A Beginners Guide to RC Soaring

By Bob Waldridge, MRCSS

Sailplane or Glider?

A glider is a ship you launch to good height that gently floats back to earth. A sailplane, on the other hand, is a ship you launch to good height and it goes on up from there!

Which one you experience largely depends on whether you have taken the time to set that new lead sled up correctly. Let’s start in the workshop.

You’ve just finished building your latest sailplane masterpiece and have installed your radio gear. All control surfaces seem to be working, your battery is charged and you’re ready for the field, right? Wrong!

There are some subtle and important steps you need to take to insure optimum performance. First of all, did you weigh your wings separately? Lateral balance not only makes your plane fly straight, it helps it perform better. Add small amounts of lead to make both wings weigh the same.

Your stabilizer should be parallel to wing leading edge and equidistant from stab tip to wingtip. Use your eyeball for the first part and a string to measure the last part. Line everything up first, then glue.

Have you set your control surface throws correctly? Look at the manufacturers recommended throws. Buy a gage and set these up--adjusting holes on the control horn or servo arm or with travel adjust on computer radios--so you don’t get more throw than you need. More throw means you’re more likely to over-control, with subsequent loss of performance and possibly even a crash. Less throw makes your flying smother.

If you are prone to over-control, dial in some dual rates with exponential on computer radios so that a large stick movement results in less control surface movement. If you don’t own a computer radio, you’ll just have to be VERY careful not to move the stick too far or too much.

While we're at it, center your servos, then center your control surfaces using clevis adjustment, not sub trim on your computer radio. Did you check for proper control surface movement? Viewing from the rear, stick forward, elevator down; stick back, elevator up. Stick right, rudder right; stick left, rudder left.

I am sure you balanced your ship, but let’s take a second look anyway. If you had to add lead in the nose, you might as well get a larger capacity battery that weighs more. Why not have more juice than lead? You’ll need it anyway for those longer flights you’re going to get after reading this!

While you’re into batteries, consider getting a larger capacity for your radio. Those small 600 mAh batteries are for wimps! New battery? Did you prime and cycle it for maximum performance? Old battery? Did you cycle and charge for the new season? Best to cycle three or four times to condition the battery for the new season. (NiMH batteries don’t need cycling but do need priming.)

Also, double check that balance point. Many newcomers incorrectly balance their plane because they read the ruler wrong or because they read the directions wrong! Use a good CG machine to do this. Don’t take chances with finger balancing or a homemade rig. The best rig I’ve seen comes from Laser Arts, makers of the Majestic. It’s simple, cheap and effective.

After that, make sure that tow hook is in FRONT of the CG. A good rule is 3/8 inch in front, but if you have an adjustable tow hook, you may move it back to within 1/8 for higher launches. You might want to wait on moving the hook until you have a few launches under your belt.

Now to the field.

At the Field

You’ve just arrived at the field with your spanking new Cloudbuster 900. You put in a lot of hours last winter building it into the perfect ship and now its time to test it out. Scary, isn’t it? Well here are a few tips to help insure your success.

Check everything carefully. Is everything nice and tight? No loose servos or batteries? You did follow the “Before You Get to the Field” instructions, didn’t you?

Always start with a range check, but before you turn on your transmitter, find out if anyone else is using your frequency!!! After assuring yourself that no one is using your frequency, turn on thetransmitter, then your receiver (reverse that order when turning everything off). Keep your antenna down and walk out onto the field about 200 feet. Facing the antenna away from the model, have a helper check to see that the control surfaces are moving. O.K.?

Go back to your ship and check for proper directional movement of control surfaces. Remember, look from rear to front. Stick forward, elevator down; stick back, elevator up. Stick right, rudder right; stick left, rudder left. Do all of the control surfaces line up with their stabilizers?

Now you are ready for the next step. It is helpful at this point if you have a buddy to assist. Pick up the sailplane and run forward with it about 15-20 feet. The idea is to get the plane up to flying speed. When you have enough speed, toss the plane out in front of you, keeping it as level as possible. Whether you or a friend does the toss, be ready to input some control surface movement to compensate for dives, stalls or veering left or right. Some guys will run farther and let the ship “bounce” up and down in their hand to get some idea of what the plane is going to do when released.

Ideally, your ship will glide straight out ahead of you and gently come to earth about 50 feet later, with little or no control surface input. If not, you may have to check your CG, lateral balance, or compensate by adjusting your trims. If you throw the plane hard and it pitches up immediately, you probably have too much nose weight.

Once the toss proves satisfactory, it’s time for the true test. Launch! But first, check to see if your tow hook is in the proper position, hang the plane upside down from the tow ring. It should hang slightly tail down. If it hangs tail up and wants to slide off the ring, you’ll need to move the hook forward. (Note: if one wing hangs down more than two inches lower than the other, see the previous section on lateral balance.

When you do launch, toss the plane hard on launch to get it up to airspeed. Don’t just let it go from your hand. You may want an “old timer” to take her up for the first time, but if you do it yourself, try to launch and fly hands-off as much as possible. Remember, you’re not looking for thermals at this point. You are just trying to get a good feel for the flight characteristics and trim needs for this particular model. Fact is, you should launch and land that new ship 20 or 30 times before you really start thermal hunting.

One thing you don’t want to do in this sport is hurry things up. Take your time. Explore your ship slowly and you will be rewarded with better piloting skills. Practice makes perfect.

Check out the “Trimming” instructions from here.

Trimming Your Lead Sled

Little at a time method.

