INS Coordinates COLD-HOT Start Up

[Esac_mirmidon]

I´ve a question about the INS and the difference between a cold or a hot startup.

 

When i enter a cold M-2000C my own L/L coordinates position is wrong by default. I must edit the 00 WP using the F10 map view to the correct ones, then align the INS and then my Flight Plan is correct. But if i dont edit my Init Position then the entire Flight Plan is incorrect and all the WP are missaligned.

 

If i enter a HOT M-2000C, all running, then my Init Position L/L coordinates are correct and the Flight Plan WPs are also correct with the normal deviation you can expect.

 

This is the normal functionality of the M-2000C or i´m doing somethinkg wrong?

 

Because i´ve not found anything about editing my initial position as a must for every cold start mission.

[Zeus67]

I´ve a question about the INS and the difference between a cold or a hot startup.

 

When i enter a cold M-2000C my own L/L coordinates position is wrong by default. I must edit the 00 WP using the F10 map view to the correct ones, then align the INS and then my Flight Plan is correct. But if i dont edit my Init Position then the entire Flight Plan is incorrect and all the WP are missaligned.

 

If i enter a HOT M-2000C, all running, then my Init Position L/L coordinates are correct and the Flight Plan WPs are also correct with the normal deviation you can expect.

 

This is the normal functionality of the M-2000C or i´m doing somethinkg wrong?

 

Because i´ve not found anything about editing my initial position as a must for every cold start mission.

 

By default you must align the INS every time you start a mission in the ramp (aircraft COLD). If you don't there is an error bias that will skew the INS navigation.

 

If you start a mission either in the runway or in the air (aircraft HOT), it is assumed that you have already performed the INS alignment. The error bias is 0.0 so INS navigation is exact.

 

There is a Special Options that allows you to start a mission in the ramp with the INS aligned. Select "INS is always aligned" and you won't need to do an INS alignment on mission start.

 

But there is a caveat. A mission builder can override this setting forcing you to do an alignment when starting cold and dark. This option was requested by several MP server masters, so if you want to enter into a MP ask if you will need to do an alignment.

[Esac_mirmidon]

That´s not my point.

 

It´s my fault not mention it before. I´m talking about a cold start WITH a complete INS alignment.

 

Steps:

 

1.- Batery ON

2.- INS in Align Mode-Status Mode.

3.- VAL button and wait for the full alignment completed.

4.- Checking my L/L coordinates AFTER the process: They are wrong AFTER the full alignment. So my Flight Plan is missaligned.

 

If i set the M-2000C Hot on the parking then my initial L/L position is correct and the Flight Plan is Ok.

 

If i repeat the same process from a cold start but BEFORE running the alignment process i edit the OO initial position and then press VAL to run the alignment, then when is complete all L/L coordinates are the correct ones.

[Zeus67]

If i repeat the same process from a cold start but BEFORE running the alignment process i edit the OO initial position and then press VAL to run the alignment, then when is complete all L/L coordinates are the correct ones.

 

That is how you do an INS alignment.

 

FIRST you enter your initial position and THEN you run the alignment process.

 

The process is detailed in the manual.

[Esac_mirmidon]

Thanks Zeus67.

 

It makes sense. Maybe my manual version is not the most updated one or i miss this part.

 

Sorry for taking your time answering that.

[Zeus67]

Thanks Zeus67.

 

It makes sense. Maybe my manual version is not the most updated one or i miss this part.

 

Sorry for taking your time answering that.

 

No problem. I'm glad to be of help. I apologize if the emphasis came a bit too strong but I wanted to make sure that it was clear for everybody the order of the steps for the INS alignment process.

[zaelu]

So the small random error in 00 Latitude/Longitude coordinates we have at each cold start that before alignment we need to check them and correct them is intended, right?

[Zeus67]

So the small random error in 00 Latitude/Longitude coordinates we have at each cold start that before alignment we need to check them and correct them is intended, right?

 

Yes.

[zaelu]

Yes.

 

Now is clear :thumbup: Thanks!

[zaelu]

I know but... :)

[Frederf]

That is how you do an INS alignment.

 

FIRST you enter your initial position and THEN you run the alignment process.

 

The process is detailed in the manual.

 

I found that is often more practical to do it in the reverse order. I align and then taxi to a known point on the airfield and type in that location into the 00 PREP. That way I only have to know one or two spots on the field instead of the values for every parking spot (and also knowing which spot I'm in). The initial value is plenty accurate to gyrocompass the heading.

