when starting to glitch. However, there are also negative considerations. For example, this is a simple system and is incapable of detecting errors, and the receiver cannot see any difference between valid and invalid pulses from the servo. For range boundaries, the pulses generally become shorter or longer due to noise, servos can glitch (a situation often caused by an incorrect antenna orientation), and short glitches often go unnoticed until it is too late to correct a problem with the plane. PCM System – PCM is the acronym for Pulse Code Modulation, a digital scheme for transmitting analog data. The signals in PCM are binary; that is, there are only two possible states, represented by logic 1 (high) and logic 0 (low). This is true no matter how complex the analog waveform happens to be. Using PCM, it is possible to digitize all forms of analog data, including the telemetry used in RC for model airplanes. For this option, the position of the switches, pots, and joysticks, initially analogue voltages, are digitized with an AD converter to 8 or 10 bits (8 to 10 servo would equate to 80 to 100 bits). This system has a 16-32 checksum per frame, synchronization sequences, and failsafe values. For a complete frame, a bit number of 100 to 160 is then required. The PCM uses two primary systems, one being a very long starting pulse that cannot ever be mistaken for data, and the second is a half-bit pulse that also makes it impossible to mistake data. The advantages of using a PCM system is that even if your model airplane is a good distance away, the servos’ movements are transmitted without glitch. system. The downfall of this system is that it is much more costly; it is sensitive to interference from adjacent channels, which means you must be very careful when ﬂying close to other radio emissions; determining the transmission quality is hard, as there is a lack of warning signs for trouble; and control issues that occur slowly are only noticed when the connection fails, possibly leading to a bad crash of the plane. In addition, servos are not damaged by pulses that are too short or too long, something that can happen with the PPM
Aeromodelling would be a whole lot duller without the spark that radio control brings to the hobby. After all, it is the ability to put you in control of the plane which makes it so exciting. So many of us would love to be pilots, to fly aloft among those fluffy clouds but are prevented from doing so by so many different reasons. Yet model airplanes bring that excitement within reach and radio control is what brings the control into our hands. So we should spend a little time trying to understand how that control comes about. For most of us it is and will remain a mystery. All we will need to know is to buy the boxes, connect up the wires the way the manual says and away we go. But for those who are interested then here goes with some basic technical stuff.
ENGINE - This is a mechanical device providing power to the airplane so it can ﬂy. It uses
battery power or internal combustion. For RC model airplanes, there are two primary choices of internal combustion engines -- glow, which burns nitromethane fuel or gasoline that burns a mixture of gas and oil. Both engines types come in two and four-stroke designs.
Another option for model airplanes are the toy RC models. Although intended for children they can also be great fun for adults. With these more basic ﬂyers everyone can learn the joy of having control of a flying model airplane. The majority of these planes are sold in RTF form including the radio gear, batteries, and a rechargeable motor battery. The nice thing about choosing a toy plane is that in addition to being affordable, most are virtually indestructible. There’s nothing like the sight of a little boy or girl’s eyes as he or she opens up a package to discover a model airplane. They make excellent and uncommonly instructive birthday and Christmas gifts--as well as “just because” gifts. There are many different models you can consider, including the following:
WWII Model Airplanes
Post WWII Model Airplanes
WWI Airplane Models