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

[oneleg]

I'm using Just Flights PA-28R. In page 71 of the plane's user manual it gives instructions on how to check the propeller. Quoting the manual:
 

"To carry out a propeller check, advance the throttle lever to obtain 2,000 RPM and then cycle the propeller lever
twice, moving it aft towards the high pitch/low RPM position and then forwards towards the low pitch/high
RPM position. Note the RPM drop on the tachometer."

My understanding is that single props planes such as this plane don't feather their props. So what does high pitch and low pitch mean?  What does it refer to?

 

[tiger1962]

Here's a Wikipedia article which explains it much better than I could:

 

https://en.wikipedia.org/w/index.php?title=Blade_pitch&oldid=1129999217

[nsproles]

6 hours ago, oneleg said:

My understanding is that single props planes such as this plane don't feather their props. So what does high pitch and low pitch mean?  What does it refer to?

 

Further to tiger1962's reply; I wonder if you are under the mistaken impression that, because an aircraft has only one engine, it can only have a fixed-pitch propeller which is not capable of being feathered.  Being single-engined does not, in itself, mean that it cannot be fitted with a variable pitch or constant speed propeller.  I believe that the PA-28R has a constant speed propeller.  Doing the check before take-off means that you are only exercising the mechanism to confirm that it is working.  You do the same with magnettos (if fitted), control surfaces etc.

[oneleg]

6 hours ago, tiger1962 said:

Here's a Wikipedia article which explains it much better than I could:

 

https://en.wikipedia.org/w/index.php?title=Blade_pitch&oldid=1129999217

Nice link. Thank you.

[oneleg]

4 hours ago, nsproles said:

Doing the check before take-off means that you are only exercising the mechanism to confirm that it is working. 

Thank you for taking the time to reply.

This is what I was doing. I tried feathering the prop by adjusting the prop lever, but the props weren't moving to the feathering position. I was curious as to why the manual refer to high and low pitch in the prop.

I was under the impression that with few exceptions single engine planes mostly do not feather their props unlike in twin engine planes. In twin engine planes, to me it makes sense to be able to feather a prop when one engine fails and you don't want that failed engine's propeller to drag the plane.  In single engine planes, it seems to me that the only reason to feather a prop is to glide the plane in an emergency situation.  And since that is rare, single engined planes do not feather to save on cost and simplify operation.

Perhaps, Just Flight's PA-28R props have prop feathering but the action is just not modelled in their version? I also don't know if the real plane feathers the prop? Can someone can confirm both ie. Just Flight vs the real plane?

[tiger1962]

Sorry to link to Wikipedia again, but the 28R does have a constant-speed prop: https://en.wikipedia.org/wiki/Piper_PA-28_Cherokee

The MSFS prop blade animation seems to be bugged; it's even modelled in some of the default planes but it's rarely visible.

In the King Air for example, I have to feather the props before engine shutdown for the blades to appear feathered when stopped.

[oneleg]

Just now, tiger1962 said:

In the King Air for example, I have to feather the props before engine shutdown for the blades to appear feathered when stopped.

The King Air has twin props. Do you know of a default MSFS single engine plane that has prop feathering?  (if I remember correctly, perhaps the TBM might have it. I need to check...).

Do ALL constant-speed props feather?

[oneleg]

7 minutes ago, oneleg said:

(if I remember correctly, perhaps the TBM might have it. I need to check...).

I checked. Yep, it does have feathering. It clearly says so at the throttle area but I just don't remember how it's done. I think there's a keystroke short-cut for it, and I think you have to turn off the engine to see the feathering animation.

[PhrogPhlyer]

8 hours ago, oneleg said:

Do ALL constant-speed props feather?

No. Propeller feathering (moving the blades to 90º) is normally found on multi-engine aircraft. Feathering eliminates the drag that a spinning propeller would have with an engine failure.

This link is to an article that gives a good definition of propellers and various propeller systems.

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

 

[nsproles]

I spoke today with an ex-air force engine fitter who said that he had never come across a single engined aircraft with a propeller that feathered.  However, some single engined aircraft do have featherable propellers but they are the exception.  It seems that being able to feather the propeller does not have much of a benefit in single engined aircraft and lugging the extra weight of the necessary fittings around the sky is not worth the effort.  That is something that I did not know so  it shows that you are never too old to learn.  When you say that you referenced page 71 of the user manual, was that the real aircraft's manual?  Often MSFS does not truly represent the real aircraft so that may be worth bearing in mind.  A diagram in the simpleflying reference provided by PhrogPhlyer clearly demonstrates pitch angle.  Whether high or coarse pitch/ low or fine pitch depends on, it seems, if you are using British or US terminology.  Have muddy waters been made clear.  Has all this answered your question?

