Setting altimeters with no radio

Notice how IFR training doesn't include procedures if your altimeter
fails. Reason?

Jim Stewart wrote:
Doug wrote:

No one has mentioned using the manifold pressure guage as an altimeter.

Or how many times your ears popped (:

Mxsmanic wrote:
Newps writes:

A satellite is a satellite. The information that spews forth from that
satellite is just information that my receiver makes use of.

Hardly. GPS satellites are very special, as are the transmissions
they produce. WAAS satellites are just commercial satellites
transmitting fairly ordinary information in fairly ordinary ways.

WAAS consists of approximately 25 ground reference stations positioned
across the United States that monitor GPS satellite data. Two master
stations, located on either coast, collect data from the reference
stations and create a GPS correction message.

This correction accounts for GPS satellite orbit and clock drift plus
signal delays caused by the atmosphere and ionosphere. The corrected
differential message is then broadcast through one of two geostationary
satellites, or satellites with a fixed position over the equator. The
information is compatible with the basic GPS signal structure, which
means any WAAS-enabled GPS receiver can read the signal.

A WAAS-capable receiver can give you a position accuracy of better than
three meters 95 percent of the time.
http://www.garmin.com/aboutGPS/waas.html
-----

- gpsman

DR wrote:

On my 12 channel boat GPS I see a
HDOP of ~1m these days.

HDOP is unitless.

Good point. I'm sorry that I was being so loose. But you could descibe
the 1 sigma dilutuion of precision in terms of distance at your position
and time -right? I was actually amazed to see that my Ryatheon GPS put
my boat right in the center of the correct dock -implying 2m accuracy
(or better)!

Cheers MC

I have to think about it. Position accuracy is given by this generic
equation:

DOP x UERE x 2 = position accuracy (2 sigma or 95%) where UERE is the
combination of the space and user equipment error sources.

Ron Lee

Travis Marlatte wrote:
"Mxsmanic" wrote in message
...
It does indeed measure angles, rest assured. Of course, it does a lot
more than that.

It is complex. But it's not triangulation.

"GPS receivers use triangulation of the GPS satellites' navigational
signals to determine their location."
http://msl.jpl.nasa.gov/Programs/gps.html

A GPSr does not measure angles, it measures timing and ranging, as in
"NAVSTAR" (NAVigation Signal Timing And Ranging).

"In addition to knowing the distance to a satellite, a receiver needs
to know the satellite's exact position in space; this is known as its
ephemeris. Each satellite's signal transmits ephemeris information
about its exact orbital location. The GPS receiver uses this
information to precisely establish the position of the satellite."
http://www.lerc.nasa.gov/WWW/MAEL/ag/gps.htm
-----

- gpsman

Doug wrote:
No one has mentioned using the manifold pressure guage as an altimeter.


Because you can't do it in the air, unless you stop the engine first.

"gpsman" wrote in message
ups.com...
Travis Marlatte wrote:
"Mxsmanic" wrote in message
...
It does indeed measure angles, rest assured. Of course, it does a lot
more than that.

It is complex. But it's not triangulation.

"GPS receivers use triangulation of the GPS satellites' navigational
signals to determine their location."
http://msl.jpl.nasa.gov/Programs/gps.html

A GPSr does not measure angles, it measures timing and ranging, as in
"NAVSTAR" (NAVigation Signal Timing And Ranging).

"In addition to knowing the distance to a satellite, a receiver needs
to know the satellite's exact position in space; this is known as its
ephemeris. Each satellite's signal transmits ephemeris information
about its exact orbital location. The GPS receiver uses this
information to precisely establish the position of the satellite."
http://www.lerc.nasa.gov/WWW/MAEL/ag/gps.htm
-----

- gpsman


I had to look up the definition of triangulation. I did not realize that it
included range finding as a technique. I stand corrected. GPS receivers
don't measure angles.

-------------------------------
Travis
Lake N3094P
PWK

No one has mentioned using the manifold pressure guage as an altimeter.
Because you can't do it in the air, unless you stop the engine first.

Well, you can, sort of, but it probably won't help much. At full
throttle, the manifold pressure will max out at a value that has the
same relationship to altitude as an altimeter. I vaguely recall it's
something like an inch loss per thousand feet high.

Jose
--
"Never trust anything that can think for itself, if you can't see where
it keeps its brain." (chapter 10 of book 3 - Harry Potter).
for Email, make the obvious change in the address.

On a normally aspirated engine, the MAP will be about 1 inch
per thousand feet from 29.92 plus about 1.5 inches for
induction losses on a running engine. So if the maximum
observed MAP is 23 inches, you are at about 5,500 feet
pressure altitude [give or take a thousand feet.
Turbocharged engines make such a check impractical.



"Jose" wrote in message
news | No one has mentioned using the manifold pressure guage
as an altimeter.
| Because you can't do it in the air, unless you stop the
engine first.
|
| Well, you can, sort of, but it probably won't help much.
At full
| throttle, the manifold pressure will max out at a value
that has the
| same relationship to altitude as an altimeter. I vaguely
recall it's
| something like an inch loss per thousand feet high.
|
| Jose
| --
| "Never trust anything that can think for itself, if you
can't see where
| it keeps its brain." (chapter 10 of book 3 - Harry
Potter).
| for Email, make the obvious change in the address.

Doug wrote:

No one has mentioned using the manifold pressure guage as an altimeter.

Or how many times your ears popped (: