Generic Turboprop Questions

[Comanche 417]

Never having flown a turboprop aircraft, I have a few questions.  This is not related to any one model or sim, for that matter. For now, i'm learning the Carenado PC-12 and soon. I will pick up the LES Saab.

 

Whenever I fly a turboprop, the aircraft seems to roll quite a bit once the brakes or released. This happens in every turboprop model I've flown in X-plane or FSX. Is this how it really is? I feel like i'm always riding the brakes when taxing along. Do these aircraft go through brake pads faster that piston or Jet aircraft?

 

I have a button on my HOTAS system set to reverse thrust. I've used this once in a while in flight with Turboprops and it does a great job of slowing the plane down when I'm coming in too fast. (something that I always have trouble with  faster aircraft).  Is that Taboo when flying turboprops? Do they every use reverse thrust in flight to slow down?

 

Forgive me if these are dumb questions,

 

Rob

[avgaskoolaid 292]

 

I have a button on my HOTAS system set to reverse thrust. I've used this once in a while in flight with Turboprops and it does a great job of slowing the plane down when I'm coming in too fast. (something that I always have trouble with  faster aircraft).  Is that Taboo when flying turboprops? Do they every use reverse thrust in flight to slow down?

Sorry, I can't comment on your first question as I've never flown a turboprop in real life, but no, they do not use reverse thrust to slow down in flight. At least, commercial turboprops such as the Saab 340 or PC-12 don't. The DHC-4 Caribou is a military transport/cargo aircraft and can use reverse thrust in flight, but it's a very unique feature.

 

Thinking about your first question some more, though, I've never had a similar problem with my Majestic Q400 in FSX. You may want to make sure that your propellers are set to the proper taxi setting.  

[MartinRex007 390]

Some turboprops have a beta range like the King Air which helps slow the aircraft which helps save on brakes. It's not a reverse thrust but acts a little like it!

[LawnDart 19]

I fly the Carenado Beech 1900D (Beautiful aircraft!) and I usually taxi with my fuel flows set to low idle and my props at about 50% feather. Once I'm at the threshold then I run everything up. I'm not a licensed Turbo pilot so I don't really know what they do in real life but this method works for me.

I also notice a certain 'heaviness' during taxi if I'm carrying a full fuel load and full aircraft.

[Longranger 148]

Well, the turboprops are in general stronger stronger, so they have a stronger torque effect, if you don't use the engine with reduced power, while on the ground.

But as some people already said: they must not use Beta settings while in flight. In fact their controls behave differently. They have control levers that are in their lower settings beta, then idle and normal thrust. But if the plane is not on the ground a lock is engaged, so that the control lever can only go t6o idle. Only after touch down you can pull the controls further back into the beta range.

 

But Beta doesn't really mean reverse thrust. Planes like the Mu-2 normally taxi in their beta range.

[Comanche 417]

Thanks for the responses. Lots of good info! 

Ive been playing with the Carenado Pilatus PC12 and found the plane really likes to run away with me, once I release the parking break. After further examination, I found the Prop pitch lever on my Saitek Throttle set was not doing anything with this aircraft. Works in my other planes.

 

So apparently, they call it a condition lever in some turboprops and it seems to not be the same thing as prop pitch. This needs to be set to idle (or something like that) during taxi or else you will be riding the brakes constantly (As I've been doing). Moving the condition lever to the middle, made a big difference. Just have to remember to move it back up before takeoff or you may not have enough power for take off! 

 

Question I have now is, How can I set a joystick or key command to move the condition lever, since it is not listed as a command axis in X-planes joystick configurations?

 

Thanks for any help,

 

Rob

[19dcavscout 39]

In the King Air we taxi with Beta thrust, which is a flatter pitch angle of the blades with engine still at idle. If you continue to pull the throttles back you will go into reverse. While taxiing I am always in Beta. You have to. At idle the engines are still producing way too much thrust and you end up riding the brakes. We taxi at high idle and props high. We do this for a few reasons, the high idle allows us to run the generators faster which in turn cools them better (they use a belt drive fan), and the air conditioner requires it. There is nothing wrong with taxiing at low idle however if its not to hot however. As for the props high, we do this because it does not matter either way and its already high for takeoff. The engines are not producing enough power to spin the props at any real speed as it is. The King Air 200 with 4 bladed props has prop speed in the 1180-1200 range.

 

As for using reverse in flight to slow down, its not possible on the King Air. The propeller has what is called Low Pitch Stops that prevent the blades from reducing to an amount that would go anywhere near reverse. If for some reason something failed and it attempted to go into reverse (which is practically impossible in the King Air's propeller system) the resulting drag would cause severe damage to the aircraft. Not to mention the resulting overtorque would case incredible damage. 

 

An easy way to slow the aircraft down is to just plan ahead and get the drag out. You would be surprised how much drag is created by a prop in High with the power lever at idle. 

 

Prop pitch and condition levers are two seperate controls. All the condition lever does is set your idle N1 speed. Thats it. The prop lever directly controls the RPM of the prop. The condition levers we keep at high idle and leave them there for the whole flight (technique) while the prop levers are left mainly at high on the ground and are constantly adjusted in the air for cruise power, climb power, etc etc. 

 

Hope this answers your questions. If you have anymore ask away.

[brucek 38]

Also not a turboprop pilot, but I do fly piston singles....

Unlike turboprops, jet engines cannot adjust propeller blade angle (pitch), so they achieve reverse thrust by channeling the "forwards" thrust in a reverse direction by a system of massive air valves... You can see these operate as a pax.

Turboprops can alter the blade angle, so "reverse thrust" is achieved by changing the blade angle to a very fine pitch where the prop blades are flat and perpendicular to cowards, creating a virtual flat disc that rapidly slows the aircraft down.

[19dcavscout 39]

 The King Air's blades actually go into a negative pitch and produce reverse thrust. The beta range puts the blades at flat pitch.

[MartinRex007 390]

The Flight 1 King AIr B200 does a reasonably good job of modelling the beta range.....given the limitation of FSX/P3D.

[Bobsk8 12,683]

The Majestic Q400 does a excellent job of modeling the taxi behavior of the real aircraft according to a Q400 pilot I spoke with. It will taxi at a good clip with the throttles at idle. 

[ryanbatc 12,837]

The Flight 1 King AIr B200 does a reasonably good job of modelling the beta range.....given the limitation of FSX/P3D.

For FSX this is the best turboprop modeling I've seen specifically for beta range. Don't have the Q400 but I've heard it good too

 

Anyway for XP the LES Saab is very good. However it is not a free turbine it's a geared turbine. Adjusting the power levers gives a more immediate response when changing power settings.