Nitro Engines
Nitro engines and electric motors are the two main options for powering radio control cars. Nitro engines are amazing miniature versions of full size internal combustion engines but with just a single cylinder. Clearly, because of the size limitations, these engines cannot have all the sophisticated control features found on full size engines but they are still remarkable in their engineering, with piston, crankshaft, clutch, glow plug, starter, carburettor and so on.
Nitro engines can be both water-cooled and air-cooled with water-cooling found on boats where the cooling water can be drawn from the pond. Air-cooled nitro engines are usually fitted to radio control cars and trucks where the engine can be easily identified by the typical large cooling fins around the sides of the cylinder to provide the maximum cooling area.
Electric start is increasingly popular but many models still use the classic pull start where a cord is pulled against the tension of a recoil spring to start the crankshaft rotating. Hopefully the little two-stroke nitro engine then bursts into life with its characteristic scream. Clutches on radio control cars are usually automatic and centrifugal or similar, kicking in and providing the drive when the engine speed reaches sufficient rpm to provide enough power to move the model car. Speed control is through the throttle servo, and braking through a brake unit synchronised with the throttle servo to provide realistic braking.
All this amazing model engineering is powered by a
special blend of rc model fuel containing nitro-methane and methanol
that is widely available at radio control hobby stores and similar
outlets. Trying to use any other fuel, or blending fuel with different
proportions of nitro and methanol without referring to the engine
makers manual will seriously damage the engine so should not be
attempted.
Typically a radio control car will run for 8 – 10 minutes on a tank of fuel, which is long enough for a challenging race or just for running the car in your own yard before taking a break. It is important to remember that although the power and noise of nitro engines makes the radio control hobby even more exciting for rc model enthusiasts, it can be a source of great irritation to friends and neighbours. Generally speaking rc nitro engines are not friendly to the environment with their high-pitched noise, even though improvements to silencer/muffler design are slowly bringing down noise levels. So if you do decide that your rc nitro car will be powered by a nitro engine then think about where you are going to run it, preferably find a club with an approved circuit for racing and testing, and don’t be a nuisance in the local area.