Why no VOR on the boat?

[Pags]

The brain is represented as an iceberg. There are only so many penguins that will fit on the iceberg. As new penguins climb on, others fall off. For example, I was a computer info systems major in college. I couldn't write a program today if my life depended on it, but I can sure recall everything from the NATOPS in my current airframe.

I am looking up the reference in Wikipedia now.

Gotcha. I'm familiar with the concept (am experiencing it now), just never heard it called that.

 

[Crowbar]

^^"Every time I learn something new it pushes some old stuff outta my brain. Remember when I took that wine tasting lesson and I forgot how to drive? "
-HJ Simpson

 

[Brett327]

You've made the classic internet/Airwarriros mistake. You've introduced facts, and not just facts, but you've actually cited a reference. No one will take you seriously because you're not just making wild ass guesses and rambling about your own opinions.

That said, good reference, and it makes sense to me (the reason, not necessarily the technical theory behind it).

Concur. As an EW/signals guy, I understand the behind the scenes details of what a TACAN is doing, and while it may be interesting from an intellectual point of view, it adds nothing to my ability to aviate (or navigate).

Brett

 

[NavyLonghorn]

It's kind of like the P-3 guys and systems. How is knowing how many bolts the engine has going to help me when I am flying? Can I control it from the cockpit? Will it help me when I am on fire? I subscribe to the penguins on the iceberg theory. It has gotten me this far and through a few emergencies/system failures of my own.

To be fair.. alot of the systems we learn have to do with how often our airplane breaks..

 

[A4sForever]

I have always wondered this. I have heard "ideas" but have never heard "facts".

Came to this kinda late --- I really can't add much to 65 previous posts )), but think about it from a historical standpoint:

WW2: HF and VHF=VOR's and ADF's = bigger package = less accurate, not as suitable for shipboard use.
Post WW2: UHF = TACAN's = smaller package = more accurate, more suitable for shipboard use; especially with the advent of faster/heavier aircraft.

A pretty good read on the evolution of the US NAVAID system is contained in the following link taken from the FAA's System Standards webpages. It was written in 1993, but still has good info and is a good concise read on the development in the US from low-frequency 4-course radio range to GPS.


And yes ... Scarlett, we do give a damn about ADF's --- quite common overseas.
Even had to shoot one at the ship Back-in-the-Day ...

http://www.webavn.jccbi.gov/index.asp?xml=fioo/fihistory

 

[goosegagnon2]

WW2: HF and VHF=VOR's and ADF's = bigger package = less accurate, not as suitable for shipboard use.

wow they had VORs in the WWII? interesting...

 

[JIMMY]

Boy, I didn't understand a word you just said.

My VOR works like this:
I turn the on/off switch to on. I tune the station in. The needle points toward the station.

Funny thing, my TACAN works exactly the same, just a different needle.

Cool.

Fokker Out.

woah woah woah, dont forget to identify the station! :icon_wink

 

[A4sForever]

wow they had VORs in the WWII? interesting...

Late '30's ... "perfected" ... or maybe "useable" is a better term --- in middle WW2.

Wars do bring about great leaps in technology, yes??

 

[Schnugg]

Aeronautical Information Manual:
1-1-5. Tactical Air Navigation (TACAN)

a. For reasons peculiar to military or naval operations (unusual siting conditions, the pitching and rolling of a naval vessel, etc.) the civil VOR/Distance Measuring Equipment (DME) system of air navigation was considered unsuitable for military or naval use. A new navigational system, TACAN, was therefore developed by the military and naval forces to more readily lend itself to military and naval requirements. As a result, the FAA has integrated TACAN facilities with the civil VOR/DME program. Although the theoretical, or technical principles of operation of TACAN equipment are quite different from those of VOR/DME facilities, the end result, as far as the navigating pilot is concerned, is the same. These integrated facilities are called VORTACs.

b. TACAN ground equipment consists of either a fixed or mobile transmitting unit. The airborne unit in conjunction with the ground unit reduces the transmitted signal to a visual presentation of both azimuth and distance information. TACAN is a pulse system and operates in the Ultrahigh Frequency (UHF) band of frequencies. Its use requires TACAN airborne equipment and does not operate through conventional VOR equipment.



I have never flown in the military, so I can only take at what the FAA puts out. VOR's work on two phases, a reference and a variable phase. Reference is a pulse in all directions while variable changes throughout different radials (360 of them.) One way of thinking of it is that at the 360 radial, the reference and variable are identical, like two sine curves that are the same (starting from the origin.) At the 180 radial, the variable phase is roughly inverted. The wave is shifted so the null points are an equal distance from each other. Another way of thinking is that the variable sine curve is flipped across the X axis.

Now DME’s work with an interrogation signal sent from DME equipment in the aircraft and the station sends a reply. The equipment measures the time it takes and calculates the distance.

TACAN’s, in my opinion from the articles I read above, are the fancier versions of NDB/ADF’s. The NDB sends out a pulse and the ADF in the plane is able to indicate the relative bearing to the station. I believe the TACAN emits a pulse and the 9 different receivers measure the signal to determine the direction and DME in the same way above. It appears that the main different between a NDB and TACAN is the LF/MF to the UHF.

So, as a CFI with an opinion and a guess, I believe TACAN’s are on ships and not VOR’s because the shifting of the ship would screw with a VOR indication on the CDI on the instrument. Navigating in close proximity to the ship could have the CDI dancing all over the place. For a TACAN, the shifting of the boat (I think) would be less detrimental due to the fact that radials are not shifting all over the sky.

As for instrument flying and IAP only being over the station, that is incorrect. With distance information, a cross radial, GPS or radar with the assistance of ATC, an IAP for a VOR type approach can be off the station.

Does this make any sense to the crustier individuals out there?

That made my head hurt, too...

I think I said the same thing 50 zillion times simpler...

Remember VOR stations are fixed and do not move.

TACANS on ships roll and heave with the ship they're on (to include small boys). LFM smooths out that so you don't see it in the cockpit.

 

[HAL Pilot]

^^^^^ classic example of the KISS principle.

 

[goosegagnon2]

Late '30's ... "perfected" ... or maybe "useable" is a better term --- in middle WW2.

Wars do bring about great leaps in technology, yes??

Yes, makes sense now though...how the **** would they get back to the boat with out getting lost? I wonder what else they used besides dead reckoning.

 

[Swmtb]

Is that anything like the cone of silence ... ?

Nice one, Maxwell. :thumbup_1

 

[NavyLonghorn]

Yes, makes sense now though...how the **** would they get back to the boat with out getting lost? I wonder what else they used besides dead reckoning.

How would you "dead rekon" to a moving target in open ocean? Back to the drawing board on that idea I think.

 

[Swmtb]

How would you "dead rekon" to a moving target in open ocean? Back to the drawing board on that idea I think.

I was wondering about that also. I guess you would have a general idea of the carrier's course and speed, after all, they're not going to move too far in the time you're gone, so you could factor that into your calculations. Not sure how long missions were back in the day though.

 

[Brett327]

I was wondering about that also. I guess you would have a general idea of the carrier's course and speed, after all, they're not going to move too far in the time you're gone, so you could factor that into your calculations. Not sure how long missions were back in the day though.

It's called a PIM (Position of Intended Movement) and it's briefed before flight ops commence - "intended" being the operative term. Tells you where the ship is supposed to be at your recovery time.

Brett