[jimmysanders]

55 minutes ago, nsproles said:

I spoke today with an ex-air force engine fitter who said that he had never come across a single engined aircraft with a propeller that feathered.  However, some single engined aircraft do have featherable propellers but they are the exception.  It seems that being able to feather the propeller does not have much of a benefit in single engined aircraft and lugging the extra weight of the necessary fittings around the sky is not worth the effort.  That is something that I did not know so  it shows that you are never too old to learn.  When you say that you referenced page 71 of the user manual, was that the real aircraft's manual?  Often MSFS does not truly represent the real aircraft so that may be worth bearing in mind.  A diagram in the simpleflying reference provided by PhrogPhlyer clearly demonstrates pitch angle.  Whether high or coarse pitch/ low or fine pitch depends on, it seems, if you are using British or US terminology.  Have muddy waters been made clear.  Has all this answered your question?

 

It's fascinating to hear about your conversation with an ex-air force engine fitter and their insights on feathering propellers in single-engined aircraft. It's true that while featherable propellers do exist in some single-engined aircraft, they are indeed the exception rather than the norm. The benefits of feathering propellers in single-engined planes may not outweigh the added weight and complexity of the necessary components.

 

The variation in terminologies, such as high/coarse pitch or low/fine pitch, between British and US terminology is a notable point to consider. It's always helpful to have clarity on the terminology used to ensure accurate communication within the aviation community.

[tiger1962]

The MSFS Cubcrafter X-Cubs have constant-speed props, this means that they are variable pitch props which are not usually featherable in single engine aircraft as nsproles confirmed above.

[lnuss]

On 6/3/2023 at 10:44 PM, oneleg said:

My understanding is that single props planes such as this plane don't feather their props. So what does high pitch and low pitch mean?  What does it refer to?

Unless I missed something in the replies above, it appears to me that you are still a bit confused about this. High and low pitch are reference to various positions of an adjustable propeller. While aircraft such as the C-172 and lower end PA-28s have fixed pitch propellers, most of the higher powered single engine aircraft have constant speed propellers. This means there is the (often blue) propeller control in most cockpits* and that the blades are movable. But not all constant speed props can be feathered, although most multi-engine aircraft do have a feathering positions

 

Perhaps it will help to understand that feathering goes beyond just being adjustable, and turns the blades so that they are 90º to the direction of flight for minimum drag, which obviously means they can't propel the aircraft any more.

 

20 hours ago, oneleg said:

it seems to me that the only reason to feather a prop is to glide the plane in an emergency situation.  And since that is rare, single engined planes do not feather to save on cost and simplify operation.

No, they don't feather because there isn't much need for it (it does save cost and complexity vs just constant speed), but they do still adjust on many singles, especially the faster ones.

 

So to understand the constant speed aspect, and the reason for them, think of it as sort of like a transmission in a car, low gear for starting out shifting to a higher gear as you get faster. So you put the prop lever full forward for takeoff giving you low pitch when you add a lot of power, thus getting a more effective bite at the air. This also allows the engine to reach max RPM so that combined you have the best takeoff performance. Once airborne and after initial climb and clearing any obstacles you bring the prop back to, say 2400-2500 RPM (from perhaps 2700 or so initially, depending on the aircraft) for best climb performance, then you bring the throttle back to perhaps 25" of manifold pressure (from maybe 29" at sea level) to get down to the rated max continuous power (typically 75%) 'til getting to cruise altitude.

 

Once at cruise altitude you bring the prop back to, perhaps 2100 to 2400 RPM, depending on whether you want more speed or more economy, and leave it there until ready for descent.

 

What all of this does is to get you in the best "gear" for each stage of flight. And it's called a constant speed propeller because it has a governor (which is what you are adjusting for RPM) to vary the blade pitch (angle) as the aircraft speed and propeller/engine loads change during flight, which results in the blades being in a relatively low pitch (almost flat with the airstream) at initial level off but gradually becoming a higher pitch (more coarse pitch) as the aircraft speeds up, with the governor maintaining a constant RPM on the prop (what you set by the tachometer) as the loads change in flight.

 

I'm not aware of any piston engine singles that have feathering props, but most (maybe all) single engine turboprops do, as much for ground operation as anything, due to the difference in the way turboprops operate.

 

So please don't confuse adjustable with feathering, two different things. Hope this helps.

 

 

[lnuss]

Well, it seems that the time for editing isn't adequate for a long post, since I forgot to add the footnote for the asterisk near the beginning and it tells me that it's too late to edit this post. So here's the footnote:
 

* Some single engine aircraft don't have the "airline style" levers, but instead have a push-pull control (and throttle and mixture also push pull) on the panel, and a few recently developed singles have a computer that does it for you leaving you with a single "power lever" for your control, sort of like an automatic transmission in a car.

