It’s unbelievable how quickly we can lose sight of the face-splitting fun in our favourite model airplane hobby! You’re either trying too hard or too confused by all the choices. And what do you do next? Sailplanes? Warbirds? Combat? Control-line? Racing? Perhaps you should re-discover what this great model airplane hobby is all about and try some fun flying.

Whether you need friendly advice, tips on flying your model airplane or have questions about different model airplanes or equipment, Fun Flying groups feature fellow enthusiasts who are willing to help the novice. They are not concerned with the size, shape, or scale of your model airplane. Instead, they focus on the joy of flying, on learning new techniques, and on how to reap the most benefit from each model airplane.

Typically, fun fly groups gather to compete in a series of missions or tasks. The idea is that through practicing new maneuvers, the novice will become a master. Tasks are divided into two categories: unlimited and fun fly. The unlimited category places no limit on the design or equipment of your model airplane, apart from meeting the Academy of Model Aeronautics’ (AMA) safety code for radio-controlled fliers.

Tasks in this category are timed from the point of intentional movement to the end of the maneuver and point that the wheels touch the ground. The fun fly category may place limits, like minimum wing loading or radio features, or may remain unlimited. These tasks are usually mission oriented, but can be timed as well. Participants enter a category in either the masters class, (top level), or the sportsman class, (entry level).

The tasks involve aerobatic precision with such stunts as loops, rolls, touchdown and take-off with your model airplane, and limbo passes in which a ribbon is stretched between two poles that are fifty feet apart and five feet high. Fun fliers compete in several of these tasks; all are timed. Missions include tasks like learning to taxi accurately on the runway, to climb in altitude and glide, to fly for exactly three minutes, to perform a spot landing, or to complete a bomb drop.

The National Competition Fun Fly Association (NCFFA), http://www.ncffafunfly.org/, is the approved Special Interest Group for fun flying by the Academy of Model Aeronautics (AMA). The group features standard tasks and model airplane missions, as well as a general layout of fun flying.

In keeping with the spirit of fun, however, the association suggests that groups create safe, new tasks and missions for fun fly events. New tasks and missions keep the fun growing for old-timers and offer more choices for newcomers. People have done things like landing with a dead engine, or playing musical airplanes, (last one down when the music stops is out).

So what might one of these fun fly events look like? Picture a model airplane warbird, sailplane, and combat model plane all racing one another. Next, a taped-together foam plane performs aerobatics, followed by a scratch built balsa model airplane, fresh paint glistening in the sun. The greatest advantage of these events is the learning factor: where else can you be exposed to so many different planes and styles of flying?

Your next step? Take what you’ve learned here and get back to some fun. Remember, all RC model airplanes are created equal in the eyes of fun.

Bruce Bird makes it easy for the beginner to quickly get a grasp of the broad range of exciting activities that make up airplane modeling. To receive his free 5 part mini-series visit http://www.modelairplanesecrets.com.

Share This

Ever wondered how that little motor on the front of your model airplane delivers such amazing power?

Model airplane engines come in many shapes and sizes from many manufacturers. By far the most common for the moment is the 2-stroke ‘glow’ engine though the modern electric motor is making rapid inroads.

The 2-stroke model airplane engine is an internal combustion engine burning ‘glow’ or ‘nitro’ fuel consisting mostly of alcohol with nitromethane to help combustion and castor oil for lubrication of the metal parts. There are also 4-stroke glow engines that work on the 4-stroke principle. While these two types of model airplane engine produce the same result, and use the same fuel, they accomplish this goal in very different ways and have different characteristics. For the moment we’re just going to consider the 2-stroke engine.

RC model airplane engines working on a two stroke principle means that there is fuel ignition on every second stroke of the piston in the cylinder. When the piston is on its down stroke down the cylinder, fuel and air will enter the combustion chamber between the top of the piston and the cylinder head. When the piston reaches the bottom of its stroke and starts to rise again it then compresses the fuel/air mixture in the rapidly shrinking volume of the combustion chamber. The fuel/air mixture is ignited by the glow plug just as the piston reaches the end of it’s upstroke. The glow plug is so called because it contains a platinum wire that continues to glow from the heat of the last fuel ignition. The new explosion forces the piston back into the next down stroke.

This sounds very simple but the clever part is that the upper, combustion chamber part of the cylinder above the piston and the lower crankcase below the piston are connected not only by the cylinder bore but also by a transfer port which enables gases to move from the crankcase to the combustion chamber. By careful design, the inlet valve for taking in fresh fuel/air mixture, the exhaust valve for expulsion of exhaust gases and the transfer port which allows movement of the fuel/air mixture from the crankcase to the combustion chamber are always open or closed at the right time by the wall of the piston as it travels up and down the cylinder bore.

