Question: Can Nitro RC Cars and Nitro Airplanes Use the Same Nitro Fuel?
RC glow engines
use nitro fuel
, a methanol-based fuel with nitromethane and oil added. The amount of nitromethane in the fuel is typically about 20% but could be anywhere in the 10% to 40% range or higher. Castor oil or synthetic oil is added to the fuel to provide lubrication and cooling. The type and amount of oil in the nitro fuel is what determines whether it is better suited to RC cars and trucks or aircraft.
There several schools of thought on whether or not the same nitro fuel is suitable for both RC cars and RC airplanes. The major difference is in the type of oil and the amount of oil added to the fuel although the percentage of nitromethane can make a difference as well.
Type of Oil in Nitro Fuel
Oil in the RC fuel helps reduce friction and helps the RC engine run cooler. Nitro fuel may contain castor oil, synthetic oil, or a mixture of both. When castor oil breaks down at high temperatures it creates a lubricating film -- desirable but somewhat messy. Synthetic oil lubricates well at low temperatures but at high tempertaures it burns off and provides little protection. Because RC car engines typically run hotter or have less efficient cooling systems than RC aircraft, nitro fuel for cars usually uses castor oil or, more commonly these days, a castor oil / synthetic oil mix. RC aircraft fuel typically uses synthetic oil but may also use a castor oil / synthetic oil mix.
Percentage of Oil in Nitro Fuel
The percentage of oil might range anywhere from 8% to 25% with 15%-20% being the typical amount of oil found in nitro fuel. There is some debate as to whether an RC aircraft that often runs at wide open throttle during most of its run needs a higher percentage of oil than an RC car that only runs at full throttle for short spurts. An RC car or truck with a hopped-up engine that does a lot of high speed racing may need a higher oil percentage than one running a stock engine and not involved in professional racing.
Other Types of RC Fuel
While 10% to 40% is the typical percentage of nitro in nitro fuel, you can buy fuel with as much as 60% nitro or with 0% nitro (FAI fuel). Most RC cars and trucks use 10%-40% nitro blends. RC airplanes may use lower nitro blends of 5%-10% nitro. There are also RC engines that run on regular gasoline
mixed with motor oil or diesel fuel (these are engines with spark plugs rather than glow plugs) as well as jet-turbine engines that use propane or kerosene. These are specialty radio controlled models and not the kind most often sold in hobby shops.
Best Fuel For an RC Nitro Engine
It is generally best to start out with the type of fuel recommended by the manufacturer for your RC engine -- and the recommended engine settings -- whether that glow engine is in a car, truck, airplane, helicopter, or boat. Once you become more familiar with your RC and understand how the various nitro blends affect performance you can start experimenting to find the nitro/oil mix that works best for the way you use your RC.