GPS and old-fashioned thinking?

Roy Smith wrote On 12/03/05 08:27,:
wrote:

The bean counters want to do away with primary radars, too. But, so
far, the security-minded have stopped that planning.


What does it mean to "do away with primary radar"? The antennae are
co-located and the systems are already built. What money would be saved by
turning the primary part of the system off? It's not even like they rotate
on different shafts so you can save a little on lubricating the bearings or
powering down the motor that makes it go round and round.


That disregards maintenence and replacement costs.

Anyway, if we turn off the primary radar, we'll only be able to see things
that want to be seen. The libertarian in me likes that idea, but I'm
enough of a realist to understand that the people intent on blowing things
up are probably smart enough to turn their transponders off.

In the long run, it means turning off the primary radar (or failing to replace
it when it dies), on interior US radar stations, especially that cover
uninteresting, open country radar areas. The ones that would stay are the
ADIZ radars (which are military anyways), and city radar. That leaves a lot
of radar that can be removed.

Don't expect anyone to fight for the idea that Montana needs radar to keep
terrorists from attacking their cow sheds.

john smith wrote On 12/03/05 11:52,:
LASER ring gyros are certainly small enough, I don't know how much they
cost. If the US military can put them in artillery shells, they should
be available for light GA inertial nav systems.

Try looking up the price of a 3 axis FOG (Fibre Optic Gyro, the cheapest type
of laser gyro). Hint: the US military has a lot of money.

Roy Smith wrote On 12/03/05 12:09,:
In article ,
john smith wrote:


LASER ring gyros are certainly small enough, I don't know how much they
cost. If the US military can put them in artillery shells, they should
be available for light GA inertial nav systems.


Googling for LRG prices surprisingly came up with mostly a blank, but I did
come up with one doc
(http://www.armadilloaerospace.com/n....ws?news_id=140)
that hints at a "6 figure price" for them. That same doc, however, talks
about commercially available Fiber Optic Gyros (which I don't know much
about) in the $1500-$2500 price range. There is an old adage, "Sooner or
later, anything made from silicon will cost $5", so I can only assume that
the days of affordable solid state gyros for GA are not too far off.

What do things like the Garmin G-1000 use?

Those are non-TSO FOGS. The current crop of "gyros" used on the electronic
displays aren't actually gyros at all. They are rate of turn accellerometers.
Turns out accellerometers are dirt cheap, that IS a product that can be
made (literally) on a silicon chip. They are not as accurate, but some
genius figgured out how to tie them to GPS position to correct their
long term drift. So, in roundabout answer to this roundabout thread, they
rely on GPS, and so negate the original idea of this thread about inertial
NAV as a backup to GPS.

By the way. Don't expect FOGs to be cheap, or small anytime soon. These are
precision wound spools of optical fibre connected to lasers. Turns out there
is a minimum "bend radius" for the spool that works out to 3" or so in
diameter, which means don't expect to see it show up in a 3" instrument
package anytime soon.

As for traditional ring gyros, you are now talking precision mirrors set up
on a rigid mechanical frame with accuracy that would do a space mission
proud. I.e., forgedda 'bout it.

wrote On 12/03/05 15:31,:

The future thinkers want to do away with even the scondary and go do ADS-B.


Exactly. We are talking having a cheap box with a standard VHF antenna supplanting
radar. That's big. We are talking about having "radar" displays at every small
airport.

G Farris wrote On 12/04/05 02:32,:

I am aware of that, and I'm certainly not pretending to be "inventing"
something here. Just seems to me that before we went whole-hog GPS we were
seeing smart loran and RNAV boxes that could integrate a number of source
signals. Then we threw it all away to go GPS. I think we could develop a smart
interim solution using a mix of GPS, eLoran (which has come a ong way since we
all turned our backs on it) and traditional graound-based nav aids.

Get rid of the VOR's? Sure. Do it hastily and without forethought? That would
be foolish, in my opinion.

GF


Because you are talking about using a single, much less reliable ground based
signal to back up a system that uses dozens of redundant, much more reliable
signals (higher frequency, line of sight that cannot be obscured by mountains).

It amazes me that intelligent pilots can regard GPS as if it were one single
station on one single frequency. This VOR = GPS thing is all in your mind.
Its like saying that one walkie talky equals the entire cell phone system.

Newps wrote On 12/04/05 08:48,:

john smith wrote:

Does LSA require and electrical system?


No.


I have yet to see a handheld transponder for GA.


And you won't. The new system eliminates transponders.


There has to be a transmitter of some type installed to broadcast.


From: http://www.gisdevelopment.net/techno...s/ma04082c.htm


You still will not see it available as a handheld system.
It will have to be installed and certified in an aircraft with an
approved electrical system.


No, ADS-B will be available as a handheld device.


I peversely agree. The FAA won't like it, but reality will make it
come true, because eventually having one with you while flying an
ultralight is going to be a good idea.

Hell, someday they are going to put ADS-B transmitters ontop of
radio towers. It will happen.

Thomas Borchert wrote On 12/05/05 04:45,:
G,


The Europeans are ready to use every available argument (the threat of the US
unilaterally invoking Selective Availability being their favorite) to
denigrate GPS, so as to pave the way for their competing system, Galileo.
They see a huge market potential in a pay-per-use system, designed to
generate windfall profits for the usual group of sweetheart companies, but
they are threatened by the free availability of GPS. They have to denigrate
it to get funding for their system, then find regulatory means to make GPS
receivers illegal.



Exactly. Sadly.


I'm sure the next step is to get the USA to fund it :-)

Roy Smith wrote On 12/05/05 07:01,:
G Farris wrote:


The Europeans are ready to use every available argument (the threat of the US
unilaterally invoking Selective Availability being their favorite) to
denigrate GPS, so as to pave the way for their competing system, Galileo.


I can't blame them. If I lived outside the US, I would be pretty wary
about depending on a navigation system which I had no control over. It's
the same battle that happening now with control of the Internet.

The "battle for control of the Internet" is far more about China wanting to
censor it than any freedom issue.

G Farris wrote:

I disagree. I think there is a more important problem. If you're flying
direct
routes and RNAV with GPS as primary(and only random route) source of
navigation, in the event of a GPS signal degradation, you have a bit of a
balancing act to do to get back to "legacy" navigation. If you're in the
middle of the Great Plains that's no issue, but if you're shooting an
approach
to White Plains it may be.

Wouldn't you be in the same situation if you were shooting an ILS
approach and the localizer went U/S?

Not at all. The missed approach is part of the procedure, and if you've done
good you have it all dialled-in, briefed and ready to fly. No transitioning to
do.

The the missed for a GPS overlay approach uses a ground-based navaid,
then you still have it dialed in and ready to go; if the missed for a
ground-based-navaid approach uses the same navaid, then you still have
a problem.


All the best,


David

I can't find the link right now, but there is an all electronic (no
spinning gyro) attitude instrument available for experimental aircraft
in the $1200 range. Essentially replaces an AI or TC. Has a yaw
indicator and lots of other functionality. It is square but fits in a
round hole (no one makes round led screeens). Non - TSO of course. Not
sure of the exact technology behind it, but it works and is not any
more expensive than a traditional all electric AI.