Welcome to our introduction to the power plants of models. Two basic types exist, fuel powered engines, and electric powered motors. These then divide into a couple of sub catogries:

Fuel Powered has for years been the choice of every modeller, partly because no alternative existed, and partly because it provides exceptional and still unbeatable performance.

Five types exist:

• Four stroke engines are more suited to the experienced modeller because of their complexity and need for periodic maintenance such as setting tappet clearances etc. They also provide what some argee is a more scale perfomance. In general and compared to two strokes any given engine size will turn a larger propeller, at lower RPM (It needent be a propeller, it applies to whatever you may have it connected to). They are also quieter, and have smaller silencers, this makes tham make easyier to contain with in a model. Most two strokes have silencers a similar size to the engine.
• Two stroke engines on the other hand are marvels of simplicity. They only have the bare essentials that are required for them to operate and yet believe it or not, in their more highly tuned versions, they are THE most powerful engines in the world for their size. Not even the best of the supercharged, nitro methane fuelled drag car engines even approach them. Some of the best model car engines will produce about 2.8 bhp from 3.5cc. Consider then that a 10 litre drag car engine would have to produce 8000 horse power to equal that. Even what we consider to be a sports engine has as much power for its size as a Formula 1 car.
• RCV(Rotating Cylinder Valve) engines are a revolutionary idea. They are4-stroke engines that only one more moving component than a 2-cycle engine. The design features a very clever combination of some old ideas such as Aspin valves. The output shaft is also geared at a ratio of 2:1. This provides the ability to turn even larger more scale looking props. The lower RPM also means less noise, both from the prop and the exhaust. They are also a very compact design which make for easy containment within your models.
• Steam Engines are as traditional and as beautiful as the models they are intended for. Mainly used in boats they are the ultimate external combustion scale accessory, you get live steam and all the inspiring sounds of the original items. Unfortunately thier poor power to weight ratio stops them from use in other models.
• Turbines are as awesome as the real thing. Reving up to 200,000 rpm and producing upto 40 lbs of thrust they are the final word in power. They are mainly used in aicraft, however we have seen then attached to trucks and helicopters.They work on a very similar principle to two and four stroke engines, in that it is expanding air that does the work. However unlike two and four stroke engines the process is continual, not perfomed in stages, therefore the power produced is much greater.
• Fuel Most model engines run on an alcohol based fuel it is a combination of methanol, oil, and optionally nitro methane. Many different fuel mixtures exist, using many different oil types. Just about everybody has there own opinion on fuels. What you choose will largely depend on what sort of model you have. For instance helicopters give engines the hardest time, they are in a badly cooled enviroment, and they are usually at 75% throttle, so you mush have a fuel with an exceptional grade of oil. Aircraft on the other hand have exceptional cooling, so you can get away with lesser fuels. Whatever you need we have several to choose from.

Further Notes

The reliability and performance of any engine is dependant on the proper care of it.  This starts when you first take it out of the box.  All engines need running in.  This helps the moving parts to bed-in together whilst causing as little wear as possible.  Consequently you will have an engine with a longer and more reliable service life. The application of your engine will have a bearing on how you run it in. It is a process that involves running the engine with only a light load and for short periods of time, allowing the engine to cool between runs.  This means gently revving the throttle so that the engine speed is varied between full power and idle enabling the engine to hold its temperature for a while and then cool down as the speed drops off.

The fuel to air mixture for running in should be rich (more fuel, less air) ensuring that the new components are well lubricated.  If, for example, your are running in a heli or aero engine, you will need to run it in this manner for at least 15 minutes, after which the engine should be run with the needle kept 2 or 3 clicks rich for the first few hours.  For a model car, we recommend the same process, not running constantly flat out and using varied speeds with a rich mixture for at least one litre of fuel (depending upon the engine).  After this it can start to be leaned off and you will find an increase in speed and performance. By caring for your engine in this way and by maintaining it throughout it's life you can almost guarantee its service. Cheaper engines generally require more running in and a greater oil content in their fuel than their more expensive counterparts.  ABC engines require very little running in.  Always read the instructions that are supplied with your engine before you try to run it!

