More cylinders!

Nothing changes direction suddenly.

I think it is more economical to run.

No 2. for me

I know about Newton, but don't get the connection

Trubo props are a lot more efficient when flying at relative low speeds like 700km/h, above that Turbofans become more efficient.
Turbofans are the jet engines hanging under most passenger planes, they have a high by pas ratio and the big first fan some what works like an propeller.
Some of these engines can go over the Mach number and are efficient in the lower range.
With higher machs (2+) turbojet becomes more efficient but these don't run so well at low speeds.

They are now also busy with something in between the turboprop and the turbofan called Propfan (or UHB, ultra high bypass), some planes have them but there are some things that make turbofan better at the moment but you see the fan getting larger and larger.

If you want I can look into my schoolbooks to give you the full explanation.

In a piston engine the pistons start at zero speed at the top or bottom of their travel. They then accelerate to very fast half way down/up the cylinder, then they slow down again as they head for the other end. Theoretically the energy they absorb from the crankshaft while accelerating is returned to it when they decelerate, but in truth, there is a lot of friction moving the piston up and down the cylinder. This energy will all be lost as heat.

A turbine engine is not subject to these losses.

Stefan - are you a propulsion specialist? Have to put my hands up, I was a simulator engineer.

Oggy, Sorry I was referring to the advantage of Turboprop over Turbofan

Oggy, I'm almost a part B1 aircraftmaintenance technician, just need to do my internship and I'm done
I also did a year Aeronautical engineering but that wasn't for me.

A simulator engineer, that sound very interesting what did you do precisely?

Speed ranges. Turboprop engines are for slower flying aircraft. Turbofans are for faster aeroplanes.

I was involved with flight simulators for 25 years. I started off a a maintenance techie - my personal choice was the hydraulics. I gradually worked my way through electronics to writing software and mathematical models of aircraft, particularly avionics.

I enjoyed it because it was never the same job twice.

Barrie this explains everything at once.
[IMG]http://i282.photobucket.com/albums/kk244/Anvh/image026.jpg[/IMG]
Draw the Propfan in it, it isn't 100% correct but it gives you an idea.

Here is a film about them link

Not really sure why they don't fly with them jet though, probably has to do with the relative new concept and it first must be tested and if it works then you can use it with restriction and over time you are allowed to fly longer and further with it.

Indeed you have had almost all the aspect involved with simulators, such fun "toys" to play with.
You probably have a quite a lot of simulated flight hours, ever thought to get your licenses to fly?

Thank You Stefan, got it now