IPBFacebook



POSTS MADE TO THIS FORUM ARE THE SOLE RESPONSIBILITY OF THE AUTHOR AND DO NOT NECESSARILY REFLECT THE VIEWS OF PILOTS FOR 911 TRUTH
FOR OFFICIAL PILOTS FOR 9/11 TRUTH STATEMENTS AND ANALYSIS, PLEASE VISIT PILOTSFOR911TRUTH.ORG


DIGITAL DOWNLOADS

WELCOME - PLEASE REGISTER OR LOG IN FOR FULL FORUM ACCESS ( Log In | Register )

3 Pages V   1 2 3 >  
Reply to this topicStart new topic
Aviation Auto Pilots

SanderO
post Jan 21 2011, 12:55 PM
Post #1





Group: Troll
Posts: 1,174
Joined: 23-December 09
From: NYC
Member No.: 4,814



I am familiar with marine recreational auto pilots and how they work. Marine navigation is a 2 navigational problem and considers the curve of the globe as flat for short distances. Long distance will require constant change of compass heading and trace a great circle as opposed to a rhumb line course. I understand how the heading to waypoint is calculated and updated and corrections applied to the rudder. Lots of number crunching and feedback.

Aviation however introduces a third axis - elevation. This is controlled by flaps and so forth, but not being a pilot I am not familiar with how this all works. I do understand that if you change the airfoil shape on one wing and not the other the plane will turn or the tail flap is moved to make a turn. I don't need a flying lesson but I can see the complexity in 3D autopilot control with so many means to control turns and climbs or descent.

My question is when did these auto pilot systems go operational for large planes?

Did this come after the DOD turned off selective availability of GPS or was it accurate enough with the SA on? Did / Do aviation GPS use DGPS or land stations for increased accuracy? Do the land based signals provide 2 D or 3 D data?

How are aviation auto pilots used? Are the navigation from waypoint to waypoint set by the pilot? Does this include altitude as well? Or are the waypoints established by ground based beacons?

Do pilots program headings or waypoints into their APs?

When were APs certified for landing commercial airliners?
Go to the top of the page
 
+Quote Post
amazed!
post Jan 22 2011, 11:56 AM
Post #2





Group: Extreme Forum Pilot
Posts: 4,017
Joined: 14-December 06
From: Fort Pierce, FL
Member No.: 331



Autopilots have been evolving for decades. Bill Lear of Learjet fame was one of the early pioneers.

The early ones were merely "wing leveler" type--they could keep the wings level for the pilot. That would be 2 axis AP. Eventually pitch control was incorporated so that it could control 3 axes and hold altitude too.

Even by the 70's or so they had AP that could track defined navigation courses, based upon at that time courses defined by land based nav radios such as VOR. The higher end types on the airliners and high end private aircraft could track defined course by various nav devices including Omega (now gone), inertial reference and eventually GPS.

For many years now the high end AP can track the Instrument Landing System (ILS) with both horizontal and vertical guidance. High end aircraft today have auto throttles and the AP can land the plane. All the pilot need do is apply the brakes on rollout.

The DOD has tinkered with SA ever since GPS came out, turning it off and on as they saw fit. I think that today SA is on full time.
Go to the top of the page
 
+Quote Post
bobcat46
post Jan 22 2011, 12:34 PM
Post #3





Group: Private Forum Pilot
Posts: 119
Joined: 27-December 06
From: Hobe Sound, FL
Member No.: 382



There are autopilots and then there are remote control devices and both have been discussed on this forum. Based on my knowledge of both, information presented on both, and information on this forum and from commercial pilots that I have talked to, the planes that crashed into the WTC buildings could have only been flown by autopilot to assure a successful mission. Therefore, I believe that the false flag attack was conducted using a combination of the two. The attack planes were taken off using remote control, until they caught up with the the commercial flights and then changed their transponder identities to take the place of the commercial flights. Then, the attack planes were turned toward the target hundreds of miles away with a pre-programmed flight plan to fly into the buildings at a certain altitude using a GPS waypoint as the target. Since they seemed to accelerate just prior to impact, the throttle control may have still been under remote control. But then again, that also might have been pre-programmed.

