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A true model jet engine adds the ultimate touch of realism to an rc jet, and commercially produced units for radio control use are now widely available. Turbine rc jet flying has become a big thing in recent years, and there are some spectacular models around.

But this aspect of the hobby is not for the novice! Many hours of flying experience and an impressive budget are needed to actively participate in flying models with real gas turbines.

Even the smaller model jet engines can cost upwards of a thousand dollars - and that's on top of the cost of the jet itself, radio gear and all the other bits needed. So, it's serious business - but ultimately has to be one of the most rewarding ways of enjoying rc flying!

Model gas turbines are also used in larger scale helicopters, but from a personal point of view I don't find these too realistic because of the sound - rc helicopters running on a turbine sound more like jets than helicopters (again, just a personal opinion!).

Shown below is a 'JetCat' turbine, one of the more popular commercially produced model jet engines readily available. JetCat USA are at the forefront of this technology, and offer some excellent turbine units:

Model rc jets have traditionally lacked the authenticity of having a true jet engine until recent years; previously jets needed to be powered by either gas or electric motors with a propeller (thus spoiling the look of the aircraft) or noisy ducted fan and 'pulse jets' (which are more rocket motors than anything else). But now they can be powered by a fully functional jet turbine.

A model jet engine design can vary from one manufacturer to another, but they all work on the same principle. The most common type nowadays is the centrifugal flow turbine, as opposed to the lengthier axial flow turbine.
A centrifugal turbine mostly differs in the stage of compression - air entering the turbine is thrown outwards as it passes over the spinning impeller. The air hits against the inside of the can and so is compressed greatly, before passing into the combustion chamber. This intense compression increases the temperature of the air, as well as the pressure.

The fuel, which is nearly always kerosene ('Jet A1'), is introduced into the combustion chamber as a very fine spray, and so mixes easily with the now very compressed air. This fuel/air mixture is then ignited by a small glow plug, much the same as the one found on a 2 or 4 cycle model airplane engine.

As the fuel/air mixture ignites and explodes within the chamber, it is forced rearwards towards the turbines. The turbines accelerate the velocity of the passing gases, and increase the pressure of them too. The gases (exhaust) finally get squeezed through the narrowing jet pipe at the very rear of the engine, exiting at great speed and pressure, thus generating the high levels of thrust.
The turbines are connected to the front impeller by way of a main shaft, so that they power the impeller as they spin.

The drawing below shows the basic principle of a centrifugal flow model jet engineost model jet engines need to be started with compressed air to initially power-up the turbine. This can be supplied from a diver's oxygen tank or a similar.
Only when the compressor has reached the necessary revolutions per minute (RPM), can the fuel be introduced into the chamber and the engine can then operate normally.:

sources : http://www.rc-airplane-world.com

Radio control flight in its simplest form comes in the shape of rc gliders.

They can differ between large scale multi function models to small 'sport' gliders, and are a great way to enjoy some peaceful, hassle-free flying.

The majority of gliders are flown on two channel rc gear, with control to either rudder and elevator or aileron and elevator. Either option is fine for starting off with, but a 3rd channel (ie rudder, elevator & aileron) is always a good option to bear in mind too.

'Sport' rc gliders like the foam Multiplex Easy Glider RTF (shown below) are a very good introduction to radio control flying , as they are easy to control and learning how to fly one doesn't take too much time at all.
A 3rd channel will of course steepen the learning curve, but will give you more flexibility in the air.

Many rc gliders, like the Easy Glider, make excellent 'all round' gliders especially with control to ailerons. Gliders of this type are also very stable and forgiving, so a wrong input at the transmitter won't turn into an irrecoverable situation! (depending on how close to the ground your glider is, of course!).
At the same time, they can handle a bit more fun-style flying (eg loops and barrell rolls) very easily.

Flying rc gliders is a very peaceful experience; typically flying speeds of gliders are slower than the speeds of powered airplanes, which gives you plenty of time to react. Of course, this depends largely on the wind strength; a long downwind-run can build up a lot of speed if the wind is strong.
One major difference with flying a glider is the approach to aerobatic maneuvers; a powered airplane can be flown at full throttle if a steep climb is needed (eg going into a loop), whereas a glider might not have the necesaary airspeed, so needs to be put into a steep nosedive first, to get that speed.

From a personal point of view, rc gliders are a favorite of mine. They require very few - if any - accessories and there are no noise issues to worry about.
In fact, the only concern is whether or not your radio gear batteries will last as long as you want to fly for - if the weather is right, you can keep a glider flying much longer than a powered airplane (excluding pilot errors!).

If you live in a hilly or mountainous area I highly recommend buying an rc glider, even if you want to fly powered airplanes too.

Powered RC gliders

When is a glider not a glider?...
Another sensible option is to purchase a powered glider such as Hanger 9's Aspire.

These are standard rc gliders that have the added feature of a small electric motor fitted, with a folding propeller.
Following a hand launch with motor on, you can fly the model up to a suitable height and then turn off the motor completely. Because of the forward movement, the air pushes back the propeller blades to minimize wind resistance, and you're flying a normal glider.
If the model is losing altitude, you simply flick the motor back on and climb away again.

Powered gliders may be a 'cheat' to the purists, but they're still gliders in my books!

The obvious advantage that a powered glider has over a normal rc glider, but not a DLG, is that you don't need to find a hill or cliff, or a large enough space to operate a bungee system; powered gliders can be launched from flat ground and in spaces that may be too small for a bungee.

Powered gliders like the Aspire are a great way to experience some gentle, relaxing rc flight.

Discus Launch Gliders (DLGs)

DLGs, such as the Great Planes Fling DL are a fairly new breed of rc glider , and are becoming very popular.
A DLG has a special design, and is launched into the air by flinging it upwards after spinning round 360 degrees while holding its wingtip, like an athlete throws a discus (hence the name...).

You don't need to be strong, because the force needed to power the glider upwards is generated during your spin, and then the design of the glider also aids the steep climb.
With a good technique, a DLG can reach a surprising height and once the glider has levelled out after its vertical climb, your normal flight can commence.

Above, the Great Planes Fling DL - a new breed of rc glider

The big advantage with a DLG is that you don't need to be on a hilltop, or have any kind of launching equipment; they can be thrown into the sky from any clear area.

Sources : http://www.rc-airplane-world.com/rc-gliders.html