Kinda FADEC?

spiderweb

spiderweb

Final Approach
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Ben
I'm reading this SR20 POH carefully these days, and filling out the required workbook before the checkout flight(s).

The SR20 has a throttle and mixture, but it has a variable pitch prop.

Does this governor act the same way as in a FADEC aircraft (which would have no mixture lever), or is it somehow less sophisticated?

And also, would it have been better to give the pilot a blue lever?
 
FADEC is a computer, what the Cirrus has is Mechanical. So the prop pitch is controlled mechanically based on the position of your power level.

Even though the Cirrus has a Mixture leaver it is capable of auto-leaning. I'm not exactly sure how the whole system on the Cirrus works but as far as I know the mixture lever is just to give you more control authority.
 
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FADEC: Fully Automatic Digital Engine Control.

You start the flight by putting the throttles into a detent and the plane takes off. After rotation you move the throttles back into another detent and climb power is set and maintained. There they sit through out the flight unless something out of the ordinary happens.

On landing some planes remind you to bring the throttle levers out of the detent by calling you a 'retard'.

I doubt the Cirrus does much of that, but have no experience. My only experience is with the FADEC itself.
 
Captain said:
After rotation you move the throttles back into another detent and climb power is set and maintained. There they sit through out the flight unless something out of the ordinary happens.
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You don't move them back in cruise? I do.
 
I don't believe the Cirrus has automatic mixture control, just a mechanical linkage that gives you different rpm settings based on throttle position. But I haven't flown one since the early models.
 
TMetzinger said:
I don't believe the Cirrus has automatic mixture control, just a mechanical linkage that gives you different rpm settings based on throttle position. But I haven't flown one since the early models.
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I don't fly the Cirrus much these days so I might not remember something. As far as I remember when you set the mixture to the full reach position it will mechanically compensate for the altitude. I don't know if it uses static ports or some other method but basically that's how it works.
 
Captain said:
: ) I find I get places quicker if I just cruise with climb power!


...yeah, I forgot a step.
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Ah got it. Was going to complain that my FADEC does not do that :).

I usually throttle down by 7% when I transition from climb to cruise in order to be "kind" to the engines.
 
Captain said:
FADEC: Fully Automatic Digital Engine Control.

You start the flight by putting the throttles into a detent and the plane takes off. After rotation you move the throttles back into another detent and climb power is set and maintained. There they sit through out the flight unless something out of the ordinary happens.

On landing some planes remind you to bring the throttle levers out of the detent by calling you a 'retard'.

I doubt the Cirrus does much of that, but have no experience. My only experience is with the FADEC itself.
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Sounds complicated. Much easier to just go to full throttle at takeoff and leave it there until you land.
 
darrell said:
What the hell?

FULL AUTHORITY not Fully Automatic.

Apologies in advance for being nitpicky, but FADEC is a lot more than just automatic.
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You are correct. It's been over half a decade since I've flown in a plane with it. Rust builds quick and my apologies. I'm going to bow right out of this thread as I've already screwed two things up!
 
spiderweb said:
I'm reading this SR20 POH carefully these days, and filling out the required workbook before the checkout flight(s).

The SR20 has a throttle and mixture, but it has a variable pitch prop.

Does this governor act the same way as in a FADEC aircraft (which would have no mixture lever), or is it somehow less sophisticated?

And also, would it have been better to give the pilot a blue lever?
Click to expand...

Not really FADEC. A cable on the throttle control is connected to the propeller governor. It really only affects cruise power settings. Below cruise, the prop stays in low pitch (high rpm). Above that position on the throttle control, the propeller RPM is variable between 2500 RPM and 2700 RPM (wide open throttle).

Sometimes I think a separate prop control would have been a whole lot easier but it is what it is.

MachFly said:
Even though the Cirrus has a Mixture leaver it is capable of auto-leaning. I'm not exactly sure how the whole system on the Cirrus works but as far as I know the mixture lever is just to give you more control authority.
Click to expand...

The SR20 has an altitude compensating fuel pump but still requires leaning.
 
HPNPilot1200 said:
The SR20 has an altitude compensating fuel pump but still requires leaning.
Click to expand...

When does it require leaning?

Most of my experience in it was at sea level and that was a while ago.


I know one who flies it out of a 5K airport and he never leans. Not sure how good of a pilot he is though.
 
MachFly said:
When does it require leaning?

Most of my experience in it was at sea level and that was a while ago.

I know one who flies it out of a 5K airport and he never leans. Not sure how good of a pilot he is though.
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I lean above 3000' MSL. It will run with the mixture full rich but you will burn a lot of gas that you don't need to and will foul the spark plugs easily. At 5000' MSL full rich will usually give you around 11.2 GPH in the SR20. Leaned out you will probably burn around 8.9 - 9.2 GPH with the mixture set LOP.
 