What happened to the commercial flights? I don't think we will ever find that out, and if we do, they will never be found as they were totally destroyed as "collateral damage." Remember, the people that were behind 9/11 are the same sick bastards that sent our soldiers into two useless wars that have killed over 5,000 of our brave soldiers, so a few hundred people on the planes were nothing to them. I just hope there is justice for these crimes at some point in time.
Go to the top of the page
 
+Quote Post
SanderO
post Jan 22 2011, 01:26 PM
Post #4





Group: Troll
Posts: 1,174
Joined: 23-December 09
From: NYC
Member No.: 4,814



I have read about various scripts to substitute planes in mid flight. The idea is that the commercial flight is "disposed of" somehow after its transponder is turned off. The second plane turns on an identical transponder as the commercial plane's transponder is switched off.

This is presumably meant to fool ATC tracking into "believing" or displaying a continuous flight from a single plane - a stealth swap so to speak.

Here's my point:

The flight data on ATC screens and tracking radar is SUPPOSED to be coming from transponders and radar returns received at various antenna and tracking stations and then relayed via land lines to the ATC center and processed into displays.

Why bother to fiddle with transponders at all, when you can simply INSERT ANY DATA DESIRED INTO THE SYSTEM AS FOLLOWS:

false radio / radar signals "aimed at receiving antennas"
false data inserted via the land lines

From the get go the actual transponders are turned off or jammed and the false data inserted.

The ATC operators have no idea and assume they are tracking REAL targets.

Remember how the ATC "tapes" were destroyed? Could that have identified the source of the data?
Go to the top of the page
 
+Quote Post
amazed!
post Jan 22 2011, 02:21 PM
Post #5





Group: Extreme Forum Pilot
Posts: 4,017
Joined: 14-December 06
From: Fort Pierce, FL
Member No.: 331



Yes, to supplement and control the autopilot, some sort of computer system is installed on the airplane, giving full control of the aircraft to some person sitting at a computer terminal.

And we know that in many if not all 'training exercises', the displays that ATC controllers see are spoofed. The entire system is tricked, in the name of training exercises. This is, after all, a digital world where youngsters play video games.

And because of that, I say "why even load the airplane with pax?" What's the advantage if you have the power to spoof the radar record? Fake targets can be generated, and the record will show thus and so, as for the public perception of what any given airplane did that day.

My bet is that the "flights" were never boarded.
Go to the top of the page
 
+Quote Post
IslandPilot
post Jan 22 2011, 03:15 PM
Post #6





Group: Core Member
Posts: 170
Joined: 16-June 10
From: Western Lake Erie, Ohio, Michigan, Canada
Member No.: 5,099



QUOTE (SanderO @ Jan 21 2011, 11:55 AM) *
I am familiar with marine recreational auto pilots and how they work. Marine navigation is a 2 navigational problem and considers the curve of the globe as flat for short distances. Long distance will require constant change of compass heading and trace a great circle as opposed to a rhumb line course. I understand how the heading to waypoint is calculated and updated and corrections applied to the rudder. Lots of number crunching and feedback.

Aviation however introduces a third axis - elevation. This is controlled by flaps and so forth, but not being a pilot I am not familiar with how this all works. I do understand that if you change the airfoil shape on one wing and not the other the plane will turn or the tail flap is moved to make a turn. I don't need a flying lesson but I can see the complexity in 3D autopilot control with so many means to control turns and climbs or descent.

My question is when did these auto pilot systems go operational for large planes?

Did this come after the DOD turned off selective availability of GPS or was it accurate enough with the SA on? Did / Do aviation GPS use DGPS or land stations for increased accuracy? Do the land based signals provide 2 D or 3 D data?

How are aviation auto pilots used? Are the navigation from waypoint to waypoint set by the pilot? Does this include altitude as well? Or are the waypoints established by ground based beacons?

Do pilots program headings or waypoints into their APs?

When were APs certified for landing commercial airliners?

