Project Tupolev Team :: View topic - NAS-1 Navigation the easy way...

KFC · ÊÂÑ

Since AP operation has been addressed, I'll continue with an easy way to use the NAS-1 navigation system. Now, I do not claim this is the right way to do it, but it has worked for me. Please correct any errors that I may have.

First of all, you have to have a fligth plan generated by the spreadsheet (Route_Planner_18.xls) that is provided on the AN24 navigation manual. You can get it on links provided on forum posts above. These will provide the proper headings or "courses" to follow for use with the HAC-1 system. Don't be afraid, there is nothing to figure out, just import the flight plan from FS format, calcuate and print it. Here is what it looks like, it will give you the "MAP ANGLES" or headings to input on the MAP ANGLE gauge for the route desired:

KFC · ÊÂÑ

Ok. I'll assume that the aircraft engines are already running (since you cannot set the electrical system -for avionics- online with the APU), and the engine generator electrics are fired up (See Quick guide post on Main Forum). I assume also all the required switches on the overhead panel are configured correctly (Just flip all of them up if you are not sure, like I do Óëûáêà

, well except the fuel control ones should be set as recommended by Mike's quick guide though)

Ok. Let's set up the NAS-1 (Press <SHIFT+1> to access the Navigator's panel) :

1.) Align the navigation gyros to local magnetic directions: Do this by placing the switch to "MK". You will notice movement start on the large compass with the funny looking arrows Óëûáêà

. Repeat the procedure for both "main" (OCH) and "secondary gyro. the selector is the switch on the right above the latitude scale. The other swith on the left selects the northern (up) or southern hemisphere. one can speed up the aligning process as described below.
When compass is finished aligning, select the middle position or "RPK". This will set the navigation systen in "Gyro" only mode.

2.) Set the latitude selector to the local latitude. You can find this by pressing <SHIFT+Z> and looking at the first two digits of the North Coordinates. Ex: "N56 32.1" would be 56 degrees north latitude: Use this number to set on dial.

3.) If the airplane compass indication was far from local magnetic values, it may take a lot of time to turn around, so click on the "fast align button" to speed up the process. Make sure the heading shown on the Large Compass gauge is the correct local magnetic heading. You can double check by using the <SHIFT+Z> method and look up the actual MAG HDG line of the plane at the moment. I'd imagine, normally you'd do this with the magnetic compass from navigator's view, but it is too small to read, so use the digital version Óëûáêà

of <SHIFT+Z> .Don't forget to place the switch on "RPK" or gyro-only mode when alignment is done.

4.) "Rotate" knob on "MAP ANGLE" gauge to value of first line shown on calculated route plane (excel flight plan). This value will be followed by Autopilot. Note, the value to follow or "MAP ANGLE" is the one shown on "HSI" in main panel and big compass card on navigator's panel, but not necessarily the one on the RMI. I have not even included aligning the RMI gauge to magnetic indications, so just ignore the heading indications of the RMI for simplicity's sake , but do use the RMI's ADF's indications of relative position of radio beacons. This "MAP ANGLE" gauge is a very important gauge as the AP will follow the "Course" or heading indications "dialed" in this gauge. You will use this gauge to follow the flight plan (command turns). Some more on this later...

5.) These are the "counters". In a nutshell, the "pointer" labeled "B" will indicate how far off laterally or "to the sides" of the course you are, while the pointer labeled "C" will keep track on how far you are from the point you turned the "counters" ON. Just click on the center of the gauge with right and left click to make both zero. More on this later.

6.) Make sure this one reads zero too by clickin on the hot spots with the mouse. This is the gauge you will use to fine tune your course or "route" since the AP responds to this gauge also. It represents how far you are laterally from Course or desired track, but with a less "coarse" resolution than the "Counters" (#5 Above).

Ok. We are setup for navigation with the pre-programmed NAS-1 system...

KFC · ÊÂÑ

Ok. We have taxied to active runway, have done our pre-takeoff checks and all that is left is activate the NAS-1. THe following is an example from a flight from USSS to UNNT (as described in flight plan).

1.) Before advancing throttles to takeoff power, we'll proceed to double check our counters needles read zero. And have a quick look at map angle and make sure it is correct (32 deg magnetic in this case)

2.) Dial in ADF tuner #1 to 187 Khz. This will be our first waypoint check.

3.) Turn on the navigation radar (switch "UP" position)

4.) and counters. (switch "UP" position).

5.) Followed by making sure the lateral navigation offset gauge reads zero and pressing the lower left hand side button to turn it "ON". A green light will verify that it is on.

From this point on , the NAS-1 is "remembering" where it was turned ON (or at least that is the way I see it), so that when you are airrborne, the NAS-1 will lead you to the correct track or "Course" in Russian. Think of it as drawing a line from where you are at to the first waypoint. It will make more sense once we look at the track on next posts...

Captain, we are ready for takeoff!
Set takeoff power...takeoff power set... engine looks good... airspeed alive............. V1, Vr, V2.... Off we go! Óëûáêà

Now, since the first heading (MAP angle programmed) required for the first waypoint is 32 degrees, we will manually turn to 32 +10 = 42 degrees since our route relative to our position will be to the right (I am taking off from runway 26 at UNSS). This will turn the plane in the direction of the desired track "to set up the autopilot (AP) to win". Note: You can use the Autopilot (AP) after 1000 ft agl, but I will not in this case to stay closer to the desired track and to stay within the limits of the AP activation criteria.

Ok, once we are heading to 42 degrees roughly (Using "HSI" or Compass card below attitude indicator), and climbing at less than 1000 m/min, turn "ON" the Autopilot. The steps below will start the AP in NAS-1 tracking mode automatically. If you were to have had the AP on already using "3K" or "heading " mode, you would just do steps 1 and 2. The operating modes have already been explained o previous posts, so the only "new" feature described will be the NAS-1 mode (or that is what I call it) Óëûáêà

.

Well see the NAS-1 in action on the next post...stay tuned.. Óëûáêà

..Climb power set manually, NAS-1 and pitch attitude set with AP...Great!
....We'll ask the flight attendant to bring in the coffee... Óëûáêà

as the AP is controlling the plane now. We can relax now a bit (but keep an eye on the airspeed/vertical velocity).

Ok. We press <SHIFT+1> to call the navigator's panel and observe the various indications from the NAS-1 system and other auxiliary gauges...

A.) We are approximately 5-6 km. to the left of the desired track or "course"(in russian terminology). WARNING: Don't confuse this gauge in telling you that you should turn to the left, it is in fact telling you to turn to the RIGHT since you are to the left of the track (by 5-6 km). (This will become clear on next post).

B.) Chances are the compass card will be still turning since the autopilot is trying to steer you back on course as programmed. You may see the heading stabilized at some number way past the programmed MAP angle value, so that you can joint the track more quickly. I don't know the criteria the programmers used for the automatic control logic, but I think it is great, not too abrupt, not too slow (awesome!). Currently it looks like the heading is stabilized at about 60 degrees, so that the next turn will be to the left, back to 32 degrees heading to joint the right track (first leg of flight plan, first programeed "Course" in Russian, first programmed flight path, etc.,etc.,etc.,,)

C.) Notice the counter are already "Doing their thing.." Óëûáêà

. Needle labeled "C", is already started counting and showing about 10 km. from point of start.

It will all come toghether on next post..hopefully.. Óëûáêà

The AP has now aligned the plane with the programed MAP Angle of 32 degress and as the below picture shows, very elegantly managed to steer it to join the desired track (or , again, "Course" in Russian terminology).

Let's look at the whole process we just went through:

A.) The plane is stabilized on the programmed track of 32 degrees (From MAP Angle) and we have the first waypoint check (the 187 Khz ADF) straight ahead. Note that we don't really look at the heading indication on this gauge for this example as it was not properly aligned (even though it may be close to correct heading). We use this gauge in this example just to check on the relative position of the ADF to our airplane (ehem. jet airplane, I mean. Óëûáêà

)

B.) Heading is showing 32 degrees, the correct Heading

INSET DIAGRAM ---> This one tells the whole story:

1.) We turned "ON" the NAS-1 system on the runway and we took off on a heading of 260 degrees.
2.) Manually turned to the right or towards the East to approximately 10 degrees more than the programed MAP Angle.
3.) Turned on the AP and the plane started to steer itself towards the desired track as we were about 5-6 KM offset from the track when the AP was turned "ON".
Note that we can see at this point what the NAS-1 does: It will look for the track that was defined by the point where the system was turned "ON" and the direction of the programmed MAP Angle. This is what I was refering to when I said to think of the system as drawing a line from the location you turned the system "ON" in a direction specified by the MAP angle gauge.

4.) AP has joined the "programmed" track and heading the correct direction in oder to keep this path. We can corroborate with the ADF such that we know we are heading the right way: The ADF pointer needle is straight ahead Óëûáêà

Wheew... Ok. Need a break. Will continue the rest of flight to look at some more of the NAS-1 Navigation.
I would recommend to read the AN-24V navigation manual as recommended by Enrique, as the full technical explanation is given there and it is not hard to read. Hope this is of some help and have not confused anybody...

regards,

Macs Óëûáêà

Enrique Del Rosario · ÊÂÑ

Congratulations Macs!... I would like to take this chance to thank you in behalf of all the readers of this thread for your nicely well done explanation on NAS-1 system. More clear than water... even my one year old daughter would understand it Óëûáêà

.
I'm sure this "tutorial" is going to be a great help and support for all the Tu134 fans.

Thanks Macs... Õîðîøî

regards,

me

KFC · ÊÂÑ

Wishmaster · ÊÂÑ

KFC
All right, but STU switch at AP may be in OFF position, it only for landing, VOR and ZK mode(Knob on NKP-4)

KFC · ÊÂÑ

Gritsevsky · Moderator

Wishmaster · ÊÂÑ

Ïîäïèñûâàþñü Ïîä Êàæäûì Ñëîâîì :î)

except · ÊÂÑ

âû ëþäåé íå çíàþùèõ ðóññêèé ÿçûê, íå ïóãàëè áû ðóññêèìè òåêñòàìè Óëûáêà

ó íèõ æå ñêîðåå âñåãî àáðà êàäàáðà. åùå íå òàê ïîäóìàþò ÷åãî Óëûáêà

LHA015 · Ïðàâàê

I can remenber, that v 0.95 had an tool tip on the knob of the MAP ANGLE gauge and the counters needles for better accuracy. Is there a possibility to implement this again?

Jure · Êóðñàíò

Juergen,

it is implemented. Óëûáêà

On my Tu134, tooltips are working perfectly. You even have distance accurate to a tenth of a kilometer on the counter needles.

Regards,
Jure

citywalker · Ïðàâàê

When I switch to the navigator panel, the tooltips will not appear immideately but within 30 seconds... so perhaps you should just give it a short wait, they should be there. Óëûáêà

LHA015 · Ïðàâàê

Thanks Jure & Arno,

I had them deactivated

Regards,
Jürgen

FlyingFox · Êóðñàíò

Hello

i tried to work through this article and follow the instructions, but there are still some problems:

1:
Where can i get the flightplan as shown in picture 2 (USSS-UNNT), it is not included in the AN24 documentation

2: why are these pictures in the article?

in my eyes they were later renamed and do not belong here. What or where are the original pictures ?

3. Where can I get a description of the navigator panel? in all the tutorials i found so far, this is always missing...Working with the AN24 panel documentation doesn't help, as it is too theoretical about the principles of NAS navigation but doesn't explain the switches in TU134.

thank you for your help...

8-)Flyingfox