Aspen Pro EDF 1000 Altitude/VS Preselect

[Pinecone]

33 minutes ago, LANCECASPER said:

The manual below, page 2-9 gives you the connection between the KAS-297B and the KEA-130A altimeter.

https://www.dropbox.com/s/6kq5oy5g8l8hoz6/KAS-297B-INSTALL-MANUAL.pdf?dl=0

You won't find a KAS-297B that wasn't originally without a KEA-130A in a Mooney. I've had 7 Mooneys and four of them have had this combo. @larryb worked his electronic magic and figured out a circuit to provide this in his Aspen installation.

The only Mooney I owned w/o alt pre-select had a KFC-200, so no KEA-130A and I also had an Ovation with a KFC-225, which has alt pre-selected built into the box, but still needed the KEA-130A. The one I have now has the GFC-700 which is the only autopilot I've ever flown with Baro corrrection in level flight.

OK, that is good.

So you are saying that the KAS-297B only gets a correction for baro setting upon level off?  Then it holds the baro pressure altitude?

[LANCECASPER]

3 hours ago, Pinecone said:

OK, that is good.

So you are saying that the KAS-297B only gets a correction for baro setting upon level off?  Then it holds the baro pressure altitude?

Nope, you're overthinking this. These autopilots are not that sophisticated. 

Let's say you are climbing to a pre-selected altitude of 10,000 feet.  Whatever the baro setting is on your altimeter that corresponds to 10,000 feet sends gray code* to your KAS-297B telling it to stop when it reaches the gray code equivalent of 10,000 feet - it actually captures it a little sooner and levels off at 10,000. Now you are level and flying along.

Five minutes later ATC gives you a new baro setting, you put that new setting in the KEA130A and notice that now you only show 9800 feet. The autopilot does nothing when you've put in your new baro setting - it's not supposed to - you'll have to use one of the three methods we've mentioned to get back to 10,000 feet: 

(1) VS of say 200 feet per minute and 10,000 ALT ARMing (which probably isn't worth it for 200 feet) or

(2) push ALT to take it off of altitude hold and hit the UP rocker to climb to 10000 feet and then hit ALT again (what I usually did) or

(3) hold CWS and get back to 10000 feet and release CWS (best choice in this scenario - what @kortopates recommended).

 

*https://www.allaboutcircuits.com/technical-articles/gray-code-basics/

[carusoam]

16 hours ago, Fly Boomer said:

1.  Sounds like you don't have a KAS-297b?

2.  Why is the KEA-130a Encoding Altimeter required if a pitot line is required

I've been trying to diagram the whole system with all the interconnections.

1) Right, I don’t have the KAS297b… one day… (or some other version made by big G)

2) BK used to have their brochures and manuals on line…. And showed the direction of data flow between all of the devices…. Somewhat centered around the HSI….

This made it obvious how interconnected everything was…. And how locked into replacing with BK stuff you will be…

It is more of a single system with a few options… than a six pack of different devices….

 

Two improvements I wanted to see after flying it IFR for a couple of years…

1) GPSS… to minimize waypoint anxiety… pushing the next way point button on time….

2) Altitude set… to minimize altitude anxiety… pushing the alt hold button on time….

I never missed any of these… but it doesn’t take more than a small distraction to allow it to occur….  

Best regards,

-a-

 

[Fly Boomer]

5 hours ago, carusoam said:

1) GPSS… to minimize waypoint anxiety… pushing the next way point button on time….

2) Altitude set… to minimize altitude anxiety… pushing the alt hold button on time….

I'm sure you have looked into it far enough to know that major players are the DAC International GDC-31, Icarus SAM, and S-Tec ST-901.  And with that last sentence, I told you everything I know -- not sure what works with what, or who is out of business.  Also, both the altitude preselect and Vertical Speed are nice, but I think it's like a turbo or TKS -- you don't miss what you never had.

That said, the more likely path now is Garmin.  Other than a lot of servo problems, and installation problems, and configuration problems, are there any downsides to the GFC-500 from an operational perspective?

[Pinecone]

On 9/5/2022 at 3:24 PM, LANCECASPER said:

Nope, you're overthinking this. These autopilots are not that sophisticated. 

Let's say you are climbing to a pre-selected altitude of 10,000 feet.  Whatever the baro setting is on your altimeter that corresponds to 10,000 feet sends gray code* to your KAS-297B telling it to stop when it reaches the gray code equivalent of 10,000 feet - it actually captures it a little sooner and levels off at 10,000. Now you are level and flying along.

Five minutes later ATC gives you a new baro setting, you put that new setting in the KEA130A and notice that now you only show 9800 feet. The autopilot does nothing when you've put in your new baro setting - it's not supposed to - you'll have to use one of the three methods we've mentioned to get back to 10,000 feet: 

(1) VS of say 200 feet per minute and 10,000 ALT ARMing (which probably isn't worth it for 200 feet) or

(2) push ALT to take it off of altitude hold and hit the UP rocker to climb to 10000 feet and then hit ALT again (what I usually did) or

(3) hold CWS and get back to 10000 feet and release CWS (best choice in this scenario - what @kortopates recommended).

 

*https://www.allaboutcircuits.com/technical-articles/gray-code-basics/

 

But the 297 needs to get some signal that says that with the current baro setting, THIS is 10,000 feet.

Why they would not use this to correct for a new baro setting makes NO sense at all.

[LANCECASPER]

12 hours ago, Pinecone said:

 

But the 297 needs to get some signal that says that with the current baro setting, THIS is 10,000 feet.

Why they would not use this to correct for a new baro setting makes NO sense at all.

It makes perfect sense when you realize when this autopilot, the KFC150, was introduced 40 some years ago no GA autopilot had that feature. You are the only person I’ve ever heard that is surprised or disappointed by this. It was cutting edge when it came out. There are a lot of features that automobiles have today that they didn’t have in the late 70’s/early 80’s. If you had cruise control then it was a great feature. But a resume feature, probably not. Distance measuring cruise control to keep you a pre-set distance from the car in front of you, nope.

To my knowledge the first GA autopilot that had the baro correct feature was the GFC700 that came in around 2006.

[Pinecone]

As an engineer, it makes no sense.

You sense the baro corrected altitude to capture the set altitude, then ignore it.  BIZARRE

[LANCECASPER]

5 hours ago, Pinecone said:

As an engineer, it makes no sense.

You sense the baro corrected altitude to capture the set altitude, then ignore it.  BIZARRE

Thank you for identifying the problem. If being an engineer or doctor or basketweaver or whatever,  defines who you are, I pity those who have to deal with you on a daily basis. 

Seriously though this type of behavior where you refuse to accept the things you can't change and fight everyone on the answers that they give you, is what gets others to hit the ignore button on Mooneyspace. You finally realize after trying to help, that you are fighting a losing battle. 

[Pinecone]

I accept that it works this way.

But I wonder WHY it does.

You seem to be perfectly accepting of poor design, just because that is the way it it.  

Luckily there are people like me that move things along so they get better and better.  If you were in charge, we would be sitting upright, in the wind in a pusher, canard aircraft.

 

[LANCECASPER]

13 hours ago, Pinecone said:

I accept that it works this way.

But I wonder WHY it does.

You seem to be perfectly accepting of poor design, just because that is the way it it.  

Luckily there are people like me that move things along so they get better and better.  If you were in charge, we would be sitting upright, in the wind in a pusher, canard aircraft.

 

Had you raised this question in 1980 when the KFC150 was introduced and then showed those inept engineers at Benidx King who had just developed the world’s first digital autopilot for General Aviation your brilliance, they would have looked at you with admiration and perhaps even have kissed your feet for your remarkable wisdom.

To now raise the question nearly a half century later shows how completely out of touch you are with what was available back then in GA.

[Will.iam]

17 hours ago, Pinecone said:

I accept that it works this way.

But I wonder WHY it does.

You seem to be perfectly accepting of poor design, just because that is the way it it.  

Luckily there are people like me that move things along so they get better and better.  If you were in charge, we would be sitting upright, in the wind in a pusher, canard aircraft.

 

It works this way because of stability. Every aircraft i have flown works this way. If the gfc-700 auto corrects then how do you set your local field altimeter when you are above fl180 with out the autopilot diving or climbing? Could you imagine the airlines when you flipped the altimeter out of standard to set a local altimeter of 30.55 or 28.35 and autopilot started rapidly trying to goto the new altitude? That is why once the autopilot captures the altitude it holds that pressure altitude. Even the brand new jets just coming off the assembly line work this way. It’s a feature not a problem. They intentionally designed it that way to give flexibility to adjust the baro without the autopilot going crazy. Now during a climb or descent messing with the baro WILL effect the autopilot and causes it to either shalow out or steepen the profile as it adjusts to the new baro setting.  

[Pinecone]

Interesting.

My time in the FLs was without an autopilot (T-37 and T-38).  We just didn't reset the altimeter until hitting 180.

So I can see the thinking for some aircraft.  I guess the idea was make them all work the same, even though the market for the KAP was more for aircraft that spent their time at lower altitudes.

[alextstone]

4 hours ago, Pinecone said:

Interesting.

My time in the FLs was without an autopilot (T-37 and T-38).  We just didn't reset the altimeter until hitting 180.

So I can see the thinking for some aircraft.  I guess the idea was make them all work the same, even though the market for the KAP was more for aircraft that spent their time at lower altitudes.

Way to go, Pinecone.  You've managed to drop that you are an engineer and an ex military jet pilot.  Bravo.  

[Pinecone]

I can drop all sorts of other things.

I mentioned those things to give people an idea of where I was coming from.

[LANCECASPER]

30 minutes ago, Pinecone said:

I can drop all sorts of other things.

And I’m sure you will . . Lol

[carusoam]

It is great to get to know everybody and their various backgrounds…

The stronger the background… the more ribbing is involved for some reason… 

 

MSers can have strange senses of humor…. Combined with lousy typing skills…

 

Mom always reminds us…

Be nice to everyone!

Best regards,

-a-