SO, you say you don't want a "flying lesson", then you ask questions requiring an advanced "course" of instruction to answer properly. I'll try my best to provide the answers I think you are "looking" for.

Autopilot systems have been used in large (and small) aircraft ever since WWII. The first systems used gyroscopic inputs for "wing leveling", and "maintaining a constant heading"... they basically used "electro-mechanical" devices to provide control inputs to aircraft control surfaces, normally used to "trim" and aircraft in flight. This can involve electric, hydraulic, or vacuum actuated "servo" mechanisms to accomplish.

With the advent of "solid state" electronics, the "state of the art" progressed rapidly, similar to what you may be familiar with in boating. Avaition has had low frequency "radio direction finding" stations, called ADF for a very long time. Eventually, other ground based, highly directional, radio frequency signal systems were developed to provide "guidance" for aircraft navigation and autopilot systems.

Most of these systems provided "horizontal"; 2D navigational information in the form of "Course Deviation Indicators" which were essentially "positive" or "negative" "voltage variations" driven by appropriately "demodulated" and amplified radio signals from the ground. These "variable voltages" can be displayed by a "voltmeter" indicator on the instrument panel, that the pilot uses to "steer" his airplane with, OR they can be fed into an electronic black box "interface" to provide inputs to aircraft control system servos.

One system of very precise directional radio signals, called ILS (Google ILS, or Instrument Landing System for more info) generates precision radio signals to a SPECIFIC RUNWAY in both the horizontal and VERTICAL planes.

Before the advent of GPS, the ILS system was the GOLD STANDARD for the precise guidance of an aircraft to a specific location on the ground in bad weather. In the "early days" of ILS systems, pilots usually flew their aircraft "by hand" following instrument panel indications to within 200 feet of the ground.

Commercial aircraft were not even legally allowed to BEGIN such an ILS Approach procedure if the reported visibility was less than 1/4 mile, or the ceiling was less than 200 ft. The pilot was "expected" to be able to SEE the runway, (and the ILS associated HIGH INTENSITY LIGHTING systems) before "normal" manuevering to a safe landing on the runway.

The ILS guidance is so precise, that it is possible to make landings without having any visible contact with the runway before the aircraft is on the ground. This happened many times, in "emergency" situations. One "story" tells about a bomber pilot who landed in thick fog, but he wasn't able to "see" where to "taxi" to after he came to a complete stop. They sent out a JEEP to guide him, but the jeep collided with his nose landing gear, which had his nosewheels straddling the runway centerline stripe.

As aircraft autopilot systems improved, they were able to "capture" and "follow" precise ILS radio signal inputs. The "technology" began to "overrun" the "legal interpretations" of the 1/4 mile visibility and 200 ft ceiling "minimums". Flight crews and aircraft systems kept improving, as well as ground based weather reporting equipment at the ILS runway threshold.

The "FAA regulatory system" worked to "catch up" with the capabilities of the new technology, which included more sophisted autopilot systems, radar altimeter installations in the aircraft, and a high level of "cockpit management" and crew coordination procedures, that justified "lower" weather minimums for these ILS based approachs. Under specificed conditions, Catagory II and Catagory III, were approved down to near "ZERO - ZERO" conditions. This was back in the 1970s.

A "problem" with decreasing minimums in a "heavy" commercial airliner, occurred upon initiating a "GO AROUND" when the pilot couldn't see the runway at the "Decision Height". The stabilized aircraft descent profile couldn't be "arrested" immediately after the GO AROUND was initiated... allowing the aircraft to (legally) "drift below" the minimum "Decision Height"... sometimes making contact with the runway... before it started to climb away.

The guys back at Boeing and Douglas, weren't sitting on their hands during this time period. They were designing their aircraft flight control systems to have increased "compatability" and "integration" with a "programmable autopilot" system. This led to the development of aircraft "auto-land" systems, which became FAA approved for certain Aircraft. I'd say "civilian auto-land" capability came out in the late 1980s. The capabilities of CIVILIAN Aircraft related electronics, seems to follow MILITARY aircraft developments by about 10 years.