Try several flights with no wind (early morning or evening). On each flight, try a few tight thermal turns at altitude with slow speed (some up elevator slows your ship in turns). Remove ¼ ounce lead on each flight until plane becomes unstable or tip stalls in turns (Note: dial in additional down trim as you remove weight). Pay attention to slow speed handling and pitch characteristics When plane gets mushy, tip stalls a lot or starts slow oscillated pitching, add back in a ¼ ounce lead and call it good.

Note: you will probably need to add nose weight under windy conditions, try ½ ounce at first


Start with the dive test – launch and trim for slow flight (up trim). Come around and fly perpendicular to yourself. Perform a shallow dive, about 30º then let go of stick.

  • Gradual pull out = O.K.
  • Immediate pull up into a climb = too much up trim holding too much nose weight. Land and remove nose weight, then re-launch, re-trim and do the dive test again. Repeat until the pullout is very gradual.

Teaching point; if your ship is flying too fast, move CG rearward by removing nose weight; if your plane porpoises a lot, you probably need to remove nose weight. During the dive test, if the dive angle increases – tuck under – add nose weight.

When it is flying more smoothly, go to early morning test.

Early morning test

Again, this involves several flights under no wind conditions. Launch (no zoom) and fly straight ahead, hands off as much as possible. Trim the rudder to fly perfectly straight. When she sinks far enough, turn straight back and land. Time each flight and change the elevator trim to optimize the flight times. Once you have determined the optimum trim setting (close to stall), remove 1/8 ounce of nose weight and start the process all over again. Your flight times will increase throughout this process. Eventually, though, she becomes unstable and you have to give so much input to keep it straight and level that flight times start to decrease again. When this happens, put ¼ ounce weight back in the nose and your good to go.

Note: if you’re having to fight for control of your plane all the time (as with porpoising), you’ve either got too much nose weight (probably the case) or too little. Either way, you’re going to have to adjust the nose weight to get smooth control.

Flying for Fun

Unless you are a competition pilot with a flat wing, full house sailplane, you’re probably just out to have a little fun soaring. Here’s how to enhance your experience.

Let your sailplane do the flying. The number one problem with beginners is overcontrol. Too much up elevator will cause a stall, leading to difficulty in trying to regain control to get the plane flying smoothly again. Near the ground, this problem spells BIG trouble. Move that stick in small increments. (Usually, just letting go of the controls will right your ship, without any input from you.)

Also, if you overcontrol, you’ll never know when your plane passes through a thermal. Again, let the plane do most—but not all--of the flying. If you read “At the Field,” you will find that it is important to get a good feel for the flight characteristics of your model. You can’t do that when you are constantly yanking the stick. Also, you should have already trimmed your rudder for perfectly straight flight. If you move rudder very much, you won’t be able to see the signal your plane makes when it hits a thermal.

Fly a pattern search. When you’re off launch, turn to the left or right and fly at about a 45° angle until you find thermal activity. If you are getting uncomfortably far out, turn into the wind and come back. Don’t turn with the wind, as you will lose ground and fly in air you’ve already flown in. Stay out in front of yourself, unless you’ve found that elusive thermal and follow it downwind to gain altitude.

When you see your plane coming down significantly, you have a choice. Either find a thermal quick or join the landing pattern. My advice for beginners, join the landing pattern. In fact, you should practice landings more than anything else, and this should be a separate activity from hunting for thermals.

Landing – Coming to Jesus

Landing can be a scary time for sailplane pilots, especially if you’re new to the sport. If you’re at this point, try these tips:

Don’t bother using spoilers or flaps, if you have them. These will just confuse the issue (and possibly cause a crash). Deploy spoilers and you’ll dive; deploy flaps and you’ll balloon or stall. Wait to use these until you have some flying experience and can quickly compensate for these effects. (A computer radio can be programmed to automatically compensate for these effects.)

Be careful when using up elevator to slow down. You can easily stall this way and, close to ground, that usually means a crash. When landing, avoid using the elevator.

Mentally create your landing pattern and practice it as often as you can, This should be a separate operation from flying for fun and hunting thermals. That’s because your mind should be focused on this one task to get good at it.

Start by entering the pattern at about 50 feet up for a good safety margin. Put in one or two clicks of down trim. This will speed things up but increased speed means better control. Going slower may give you more time to react, but it also creates more opportunity for accidents like stalling. Come to your left or right, as you prefer, and sink to about 20 feet. At this point, you should be about 100 feet out to your side. When you get about 40 feet behind you, start a gentle turn to the left (or right). When your ship gets about 20 feet out from your side, make another gentle turn toward you. (See the illustration) Watch that up elevator!

If you are too high on approach, you can turn downwind slightly and come around from the other side of you. You can also zig-zag behind you on final approach to bleed off altitude and energy. If you are too low, shorten the approach by spending less time between turns. Practice, practice, practice!

Keep the wings straight and level, then let her settle in. You can give slight up elevator when she is about a foot above ground. This will slow the model. (Remember, when you are looking at the nose of your plane coming toward you, move the stick in the direction the wing is dipping. This is opposite of when you are looking at the tail of your plane in front of you.) If it rolls right past you and seems not to want to land, just let it go. It’s better to walk a distance to your plane than to pick up the pieces at your feet. Next time, fly a little further past yourself before making the turns.

When it’s windy, don’t fly past yourself. Make your first turn when your ship is at a right angle to you or even in front slightly. That’s because the wind will carry it downwind by the time your make your final approach.

Have fun with MRCSS!