Question on how to check the propeller (blue lever) before take-off

[oneleg]

I was editing the above post, but the forum didn't want to post my edit after completing it.

What I wanted to correct and re-state was....  What exactly is being changed?  What is 'pitching' when the blue lever is changed. Is it changing the pitch of the plane, the pitch of the propeller, just parts of the propeller only (the blades only), or is it pitching something else?   Isn't saying the aircraft is variable pitch and non-feathering a contradiction in terminology and an oxymoron?  It's like saying "act seriously", "found missing", "half full", etc.....

[tiger1962]

The blue lever changes the pitch of the propeller blades.

[Nels_Anderson]

The blue lever changes the angle of the propeller blades relative to the wind.

 

In an earlier post you mentioned not seeing the animation.  Given that the propeller is rotating at a high speed and the change in angle is not all that great, I'm not sure you should be able to see anything.

 

A prop certainly can be both "variable pitch" and "non-feathering".  On planes like the Arrow the pitch is variable only between a certain range. Feathering would be a pitch change that is far outside this range.

[PhrogPhlyer]

3 hours ago, oneleg said:

What exactly is being changed?  What is 'pitching' when the blue lever is changed.

You may want to review this article, I posted the link in an earlier reply.

https://simpleflying.com/how-an-airplane-propeller-works/

At this point I believe that all the excellent responses MORE than cover any question anyone may have on propellers (fixed and controllable pitch), feathering, rpm, etc.

All it takes is to actually and carefully READ all the responses by Nels, lnuss, tiger1962, nsproles, jimmysanders, ScottishMike, and myself.

Reading in not only essential, it is the start of all great discoveries.

Happy simming!

 

[oneleg]

5 hours ago, Nels_Anderson said:

A prop certainly can be both "variable pitch" and "non-feathering".  On planes like the Arrow the pitch is variable only between a certain range. Feathering would be a pitch change that is far outside this range.

This was the answer I was looking for.  Specifically, the phrase: "the pitch is variable only between a certain range".  Thank you.

And thank you to all also for trying to clarify the question for me.

Onwards... to the second question: since both throttle and prop lever can control the RPM, which one should one use to control the RPM ... the throttle or the prop lever.  Why and when?

[tiger1962]

The throttle controls rpm first and foremost; move your prop lever second and then re-adjust the throttle as required.

[PhrogPhlyer]

54 minutes ago, tiger1962 said:

The throttle controls rpm first and foremost; move your prop lever second and then re-adjust the throttle as required.

With a fixed pitch propeller the throttle controls rpm. With a variable pitch propeller (constant-speed) the propeller lever controls rpm.

For example, when you increase the power lever  with a  constant-speed prop, at the first sign of rpm rise the governor increases the pitch of the propeller, taking a bigger "bite" of air, which slows the prop back to the rpm set with the propeller lever. 

If you want a higher or lower rpm, you adjust with the propeller lever. If you want more or less torque (power) you adjust with the throttle.

[jimmysanders]

On 6/5/2023 at 11:52 AM, jimmysanders said:

I find it truly fascinating to hear about your recent conversation with an ex-air force engine fitter and the valuable insights they shared regarding the concept of feathering propellers in single-engined aircraft. It is undeniably true that while there are instances where featherable propellers are found in certain single-engined planes, they are actually more of an exception than a standard feature.

 

When examining the feasibility and practicality of incorporating feathering propellers in single-engined aircraft, it becomes apparent that the advantages they offer may not always justify the additional weight and complexity of the components required. Designers and manufacturers meticulously evaluate various factors, including performance, fuel efficiency, reliability, and cost-effectiveness, before making decisions regarding the inclusion of such features.

 

Furthermore, it is worth noting the variation in terminologies used to describe propeller pitch, such as high/coarse pitch or low/fine pitch, between British and US aviation terminology. This disparity highlights the importance of achieving clarity and consistency in communication within the aviation community. By ensuring a mutual understanding of the terminologies used, we can enhance accurate information exchange, minimize potential misunderstandings, and promote safer operations within the industry.

 

Engaging in discussions that delve into the technical aspects of aviation, like feathering propellers and associated terminologies, allows us to broaden our knowledge and gain a deeper appreciation for the intricate details involved in aircraft design and operation. It is through sharing experiences and insights that we can collectively foster a comprehensive understanding of aviation practices and continue to advance the field of https://onlinecasinohex.ph/casino-bonuses/no-deposit/.

Absolutely, the insights shared by an ex-air force engine fitter regarding feathering propellers in single-engined aircraft are indeed fascinating. Featherable propellers do exist in some single-engined planes, but they are not commonly found. The decision to incorporate feathering propellers depends on various factors, including the specific aircraft design and intended purpose.