Getting back to these questions:
QUOTE
How are aviation auto pilots used? Are the navigation from waypoint to waypoint set by the pilot? Does this include altitude as well? Or are the waypoints established by ground based beacons?

Do pilots program headings or waypoints into their APs?

There are TWO basic components related to autopilot control systems.
The FIRST component generates "navigational" COURSE DEVIATION inputs... which can be selected from different "sources" or "modes"....
that are transmitted to a SECOND group of components to manipulate the aircraft "flight controls", through connections to the autopilot "black box".

Pilots can SELECT several from different "modes", to supply the CDI signals to operate the aircraft autopilot system.

"HEADING" mode can be selected, as is usually done when being "vectored" by a ground controller; and the autopilot will turn to, and maintain the HEADING the pilot has "dialed in" to his cockpit display.

Various "NAV" modes can be selected for the aircraft to "track" various "raw" ground based radio signal "navigation aids" (NAVAIDS)... including ADF??, VOR, TACAN (military), VORTAC, LOC, ILS, GS, MLS, LORAN C (now obselete). These "ground based", "point-to-point" navigational sysetms are used to follow published "airways" in a "controlled" airspace environment.

When DME (TACAN) capability became available, it was possible to determine DISTANCE between an aircraft and various VORTAC stations on the ground.
By combining DME (distance measuring equipment) capability, with emerging "MICROPROCESSOR" technology, the RNAV system of "area navigation" open up a whole new system for more DIRECT navigation between specificed and published "RNAV WAYPOINTS".

Of course, RNAV databases were continually being updated and improved, so the processing boxes required methods for UPDATING their "memories", as well as allowing new "user" data entries. This is usually accomplished with a "memory card" of some kind.

LORAN C seemed to be the ULTIMATE Navigational "CAT's MEOW" for aerial navigation in the late 1980's. All you needed to do was to connect two power supply wires, and an antenna, and you could fly direct to anywhere you wanted, just by following the CDI indications on the front of the box. (it was more complex, but fairly easy, to connect the "optional" CDI wiring to the aircraft autopilot system.). As long as the Sun was shining, Loran C was GREAT. In bad weather, IT SUCKED! The Loran C radio frequencies were USELESS due to "precipation static" picked up by their antenna systems.

GPS became the "ultimate" answer, for campers, boaters, pilots, lost motorists, cell phone users, etc.. etc. GPS inputs now allow "non precision" approaches to airports, without radio NAVAID capabilities, in marginal weather. Precision GPS approaches are now "approved" down to comperable "ILS MINIMUMS" when ground based "differential" transmissions (DGPS/WAAS) are available.

Before moving on to 3D Navigation, we have established that 2D navigational "deviation signals" are provided from several "pilot selectable" sources, which are then fed into the "aircraft autopilot system". Each AIRCRAFT AUTOPILOT SYSTEM is UNIQUE to that specific aircraft "make and model". How it processes the raw CDI inputs to manipulate aircraft flight controls, for 3 axis pitch, roll, and yaw OUTPUTS, that include "feedback" mechanisms is PFM (Pure F... Magic) according to one Avionics Guru I know. All of these systems are different and individually tailored and tested, before being "Approved" for use in a commercial aircraft. Bottom line.... Navigation "deviation" Signals are provided to an aircraft Autopilot system, that can be used for the precise control of an aircraft's flight path.

The autopilot system normally makes "small", "limited" corrections, through the aircraft "trim control" system. Autopilot inputs for control surface "deflections" and "forces" have specific "limitations". They do not normally "actuate" whole flight control surfaces like Ailerons, Rudder, or Elevator. They cannot cause "ABRUPT" control surface movements, or make "SUDDEN" changes in an aircraft's flight path.

In ALL cases, PILOT CONTROL INPUTS, MUST be able to OVERPOWER any ADVERSE INPUT that a "defective" Autopilot may be capable of making. The autopilot must immediately "DISENGAGE" when the pilot wants it to. Also, if the aircraft control yoke is "bumped" while the autopilot is "engaged"... it is designed to "DISENGAGE" immediately if either pilot manually deflects the control yoke, to "counter" the autopilot inputs.

