Altitude Indicator setting

[MooneyBob]

Here's one stupid rookie question:

I am about to start my IR lessons.

What is the best way to reset ( or whatever you call it) the altitude indicator for a level flight?

When should I move the miniature plane to the horizon bar? Is the plane on the level ground in the same attitude as it is in a cruise level flight?

Bob

[Rwsavory]

I adjust it during level flight if necessary.  Mostly I just leave it alone.

[Bob - S50]

Here's one stupid rookie question:

I am about to start my IR lessons.

What is the best way to reset ( or whatever you call it) the altitude indicator for a level flight?

When should I move the miniature plane to the horizon bar? Is the plane on the level ground in the same attitude as it is in a cruise level flight?

Bob

I personally would not mess with the pitch setting.  On any given flight the pitch of the plane for level flight will change with any change in airspeed or configuration.  Given enough fuel burn, it will even change due to weight.  If you adjust it for one speed/configuration, it will just be off later.

 

Develop a good cross check and trim, trim, trim.

 

Best of luck and have fun.

 

Bob

[MooneyBob]

I personally would not mess with the pitch setting. On any given flight the pitch of the plane for level flight will change with any change in airspeed or configuration. Given enough fuel burn, it will even change due to weight. If you adjust it for one speed/configuration, it will just be off later.

Develop a good cross check and trim, trim, trim.

Best of luck and have fun.

Bob

I wouldn't play with it at all once I set it up. But how can I set it up to proper position? Specially when the pitch of the level flight changes under different conditions. That's what I meant by my original question.

[Marauder]

I personally found it close to impossible to make a meaningful adjustment of my mechanical AI while flying. I do like the way the Aspen AI works. Much more indication of pitch change, making it easier to be more precise.

[MooneyBob]

I personally found it close to impossible to make a meaningful adjustment of my mechanical AI while flying. I do like the way the Aspen AI works. Much more indication of pitch change, making it easier to be more precise.

How the Aspen determines when the plane is in level attitude?

[Hank]

Set on the ground, takeoff, readjust when level (VSI = 0, altimeter steady). Then you're good in the clouds / under the hood.

[Marauder]

How the Aspen determines when the plane is in level attitude?

It uses an AHRS system.

[jetdriven]

Here's one stupid rookie question:

I am about to start my IR lessons.

What is the best way to reset ( or whatever you call it) the altitude indicator for a level flight?

When should I move the miniature plane to the horizon bar? Is the plane on the level ground in the same attitude as it is in a cruise level flight?

Bob

Set it to zero degrees at 75% cruise and leave it there. It will likely indicate +2 to +3 degrees nose up on the ground.

[MooneyBob]

It uses an AHRS system.

But it had to be calibrated at some point during the installation, right?

[Marauder]

But it had to be calibrated at some point during the installation, right?

This kind of gives you a layman's view of the calibration for an AHRS system

http://www.ti.com/lit/an/slaa518a/slaa518a.pdf

I did not ask my installer specifically, but I know they did do some work on calibrating the system at installation.

Sent using Tapatalk

[MooneyBob]

I see. This is easy one as they actually calibrate the AHRS itself on the flat level surface. It is calibrated before the installation in the plane. Make perfect sense. So the best and most precise way to figure out my AI level setting would be to have it on the bench, level it off, set it up and then put it back to the panel.

 

Thanks.

[Bob - S50]

I wouldn't play with it at all once I set it up. But how can I set it up to proper position? Specially when the pitch of the level flight changes under different conditions. That's what I meant by my original question.

The plane sits nose high on the ground.  Pick some pitch attitude, say maybe 3 to 5 degrees nose high and set it before you take off.  Then don't mess with it the rest of the flight.  See how you like it.  If you don't like it, use something different the next time.

 

Once airborne, it doesn't really matter what pitch the attitude indicator shows for level flight.  You aren't really at 0 degrees pitch for level flight anyway.  The only time knowing what pitch indication to use for level flight is handy, is for setting an initial pitch attitude if you lose your airspeed indicator.  In that case you'll use known pitch and power indications.

 

For IMC flying you'll set a pitch attitude (with the yoke, not the adjustment knob) then check the performance instruments (airspeed, altimeter, VSI, and HSI or DG).  If they are not showing what you want, go back to the attitude indicator, look at what it shows, and make an adjustment.  Trim if need be.  So if you want level flight but your altimeter shows a descent and your VSI shows 200 fpm descent, go back to the attitude indicator.  Whatever it shows, whether that be 5 degrees nose down, level, 2 degrees nose up, it doesn't matter; raise it up a degree or so, then go back and check the performance instruments again.... and don't forget to trim, trim, trim so the nose doesn't fall again.