The down stroke is created by the rapid expansion of the exhaust gases after the fuel/air mixture ignites. Both the exhaust port and the transfer port are opened as the piston descends in the cylinder bore while the fuel/air inlet is closed. The downward movement of the piston now compresses the fuel/air mixture drawn into the crankcase on the previous upstroke which now rushes up the transfer port into the combustion chamber and helps force out the exhaust gases from that space - and the cycle begins again.

As the speed of this cycle increases, the power output of your RC model airplane engine is increased. Due to it’s simplicity the 2-stroke engine can operate to high RPM and high power outputs. Unfortunately, this also means high noise levels.

The 2-stroke engine in all it’s forms is a very elegant engineering solution. The piston takes the place of 3 mechanical valves, a timing mechanism and a fuel pump - thereby keeping the weight down and reliability up. In addition, the glow plug combustion method allows the battery to be removed after starting thereby dramatically reducing the weight so it is easy to see why the glow 2-stroke has been so popular for so long.

The 2-stroke glow engine is only one of a number of choices you can make for your model airplane engine. Where outright power and speed are the primary requirement it has little competition and the simplicity and high volume production has led to highly reliable and cost effective engines being developed. Noise is really the only negative consideration.

So for your next project balance the cost, maintenance, exhaust noise level, and weight in order to choose the right sort of model airplane engine for your project.

Bruce Bird makes it easy for the beginner to quickly get a grasp of the broad range of exciting activities that make up airplane modeling. To receive his FREE 5 part mini-series and learn more about
model airplane engines visit his website at http://www.modelairplanesecrets.com

Share This

What happened to that mosquito snarl that always seemed to accompany the sight of model airplanes? The answer is they’re going electric and silent. Li-Po (Lithium Polymer or Li-Poly) batteries are rapidly becoming the standard power source for electric model airplanes. Li-Po batteries are smaller, lighter and hold more power than their predecessors (Nickel Cadmium and Nickel Metal Hydride). There are three specifications that need to be taken into consideration when making a Li-Po battery purchase for your electric model airplane.

The voltage of the battery will tell you how powerful it is, the amperage rating will give you an idea how long it will last, and the burst/constant power rating will tell you how quickly the power will discharge. A major difference between Li-Po batteries and others available for RC model airplane use is that it is much easier to mistreat the battery thereby creating unsafe situations the consequences oc which can be dramatic. Li-Po batteries can be very dangerous if you don’t follow all of the safe handling procedures set out by the battery manufacturers.

In most cases, Li-Pos used for model airplanes come in two voltage ratings ratings; 11.1v and 7.4v. The rating dictates how many volts the battery will discharge to your brushless RC motor. Electric RC model aircraft motors themselves have ratings that relate to this voltage discharge specification. The voltage of a Li-Po battery is directly tied to the RPM output of a brushless motor in that a motor rated for 1000kvm will rotate 1000 times per minute for every volt it receives from the battery. In other words, a 1000kvm motor is capable of 7400 RPM when using a 7.4v Li-Po, and 11,100 RPM when using an 11.1v Li-Po. This information, combined with the prop type and weight of the plane gives you all the data needed to calculate the final thrust output of a given motor.

The amperage rating of Li-Po batteries is rated in milliamp hours (mAh). This technical term describes how long the Li-Po will provide electrical power in much the same way that the size of the fuel tank on a glow powered airplane will dictate how long the engine can keep running. Typical electric RC model airplane flights can last 20%-50% longer when using Li-Po compared to other batteries. The larger the mAh rating, the bigger and heavier the battery will be. This is a major factor to take into consideration when putting together any electric RC model aircraft.

Li-Po battery burst rates describe the output characteristics of the battery. Burst rates tell you how much power the battery is safely capable of discharging in one big burst. This number is often higher than the constant power rating. Once the burst of energy has been discharged, the constant power rating tells you where the power output will settle down to.

Li-Pos come with very strict safety guidelines that tell you how to care for them. Charging rates, charging times, and damaged battery disposal procedures just to name a few. Damage to your RC electric model airplane can be avoided by following these guidelines. Properly matched brushless motors and Li-Po batteries can provide hours of clean and quiet flying enjoyment. Take the time to understand everything that’s involved with a Li-Po setup and you will have more fun and more time in the sky with your electric model airplane.

Copyright 2006 Bravos Direct

Bruce Bird makes it easy for the beginner to quickly get a grasp of the broad range of exciting activities that make up airplane modeling. To receive his free 5 part mini-series visit http://www.modelairplanesecrets.com/adtrackz/go.php?c=li_po.

Share This