Don't sell your loran

Michael wrote:

wrote
I would prefer to have one of those boxes (I forget what they're called
- they're from before my time 8^) ) that creates virtual waypoints using
VORs and DME. I would think that would be the ideal alternative to GPS,
seeing as the VOR/DME signals are less susceptible to environmentally
caused signal degradation.

They're caller rho-theta RNAV (also VOR-DME RNAV). The KNS-80 was
probably the most popular, and it works well, but there are quirks.
Most importantly, it won't usbstitute for the underlying navaid on an
approach, the way GPS and LORAN will - get low and you lose the VOR
and/or DME signal.

The KNS-80 is a very nice box. Calculates time and distance to any waypoint
defined by a radial and distance from a VOR. Enroute and Approach modes.
Includes 4 waypoints with non-volatile memory. Easy to have an autopilot
slaved to it. Best of all, no damned database to update every 56 days (or any
time) to keep it current for IFR. It's successor (KNS-82 or KNS-88?) box had
additional waypoint memory.

Unfortunately, I don't believe that Bendix-King/Allied-Signal/Honeywell has
manufactured the KNS-80 and related boxes in years. LORAN and then GPS really
killed the market for that box, as everyone preferred the more sophisticated
boxes. It's still a nice thing to have though.

Jeff Saylor wrote
Unfortunately, I don't believe that Bendix-King/Allied-Signal/Honeywell has
manufactured the KNS-80 and related boxes in years.

No, but they're avaiable on the used market dirt cheap. I've got a
friend who will happily sell his for $300.

Michael

wrote in message
...

I've never used a LORAN either, so I don't have any personal experience
with how they behave overall. But if they can be compared to NDB/ADF
behavior in any way, count me out.

I have GPS, Loran, NDB, and also KNS-80 VOR/DME RNAV in my airplane.

If the chips go down, the Loran is much more reliable/accurate than the
VOR/DME RNAV.

VOR/DME RNAV relies on the accuracy of the VOR receiver and how well you
dial in a radial; it can easily be a mile or so off on a waypont.

Loran is much more reliable and accurate then VOR/DME RNAV. Loran got a bad
name simply because its signal tends to degrade in active precipitation,
especially snow... this can be reduced considerably however by placing
static wicks on the airplane.



--------------------
Richard Kaplan, CFII

www.flyimc.com

Richard Kaplan wrote:

Loran got a bad
name simply because its signal tends to degrade in active precipitation,
especially snow...

Actually, I think most of the blame can be laid to the state of the art in computers
when the LORANs were developed. Mine takes several minutes to adjust to a change in
course, and I have seen it report a steady decrease in distance to an airport for
quite some time after one has turned directly away. It would not be useful for
maintaining distance from a controlled field.

Maybe with a faster CPU, LORAN would get more respect.

George Patterson
If you don't tell lies, you never have to remember what you said.

"G.R. Patterson III" wrote in message
...
[...] Mine takes several minutes to adjust to a change in
course, and I have seen it report a steady decrease in distance to an
airport for
quite some time after one has turned directly away. It would not be useful
for
maintaining distance from a controlled field.

\What LORAN receiver do you have? My Northstar M1 LORAN exhibits neither of
those problems.

What it *does* do is suffer significant errors in position on occasion,
which I haven't gotten a good explanation for. The errors are up to 20
miles off at times, and I have only noticed them when flying near home (but
of course, this is where I do most of my flying, so that may not indicate
anything). I do notice that when I fly long cross-country flights, I don't
have to go very far (50-100 miles) before the LORAN wants to change from one
GRI (or is that just my LORAN's way of saying "grid"? I can't remember) to
another. Maybe I'm right on the edge of reception for the one that the
LORAN unit wants to use (or on the edge of multiples, for all I know).

I doubt that this issue is a programming problem though. More likely a
fundamental limitation of the ground-based radio chain.

Pete

"G.R. Patterson III" wrote in message
...

when the LORANs were developed. Mine takes several minutes to adjust to a
change in
course, and I have seen it report a steady decrease in distance to an
airport for
quite some time after one has turned directly away. It would not be useful
for
maintaining distance from a controlled field.

