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TACAN



 
 
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  #21  
Old January 4th 06, 03:52 PM posted to rec.aviation.ifr,rec.aviation.military
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Default TACAN

Stubby wrote:

Hilton wrote:
Bob Moore wrote:
A VOR

antenna must be permanently aligned to the earth,


Why? Why not have a heading indicator (or DG) to drive the 'angles' (i.e.
phase) it sends out?


An advantage of VORs over TACANs is the VOR antenna does not physically
more, whereas it does in a TACAN. Electronic "rotation" of the antenna
intuitively makes shipboard use easier, but I might not understand ships
enough!


Operating frequencies dictate the size of the antenna array.
Compare this picture of a TACAN site at
http://en.wikipedia.org/wiki/TACAN with this one of a VOR site at
http://en.wikipedia.org/wiki/VOR.

Other advantages:
Range: TACAN DME has a maximum range of 300 NM miles. VOR
reception range is limited to 25 - 130 NM, depending on the
site's transmitter power.

Bearing accuracy: TACAN can provide bearing resolution of +- 1
degree. Typical VOR bearing accuracy is +- 2 degrees.

A bearing error of 1 degree at 100 miles isn't likely to be
critical on land, but that same error at sea can mean the
difference between finding your carrier and a very long swim
home.

| George Ruch
| "Is there life in Clovis after Clovis Man?"
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  #22  
Old January 4th 06, 04:26 PM posted to rec.aviation.ifr,rec.aviation.military
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Default TACAN

George Ruch wrote

Operating frequencies dictate the size of the antenna array.
Compare this picture of a TACAN site at
http://en.wikipedia.org/wiki/TACAN with this one of a VOR site
at http://en.wikipedia.org/wiki/VOR.


Actually George, the first picture is a VORTAC, a TACAN and VOR
installation. The TACAN is just the round cylinder part and that
is what makes it so easy to mount onboard a ship.

Bob Moore
  #23  
Old January 5th 06, 03:02 AM posted to rec.aviation.ifr,rec.aviation.military
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Default TACAN

Bob Moore wrote:

George Ruch wrote

Operating frequencies dictate the size of the antenna array.
Compare this picture of a TACAN site at
http://en.wikipedia.org/wiki/TACAN with this one of a VOR site
at http://en.wikipedia.org/wiki/VOR.


Actually George, the first picture is a VORTAC, a TACAN and VOR
installation. The TACAN is just the round cylinder part and that
is what makes it so easy to mount onboard a ship.


Oops. My mistake on that. I was focusing on the size of the VOR
antenna ring.

| George Ruch
| "Is there life in Clovis after Clovis Man?"
  #24  
Old January 5th 06, 03:39 AM posted to rec.aviation.ifr,rec.aviation.military
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Default TACAN

Bob Moore wrote:
George Ruch wrote


Operating frequencies dictate the size of the antenna array.
Compare this picture of a TACAN site at
http://en.wikipedia.org/wiki/TACAN with this one of a VOR site
at http://en.wikipedia.org/wiki/VOR.



Actually George, the first picture is a VORTAC, a TACAN and VOR
installation. The TACAN is just the round cylinder part and that
is what makes it so easy to mount onboard a ship.

Bob Moore


We used to carry a portable TACAN (TRN-41) in a backpack for
contingencies in the USAF. Didn't take long to set up and then align so
it could be used.
http://esc.hanscom.af.mil/esc-ga/Products/trn-41.htm
JPH
  #25  
Old January 6th 06, 08:39 AM posted to rec.aviation.ifr,rec.aviation.military
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Default TACAN

I wonder if the TACAN has to move physically. That may be an old
design. Looking at the portable tacan posted later in the threads, it
doesn't look very mechanical.


Stubby wrote:
Hilton wrote:
Bob Moore wrote:
A VOR

antenna must be permanently aligned to the earth,



Why? Why not have a heading indicator (or DG) to drive the 'angles' (i.e.
phase) it sends out?


An advantage of VORs over TACANs is the VOR antenna does not physically
more, whereas it does in a TACAN. Electronic "rotation" of the antenna
intuitively makes shipboard use easier, but I might not understand ships
enough!


  #26  
Old January 7th 06, 12:56 AM posted to rec.aviation.ifr,rec.aviation.military
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Default TACAN

George Ruch wrote:

That's a fine reference. I saved a bookmark there. It looks as if the
UK TACAN is the same as the USAF TACAN, but I'm still not clear as to
the differences from a VOR. Maybe it's just the frequencies. Or, I
believe all TACANs are supposed to have DME built in.


I don't know much about how either works, other than TACAN transmits its
azimuth signal in the UHF band and DME is an intergal part of the TACAN
station. The DME portion of the TACAN is compatible with civil DME
avionics.

Many of the en route VORs in this country have VOR and TACAN at the same
site. The civil users's airborne DME equipment use the DME portion of
the TACAN station. The official name of one of these sites is VORTAC.
  #27  
Old January 7th 06, 02:57 AM posted to rec.aviation.ifr,rec.aviation.military
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Default TACAN

M. J. Powell wrote:
Is TACAN still in use? I worked on it briefly in 1956 when I was in the
RAF.


I remember from a recent history or discovery channel program that
air-to-air tacan is still used for aerial refueling operations.

Here's a page about it from Rockwell:
http://www.rockwellcollins.com/ecat/gs/TCN-550_Tacan.html

- Ray
  #28  
Old January 7th 06, 03:48 AM posted to rec.aviation.ifr,rec.aviation.military
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Default TACAN

Ray wrote:

M. J. Powell wrote:
Is TACAN still in use? I worked on it briefly in 1956 when I was in the
RAF.


I remember from a recent history or discovery channel program that
air-to-air tacan is still used for aerial refueling operations.

Here's a page about it from Rockwell:
http://www.rockwellcollins.com/ecat/gs/TCN-550_Tacan.html


When I was stationed in Thailand, I also heard about A-A mode
being used in a two-ship formation when a major system (attack
radar or INS) failed. The aircraft with working systems would
lead, and the aircraft with the failed system would follow the
leader. As I understand it, buddy bombing was possible, but may
not have been all that accurate.

| George Ruch
| "Is there life in Clovis after Clovis Man?"
  #29  
Old January 7th 06, 11:54 AM posted to rec.aviation.ifr,rec.aviation.military
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Default TACAN

George Ruch wrote:


Other advantages:
Range: TACAN DME has a maximum range of 300 NM miles. VOR
reception range is limited to 25 - 130 NM, depending on the
site's transmitter power.


But, civil aircraft use the TACAN's DME, so they should see the same
range for DME, shouldn't they

Bearing accuracy: TACAN can provide bearing resolution of +- 1
degree. Typical VOR bearing accuracy is +- 2 degrees.

A bearing error of 1 degree at 100 miles isn't likely to be
critical on land, but that same error at sea can mean the
difference between finding your carrier and a very long swim
home.

Help me with that one. The TACAN ground station is on the ship, right?

If so, angular errors diminish as you approach the station and you
should end up at the ship, whether you started at 150 miles out with a 1
or 2 degree error.
  #30  
Old April 6th 11, 05:11 PM
itsbob itsbob is offline
Junior Member
 
First recorded activity by AviationBanter: Apr 2011
Posts: 1
Default

Quote:
Originally Posted by View Post
Bearing accuracy: TACAN can provide bearing resolution of +- 1
degree. Typical VOR bearing accuracy is +- 2 degrees.

A bearing error of 1 degree at 100 miles isn't likely to be
critical on land, but that same error at sea can mean the
difference between finding your carrier and a very long swim
home.
[/color]
Help me with that one. The TACAN ground station is on the ship, right?

If so, angular errors diminish as you approach the station and you
should end up at the ship, whether you started at 150 miles out with a 1
or 2 degree error.

Know this is an old thread.. but..

1 degree sounds like a lot, and would be significant if you were 10 miles away, shot an azimuth and followed that for ten miles.. but with TACAN it's continuous feed of direction and distance so as you get close (picture a funnel) the error becomes less and less, and of course as a plane gets closer to a carrier there are many more control systems that "Capture" the aircraft and provide guidance and landing control.

For an idea of current TACAN and future trends (TACAN is not going away) google TRN 47 Marine Man Portable TACAN, URN 32 Shipboard TACAN.. Fernau TACAN 2010, and Moog MM7000
 




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