HPNPilot1200 said:
I lean above 3000' MSL. It will run with the mixture full rich but you will burn a lot of gas that you don't need to and will foul the spark plugs easily. At 5000' MSL full rich will usually give you around 11.2 GPH in the SR20. Leaned out you will probably burn around 8.9 - 9.2 GPH with the mixture set LOP.
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So it compensated only to 3K?

Interesting.
 
The altitude-compensating fuel pumps on Continentals maintain roughly the same air/fuel ratio regardless of altitude (so goes the theory). It will still give you that same full rich air/fuel ratio. If you want to run at a best power mixture, then you probably don't need to touch it much. If you want to run LOP, then you will need to touch it.

A standard Continental at full throttle, full rich will provide the same fuel flow for given lever positions, regardless of altitude. So, full throttle, full RPM, full rich on the IO-520-Es in the 310 I fly will produce ~23 gph. As I go up, my manifold pressure goes down, and the fuel flow will remain the same. Therefore my air/fuel ratio increases, gets richer, etc.

I don't keep up with the latest and greatest from the plastic airplane giant, but the Cirrus planes I've flown in don't have a FADEC in any way, shape, or form. They strictly use mechanical means to reduce the levers available to the pilot. Maybe that's why I don't like the Cirrus - I like levers! :)
 
The single power lever is one of my gripes on the cirrus planes. I like the ability to bring back the RPMs at full throttle, especially on a non turboed plane.
 
spiderweb said:
I'm reading this SR20 POH carefully these days, and filling out the required workbook before the checkout flight(s).

The SR20 has a throttle and mixture, but it has a variable pitch prop.

Does this governor act the same way as in a FADEC aircraft (which would have no mixture lever), or is it somehow less sophisticated?

And also, would it have been better to give the pilot a blue lever?
Click to expand...


Has nothing to do with FADEC, FADEC is a computer that gets rid of the mixture handle as well and the magnetos for digital electronic ignition control; automatically keeping everything tuned to best parameters for the power ask in real time multiple times a second. Cirrus is like Apple in that regard, they make you use what they want you to use for RPM/MP combination through a mechanical linkage combiner. For most people, like a Mac, it's a good thing because they don't understand what all the effects the prop handle actually has inside the engine relative to ICP event timing and detonation.
 
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Inverted said:
Why? Just curious.
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Greater efficiency. Lindbergh Doctrine from WWII: Maximum Manifold Pressure and minimum RPM for any given airspeed will provide you the greatest range. That and LOP and he basically doubled the effective combat radius of the P-40s in Burma flying under Chenault. The rest of the services caught up with that very quickly.
 
Henning,
Wasn't Cirrus the first manufacture to recommend LOP operations? So yes, the RPM's come back to about 2500, but you can stay WOT and do the big mixture pull to LOP with zero issues.

But I am no expert in this arena! Also, what is the most efficient Prop RPM?
 
jmp470 said:
Henning,
Wasn't Cirrus the first manufacture to recommend LOP operations? So yes, the RPM's come back to about 2500, but you can stay WOT and do the big mixture pull to LOP with zero issues.

But I am no expert in this arena! Also, what is the most efficient Prop RPM?
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The first person I recall reading recommending LOP was Charles Lindbergh, I think he and the AAC and US Navy training departments predate Cirrus by a couple of weeks at least.;)

The most efficient prop RPM will be the slowest one you can turn for your desired airspeed and not get the ICP event timed back into detonation.

The closer you can get to bottom green arc RPM while making your speed will be the most efficient. The closer to LD max you operate, the more efficient you will become.
 
Skylane81E said:
The single power lever is one of my gripes on the cirrus planes. I like the ability to bring back the RPMs at full throttle, especially on a non turboed plane.
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I prefer having more options on the MP/RPM combination as well. However it should be noted that the way the Cirrus is designed to work, full throttle exists between something like 2500-2700 RPM. I forget the exact range.

jmp470 said:
Henning,
Wasn't Cirrus the first manufacture to recommend LOP operations? So yes, the RPM's come back to about 2500, but you can stay WOT and do the big mixture pull to LOP with zero issues.
Click to expand...

Many people prior to Cirrus recommended LOP operations. In fact, it's interesting to look back in some Navajo manuals which even allow it. The issue was that, prior to the advent of detailed instrumentation, it tended to have more issues that were difficult to diagnose and poorly understood. This made LOP operation more difficult from a practical perspective.

But I am no expert in this arena! Also, what is the most efficient Prop RPM?
Click to expand...
This is going to vary on the engine/prop combination. Typically, I'll operate at 2200-2300 RPM for efficiency, 2300-2500 RPM for power.

Keep in mind that certain MP/RPM combinations won't be permitted by the manufacturer. Make sure to avoid those - they're forbidden areas for good reasons.
 