Electric Powered has in recent year and through advances in technology become a viable alternative to fuel power. The main problem with electric powered arangments has been weight, particullary of the batteries you need to carry to get an decent duration. In previous years electric duration was limited to 2-3 minutes if you wanted any power. It has however improved quite a bit in recent years, and many models now use it. In fact it has several advantages over fuel powered, it is clean, easy to start, and much quieter. Two types exist for modelling, but we only stock the first.

• Permanent Magnet DC motors form about 90% of motor used in models. They convert electrical energy to mechanical enrgy in a much more efficient way that fuel povered engines convert chemical energy. Some electric motors, especially large ones can be upward of 80% efficient, where as fuel engines are at most 30% efficent. They use magnetic fields to create rotaion. Permanet magnets are around the outside of the motor and a rotating electro magnet is in the centre.
• Brushless DC motors are not as widely used. They are pretty much an inverse construction of permanent DC motors. They have rotating permanent magents at the centre, and fixed electro magnets on the outside. This provides a mechanically much simpler design, which carries with it better cooling, and more perfomance. As you may guess however this perfomance does dot go without its cost. The key is when I said above "mechanically much simpler", which they are, but they require a much more complicated electronic control unit, which as you may guess make the prospect of brushless DC motors much more expensive.
• Batteries are the fuel tanks of electric models, however unlike fuel tanks they are a good deal more complicated. Batteries not only come in many shape and sizes, they also come with differing elecrical specifications. Similar batteries physically can behave very differently. The main differences are:
  • Capacity. How much energy the cell will hold.
  • Internal resistance. This basically effects how fast you can pull current from the cell and how much you can pull.
  • Packs of cells are only as good as the weakest link. In a batch of 400 1700mAh cells some may be exceptional with a capacity of 1900mAh and some may be only average at 1700mAh. Some companies will match only very similar cells into packs, this is called matching strangely enough. This gives you a pack where everyone is pulling an equal weight. This type of pack features mainly in the racing world. Two types of matched pack exist. Factory matched - this basically means the cells came of the production line one after another and went into a pack. Computer matched - a company gets a box of cells and test each one individually with a computer, and then constructs packs from them. Computer matching is far better and therefore more expensive.  Usually with computer matched pack you get a printout of its electrical specification with it.
  • Some cells, such as Reedy Zappers under go a process wish is kept secret I am afraid, to increase their performance. Again these types of cells are mainly found in the racing world.
  • Manufactures classification. Sanyo for example have three classifications of cells. Extra - these are high capacity but at the expense of a higher internal resistance. Standard - Just like the name says middle of the road cells, very solid work horses. Racing - low capacity per volume, but also very low internal resistance, theses cells will stand alot of absue.
  • Construction materials. Nickel Cadmium, Nickel Hydride, and Lithium Ion. Nickel Hydride and Lithium Ion offer higher capacity per volume, but again they sacrifice robustness to achive this. Although in recent time Nickel Hydride has advanced enough to make packs suitable for car racing, the most demaining disipline of them all.

  All this said a gereral rule of thumb is the higher the cells capacity density (capacity per volume) the more fragile it is, but they are getting better all the time. Who knows what coming but be sure it is.

  With cars if you are a beginner and considering spending a bit extra on battery packs in terms of quality of duration, rather that buy a top-of-the-range Reedy pack, you would be better off investing in a couple of standard 1300mAh or 1700mAh nicads and charging one while your use the other. The layout of your car will determine whether or not you require a saddle or a stick pack.

  Generally speaking, the larger the capacity of the battery, the greater run time you will have, however, this is also very dependent upon which speed controller and motor you are using.

With such a wide variety of power sources on the market choosing the right make and size can be difficult.  The physical size and desired performance of your model will determine the type of engine/motor you want, the make and model will depend upon what you can afford.  Generally speaking you will pay for what you get.

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