INS Alignment at Sea

42 knots was no problem on the big "E" It is my understanding that it has the
highest max speed of all carriers due to its longer waterline and narrower
beam. The snipes told me the limits are the number of twists they can put into
the shafts or the bow being crushed by being forced through the water. I have
seen 50+
Alignments. I went from the A-6 were we learned all the manutia of alignments
to the Prower were it was pretty much turn it on and it works.
First thing is a level then the next is True North since all platform torques
are based on that.
Remember that the Intruder was a weapons delivery platform so it must derive
its position to the nats ass. In the Prowler if it was 1000 feet off no big
deal.
I used to laugh at the 129 cone heads trying to fix True north since it had to
compute TN to milli radians for the allignmet to work. Here he was ham handing
a degree or 2. If the platform alligned the TN was going to be correct.

On the boat Sins cable was prefered then the RF alignment but the first things
that the platform has to do is go to local level then True North then start to
factor in the ships movement. In the A-6 we got a software upgrade (85 or so)
and if everything worked it was 9 minutes to allign. Sometimes the AT
troubleshooter would start the alignment especially if the BN scheduled to fly
the plane was a little weak. I recall 20 minutes to be the norm. I think the
Prowler was faster.

Sparky

Gary,

I was intersted to hear that the alignments would go "south" during the
catapult stage. Did air alignments work out ok as I realize you were getting
lat/long info from another aircraft but can't imagine having the time to
carry out the process.

In the early 1970s A-6A, inflight alignments of the AN/ASN-31 inertial
navigation system were both common and more often than not "reasonably"
accurate - at least for providing a stable reference of aircraft heading,
attitude, and horizontal and vertical velocities. The A-6A/B/C NATOPS
referred to these as "rough alignments".

("Reasonably accurate" = accurate enough to complete the mission
successfully.)

An inflight alignment of the ASN-31 required true heading (which one got
from the magnetic wet compass and then adjusted for local magnetic
variation), aircraft velocity and the latitude of the inflight alignment
starting point. B/Ns made it a point to write down the ship's current
LAT/LONG during shipboard (SINS) alignments, since the cat shot was the most
likely flight phase for an inertial dump and the inflight alignment could be
started almost immediately after launch.

Entering the LONG in addition to the other three parameters above usually
produced a fix for the inertial accurate to +/- 3 to 5 miles, depending upon
the distance traveled by the ship between SINS alignment and inertial dump.
(There was also a fair amount of dead reckoning thrown in here as well,
using inputs like ship's estimated course and speed changes since SINS
alignment.)

In the A-6A, the real keeper of position was the AN/ASQ-61 ballistics / nav
computer and not the ASN-31. It obtained its initial reference from the
ASN-31's aligned position, and took as inputs throughout the flight the
velocities generated by the ASN-31. The ASQ-61 also took inputs from the
aircraft's pitot-static system, radars, and the knobology activities of the
crew.

During the mission the crew would update the ASQ-61's position with fixes
off the search radar, or visually if crossing a known position like the CIP.
These updates minimized computed position errors.

At least that was how it was SUPPOSED to work. g

As Woody and others point out things are much different today, especially
the need for accurate posit inputs into the smart weapons we didn't have
back in the early 1970s.

--
Mike Kanze

436 Greenbrier Road
Half Moon Bay, California 94019-2259
USA

650-726-7890

"When was the last time in world history in which 'suicide' and 'martyrdom'
were the code of enlightened action admired by any society?"

- Roy Fassel (WALL STREET JOURNAL, 10/27/03)


"Gary Watson" cf104@ihate spam.shaw.ca wrote in message
news:CHbpb.260660$6C4.185337@pd7tw1no...
[rest snipped]

On 11/2/03 8:42 PM, in article ,
"Elmshoot" wrote:

42 knots was no problem on the big "E" It is my understanding that it has the
highest max speed of all carriers due to its longer waterline and narrower
beam. The snipes told me the limits are the number of twists they can put into
the shafts or the bow being crushed by being forced through the water. I have
seen 50+
Alignments. I went from the A-6 were we learned all the manutia of alignments
to the Prower were it was pretty much turn it on and it works.
First thing is a level then the next is True North since all platform torques
are based on that.
Remember that the Intruder was a weapons delivery platform so it must derive
its position to the nats ass. In the Prowler if it was 1000 feet off no big
deal.
I used to laugh at the 129 cone heads trying to fix True north since it had to
compute TN to milli radians for the allignmet to work. Here he was ham handing
a degree or 2. If the platform alligned the TN was going to be correct.

On the boat Sins cable was prefered then the RF alignment but the first things
that the platform has to do is go to local level then True North then start to
factor in the ships movement. In the A-6 we got a software upgrade (85 or so)
and if everything worked it was 9 minutes to allign. Sometimes the AT
troubleshooter would start the alignment especially if the BN scheduled to fly
the plane was a little weak. I recall 20 minutes to be the norm. I think the
Prowler was faster.

Sparky



Sparky,

The reason for the difference is that the Prowler used the same ASN-130 that
the early F/A-18 used. In fact, I think it has been upgraded to ASN-139
lately.

--Woody

On 11/3/03 8:27 AM, in article ,
"Pechs1" wrote:

cf- I am conversant with commercial INS and old military INS (LN3) and know
that
the best alignment occurs when the a/c is stationary. Now my question.
How is the INS aligned at sea on a carrier that is moving at 30kts? BRBR

geeezzz, INS, GPS....what a bunch of girls..
P. C. Chisholm
CDR, USN(ret.)
Old Phart Phormer Phantom, Turkey, Viper, Scooter and Combat Buckeye Phlyer

Ouch. Here I thought I was a stud. |:-)

Two axis VGI, TACAN and ADF, cockpit lighting by afterthought, single
engine, "interesting" dirty flying qualities. A night in the life I'm glad
is far behind me.

OBTW, T-45 GINA (integrated GPS/INS) has no SINS cable. Uses GPS in the
ship alignment mode and must calculate ship's movement null factor (whatever
the hell that is). From power-up: Full alignment on concrete = 3 minutes.
Full alignment in flight = 6-7 minutes. Full alignment on flight deck =
16-24 minutes. Go figure.

R / John

"Doug "Woody" and Erin Beal" wrote in message
...
On 11/3/03 8:27 AM, in article
,
"Pechs1" wrote:

cf- I am conversant with commercial INS and old military INS (LN3) and
know
that
the best alignment occurs when the a/c is stationary. Now my question.
How is the INS aligned at sea on a carrier that is moving at 30kts?
BRBR

geeezzz, INS, GPS....what a bunch of girls..
P. C. Chisholm
CDR, USN(ret.)
Old Phart Phormer Phantom, Turkey, Viper, Scooter and Combat Buckeye
Phlyer

Ouch. Here I thought I was a stud. |:-)

We "girls" led more than one little lost lamb of a fighter through the goo.
And gave them gas as well.

--
Mike Kanze

436 Greenbrier Road
Half Moon Bay, California 94019-2259
USA

650-726-7890

"When was the last time in world history in which 'suicide' and 'martyrdom'
were the code of enlightened action admired by any society?"

- Roy Fassel (WALL STREET JOURNAL, 10/27/03)


"Pechs1" wrote in message
...
cf- I am conversant with commercial INS and old military INS (LN3) and
know
that
the best alignment occurs when the a/c is stationary. Now my question.
How is the INS aligned at sea on a carrier that is moving at 30kts?
BRBR

geeezzz, INS, GPS....what a bunch of girls..
P. C. Chisholm
CDR, USN(ret.)
Old Phart Phormer Phantom, Turkey, Viper, Scooter and Combat Buckeye
Phlyer

On 11/3/03 2:17 PM, in article , "John
Carrier" wrote:

Two axis VGI, TACAN and ADF, cockpit lighting by afterthought, single
engine, "interesting" dirty flying qualities. A night in the life I'm glad
is far behind me.

OBTW, T-45 GINA (integrated GPS/INS) has no SINS cable. Uses GPS in the
ship alignment mode and must calculate ship's movement null factor (whatever
the hell that is). From power-up: Full alignment on concrete = 3 minutes.
Full alignment in flight = 6-7 minutes. Full alignment on flight deck =
16-24 minutes. Go figure.

R / John


John,

Hornet EGI (Embedded GPS/INS) produces fairly similar numbers--slightly
longer for the concrete alignment (5-6 mins for the full 0.5 OK). Using the
GPS to generate POS/AINS (aided nav) is at the pilot's option.

GPS IFA's in flight take about 6-8 minutes. CV on-deck alignments are about
12-15 or so depending. Although on my last cruise I found myself
occasionally wrestling the jet through 3 alignments before getting the third
one to take (about a 25 minute evolution) with the Boss querying me for a
status as I took the third one.

--Woody

Boy do I feel old. In the true bomber days of the A-3 we actually
carried a chronometer and a bubble sextant, shot the stars and got a
three-point fix. Ditto the sun and LAN local apparent noon. Plus a
"potty" of sorts and a working p-tube. Box lunches were in order, 3 or 4
hour cycles were the norm (I even flew once with Charlie James refueling
from A-4 tankers for eight hours.) We'd estimate surface winds by
checking the sea, and we even did pressure pattern navigation out to
Bermuda.

What's all this about gyros and other gizmos? (OK, Whidbey started
getting ASB-7 c. 1961 while we on the east coast stuck with the modified
Norden ASB-1a bombing system.)
Joel McEachen VAH-5 (Mushmouths)

Mike Kanze wrote:

We "girls" led more than one little lost lamb of a fighter through the goo.
And gave them gas as well.

Old Girls??
Try doing a "must make it" approach into one of our winter wonderland
seismic strips on Melville Island NWT (That's just past Resolute Bay for
those that don't know the North) with 100 + nuthing in snow using an ****ty
DG and a very good set of Eyeballs, or motoring around the Beaufort Sea with
ADFs and a very erractic Omega. Of course this wasn't combat as no one
except the locals were shooting at us when we were in Alaska flying out of
Barrow. (wait a minute isn't that the same thing?) I found a few 30-30 holes
in our Aztec so I guess that applies
Sum of us old Farts really like using the new stuff after those days

GW
EX RCAF with 20+ years in the North where men are men and Polar Bears are
always hungry



"Doug "Woody" and Erin Beal" wrote in message
...
On 11/3/03 8:27 AM, in article
,
"Pechs1" wrote:

cf- I am conversant with commercial INS and old military INS (LN3) and
know
that
the best alignment occurs when the a/c is stationary. Now my question.
How is the INS aligned at sea on a carrier that is moving at 30kts?
BRBR

geeezzz, INS, GPS....what a bunch of girls..
P. C. Chisholm
CDR, USN(ret.)
Old Phart Phormer Phantom, Turkey, Viper, Scooter and Combat Buckeye
Phlyer

Ouch. Here I thought I was a stud. |:-)

"J. McEachen" wrote in message

Boy do I feel old. In the true bomber days of the A-3 we actually
carried a chronometer and a bubble sextant, shot the stars and got a
three-point fix. Ditto the sun and LAN local apparent noon. Plus a
"potty" of sorts and a working p-tube. Box lunches were in order, 3 or 4
hour cycles were the norm (I even flew once with Charlie James refueling
from A-4 tankers for eight hours.) We'd estimate surface winds by
checking the sea, and we even did pressure pattern navigation out to
Bermuda.

YOU feel old?!?!?!?!?!

Hell, I used to teach the MK6 Plotting Board to S2 types as FASOTRAGRULANT
QUONSET & CECIL in '72-'73!!!!! :-)

My primary traning film was made during WWII (and that's a No ****; we were
ordered to destroy it in 1973 due to references to "Japs" and other
politically incorrect language and immagery; we kept using it until the S2
program shut down).

What's all this about gyros and other gizmos? (OK, Whidbey started
getting ASB-7 c. 1961 while we on the east coast stuck with the modified
Norden ASB-1a bombing system.)
Joel McEachen VAH-5 (Mushmouths)

The good old Stoof had the ASN-30A. It was an electro-mechanical plotter
that got fed by a TAS computer, gyro, and doppler radar. The warranty was
good for 3 traps and/or arrestments. Then it would give up the ghost and it
was back to the ouija board (MK6). And, of course, the polar plotting
charts used by the 'Shoes (I can't remember the designation). Trying to do
Julie plotting at 100' using dividers with string attached to calculate A+B
elipses was interesting work.

Bill Kambic

If, by any act, error, or omission, I have, intentionally or
unintentionally, displayed any breedist, disciplinist, sexist, racist,
culturalist, nationalist, regionalist, localist, ageist, lookist, ableist,
sizeist, speciesist, intellectualist, socioeconomicist, ethnocentrist,
phallocentrist, heteropatriarchalist, or other violation of the rules of
political correctness, known or unknown, I am not sorry and I encourage you
to get over it.