While feathering propellers offer benefits such as reduced drag and improved safety during engine failures, the additional weight and complexity they introduce can be a drawback. Manufacturers carefully consider these trade-offs when designing aircraft, taking into account factors like performance, fuel efficiency, and overall reliability.

The variation in terminologies related to propeller pitch, such as high/coarse pitch or low/fine pitch, between British and US terminology is an important point to highlight. Clear and accurate communication within the aviation community is crucial to ensure understanding and promote safety.

Engaging in discussions that shed light on these technical aspects of aviation enriches our understanding of the intricacies involved in aircraft design and operation. It's always beneficial to exchange knowledge and perspectives within the aviation community, fostering a deeper appreciation for the complexities of flight.

Edited June 6, 2023 by jimmysanders

[tiger1962]

2 hours ago, PhrogPhlyer said:

With a fixed pitch propeller the throttle controls rpm. With a variable pitch propeller (constant-speed) the propeller lever controls rpm.

If you want a higher or lower rpm, you adjust with the propeller lever. If you want more or less torque (power) you adjust with the throttle.

 

That's right, I was thinking of turboprops. There's always some inertia with prop rpm on turboprops.

[nsproles]

Quote

...second question: since both throttle and prop lever can control the RPM, which one should one use to control the RPM ... the throttle or the prop lever.  Why and when?

In piston-engined aircraft with a constant speed propeller, the throttle controls manifold pressure and the propeller control controls RPM.   There will be a manifold pressure gauge on the control panel.  So, you need to understand manifold pressure and a good start is https://pilotinstitute.com/what-is-manifold-pressure/#What Is Manifold Pressure?  Alteration of throttle and propeller control must be done in a definite sequence to avoid over-pressurising the cylinders i.e. increase propeller control (RPM) before increasing throttle (manifold pressure) and reduce throttle (manifold pressure) before reducing RPM (propeller control).  

It is interesting that back in the 1940s, the German Fw 190 fighter incorporated throttle (manifold pressure), propeller RPM, and mixture into one control lever.

[Rupert]

That is a good link nsproles.  

 

In my experience there are good applications for both constant speed and full feathering props.  And as more than one poster pointed out, there are also many applications where the installation of neither is more appropriate as well.  

 

RW: In a unfamiliar aircraft it's important to understand the equipment installed before you even turn the battery switch on.  That's why RW pilots, even those with a ton of flight hours, should take check rides with a certified instructor on aircraft they aren't already rated for!  And of course learning which prop/s are installed on any specific aircraft and how to control it, or them, should be part of that checkout as well.

 

When learning a new sim aircraft I just try read the provided instructions and act accordingly.  While flying a sim I'm not risking my or others lives and/or limbs if I get something wrong.

 

Michael

 

[KiloWatt]

On 6/5/2023 at 6:47 PM, Nels_Anderson said:

The blue lever changes the angle of the propeller blades relative to the wind.

 

In an earlier post you mentioned not seeing the animation.  Given that the propeller is rotating at a high speed and the change in angle is not all that great, I'm not sure you should be able to see anything.

 

A prop certainly can be both "variable pitch" and "non-feathering".  On planes like the Arrow the pitch is variable only between a certain range. Feathering would be a pitch change that is far outside this range.

 

I was a passenger on a turboprop (Q400) about an hour ago and when we landed at Calgary I kept this comment in mind; I can confirm you are correct.

 

After touchdown, and as I was looking at the prop, the pilot went into the beta range. Indeed, it didn't look any different even though the sound and vibrtation was very obvious.

[Nels_Anderson]

15 hours ago, KiloWatt said:

 

I was a passenger on a turboprop (Q400) about an hour ago and when we landed at Calgary I kept this comment in mind; I can confirm you are correct.

 

After touchdown, and as I was looking at the prop, the pilot went into the beta range. Indeed, it didn't look any different even though the sound and vibrtation was very obvious.

 

This is true of the piston powered planes with non-feathering props as well. During the run-up tests you will quite clearly hear when the exercise to blue lever.

[snave]

Beta and constant speed are different functions. Beta and reverse thrust are related . Learn the difference would be my recommendation. It'd be core to understanding the various operations

[oneleg]

Thank you all. Got it figured out with all you help. Much appreciated. 

[oneleg]

I missed one thing.  When someone say you need to cruise at 75% power, exactly what does that mean?  75% of what? In other words, how is that calculated.  Is that 75% of maximum RPM, maximum speed (eg. VNE), maximum manifold pressure, or something else in the plane panel? Thank you.

