Control Line flying is a unique way of experiencing the flight of your model. Unlike Radio Control, you are directly attached to your model through a set of lines. The model is only a short distance away, and the pilot is able to tell what the model is doing, even without looking. It is totally possible to fly a CL model "eyes off", even through maneuvers.
Due to the proximity to the flier and to spectators, Control Line offers both unique challenges and unique advantages over other forms of model aviation.
For instance, the Stunt pilot must be able to put his aircraft through abrupt pull-ups a mere five feet off the ground. The Scale pilot has to contend with wind. The Combat pilot must be able to avoid hitting another airplane flying in a very limited amount of airspace. By the same token, CL Scale models fly very close to the pilot and spectators, who can see in detail flaps being lowered, landing gear being retracted, bombs being dropped. CL Combat happens in close quarters, so more is apt to happen than with its RC counterpart (where many matches can go by without cuts, since depth perception isn't good enough to bring the two opponents into close proximity). It more closely simulates a "knife fight" than RC combat.
Control line sport flying is also a lot cheaper than RC
sport flying, and takes a lot less room. Noise is less a concern, since
the airplane gets no more than 80 feet of the ground, at the worst.
Fuel. Regular glow fuel with 5-10% nitro is adequate for
most flying. If you fly diesels, get diesel fuel, and if you fly small
motors (less than .09 cu. in.) get a high nitro fuel (25% or higher nitro).
Avoid buying small cans of fuel, these are very uneconomical.
Glow driver. Almost anything will work here, including power panels, Ni-starters, and units made out of alkaline D cells taped together in parallel. If it can put out 1.5 volts and 2-3 amps, you're set. Clothespin-like glow clips work best. If you fly over grass, with hand-launched models, it helps to have glowplug leads long enough for the starter and the holder to stand up. Some events allow electric starters (and if you're sport flying, they work well). Others require that you hand-start.
Fuel tanks. You can still buy metal "control line"
tanks. GRW, for instance, makes a series of tanks for CL combat and for
Stunt. For regular sport flying, the wedge-shaped "stunt" tanks
work well. But regular RC clunk tanks work well, too, if the venting is
set up correctly. If you run diesels, make sure your fuel tank and tubing
can stand up to the fuel, which is a lot more aggressive than glow fuel.
Control handles and lines: What you need here varies greatly depending on the kind of model you will be flying. ½-A airplanes can be flown on the dacron lines supplied with Cox kits, or with the SIG ½-A handle, though they will fly far better on .008" to .012" steel lines. Do NOT use dacron lines or use handles designed for ½-As on larger models, though. The standard control material used for control lines is three to seven strand stainless or carbon steel (most CL wire found in the States is seven strand stainless, while in Europe, "Laystrate" wire is common). ½-A airplanes can be flown on .008" diameter wire (though .012" is more durable for shorter line lengths), .15 to .21 sport models can be flown on .012, up to .40-sized models on .015 and larger on .018 lines. Line lengths vary from 35-42 feet for ½-As, up to 70-75 feet for large Stunt and Scale models.
For competition, follow the rules of the event the airplane was designed for. Tables for line lengths and diameters can be found in the AMA rule book.
Lines and connector hardware are available from a variety of sources. SIG sells a good selection, as do Sullivan and Brodak. Suppliers of Combat equipment can sell you very large rolls of braided wire, which is the way to go if you need (or plan to need) lots of sets. Line ends can be made using the methods specified in the AMA rule book, or on the back of the blister packaging for SIG's control line wire.
Inexpensive handles for ½-A can be obtained from Cox, Goldberg and SIG. SIG handles tend to last a little longer, and come with a roll of dacron line, which, even if not used as control-line can be used for tying hinges, etc. Sullivan also makes a unit that can be used for ½-A, which is considerably tougher than the small plastic handles. ½-A handles need to have narrow line spacing, as the bellcranks used are smaller than the 2 and 3 inch ones used on larger models.
For anything larger than ½-A, use a properly designed
handle. Sullivan makes two kinds, and you can get nicely made adjustable
handles from Brodak. For Combat use, the Magnum handle is available from
Bear Model Products, and Medjlik Modellbau makes a nice, in-air-adjustable
unit.
There are advantages and disadvantages to both approaches.
½-A airplanes, provided that they are light and have sufficient wing area, can be made to fly well. However, they tend to be twitchy, and can't handle wind nearly as well as bigger models can. On the plus side, motors and kits are very inexpensive, and crashes often do not result in as much damage, especially if you fly off grass.
Larger planes are actually easier to fly than ½-As, since they can use longer lines and handle the wind a lot better. They also use up a lot less sky when you start to learn maneuvers. The drawback, of course, is that they take much longer to build, and usually end up with harder-to-fix damage after a crash.
Larger planes pull harder on the lines, so for training small children the ½-As are probably better.
Paint your airplane adequately, so that it does not end up fuel-soaked. Polyurethane-based paints are best (eg. Red Devil). Don't worry too much about weight at this point.
Save the flapped stunters (eg. SIG Banshee) and nice covering/paint jobs for when you can keep the airplane out of the ground.
Suggested ½-A Trainers
SIG Deweybird, Skyray
Sterling Baby Ringmaster
Brodak Baby Lightning Streak, Baby Clown,
Goldberg Swordsman, Li'l Wizard, Stuntman.
The SIG Deweybird and Skyray are all-sheet. They are easier
and quicker to build, and you will not need any covering skills. But they
are more fragile in a crash. Built properly, the airplanes with built-up
wings should survive most crashes when flown over soft ground.
Suggested bigger trainers
Strangely enough, Slow Combat planes make good trainers, especially if you build them nose heavy. The following airplanes are either Slow Combat planes, or are similar in concept. They are quick to build and relatively easy to repair. You will want to add landing gear, of course. The SIG Buster and Shoestring are small, with sheet wings. Build the planes nose-heavy and use a mild (though not a weak or unreliable) motor. The Gotcha has a foam wing, is quick to build, and tough. The Sidewinder may no longer be available, but makes a nice trainer with its pine fuselage and relatively low number of ribs. However, modify it to use maple motor mounts - the pine tends to crush.
Corehouse Gotcha Super Slow
Bear Super Sidewinder
SIG Buster, Shoestring, *Skyray .35
Midwest Flight Streak (and variants)
Brodak Lightning Streak, Galaxy, Buster, Super Clown
Like with RC, its best to have an instructor. The two-hands-on-a-handle approach is good - the student pilot holds the handle, and the instructor stands slightly behind and to the right. The instructor's left hand should be on the trainee's left shoulder and the right hand wrapped around the trainee's hand on the handle. A third person will be needed to launch the model.
The Muncie Control-liners have special dual handles. Having one or two of these units around is a ood investment for a club.
An instructor can also help you preflight, pull-test and adjust your airplane before it actually takes to the air. Remember that if your airplane is not balanced correctly (you DID put in that weight in the outboard wingtip, didn't you?) it won't fly well. For learning purposes, nose heavy is good.
The basic idea behind flying a control line airplane is that when you tilt the handle back towards yourself, you pull on the top line. This causes the airplane to go up. Inversely, when you tilt the handle the other way, the airplane goes down.
The big temptation for the beginner is to use the wrist to control the airplane. Don't use the wrist. Instead, aim your arm at the airplane, keeping the wrist stiff in the "neutral" position. Moving the entire arm up (pivoting at the shoulder) will cause the airplane to rise until it is right where you are pointing. Lowering the arm will cause the plane to descend. This rule works, until you start to fly inverted, which you won't for a while.
Flying off (short) grass (especially when the ground is soft) is best. Crashes will then result in far less damage. That said, launching off grass can be a problem. If you are learning by yourself, taking off the ground is the preferred way. Hand launches take a little getting used to, though if you have an instructor, the instructor can handle the takeoff. Hand launches, with neophyte pilots, usually result in the airplane ballooning and stalling. So bring some carpet remnants or cardboard to lay on the grass for take-off.
