I noticed that many aircraft have a turboprop engine and I don't know anything about flying them. I know only how they work in theory. So:
1. How do I start this engine? Beside pressing CTRL+E?
2. I know that I first have to engage the engine start buttons, when I do that I hear some sound but the propeller is not turning. What is that sound? The turbine? If that's the sound of the turbine how come the propeller is not turning with it?
3. How do those jet engines (turbojet, turbofan and turboprop) start working? I don't mean on buttons now, I mean on the starting system. How does it work?
4. What's the condition lever for? And how do I fly with it? Do I have to change it's settings during takeoff, climb, cruise, descent and landing?
5. In turbojet and turbofan engines the air is blown out trough the exhaust and that pushes the aircraft forward. But where does the air go in a turboprop engine?
1. Turbofans are usually electrically started. So the procedure usually involves similar steps to that of a piston engine until you get to the start switch. On a turbofan, you usually just press and release the start switch and it will go through the start sequence itself. You do have to monitor the ITT to and be ready to abort if it is a hot start.
2. The most popular turboprop engine in the world is the PWC PT6. The PT6 has two turbine stages on independent shafts. One drives the compressors and the accessories, the other drives the gear box to the propeller. Since they are independent, the spool with the prop doesn't spin up immediately on start. [Kids, don't try this at home] I've heard that you can put a shoulder under a stopped King Air blade and hold it in place as the engine starts with no difficulty.
3. All turbines start by spinning up one of the spools (usually the one closest to the combustion chamber). Once it has reached a critical speed, the fuel flow and igniters are turned on. Once the flame lights off, the engine will begin to accelerate under its own power until all spools are running stable at idle speed. Turboprops and turboshafts usually use an electric starter to drive the spool. Turbojets and Turbofans usually use a pneumatic starter, where high-pressure air is used to spin up the engine.
4. The condition lever is not like a mixture lever. It is more of a 3 position switch. Cutoff turns the fuel flow to the engine off entirely. Low Idle could probably be more aptly named "Ground Idle", it lets the engine idle a lower speed so you have less idle thrust, which you want for ground operations. High Idle could be called "Flight Idle". This is what you want for air operations. The lever should be set to Low Idle after start and while taxing. It should be set to High Idle prior to taking the runway for takeoff and left there the entire flight. It should be set to Low Idle again after clearing the runway on landing. And should be set to Cutoff to shutdown the engine.
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