If you didn't look at the name of my unit, you would be hard-pressed to tell
based on performance if I have a Northstar M1 Loran or a Northstar M3 GPS.


--------------------
Richard Kaplan, CFII

www.flyimc.com

Peter Duniho wrote:

What LORAN receiver do you have? My Northstar M1 LORAN exhibits neither of
those problems.

I have the Foster LRN-501.

What it *does* do is suffer significant errors in position on occasion,
which I haven't gotten a good explanation for. The errors are up to 20
miles off at times, and I have only noticed them when flying near home (but
of course, this is where I do most of my flying, so that may not indicate
anything).

From the Foster manual. There are 6 LORAN chains in the U.S. (4 in the lower 48) and
more outside, and each is made up of a "master" transmitter and two or three "slave"
transmitters. These are synchronized and transmit timing info as part of the signals.
The receiver figures out where you are by calculating the difference between the
three transmitters and triangulating. Significant position errors can result when the
master and either of the slave stations are in line with your aircraft (you're
between them or they are both off to one side).

I do notice that when I fly long cross-country flights, I don't
have to go very far (50-100 miles) before the LORAN wants to change from one
GRI (or is that just my LORAN's way of saying "grid"? I can't remember) to
another.

GRI is "Group Repetition Interval', but basically it's saying it wants to change
chains.

Maybe I'm right on the edge of reception for the one that the
LORAN unit wants to use (or on the edge of multiples, for all I know).

Yep. Mine wants to change chains about the North Carolina/South Carolina border.
Reception sucks sometimes in Knoxville, and that's on a border as well. IIRC, you're
in Washington State? If so, you're at the boundary of the U.S and Canadian West Coast
chains. To make matters worse, the slave in your area (located in the middle of the
State) is shared by both chains.

I doubt that this issue is a programming problem though. More likely a
fundamental limitation of the ground-based radio chain.

Yep again. Programming would never enter into the situation. A faster CPU would,
however, result in the unit refreshing its idea of your position more rapidly after a
change of course (or your speed after leveling off, etc.).

George Patterson
If you don't tell lies, you never have to remember what you said.

"G.R. Patterson III" wrote in message
...
[...] Significant position errors can result when the
master and either of the slave stations are in line with your aircraft
(you're
between them or they are both off to one side).

Interesting. My position errors always occur in the same geographical
location (just east of the Olympic Mountains)...I wonder if that location
happens to be in line with a master and a slave.

Yep. Mine wants to change chains about the North Carolina/South Carolina
border.
Reception sucks sometimes in Knoxville, and that's on a border as well.
IIRC, you're
in Washington State? If so, you're at the boundary of the U.S and Canadian
West Coast
chains. To make matters worse, the slave in your area (located in the
middle of the
State) is shared by both chains.

You recall correctly. Based out of Paine Field, just north of Seattle. The
"zone of confusion" lies about 15-25 miles roughly southwest of Paine. I
have noticed that the receiver is marginally better when using the US West
Coast chain, but for whatever reason it always wants to use the Canadian
West Coast chain in the Puget Sound region. That's certainly a programming
issue: no way to override the chain in use. I can switch it manually, but
the LORAN unit immediately starts bugging me to switch back.

Back to the previous question of position errors... I found the locations
of the various LORAN chains, with the master and slaves. It doesn't appear
that the general area where I get the errors is in line with the master (in
Williams Lake, BC) and the slave (in George, WA). In fact, I'd have to be
over on the other side of the Cascades for that to happen.

However, I *am* flying near the Olympic Mountains, which might cause signal
reflections. I have seen some bizarre effects flying NDB approaches near
shorelines, where the ADF shows me right on course, but visually I can see
I'm well to the side (over a mile off in some cases). I wonder if similar
variations affect LORAN. The calculations must assume straight-line signal
propagation, so I suppose anything that caused the signal to not follow a
straight line would cause errors.

Though, now that I think about it, a reflection would make it appear I was
farther from the station, and the errors I'm getting are putting me closer
to it.

Ahh well...the mystery continues. Anyway, just wanted to mention that not
all units are afflicted with the same delay in position calculations your
unit appears to be.

Pete