Getting dizzy while flying can be a problem, but after a few flights you will not get dizzy anymore. The smaller airplanes will tend to go around faster than the big ones (since the line lengths are shorter). In any case, you will usually get dizzy after the flight rather than while you are actually flying, since you are concentrating on your airplane rather than on the surroundings. To handle post-flight vertigo, after the flight is over, stand in the middle of the circle with your eyes shut. The world will seem to go around in the other direction, but the nausea and vertigo will disappear. When the world stops spinning, you can again open your eyes.
MAKE SURE THAT YOUR FLYING CIRCLE IS FREE OF OBSTRUCTIONS,
THAT ANY SPECTATORS (WATCH OUT FOR SMALL CHILDREN!!) ARE FAR AWAY FROM
THE CIRCLE AND THAT YOUR CIRCLE IS FAR AWAY FROM ANY ELECTRICAL WIRES!
Once you can fly level, and do climbs and dives, and can complete entire flights without crashing, you are ready to learn stunts.
If you have, to this point, been using an airplane with a smallish wing area, or have been using a ½-A airplane, its time to switch. A large airplane will have a lower apparent speed, and will keep line tension better at altitude. A model with about 350-400 square inches of wing area, a .25 to .35 motor on 60 foot lines will work well, especially in wind. Actually, a Fast Combat model, set up a little nose heavy and with a mild engine is good for this phase (assuming you have someone who can handle bladder tanks). It will be pretty near indestructible, if built right.
Fly all your stunts downwind. The Pros do, and they do it for a good reason.
The first stunt to learn is the loop. Start with level flight, maybe 15 feet off the ground. Pull "up", and continue to keep applying up (with the wrist if need be) as the plane comes around. Once the airplane completes the loop (the plane's fuselage will be level with the ground) release the "up" on the handle and the plane will settle into level flight. Your first loops will look egg-shaped, with the pullout considerably higher than the entry, but eventually you will learn to finesse the maneuver so that they look round. Don't do more than 6-7 inside loops during a flight, and remember to untwist your lines in between flights.
The next maneuver to learn is the Lazy 8. The Lazy 8 is a horizontal figure 8, with the airplane turning away from the ground at either end. In other words, an inside loop on the left and an outside loop on the right. It is relatively safe for the beginner to learn, since the airplane is always turning away from the ground. Once you learn to do Lazy 8s, you will easily be able to fly outside loops, and you will be able to learn to fly inverted.
For your first attempt at a Lazy 8, pull into an inside loop. As the plane goes over the top of the loop, feed in a lot of down elevator. Your first attempt will look like a reversed letter "S". This will at least convince you that "down" elevator can make the plane go "up". When you try it again, let the plane go further around the loop (perhaps up to the point where the nose is pointing down 20 degrees or so) before hitting "down". Eventually, you will be able to fly nice, round 8s with nice, almost vertical intersections. At this point, try flying consecutive Lazy 8's, and perhaps try doing consecutive inside (the left side of the 8) outside loops (the right side of the 8). You should very soon be able to spend entire flights doing loops and 8s downwind. It will become imprinted in your mind that "up" elevator turns the airplane in a clockwise loop, and "down" will turn the plane anti clockwise.
Once you get to this point, inverted flight will be easy. Just do elongated Lazy 8s. Stretch them out until the inside and outside turns are about a half lap apart. Practice this for a while, then try extending the 8 to ¾ laps, then to a full lap. If you can do this without crashing, then you can try flying several laps inverted, always entering inverted flight with a half inside loop and exiting it with a half outside loop (always, turn away from the ground).
Once you are comfortable with all this, you can try practicing other maneuvers, including outside loops started at the top, and Competition 8s (the same as a lazy eight, but you're turning towards the ground at each end - the inside loop is now on the right side).
At this point, you should be able to survive a Super Slow
Combat match. You may even have a pretty good chance of winning, and will
at least look competent. (In RC terms, you will have become a competent
Sunday Ugly Stik flyer). To become a competent Precision Aerobatics pilot,
though, you will have to learn some other maneuvers, and you will have
to practice them assiduously, since the idea is to fly these maneuvers
accurately.