I understand the basic operation of constant speed propeller aircraft. What I have never understood is why there are so many potential settings on the blue lever/handle, almost all of which are useless. All of the planes in MSFS tend to operate around 2000-2600RPM, which is like the top 10% of the RPM lever. Is this realistic? Why would it be designed this way? It just seems silly to have all that space wasted, and it forces you to move the lever the tiniest amount to make meaningful adjustments. Perhaps a real world pilot could shed some light on this.
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Even if it´s a not so popular engine control it allows to generate the optimal air flow for each given engine power condition, to obtain the max speed with the lowest possible rpms. So basically it helps to achieve the lowest fuel consumption and to set the optimal rpms during the different phases of flight.
But it´s also helping to prevent engine overheating and wear by reducing the rpms. I think this is relevant in some advanced models like PMDG DC-6 but not in the stock aircraft (at least so far).
Also during heavy ice conditions it should be set to max periodically and back to the optimal setting to prevent ice formation, for instance.
Cheers
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Excellent question. In my current aircraft at 2,500 feet over southern Australia, 100% blue lever gives an RPM of 2700, a speed of 132 knots, and a fuel usage of 16 GPH. If I pull it back to a minimum then the RPM is 1892, the speed drops to 107 knots, and fuel usage of 10 GPH. The fuel-saving is so great for an acceptable reduction in speed that itâs bad not to use the lever to almost its full extent.
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While that is a significant fuel savings, approx 23%, we must also consider that seldom if ever are we going to fly at 100% of the black lever, (throttle).
Most pilots will cruise around 75% power. Also make sure that the RPM and MP remain in the green arc on the gauge. Green means normal operating range. Except when actually landing, those needles should always be in the green. The POH (Pilotâs Operating Handbook) will give you a chart for cruise power/rpm settings for best performance, best economy, and best endurance.
Normal operations would mean you will be âcruisingâ the aircraft not âbeatingâ the aircraft. Reliability is paramount in aviation. You canât drive at max performance and simply pull over if something breaks. ALWAYS baby your aircraft if you want it to get you home.
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The blue levers full extent is hardly ever used in normal operations. However, if you suffer an engine failure the extra drag that the propellor creates can be very costly. If you do experience an engine failure you would idle the throttle, pull the prop pitch right back (feathering the prop) then cut the mixture. Try it in the sim and see what happens! Itâs something I tested.
A constant speed propeller is a propeller that is designed to automatically change its blade pitch to allow it to maintain a constant RPM, irrespective of the amount of engine torque being produced or the airspeed or altitude at which the aircraft is flying.
With regard to ice forming on the blades: if you find yourself in conditions where that is happening, more than likely youâll end up as a statistic in a report authored by the NTSB.
Propeller-driven aircraft designed to fly through icing conditions almost always have heated surfaces, including the propeller blades.
Itâs a mechanical linkage in many small aircraft, which means that itâs going to vary a lot depending on the specific equipment used. In my experience, even between two engines on the same aircraft, the levers react slightly differently.
That being said, I donât really take issue with the representation of the lever in the sim. I can still dial in the correct RPM usually within +/-10 without too much difficulty, but I am using a hardware lever. Maybe clicking and dragging is more difficult.
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Itâs not that itâs particularly difficult, per se. Itâs just that 90% of the adjustable area is never used, which doesnât make any sense from a design standpoint (why not just make the usable 10% cover the whole area?). Iâm wondering if itâs like that in reality, too, or if itâs just an artifact of the way the sim handles it.
I get that, but even accounting for the feather option at the full out position, that still leaves 89% of the extent useless. Why not design it so that the standard-use top 10% of the lever covers the whole range and then simply have a button for emergency feather mode?
It can be like that in reality, yes. It can also use the whole arc. In the Baron E55 that I flew, the propeller levers entire arc was usable in the way you describe. Pulling it all the way back to the start of the feather detent would only bring the prop RPM down to the bottom of the green arc, which ended at 2000 RPM. Again, it heavily depends on the aircraft.
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Do those guages actually provide any meaningful feedback in the Asobo aircraft?
Some aircraft do have the option. Itâs usually in turbo props. They will have an auto feather system but it isnât always that reliable, and can feather the prop undesirably during rapid movements of the thrust levers. I always used to fly with it off in the F406.
Everyoneâs answers are correct though. There is a nominal operating range (green arc) that is specified in the AFM. Can you set the RPM to something outside that range? Yes, but may not be economical or good for the engine.
Why is it that way? Cost probably. Itâs easier to design and install a linear control system, even with a FADEC, in most aircraft.
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Not sure I understand the question.
The gauges in the sim aircraft reflect the gauges in the real aircraft.
If you are suggesting that it doesnât matter what power settings you choose to fly with in the sim, then you are absolutely correct. It is a sim. Do what you want. Just remember that the aircraft are designed to operate in a defined ânormalâ range. Outside that range you will encounter controllability issues, particularly trimming. If you find it difficult to control the aircraft and chose to ignore the normal range then please donât start a new thread about how terrible the flight model is.
Iâm not questioning the flight model, and I understand how to set power correctly and read the engine instruments. My point is that the control for setting the RPM is mostly unused. The ânormal range,â as you say, exists only in the last 10% of the control range that sets it. 90% of possible prop settings would land you outside what is normal. This is apparently realistic; I just found it odd from a design standpoint.
I was replying to @somethingbrite.
I completely understood your question. As mentioned previously, your assertion is entirely aircraft specific. Most aircraft I have flown in the sim and in RL use a fair range of the controls depending on flight parameters.
Something that is not mentioned is that during run up, the full range is used when exercising the prop. This is necessary as during flight, the movement of the prop is significantly more than your inputs and the full range of movement needs to be confirmed prior to flight.
There are a lot of variables involved determining the range of control input. Having a large range of movement allows for more precise control. If you have ever been in a twin IRL when the pilot did not take the time to make those fine adjustments to sync up the RPM of both engines you would understand the need for that precise control availability. If the full range of movement was defined within a short throw of the lever most twin pilots would have lost their mind and voluntarily flown into the side of a mountain.
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I was simply asking do the gauges in the vanilla aircraft actually work properly, do they provide meaningful feedback?
I think Iâve read various posts on the topic but I canât find any of them back.
While some of the ancillary gauges, ammeter, vacuum, etc. may not act accurately or correctly. The primary instruments are all pretty accurate.
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The Throttle and the prop lever and even the mixture lever work together to give you the most power for the least fuel burn.
Each aircraft has a chart which tells you what setting will give you the best fuel burn for a specific altitude.
RPM. Throttle Setting, Manifold Pressure and CHT are all very relevant to what the engine is producing.
Takeoff is generally all levers full forward. At altitude set the prop to the desired RPM and then the throttle to obtain the desired manifold pressure. Then set the mixture to obtain max CHT then back it off a bit.
The range of motion of the prop lever functions through the entire range but for âNormalâ operations you will only use the top few inches of travel.