[PhrogPhlyer]

10 hours ago, oneleg said:

75% power

You've actually answered your own question. A review of the responses will show that torque or manifold pressure (depending on aircraft) are indications of power. 75% means a percentage of maximum (100%) power; i.e. max torque or max rpm.

[oneleg]

46 minutes ago, PhrogPhlyer said:

max torque

Max torque is maximum power ie. one and the same?

[oneleg]

51 minutes ago, oneleg said:

Max torque is maximum power ie. one and the same?

Typo correction: Max torque IS maximum RPM ie. one and the same?

[PhrogPhlyer]

3 hours ago, PhrogPhlyer said:

max torque or max rpm

No this is not mis-type. Depending on the type of aircraft power might be determined based on either  torque OR rpm or manifold pressure.

One must read the aircraft specific manual or look at the gauges.

In the following picture note that the KingAir panel has a torque indicator, the J-3 Cub panel has and RPM gauge, and the Malibu has a manifold pressure indicator. Thee aircraft, three different ways to determine power.

 

KingAir - Torque

 

Piper J-3 Gub - RPM

 

Malibu - Manifold Pressure

[nsproles]

Quote

When someone say you need to cruise at 75% power, exactly what does that mean?  

I am assuming that you are still referring to piloting the Piper PA 28R?  If so, 75% power is a combination of throttle (manifold pressure) and propeller control (RPM).  The manufacturer has done all the hard work so you don't have to work this combination out for yourself.  They are produced in tables in the pilot operating handbook.  For the purposes of MSFS, a google search should also provide them.  They will tell you the necessary settings for, say, 55%, 65%, 75% etc power at varying pressure altitudes.  Forget about torque with the PA 28R as torque is used with turboprops such as the King Air.  The Piper J3 Cub indicates power with RPM only as it has a fixed pitch propeller.  The Malibu has a constant speed propeller, as does the PA 28R, so it has gauges for both RPM and MP.   When read in conjunction with the relevant manufacturer's tables, this combination of readings will tell you the percentage of power being developed.  Note the little yellow note taped beside the MP gauge in PhrogPhlyer's photo above; I believe that it may indicate that it reads  100 RPM up or down.

[oneleg]

Thank you both @nsproles and @PhrogPhlyer for the excellent advice and guidance!

At the table below, at 75% POWER, why would anyone use an RPM of 2575 with an MP of 31.5, instead of an RPM of 2300 with an MP of 34.8? Does the difference have anything to do with the aircraft speed or something else?

Also, is S.L. = "sea level"?

[PhrogPhlyer]

43 minutes ago, oneleg said:

would anyone use an RPM of 2575 with an MP of 31.5, instead of an RPM of 2300 with an MP of 34.8?

 

For a climb you want lower pitch, and less drag. Less drag results in higher RPM and more horsepower capability, which increases performance during takeoffs and climbs, but decreases performance during cruising flight.

For cruise you want a higher pitch, therefore more drag. More drag results in lower RPM and less horsepower capability, which decreases performance during takeoffs and climbs, but increases efficiency during cruising flight.

This is why the difference in the performance charts, and is reflected in the T/O, Cruise, and Landing procedures.

 

45 minutes ago, oneleg said:

Also, is S.L. = "sea level"?

Yes.

[nsproles]

Try this link;       https://www.aopa.org/news-and-media/all-news/1998/november/flight-training-magazine/engine-power-settings

[oneleg]

Thank you both. I think the line below from the link above best sums up the difference: 

"...all other things being equal, you want to operate at lower RPM values in cruise flight and higher RPM values while climbing."

The article also mentions noise and vibration which reminds me of a trip over the Grand Canyon some years back. I think I have a strong stomach but on this trip it was different. The Cessna 206 was generating excessive noise, vibration, and heat throughout the one hour plus trip. The heat felt like a hair dryer on high heat was blowing on your face.  The noise was earth shaking loud that I couldn't even speak to anyone (no headphones). Thinking was hard too.

With me was an English tourist and apparently this was his first small plane trip in desert heat during the summer. Long story short, he kept vomiting and used up all the barf bags in the plane.  His constant vomiting also made me want to do the same but thankfully I managed to hold it in especially since he used up all the vomit bags.  As soon as we landed, he jumped and laid down on the tarmac and was asked by the pilot if he wanted '911'.  He said no.  Seeing him laying down on the runway is a memory that has always stuck with me.   It keeps reminding me that flying in the sim is probably better than real flying, at least for me (I learned the same lesson after experiencing deep sea fishing in a small boat. Never again will I go on the ocean on a small boat. A small boat on choppy seas doesn't just go up and down. It goes sideways and diagonally up and down. Reality is different than in the movies!).