Inverted said:
Why? Just curious.
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Because as I have nothing to boost up my MP I can set it by adjusting my altitude.

If I want 22 inhg I can throttle back OR climb to the neighborhood of 7000ft. There I get the least drag possible while still maintaining desired engine performance. The engine doesn't care HOW you set the power, just that you set it. 22 squared is 22 squared regardless of how I set it up. Might as well let the plane true out while I'm at it.
 
Ted DuPuis said:
I prefer having more options on the MP/RPM combination as well. However it should be noted that the way the Cirrus is designed to work, full throttle exists between something like 2500-2700 RPM. I forget the exact range.
Click to expand...

I've noted that while the amount of throttle reduction is smaller, it is still there when you pull back the prop the MP goes down in the cirrus I've flown. Where as in my plane it goes up slightly do to the reduction in pumping.
 
What's the point of having an "automatic" prop control? I can understand if everything was one-lever FADEC, but if not, isn't it better to allow the pilot to control it?
 
spiderweb said:
What's the point of having an "automatic" prop control? I can understand if everything was one-lever FADEC, but if not, isn't it better to allow the pilot to control it?
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Maybe, maybe not, if the pilot doesn't understand how to combine them correctly, he has the potential for doing damage. Cirrus is all about adding features and elements to keep people from learning how not to kill themselves.
 
Henning said:
Maybe, maybe not, if the pilot doesn't understand how to combine them correctly, he has the potential for doing damage. Cirrus is all about adding features and elements to keep people from learning how not to kill themselves.
Click to expand...

How does the governor know when to hold MP or RPM to a certain value? Looking at the POH, it seems it is mostly a mechanical process (not so much computer).
 
spiderweb said:
How does the governor know when to hold MP or RPM to a certain value? Looking at the POH, it seems it is mostly a mechanical process (not so much computer).
Click to expand...

All mechanical, controls are mixed mechanically pull lever back and the prop comes back as well as the throttle in ratios speced by Cirrus.
 
Skylane81E said:
All mechanical, controls are mixed mechanically pull lever back and the prop comes back as well as the throttle in ratios speced by Cirrus.
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I see. I wonder what the testing on that was. Or, was it just something they plugged into a computer to get the best numbers for that ratio.
 
spiderweb said:
I see. I wonder what the testing on that was. Or, was it just something they plugged into a computer to get the best numbers for that ratio.
Click to expand...

It had to do with the manifold pressure and RPM combinations they needed to get the performance they wanted.

From there, the mechanical linkage was pretty simple.
 
spiderweb said:
How does the governor know when to hold MP or RPM to a certain value? Looking at the POH, it seems it is mostly a mechanical process (not so much computer).
Click to expand...

Simple, known safe operating values for the conditions. They know as long as they stay above 2500 rpm (conservative number) they will not run into a detonation event. They aren't all that incorrect really, but I wish they would bring it back to 24" 2200 for a pulled back 'econo cruise' run hard LOP.
 
Captain said:
FADEC: Fully Automatic Digital Engine Control.

You start the flight by putting the throttles into a detent and the plane takes off. After rotation you move the throttles back into another detent and climb power is set and maintained. There they sit through out the flight unless something out of the ordinary happens.

On landing some planes remind you to bring the throttle levers out of the detent by calling you a 'retard'.

I doubt the Cirrus does much of that, but have no experience. My only experience is with the FADEC itself.
Click to expand...


Full authority means the computer controls every function of the engine.

What you talk about is digital auto throttle. Many new small jets have FADEC without auto throttle.
 
Henning said:
Simple, known safe operating values for the conditions. They know as long as they stay above 2500 rpm (conservative number) they will not run into a detonation event. They aren't all that incorrect really, but I wish they would bring it back to 24" 2200 for a pulled back 'econo cruise' run hard LOP.
Click to expand...

OK so now I wonder what the loss in cruise would be if they used a fixed pitch prop. Not that I want them to do that!

I mean, we're pilots! We like to have lots of levers and buttons that need constant attention to maintain perfect flying conditions!
 
Pilots don't like it or else some other company would have sold 5500 planes over the past decade! While, it might not be everyone cup of tea, it works just fine. I was hoping, as I'm sure others were to that someone would have built a FADEC engine for Cirrus. Thus, only having one lever.
 
jmp470 said:
Pilots don't like it or else some other company would have sold 5500 planes over the past decade! While, it might not be everyone cup of tea, it works just fine. I was hoping, as I'm sure others were to that someone would have built a FADEC engine for Cirrus. Thus, only having one lever.
Click to expand...

OK, see there it is. My thought is this: either give me control of those things that have traditionally been in the pilot's control; or just go FADEC, and let me feel super-cool flying my starship with just one lever!
 
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