 

[PhrogPhlyer]

1 hour ago, lnuss said:

it seems to me that the only reason to feather a prop is to glide the plane in an emergency situation

As already stated, you feather a prop with an engine failure in  a multi-engine aircraft to eliminate the drag caused by a wind-milling prop and the yaw that creates (drag on one side of the centerline, the failed engine side).

This drag does not hinder flying to a safe emergency landing with a single engine aircraft,  so these do not have the added cost and mechanical complexity of a feathering prop.

[PhrogPhlyer]

1 hour ago, lnuss said:

Well, it seems that the time for editing isn't adequate for a long post

What is the actual time to be able to edit a post?

It would be nice to be able to make a change a few minutes after you post, as it takes a while to notice misspellings, or addl. material you forgot initially.

[mrzippy]

44 minutes ago, PhrogPhlyer said:

What is the actual time to be able to edit a post?

It would be nice to be able to make a change a few minutes after you post, as it takes a while to notice misspellings, or addl. material you forgot initially.

I'm thinking about 2 minutes after hitting "Submit Reply".  I have already complained to Adrian about it and got no reply back.  Maybe if more of us would PM him and complain, it might be fixed.

[ScottishMike]

Take the Beech 36G that comes with the sim. It has a constant speed prop. To check it's functioning before take off note RPM with the blue lever fully forward, then pull the leaver back and see RPM drop:

 

High RPM position 1070 RPM

 

 

Low RPM position 690 RPM

 

 

I don't know if the Beech G36 can fully feather it's prop, nonetheless it is adjustable.

[lnuss]

7 minutes ago, ScottishMike said:

I don't know if the Beech G36 can fully feather it's prop, nonetheless it is adjustable.

I don't know about the sim, but the real world one cannot.

[oneleg]

9 hours ago, nsproles said:

When you say that you referenced page 71 of the user manual, was that the real aircraft's manual? 

These pictures should answer a question or two I was asked about.

I'm trying to determine if Just Flight's PA-28R "Arrow" is supposed to have feathering.

On the one hand, apparently so (see manual below, and also google the Piper PA-28R and 'constant' or variable pitch-props. The PA-28R is supposed to have a constant propeller. It's on page 6 of the Just Flight manual for the plane). But on the other hand, it is a single engine prop, and single prop planes don't need them, so the answer is "no".  Which is it? Why am I not seeing feathering in Just Flight's PA-28R Turbo Arrow III which has a constant prop?

[oneleg]

5 hours ago, lnuss said:

So please don't confuse adjustable with feathering, two different things.

Thank you for taking the time to reply. Maybe, as someone mentioned, it's a question of terminology. I'm from the US (California) and maybe that's the problem.

But to me, when you feather you are moving the prop lever. And to me 'moving' is the same or synonymous to 'adjusting'.  Is it possible that you are using the term 'adjusting' in the context of using the throttle to increase or decrease the RPM, and 'feathering' or using the prop lever to increase or decrease the RPM?

[oneleg]

I should mention that in MSFS' default TBM 930; to feather the prop, you use the "condition lever".  There is no prop or blue lever. The TBM is a single-engine turboprop.

[nsproles]

According to a website page on the PA-28R-201 ARROW III Vital Statistics, the PA28R  Propeller System Type is constant speed, variable pitch, non-feathering.

Elsewhere, the TBM 930 Pilot's Information Manual states that the TBM  Propeller type is Adjustable constant speed, with feathering and hydraulic control reverse.

The Mooney Missile and Rocket conversions were examples of single engined aircraft with fully feathering propellers.

The Fairey Gannet had two engines connected via a single shaft to contra-rotating propellers which could be fully feathered.  This may be stretching the point somewhat.

[tiger1962]

55 minutes ago, oneleg said:

I should mention that in MSFS' default TBM 930; to feather the prop, you use the "condition lever".  There is no prop or blue lever. The TBM is a single-engine turboprop.

 

Turboprops are fitted with feathering props because turpoprops work very differently to piston props - the TBM along with many other modern turboprops also has an automatic gearbox-style system for synchronising prop pitch with the turbine rpm/torque output. The turboprop's fully feathered lever position is equal to an automatic gearbox neutral or 'N' position. Turboprops are driven by their prop pitch, not their engine rpm like piston engined aircraft.

Piston engined aircraft have variable pitch props, not feathering props, so when you move the blue lever you are varying the propeller pitch not feathering it.

[oneleg]

1 hour ago, nsproles said:

variable pitch, non-feathering.

Hmmm.... again, this might be a question of terminology on my part.

What exactly is 'variable pitch". What are you changing.  You are 'pitching' what... the plane or the propeller or something else??