[Zeus67]

I found that is often more practical to do it in the reverse order. I align and then taxi to a known point on the airfield and type in that location into the 00 PREP. That way I only have to know one or two spots on the field instead of the values for every parking spot (and also knowing which spot I'm in). The initial value is plenty accurate to gyrocompass the heading.

 

There is no need to memorize the coordinates for each parking spot. All you have to do is press F2 and you can read current position in the status bar.

[zaelu]

I found that is often more practical to do it in the reverse order. I align and then taxi to a known point on the airfield and type in that location into the 00 PREP. That way I only have to know one or two spots on the field instead of the values for every parking spot (and also knowing which spot I'm in). The initial value is plenty accurate to gyrocompass the heading.

 

But first coordinates are always wrong... wouldn't your alignment be off then?

[baltic_dragon]

In real life parking spot coordinates are well known and these are used for alignment. Whether you get them as part of mission briefing (as you will in the campaign) or you use F2 or F10 to obtain them is pretty realistic. Even fast alignment in jet which has not been moved since shut down will not provide you with best accuracy (as for INS not only starting coordinates are important, but even more so proper alignment of all gyros and other parts of the system).

[Frederf]

There is no need to memorize the coordinates for each parking spot. All you have to do is press F2 and you can read current position in the status bar.

You can't if external views are disabled.

 

But first coordinates are always wrong... wouldn't your alignment be off then?

There would be a misalignment between INS assumed position and true position for the brief taxi to the registration point. The other aspects about the alignment: attitude, velocities, heading would be correct. So you taxi 1000m to the registration point, bring up the L/L PREP 00 (which contains the wrong assumed position) and type in what you know the correct position to be.

 

It's essentially a pre-takeoff "rollover" flyover INS update. Presumably the INS would also detect that velocities are below a threshold and this update would also be a zero-velocity update.

[zaelu]

You can't if external views are disabled.

 

The F10 map is almost always available and you can work your position on the airport by looking outside from inside the cockpit. You can also press LCtrl+F10 iirc and the map will show locked on your actual position... you need just to zoom in.

 

 

There would be a misalignment between INS assumed position and true position for the brief taxi to the registration point. The other aspects about the alignment: attitude, velocities, heading would be correct. So you taxi 1000m to the registration point, bring up the L/L PREP 00 (which contains the wrong assumed position) and type in what you know the correct position to be.

 

It's essentially a pre-takeoff "rollover" flyover INS update. Presumably the INS would also detect that velocities are below a threshold and this update would also be a zero-velocity update.

 

Sounds a lot more complicated than doing it during the ramp start. I for example didn't understood what you are doing exactly :D .

 

Me:

 

I connect the plane to ground power

Battery on

INS PSM in StandBy

check coordinates on F10

Enter them in PCN

Switch PSM to Align

Validate on PCN

Switch PSM to STS to see if I have time to move the laundry from washing machine to dryer :D

 

Continue with start up. At the end of 8 minutes PSM back to N and NAV

 

Simple :)

[Esac_mirmidon]

Same process here.

[baltic_dragon]

 

Me:

 

I connect the plane to ground power

Battery on

INS PSM in StandBy

check coordinates on F10

Enter them in PCN

Switch PSM to Align

Validate on PCN

Switch PSM to STS to see if I have time to move the laundry from washing machine to dryer :D

 

Continue with start up. At the end of 8 minutes PSM back to N and NAV

 

Simple :)

 

And correct :) AFAIK in real life pilots would wait for full alignment before turning on the engines (the INS gyros are very sensitive). So they have 8 minutes to get out of the pit and run to the base laundry :D

[Azrayen]

So they have 8 minutes to get out of the pit and run to the base laundry :D

 

:thumbsup:

 

More seriously, they make their pre-flight inspection, then strap-in.

1/ climb into the aircraft, launch the ALN

2/ climb out, preflight inspection

3/ climb in again, strap in

4/ continue before start-up check list

5/ start-up check list

 

:)

[ZHeN]

Battery on

dude you're wasting your battery ! ;)

[kobeshow]

dude you're wasting your battery ! ;)

small detail, but if you don't activate the battery before spooling up the engines, the radios won't work on groundpower alone.

[ZHeN]

yea, we discussed this some time before

[Azrayen]

dude you're wasting your battery ! ;)

No.

That's called adhering to SOPs.:smartass:

 

Plus, with the ground power connected:

- if battery switch is on, then the battery is charging (from AC => DC "TR" converters)

- if battery switch is off, the the battery is discharging because it power "battery bus" alone, which is not connected to the rest of the electric network of the aircraft.

 

Look at the electric system schematics included in Razbam's manual :book: