Kinda FADEC?

Ted DuPuis said:
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.
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Uhh, fuel-injected Continentals, you mean. ;)

I gotta move my big red handle. I have the best 1950's aluminum farm tractor technology that,one could buy 25 years later in 1975. ;)
 
spiderweb said:
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!
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Fixed pitch prop would be a big loss in performance.
 
Ted DuPuis said:
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.
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I see
 
The ol' Skyhawk will make 2450 at 16,5 - does that mean that is where it is most efficient? (2450 is the power setting for cruise I like)
 
n20junkie said:
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.
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Nope, he's talking about a simple mechanical cam alignment linkage, nothing more.
 
The Cirrus is pseudo-fadec

I sat in an 09' SR22 with a cirrus instructor and he explained the systems to me. If it has a single throttle and a mixture, the mixture works like it normally would. The throttle is connected to the prop control via a linkage. The prop speed is set via throttle position. When you move the throttle through its range of travel, you can feel areas with increased resistance (little like a detent), and when passing through these areas the prop RPM is changed.

For leaning, the newer models engine monitoring software shows the settings for best power and economy cruise, you lean until the computer says you are within the parameters for either.

And the "go around" button on the throttle sure is nice. Tells the garmin that you are going missed, and sets the flight director thingy to 7degrees pitch up (the newer ones will do this on autopilot)
 
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dell30rb said:
The Cirrus is pseudo-fadec

I sat in an 09' SR22 with a cirrus instructor and he explained the systems to me. If it has a single throttle and a mixture, the mixture works like it normally would. The throttle is connected to the prop control via a linkage. The prop speed is set via throttle position. When you move the throttle through its range of travel, you can feel areas with increased resistance (little like a detent), and when passing through these areas the prop RPM is changed.

For leaning, the newer models engine monitoring software shows the settings for best power and economy cruise, you lean until the computer says you are within the parameters for either.

And the "go around" button on the throttle sure is nice. Tells the garmin that you are going missed, and sets the flight director thingy to 7degrees pitch up (the newer ones will do this on autopilot)
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I'm really looking forward to that last feature!
 
dell30rb said:
The Cirrus is pseudo-fadec
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Well, it's really not a FADEC, or anything close to it. All it really does is have the computer tell you when you've got the numbers that previously you had to look in a book to tell you.

There's no computer control of the engine. None.

And the "go around" button on the throttle sure is nice. Tells the garmin that you are going missed, and sets the flight director thingy to 7degrees pitch up (the newer ones will do this on autopilot)
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Should be noted, this is a standard feature on most flight directors and has been around for decades. It's just been a more recent development to see flight directors in smaller aircraft.
 
spiderweb said:
I'm really looking forward to that last feature!
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I don't find it to be as useful as it sounds, but then again I tend to not use flight directors even when installed.
 
Ted DuPuis said:
Well, it's really not a FADEC, or anything close to it. All it really does is have the computer tell you when you've got the numbers that previously you had to look in a book to tell you.

There's no computer control of the engine. None.



Should be noted, this is a standard feature on most flight directors and has been around for decades. It's just been a more recent development to see flight directors in smaller aircraft.
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Indeed our 79 Navajo has the same.
 
Skylane81E said:
Indeed our 79 Navajo has the same.
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None of the Navajos I fly have a flight director, but 79 is newer than the ones I fly. I think somewhere around that time they changed to one of the KFC series autopilots instead of the Century, and the KFCs have a flight director built-in.
 
dell30rb said:
The Cirrus is pseudo-fadec

I sat in an 09' SR22 with a cirrus instructor and he explained the systems to me. If it has a single throttle and a mixture, the mixture works like it normally would. The throttle is connected to the prop control via a linkage. The prop speed is set via throttle position. When you move the throttle through its range of travel, you can feel areas with increased resistance (little like a detent), and when passing through these areas the prop RPM is changed.

For leaning, the newer models engine monitoring software shows the settings for best power and economy cruise, you lean until the computer says you are within the parameters for either.

And the "go around" button on the throttle sure is nice. Tells the garmin that you are going missed, and sets the flight director thingy to 7degrees pitch up (the newer ones will do this on autopilot)
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Please see my post. Nothing you mentioned is remotely close to FADEC.
 
n20junkie said:
Please see my post. Nothing you mentioned is remotely close to FADEC.
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He said pseudo, and pseudo it is. It's half the system (well, most of it), the information half. The action half is missing and replaced by a human.
 
The throttle/pitch lever on a Cirrus is such that the throttle is physically full open down to 2500 RPM. At that point the throttle starts closing. Cirrus adopted the system but it was designed by Continental prior to Cirrus.

At least one FADEC Cirrus is flying although prop control is still mechanical through the throttle lever. I have heard the problems are, cost, weight and complexity.
 
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Henning said:
He said pseudo, and pseudo it is. It's half the system (well, most of it), the information half. The action half is missing and replaced by a human.
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...which makes it not a FADEC any more than a JPI. Only difference is it keeps some of these values pre-programed in.

peppy said:
At least one FADEC Cirrus is flying although prop control is still mechanical through the throttle lever. I have heard the problems are, cost, weight and complexity.
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This is typically the problems with FADECs. It's a new technology for the piston world. Since an off-the-shelf system can't be easily adapted (primarily due to certification reasons), one must be developed from scratch. This drives up the cost. To get the features in that are necessary once you take control of the red knob away from the pilot, it ends up being complex, and that adds weight.

People are looking for something without a weight, cost, or reliability penalty. Gen 1 will simply not be that way. Gen 2, 3, etc. may.
 
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