enter a turn smoothly.
- When moving the ailerons left, the rudder should also move left. Trim the value until a simple push of the aileron sticks initiates a smooth turn.
- Typically, this mixing is only used in cruise and float modes, please trim this value independently on each flight mode that you would like to use it on.
Elevator to Camber Mix (Snap Flaps)
- To increase efficiency during pitch maneuvers, camber is added whenever the elevator is moved to change the wing's lift characteristics.
- Up elevator deflection will result in down camber deflection. Down elevator deflection will result in up camber deflection.
- To start, add a 2~5% mix, and adjust the up and down deflections independently in each flight mode for best results.
- Each flight mode must be independent.
- Up and down deflection must be independent.
Dual/Triple Rates and Exponential (Expo)
- Gliders must fly smoothly to be efficient, so you only need small deflections on the control surfaces. The exception is on down elevator deflection, where you want to maximize it in order to have good authority during pushover at the apex of the launch.
- On the flaperons, I usually set 60%>80%>100% rates. Typically I will fly on the lowest or medium rates, and only use high rates if I am hugging trees or the wind is very turbulent.
- Flaperons and up elevator will usually run 10-20% expo to smooth out the action near the center.
- I run more expo on down elevator deflection to try to get the elevator response as symmetrical as possible near the center.
So, there it is! You now have a glider that is trimmed close to its peak performance. Take your time, and continue to tweak with settings until you have the best possible setup on your plane to suit YOUR flying style and skillset. Remember to do each tweak systematically, and never be afraid to experiment.