Simviation Forum - Default DC-3 radio compass problem?

Mar 11^th, 2010 at 8:44pm

aeroart Offline
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In the default DC-3, are the ADF needles supposed to point to VOR stations when you have a VOR frequency tuned and you've set the radio's NAV/ADF toggle switch to NAV?

When I tune an NDB and set the radio's toggle switch to ADF, the needle points to the correct relative bearing, just like any fixed-card radio compass (0 always at the top).

However, when I tune a VOR and set the toggle switch to NAV, the bearing is way off.

Is there something wrong with my radio compass or am I not using it right?

Art

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Reply #1 - Mar 11^th, 2010 at 10:14pm

aeroart Offline
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Never mind. I found the answer.

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Reply #2 - Mar 11^th, 2010 at 11:19pm

Capt.Propwash Offline
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what was the answer oh great Obi Wan?

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Reply #3 - Mar 12^th, 2010 at 8:13am

aeroart Offline
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The answer, Hans, is that, when tuned to a VOR, the head of the needle will point to the magnetic course to the station. The tail will point to the name of the radial, its outbound magnetic course.

If you're crossing the 060-degree radial northeast of the station, the head will point to 240 degrees, while the needle's tail is pointing to 060, regardless of your heading. If your heading is 270 degrees, the needle will be 120 degrees to the left of zero (zero always at the top of the radio compass card), not 30 degrees to the left. The needle does not point to the station, as it would if tuned to an NDB. To go directly to the station, turn 30 degrees left to a heading of 240.

May The Force be with you.

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Reply #4 - Mar 12^th, 2010 at 8:49am

dave3cu Offline
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You can also use it as you would the normal OBI to intercept a radial.

Rotate the card ('var' knob) to your desired course intercept. You then read the needle as the CDI, and the 'pointy' end as the to/from indicator.

Dave

At that time [1909] the chief engineer was almost always the chief test pilot as well. That had the fortunate result of eliminating poor engineering early in aviation. Igor Sikorsky

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Reply #5 - Mar 12^th, 2010 at 12:23pm

aeroart Offline
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I was surprised that a radio that simulates a 1930s radio includes VHF tuning. I have a book published in 1938 entitled, "Through the Overcast." Its purpose is to teach instrument flying, and is based on American Airlines' DC-3s of that era. But nowhere in the book is there any mention of VOR or VHF or even megacycles. All references to radio navigation refer to low frequency and kilocycles.

Anyone have access to more complete information?

Art

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Reply #6 - Mar 12^th, 2010 at 1:18pm

dave3cu Offline
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I'm no historian, but believe vor didn't come into existance or use until the late 40's.

During the 30's and 40's the system used for instrument flying was the Low Freq. Radio Range (LFR) system, often known as 'A-N radio range', or just 'the range'.

Wikipedia on LFR-http://en.wikipedia.org/wiki/Low_Frequency_radio_range

If you're interested, there is a package for FS2004 that includes scenery for the LFR transmitters, the gauges and documentation.

Cal Classic discussion on it's release (2007)-http://www.calclassic.com/cgi-bin/yabb/YaBB.cgi?board=General;action=display;num...

Download Radio Range v4-http://www.simviation.com/fs2004utilities8.htm

Dave

At that time [1909] the chief engineer was almost always the chief test pilot as well. That had the fortunate result of eliminating poor engineering early in aviation. Igor Sikorsky

I intend to live forever....so far, so good. Steven Wright

You know....you can just rip up a to-do list.

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Reply #7 - Mar 12^th, 2010 at 1:43pm

aeroart Offline
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Hi Dave,

That was my understanding about when VORs came into being.

I saw the wikipedia writeup during my Googling, but didn't know anything about the other two downloads. I'll be sure to take a look at them. Thanks!

Art

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