Navigation Questions

[JG14_Smil]

Hello, I thought I would ask this here so it stays focused on the L-39.

 

It has been a long time since I have flown and I have forgotten a lot. I was hoping to ask some refresher questions here. This will be important in a bug hunt I will be doing in the future.

 

- True North is used only on charts(?). Magnetic North is used in flight.

 

- A digital gyro (DG) is set to match the magnetic compass in pre-flight, correct?

 

That is all for now. I will be asking some chart questions later on when I get a screen shot.

 

Thanks in advance for help.

[JG14_Smil]

Reserved

[WildBillKelsoe]

Hello, I thought I would ask this here so it stays focused on the L-39.

 

It has been a long time since I have flown and I have forgotten a lot. I was hoping to ask some refresher questions here. This will be important in a bug hunt I will be doing in the future.

 

- True North is used only on charts(?). Magnetic North is used in flight.

 

- A digital gyro (DG) is set to match the magnetic compass in pre-flight, correct?

 

That is all for now. I will be asking some chart questions later on when I get a screen shot.

 

Thanks in advance for help.

 

around 45 mins in flight the sync button should be depressed to sync the directional gyro to the known RSBN stations. Azimuth and Distance correct should light up. Holds true for excessive banks due to vibration. the primary means of navigation is the ADF and RSBN. Using pre-planned headings to and from RSBN stations and ADF, as well as drift correction using formulae, the cross track error should be minimal.

 

the second question I can answer based on my limited experience. No, you don't need to set the directional gyro to the magnetic compass heading, only the magnetic declination in the panel iirc which is 7 degrees. Also you need to set the airfield latitude and conform the DG to the starting heading by the 0-360 SPDT by the right thigh. Please pardon me but this is from the back of my head.

[Pineapple Pete]

You probably remember this. On a VFR chart the course you draw from point A to point B is referenced to true north. The course you fly (no wind) is a magnetic course determined by local magnetic variation. Your directional gyro is set by matching it to your magnetic compass. For best accuracy steady state flight or stopped on the ground.

This is very basic private pilot ground school stuff.

IFR charts are all magnetic.

I hope that this is a little help.

 

 

Sent from my iPhone using Tapatalk

[JG14_Smil]

Thanks to both of you. I am doing a lot of refreshing.

 

Pineapple Pete is spot on, it is basic Ground School stuff and that is exactly what I am asking about.

 

WildBill, I'm really referring to the NTTR, haven't made that clear as of yet. Very different there from where I flew at home (long ago). No RSBN, no ARK, just Dead Reckoning basics.

 

I have to get my terminology back up to date!

 

Example: NTTR Instant Action, Take off mission. Lined up on Runway 03L.

 

Magnetic heading is 028 degrees. DG heading is 040. KM-8 Correction is set to +12 degrees. DG and MH do not match with KM-8 set correctly.

 

Set KM-8 to 0. DG and MH now match. Incorrect KM-8 setting.

 

So, In DCS, correction is being added to MH (magnetic heading), which is wrong and should be added to TH (true heading).

 

Is the bold statement above true or false?

Edited April 23, 2017 by JG14_Smil

[Frederf]

KM-8 set to 0 would mean the heading instruments are reading in magnetic directly with no correction from the flux gate compass.

 

If you want to have heading gyro instruments read true heading then you must set KM-8 to apply the correction between true and magnetic so the instruments know how far wrong from magnetic data input to display true heading.

 

If NTTR variation is 12°E this means that when facing 360° true a magnetic compass will show 12°E. In the above example if the magnetic compass shows 28° then the true heading is 16° (magnetic is +12° from true).

 

It is best to understand magnetic as the real physical phenomena and variation value must be subtracted to convert it to the imaginary construction which is true heading.

[JG14_Smil]

Yes, Thanks much as usual Frederf.

 

We are I'm complete agreement about what you said in the post above.

 

In my test situation above, there is no good reason for the DG to say 040 degrees. If I fly 040 when I should be flying 028, I will end up dead in the desert.

 

In RL, we lay out a course with True North and TH, then the correction is added to our TH to get our MH. (I am leaving out wind/speed for now).

 

In DCS, correction is added to the MH, which then gives us an erroneous number.

 

My point is highlighted in bold.

 

Thanks for helping me learn this again. It is starting to feel like a losing battle as I was taught one thing and I see something else in DCS. I will soon stop beating this dead horse.

[JG14_Smil]

To go True North, we fly Magnetic 012*.

 

We add Km-8 correction and our DG now has us flying 024*

 

The Km-8 should have subtracted the 12*, then DG would have us fly 0* True, 012* MH.

 

That's the bottom line as I see it.

Edited April 24, 2017 by JG14_Smil

[JG14_Smil]

You know, I can remember back in Ground School when I learned how large the magnetic variation is out west. I thought, how in the $#@! do they fly with that? I guess I am learning.

 

Sure is a lot easier around here where I live! :)

[Justin Case]

around 45 mins in flight the sync button should be depressed to sync the directional gyro to the known RSBN stations. Azimuth and Distance correct should light up.

 

I'm not sure that has anything to do with RSBN though, if you mean the button of the front panel in both cockpits. That one seems to sync the GMK (gyro) with the current magnetic heading.