RC soaring: An intro to flying gliders/sailplanes

By V Kadamatt | Guides

May 18
RC Soaring glider

Do you think flying RC helicopters, quadcopters and planes are fun? You better know that you haven’t seen all the ‘fun’ yet! Gliders arguably offer the most exhilarating experience of all flying machines. You may think you need a battery or fuel powered motor to stay up in the sky and that your flight times are limited by the fuel source. This is not the case with RC soaring!

With gliders, your potential to stay up in the air is determined by environment: wind, thermals etc. and your ability to utilize those environmental forces. This is what makes soaring so much fun! You need to be really watchful of not only your craft but also of the surroundings. You simply cannot expect to fly a motor-less glider without this skill.

LiPo Management Cheat Sheet to Make your Battery Management Easier!

Improve drone battery life and and flight times by following through this EASY cheat sheet!

Gliders/Sailplanes can be the most relaxing and ‘liberating’ flying experience you’ve had but at the same time, these often underestimated flying beasts hit the fastest flight speeds in the world with dynamic soaring. Surprised? Here is a video of a glider walking the talk:

Here is a video that demonstrates the other end of the spectrum (smooth and relaxing):

It is a shame that RC soaring isn’t as popular as other types of flying. With this article, apart from providing the information for you, it is our hope to motivate more of you to try out this wonderful flying craft!

RC glider/sailplane basics

As with every other type of flying craft, the first thing that you may ask is what are the types of gliders and sailplanes out there? How do you pick the right one?

There are a wide array of different gliders out there, ranging from simple 2 channel gliders to gliders that have 3 channels or more. They can also be classified under launch types, size and type of soaring.

Launch type

Different gliders are typically built for different launch types (which we will cover in this article). For example, hand launched gliders (or ‘chuck gliders’) are typically smaller in size to allow for easy throw ability. Hand launched gliders are excellent for easy launching without external aid.

The other main launch type build for gliders are the discuss launch gliders. These gliders have a special handle at the wing tip that you hold with your thumb and index finger all the way till launch. The pilot is supposed to spin and launch the glider into the wind much like throwing a discus. Here is a great video by Flite Test:

Soaring type

The other way to classify different types of gliders are according to what kind of flight they are built for. For example, if you want a model capable of enduring the speeds involved with dynamic soaring, you will need strong structural reinforcement in the wing and fuselage whereas with thermal soaring, the models tend to be light with large wingspans. Combat gliders on the other hand are made with durability in mind. These gliders are built typically small, with EPP foam, making them incredibly durable.

Size

Lastly, gliders are classified according to their size. Obviously, as we discussed in the earlier sections, size will vary with and is directly connected to the launch type and soaring type. There is however, one more variety of gliders that are worth discussing – the scale model glider.

These are models of real, full scale model gliders and are typically large in size (although not necessarily). Larger the glider gets, the more difficult it is to launch it with traditional launching methods. Often, you might need an intermediate-advanced launching method like aerotow launch to get these beasts up in the air.

Building your own vs purchasing

The very first decision you will need to make is whether to start off building your own craft versus purchasing an ARF (Almost ready to fly) kit. With motor-less RC gliders, It should be noted that not many RTF (Ready to fly) options are available for purchase, so you will probably need to do some sort of building/assembling regardless.

An ARF kit can be assembled and put to use within a couple of hours whereas it will take a week or more to build your own glider in your spare time, as a beginner. Not to mention, at the end of all of it, the craft may not fly appropriately or not fly at all.

The major advantage with building your own craft is that you will build a useful skill that will come in handy throughout your hobby career. The very process of building the craft can be just as enjoyable as flying the craft itself!

It is also worth mentioning that watching something that you built soar the skies is far more exhilarating than flying a craft made from an ARF kit.

The other advantage is that you will be skilled enough to repair your craft in case it crashes. This will really come in handy for you especially if you are a beginner flyer, because you will be prone to crashing the more than the experts.

So what should you pick if you are a beginner?

If you have decided to build your own glider, then things are going to take much longer. You will need to scour the internet in search of build ideas and how to build if you have no clue and no one to help you out. We’ll be posting articles on DroneyBee, guiding you through much of the process, so be sure to check that It out!

However, if you think building on your own is too much at this point, we suggest you pick a simple two channel glider kit like the classic Goldberg Gentle Lady. These are typically durable, versatile, long lasting and perfect for beginners to train on, before moving onto more advanced models with more channels.

 

RC soaring basics – Types of soaring

RC sailplane soaring : Infographic

Slope soaring

With slope soaring, you essentially get your glider up in the air from wind blowing upward a slope. The blowing of wind in this upward fashion is called ‘ridge lift’. If the wind is strong enough, then this upward force is what lets gliders stay up in the air.

Slope soaring should be the easiest, for a beginner to get into. That being said, you need to find a proper hill or a slope for this. Ideal conditions for slope soaring may not be available where you live.

The hill or slope must be high enough for the glider to fall off a bit without crashing down at the bottom and steep enough so that the wind blows upwards and not nearly straight. Note that slope alone will not get your glider up. Wind and its direction is just as important.

It is also important that the direction of the wind is toward the slope of the hill, raising up and not the other way around. Coastal regions with mountain ridges or a cliffs, where sea breeze coming inland are perfect examples for this.

Thermal soaring

Thermal soaring is second in terms of difficulty. ‘Thermal or Thermal column’ according to Wikipedia definition is “a column of rising air in the lower altitudes of the Earth’s atmosphere”. It is caused by warmer air near the ground relative to the air above it due to the heating of the ground by the Sun.

The warmer air tends to be less dense (and hence lighter), causing it to rise up. This is where our glider comes in. With thermal soaring, our goal is to find these rising columns of air and use them to gain altitude. Ever wondered how birds like eagles stay up in the sky without ever flapping their wings? Thermal soaring is the answer.

Thermals happen frequently in summer, but it is a temperature contrast that makes thermals, so they can happen in winter if the mass of air is colder than ordinary.

In thermal soaring, these lifts are typically isolated by huge areas of sink, in which case the pilot hovers around the thermals to gain maximum altitude and then continues to fly around till it is time to ‘re-fill’ the altitude again, in which case it is time to find thermals again.

Dynamic soaring

Dynamic soaring (DS) requires skill and reaction unlike any other kind of soaring. If you want speed and roller-coaster like exhilaration, then this is it! Like we already discussed, it can take your glider to record breaking speeds.

Dynamic RC soaring is done by launching the glider, much like slope soaring and then turning into ‘leeward’ side of the hill with a slope, where the wind blows away from the hill.  The part below that is nearer to the ground of the slope will typically have wind that is still or slower relative to the upper part where the wind is blowing away.

The glider keeps picking up speed with each round by flying in this zone where at the top, the wind blows away from the hill and at the bottom, where is slow or relatively still. The speed is preserved at the bottom part of the flight while it is increased at the top, where the glider moves in the direction of the wind, gaining speed. The following video demonstrates this concept excellently:

Although it is better if you join an RC soaring club near you if you want to get started in any kind of soaring, with Dynamic soaring, it is HIGHLY recommended that you do not attempt this on your own! The skill and dexterity required of dynamic soaring at high speeds is far higher than any other kind of soaring. It is important to have mentors to guide you and be there to help you out if things go south

 

RC glider launching

Motor-less gliders can be launched in multiple ways. Here we’ll cover different launching methods and how to execute them.

Simple launch

Simple launch is just a straight forward throw. What you basically do is launch the glider off your hand directly with a firm push like how one would throw a javelin. In order to perform this launch during thermal soaring, it is imperative that there is strong, favorable wind condition. Also, if the glider is bigger than a certain threshold, it becomes near impossible to perform this throw if you want to thermal soar.

A simple launch is best done if you are slope soaring or dynamic soaring in a slope where the wind conditions are appropriate. Essentially, you throw the glider horizontally into the wind and immediately get your hands back onto the transmitter.

The advantage of this type of launch is that you can do it alone and without assistance from any external tool or person.

Bungee launching

One of best launches for the sake of thermal soaring is the bungee launch, provided you install the setup on your flying field. Bungee launching is easy for beginners and will quickly get your glider up in the air. The following video pretty much demonstrates what it is:

Essentially, what you need is a bungee cord with a decent amount of elasticity and a stake installed on the ground. Attach one end of the bungee cord to the stake and the other end to a hook that is attached to your glider. Some gliders have these hooks pre-built. If yours doesn’t, you may need to fix one by yourself.

Once you have attached the cord as necessary, walk back with the glider until the cord stretches with enough elastic potential energy. You may have to try out different distances from the stake before you find the golden distance for your particular glider.

Once you have walked the appropriate distance from the stake, release with a little bit of force, noise pointed slightly upwards and immediately return your hand to the transmitter. As the glider approaches the top position of the launch, gently pull back on the elevator to cut off the bungee cord and begin soaring!

Discus launching

The discus launch is perfect for thermal soaring. You do not need additional equipment like a bungee cord and stake, nor do you have to walk back, reattach and go through the same long process like the bungee launch. Most of the time, you can perform a discus launch solo, without hiccups.

The only problem however, is that it can take some time getting used to it and master it. You will probably fail and crash a couple of times before hitting that perfect discus launch. It is definitely worth mastering the discus launch if you want to be a complete RC glider pilot.

To perform the discus launch, you have to first get the holding of the glider correct. Discus launch gliders have a pin on one of the wing tips on which you place your middle finger and index finger to hold the glider. If there is no pin, you may want to DIY install one on the wingtip of your glider yourself.

Keeping your arm straight out, place the opposite leg forward and rotate your torso toward the side of the leg. Now, place the other leg further forward and rotate your torso to a complete 360 degree rotation. As the rotation is finished, the glider should slide out of your fingers out into the open air. Make sure your arm is kept straight throughout the rotation.

Note: The power is not achieved from using arm force, but through the rotation of your torso. You will probably be able to perform a discus glider throw even if you are a weakling.

Aerotow launching

Regular launch methods do not work with gliders that have wing spans larger than life (4 m gliders, for example). Good luck trying to discus throw a large glider.

This is where advanced launch methods like the aerotow comes in. Essentially, the glider is ‘towed’ up by a powered RC plane via a towline attached to the RC plane on one end and the glider on the other.

Yes, to perform this launch, two pilots are required – one to pilot the RC plane and the other on the glider. Not only this, it is essential that both pilots be incredibly skilled and coordinated with each other. For this reason, this launch is typically not recommended for beginners.

However, if you think you have some level of mastery gliding in general, you can go ahead and practice the aerotow on a small, cheap, foam made glider. It is recommended that you find a partner who knows what he/she is doing or join an RC club with people that do. Social flying is better than flying alone anyway, trust me! J

Piggyback launching

Piggyback is yet another way to launch your glider. With piggy back launching, you’ll need an expert powered RC plane pilot who will fly the RC plane on which your glider sits on.

There is no specific, all size fits tactics for piggyback launching as different plane/glider combination will feel and act different. The only real answer to piggyback launching is to be prepared at all times and to have enough dexterity and skill before performing this maneuver.

Really, the manner in which you would want to launch your glider will depend on what type of soaring you are looking forward to. For thermal soaring, discus launch or the bungee launch will be ideal.

 

How to fly RC glider/sailplanes – Thermal soaring

 

How to spot and catch thermals

Learning how to spot thermals is at the heart of thermal soaring. Thermals are the ‘fuel’ for a motor-less glider to gain or maintain its altitude. It is what creates the ‘lift’.

Like we have already discussed, these lifts are typically isolated by huge areas of sink, in which case the pilot hovers around the thermals to gain maximum altitude and then continues to fly around till it is time to ‘re-fill’ the altitude again, in which case it is time to find thermals again. Here are the things to look out for, in order to find a thermal and use it:

Birds

Stay on the lookout for birds that soar. How exactly they find thermals to soar is currently unknown, but no one and nothing can best a bird in their ability to find thermals. If you spot a bird, such as an eagle soaring in a circle, you’ve found a thermal.

Clouds

Watch out for cloud formations. Thermals that are still in action form Cumulus clouds that tend to be curved inwards at the bottom and curved outwards at the top. You are most likely to experience a lift if you go under one of these clouds.

Topography

If you fly your RC glider above mountain peaks and passes, cirques facing the sun and ground that would soak up a lot of heat relative to the sun would generally have thermals and you would likely experience a lift.  Wet ground on the other hand, can be poor hosts for thermals.

Dust Devils

A dust devil is a small whirlwind that is generally very visible due to accumulation of dust and other materials. Flying your RC glider into one can give it a tremendous lift:

As you approach the dust devil with your RC glider, it is necessary to make sure that the angle of approach is against the rotation of the dust devil. A dust devil may swirl your glider out, crashing it if you approach it at an angle that is aligned with the rotation.

Direction of the sunlight

It is important to note what time of the day it is, especially if you are flying in a hilly area. The direction of sunlight will directly affect where thermals are formed. Remember: Thermals are formed by the heating of the ground.

Secrets of thermal soaring: Thermal tips and techniques

As you get better at piloting RC gliders, you’ll start to develop an intuition as to where thermals are formed, especially in your local flying area. However, simply being able to detect where thermals occur isn’t enough. It is important to be able to utilize the thermals to the maximum. Here are some tips and techniques to consider:

Keep your hands off the elevator

To be able to properly utilize a thermal, you must be able to recognize if you actually found one! Refrain from constantly pulling and pushing at the elevator controls or else it will be difficult to spot the glider lift if and when it passes a thermal.

Recognize the diameter and location of the thermal

It is necessary to let your glider pass through the thermal completely before you turn around back into it, so let the glider go (until there is no sinking) to determine the actual diameter of the thermal. You may lose a couple of altitude with this process, but worry not. Do not rush the bank turn. Understanding and ‘feeling’ the thermal you’ve found will help you go up faster in altitude than if you did not. (Covered more in detail in the next section)

Always note the sink rate of your glider

Finding and being in a thermal zone does not necessarily mean there will be a lift. A better gauge is to note how much your glider is sinking. If your glider hasn’t been sinking in altitude for a while, you’ve been in a thermal all along.

Thermal detectors: Variometer

A variometer is a device with which you can measure variations in air pressure. Perfect tool for thermal soaring! It will enable you to determine whether your glider is ascending or descending. This is crucial to centering your glider in a thermal!

Here is a video that explains what a variometer and how it is used:

An important thing to note with variometers is that it does not show instantaneous reading. Usually, there is a 2-3 second delay for variometers to beep after thermal detection.

Centering a glider in a thermal

After you have found a thermal, to utilize it, you must be able to center your glider in it. Flying in half in and out of the thermal is very inefficient, which is why the recognition phase is so important!

RC thermal soaring : Lift distribution

The very first thing you will need to master is to maintain speed and bank (turn) angle. The main reason for this is because even the most subtle differences in angle or speed will gradually take your glider away from the thermal. Learning how to keep your turns consistent will take time and practice.

RC thermal soaring : gradual drift away

Since there is a delay with variometer reading, it is understood that the thermal is most likely now BEHIND the glider already (unless there is a steady climb in the reading, in which case the glider is directly passing through the center). Once you have a variometer beeping for thermal, bank the glider into the direction of the lift at an angle of about 40 degrees.

RC thermal soaring : Variometer delay

Once the glider re-enters the radius of the thermal, you will now have an approximate idea of the diameter of the thermal. Bank again back into the thermal and find the area where the lift is even higher (stronger variometer reading) and repeat the same process to get an approximate idea of the location and diameter of this higher lift, within the larger thermal diameter.

Repeat until you find the area of the highest lift and center the glider around it by repeated banking. A useful point to remember would be to: Bank harder (increased angle as the climb rate/variometer reading increases and ease up on the banking angle if the lift decreases to find the optimal location inside the thermal and keep inside it)

Thermal soaring : BANK ANGLE

This video pretty much explains when to turn and how to find the center via variometer beeping:

This is an excellent and insightful watch for all thermal gliding pilots, RC or not:

 

RC soaring: How to slope soar an RC glider

As we have already discussed earlier, for slope soaring you need to find a proper hill or a slope. The hill or slope must be high enough for the glider to fall off a bit without crashing down at the bottom and steep enough so that the wind blows upwards and not nearly straight.

Slope alone will not get your glider up, wind should be strong and the direction should be so that it blows toward the slope of the hill, pushing the wind upwards. This upward push of the wind is what our glider will use to gain altitude.

RC slope soaring: Glider push

Another important thing to consider is to make sure that the slope is clear of trees and other obstacles. Obviously, flying a glider in such a situation will be not ideal.

Unlike thermal soaring, the technicalities and learning curve shouldn’t be too much for a beginner and hence, this would be the perfect way to start off learning how to glide and master your controls, bank angles and such, before moving onto thermal soaring.

Gaining altitude

As with any kind of motor-less RC soaring, the goal with slope soaring is to use the wind to gain and maintain energy and altitude. After you have launched the glider into the wind, down the slope, your goal is to turn and fly within the range of the rising wind. Do not fly too far away from this range or else you may lose a LOT of altitude to the point of no recovery. Fly side to side and turn into the wind.

RC Slope soaring

Always turn your glider opposite to the direction of the wind. You can probably imagine what will happen if you don’t. Your glider will be gradually pushed inwards and that is not what you want.

Turning against the wind is perfect because the wind will keep the glider from gradually flying too far away from and the turning will keep the glider from flying towards you.

 Landing

In order to land, your glider must lose altitude and energy. Usually, this is done by making a large turn back onto where you are standing and into the opposite side of the direction of the wind. This flight against the wind should result in an altitude/energy loss and prepare you for landing.

RC soaring : Slope soaring landing

 

Fly your glider like you normally would. Only this time let the glider make a wide turn back above the land you are standing, opposite to the direction of the wind and gradually land your glider, it facing the direction you were facing all along, when you were flying it.

Conclusion

If you are only used to flying planes with motors, soaring a motor less glider can take a while to get used to, regardless of what kind of soaring it is. If you are a beginner, RC soaring is arguably the best way to get into RC plane flying. You will not only learn how to handle the different controls (which will prepare you for motored flying), you will go above and beyond the minimum required skills, if you master soaring. You will learn to be watchful of the environment and wind conditions around you, which will go a long way in any kind of RC flying.

That’s all folks! Please post your comments/questions down below if you have any. Are you a seasoned RC soaring expert? Let us know what you think. We would love to gain some insight!

 

 

RC soaring: An intro to flying gliders/sailplanes was last modified: August 2nd, 2017 by V Kadamatt

About the Author

Artificial Intelligence , UAV and RC enthusiast. Software professional, part time philosopher and star gazer. Also loves physics, mathematics, economics, psychology, fantasy, Sci-Fi and futurology.

Leave a Comment:

Leave a Comment:






Improve drone flight times and battery life by following through this EASY cheat sheet!