|Four stroke engines running on gasoline||- 4 Stroke Gasoline|
Above: one of the two SAITO FG-30 four stroke gasoline powered engines on the InView unmanned aircraft.
Four cylinder engines are the most fuel efficient internal combustion engines. They however have lower vibration and noise levels than the two stroke engines, but have a higher vibration level than a Wankel engine. They also have a lower power-to-weight ratio than a two stroke engine of comparable power output.
- from http://www.sussex-model-centre.co.uk/shopexd.asp?id=24406
Development of the Saito FG series of petrol engines continues apace. The latest addition is the new FG14/82. The last two digits refer to its .82 cu.in. capacity. Performance wise the FG-14 is comparable to the FA-72 glow engine. As with other FG engines, it employs a carburettor with a diaphragm pump. This helps make the engine non-critical in terms of fuel levels, allowing the fuel tank to be mounted in a wider range of locations, as well as sustaining fuel flow during aggressive aerobatics and vertical manoeuvres. Each engine is supplied with a sparkplug, muffler and an electronic ignition system. Due to the fuel efficiency of this engine it only requires a tank with one-third the capacity of a similar glow engine. Fuel consumption is rated at 8 cc per minute. The FG-14 runs with any good quality forecourt petrol, mixed 20:1 with oil. Not only does this keep running costs low, it helps keep your airframe clean too as there is minimal exhaust residue.
This 20cc power house brings petrol power to a wide range of medium size models and will be especially welcome in 120 size scale and freestyle aerobatic aeroplanes. Using forecourt quality petrol, mixed 20/30:1 with oil, it is very tolerant of a wide range of fuel levels, so you can fit the fuel tank (just one third capacity of the equivalent glow version) in the best possible position to suit your model's Centre of Gravity. This is made possible by the use of an efficient carburettor fitted with a diaphragm pump.
Besides low running costs and economical fuel consumption at 10cc per minute, the FG-20 is also a very clean running engine and will not foul the airframe with lots of exhaust residues. The power output of the Saito FG-20 is comparable to that of a standard Saito FA-125a glow engine.
With the new FG-30, Saito continue to expand their successful range of petrol engines based upon the most popular sizes of four stroke glow engines. The FG-30 is based on the FA-180 and offers a similar level of performance but at much reduced fuel cost. Each engine comes ready mounted to a matching engine mount to help draw maximum heat from the engine when cowled. The FG-30 is fitted with a Walbro carburetor and is supplied with a Saito electronic ignition system and an efficient muffler.
Before you run your Saito petrol four stoke engine for the first time please lubricate the engine through the back plate breather nipple with a small amount of light machine oil or two stroke oil that you are going to mix into your fuel. This will help to lubricate the moving parts of the engine until the fuel/oil mix is able to reach these parts during the engines first run.
The Saito FG-36 is supplied with a CE approved electronic ignition system and a purpose made aluminium engine mount. The carburettor employs a diaphragm pump for reliable fuel feed in any attitude - even the wildest of 3D stunts! This also means that it is not sensitive to the position of the fuel tank, which allows the tank to be positioned to maximise the CG position. You can use forecourt quality petrol mixed in a ratio of 20:1 to 30:1 petrol to oil. The FG-36 is very clean running and is very economical.
Saito is proud to introduce their first twin cylinder gas engine – The FG-57 Twin Gas Engine. The FG-57T is designed for larger models, specifically scale applications where the sound of the engine is a key factor in the flying experience. The FG-57T is the only twin cylinder 4-stroke engine on the market that is fueled by gasoline. As a result, the benefits are easier tuning and operating costs savings of up to 90% over similar glow power systems. Decreased operating costs of up to 90% over nitro engine performance based on fuel consumption and price per gallon.
By combining the reliability of gas with the sweet sound of Saito, advanced technology and foresight are once again helping Saito lead the way into the future. And, like all Saito engines, these powerhouses are engineered with that same Saito quality and reliability our customers have come to know and trust.
The Kavan engine: photograph from www.mecoa.com
- from http://www.rotax.com/en/
This large engine is included to give a data point for a high capacity engine. The Rotax engine has been used in the Predator and other UAVs.