 

Here's a rule of thumb for you too.  Since 1 degree of pitch equates to 100'/nm, if you'll take your TAS in nm/minute times 100, that is about the VSI change you'll get from a 1 degree pitch change.  For example, if I'm cruising at 150 KTAS, that's 2.5 nm/minute.  Multiply by 100 gives me 250.  So as a rough starting point a 1 degree pitch change will result in about a 250 fpm change on the VSI.  It won't be perfect but it should put you in the ballpark, then crosscheck your performance instruments and continue making fine adjustments.  Did I mention trim, trim, trim?

 

By the way, you can use the same rule of thumb through different logic to get a rough guess of how much crosswind you are fighting.  Again, if I'm flying 2.5 nm/minute, every 1 degree of crosswind correction will cancel out about 2.5 knots of crosswind.  So if I'm having to fly with a 6 degree crab to stay on course, there is probably about a 15 knot crosswind component.

 

Have fun,

 

Bob

[Marauder]

Here are a couple of pictures of my Aspen on the ground and in flight - no adjustments made.

Sent using Tapatalk

[carusoam]

Mechanical dials allow for parallax. In a rented plane, different pilots set the instrument differently based on the individual's sitting height.

If you are the only pilot, you will probably set it once and don't change it until your sitting height changes?

-or-

You like to be precise with a non precision tool. Set the horizon several times during a flight. The tool is precise but to be able to read it with precision is the challenge... Reminds me of an old school thermometer.

Setting it on the ground sounds ideal, but Chris has pointed out the flaw with that.

Setting 1 deg of climb is quite a challenge while bumping around on a choppy day.

Trying to use this tool to level off after the climb? (Uses many brain cells, procedures, memory and practice)

-or-

Hit the magic alt hold button as you reach altitude. The overshoot is minimal compared to hand flying.

Maybe I made some assumptions...?

Best regards,

-a-

[Cruiser]

from KMC PUBLICATION NO. 1403 

RCA 26 SERIES

ATTITUDE GYRO

INSTALLATION/OPERATION GUIDE..............

 

SYMBOLIC AIRPLANE ADJUST

 Adjusts the Symbolic Airplane to compensate for viewing parallax. Adjust Symbolic Airplane so that it is visually aligned with 

the horizon from pilot’s normal sitting position.

 

3.1 PRE-FLIGHT PROCEDURES - Adjust the “Symbolic Airplane” to visually align the “wings” with the horizon line. This adjustment compensates for viewing parallax error (pilot’s viewing angle)

 

3.2 IN-FLIGHT PROCEDURES - You may also adjust the Symbolic Airplane indicator at any time.

....................................................................................................

This parallax adjustment is for viewing purposes only. It does not change anything other than the sight line of the pilot in different seat positions or different pilot heights. (Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight,)

[Hank]

1. Set attitude indicator to level on the ground.
2. Take off and climb to altitude.
3. Level off, accelerate, set power.
4. Reset attitude indicator, since cruise attitude will vary with load, speed and CG. Takes three seconds and one brain cell; in IMC, it takes three seconds and four brain cells.

[MooneyBob]

It looks like I am overthinking the issue. I just wanted to make sure that if my power and attitude setting in IMC are for a level flight it is really a level flight. I guess it comes naturally with the experience and cross checking of other instruments.

[Marauder]

Don't worry Bob... You and your attitude indicator will learn to love each other when you go through your IFR training. You will also find out how little you actually know about power settings. I had my Mooney for about a year before I started IFR training. Just understanding what power settings yielded what speeds was worth it...

[carusoam]

Consider the MAPA training. The book comes with a page of power and other settings that is very valuable. You will spend enough time verifying the MAPA data instead of creating it on you own...

You get to meet some incredible pilots this way too.

Best regards,

-a-

[MooneyBob]

Consider the MAPA training. The book comes with a page of power and other settings that is very valuable. You will spend enough time verifying the MAPA data instead of creating it on you own...

You get to meet some incredible pilots this way too.

Best regards,

-a-

I have the MAPA power setting chart printed out and ready to use for my first lesson which is on Thursday.

I have alternated it in Excel and have prepared blank fields to fill my own data if they differ from the MAPA ones. That's my goal for few first lessons.

Thanks.

[carusoam]

How's your memory?

I heard it's the first thing that....

sometimes I make myself chuckle...

Best regards,

-a-