Now, back to aircraft ALTITUDE control. ALL AIRCRAFT ALTITUDES above 18,000 ft (in the USA) are "referenced" to "barometric pressure sensing" devices set to a "standard pressure" of 29.92 inches of mercury; that corresponds to a sea level barometric pressure under "standard" conditions. This is done to maintain a maximum SEPARATION between ALL AIRCRAFT using SENSITIVE BAROMETRIC INSTRUMENTS referenced to the same IDENTICAL STANDARD PRESSURE.

Below 18,000 feet, aircraft altitudes are referenced to "local" ACTUAL barometric pressure readings on the ground. Pilots and Air traffic Controllers update these altimeter "reference" settings constantly, to allow for different "weather conditions" at different locations.

In order for the GPS system to provide useable 2D navigation on the surface of the earth, it requires 3 satellites to "calculate" a SINGLE, THREE DIMENSIONAL "FIX" to establish a 2D location, even in your boat. The accuracy of the GPS system is so great, that it MUST make allowances for our "Pear Shaped Earth" to provide the necessary information for "NORMAL" navigational useage by aircraft. It does this by PFM, as I stated earlier. The GPS system CAN provide ALTITUDE information to an aircraft in flight.

This GPS generated ALTITUDE INFORMATION is NEVER used to provide input signals to an autopilot system, unless the "APPROACH" mode has been selected by the pilot. In the approach mode, the autopilot will respond to GLIDESCOPE DEVIATION SIGNALS generated by ILS Glideslope Transmitters for a specific runway, or it may respond to "virtual GLIDESLOPE DESCENT path" DEVIATION signals generated by the GPS microprocessors.

I have an OLD Handheld, GPS receiver, with a "monochrome" display, that can give me an accurate runway centerline location, including an airport elveation above sea level, at local airports in my area, without the enhanced WAAS/DGPS capability. Airport Runway navigational reference points keep getting updated, and more accurate as time goes by.

Another "capability" of aircraft navigational and autopilot flight control systems involves the capability to "PRE PROGRAM" an aircraft flight path from DEPARTURE TO DESTINATION. This capability has been available on Boeing 757 Aircraft since the early 1990s. I was a "jumpseat" passenger on such an aircraft flying between Louisville and Miami one night. Neither pilot touched any flight control after take off until the time it approached the Miami area. The copilot was busy explaining the "Glass Cockpit" capabilities of this fantastic machine, while we observed the aircraft LEVEL OFF after reaching its "PREPROGRAMED" Flight Level..... THEN.... we were ASTOUNDED when the ENGINE POWER levers came back AUTOMATICALLY to maintain the "BARBER POLE" Maximum Allowable Airspeed we had maintained throughout most of the climb.

A "message" came up through the MODE "S" transponder link from the AIRLINE OPS or Maintenance guys on ground... "WHY BARBER POLE?". Our take-off had been delayed, and the flight crew was trying to "catch up" with their normal schedule.

Applying this "KNOWLEDGE" to the events of 911, if I were a suicidal Muslim Terrorist, who didn't know much about flying an airplane, I could've taken a handheld GPS into one of the twin towers and held it next to a window around the 80th floor. Could I have "saved" those co-ordinates, to be used later as "waypoints" for a B-757 or B-767 autopilot? Probably.

And then after the aircraft was hijacked, and with the "tower waypoint" entered into the autopilot, all I would have to do is to point the airplane in the general direction, select the Autopilot "waypoint" and hit the "GO TO" button... to crash into my "target Tower". Is that possible? Maybe and Maybe NOT!

In the case of Tower 1, where an abrupt turning pull-up maneuver has been reported: I'd say "probably NOT!
In the case of the second tower, where we all "saw" something approaching the tower at a relatively constant altitude; I'd have to say Definately MAYBE...

In the case of the PentaCON.... NO WAY! NO Normal COMMERCIAL AIRCRAFT Autopilot system is gonna "capture" and "track" any kind of "flight path" into the Pentagon AFTER that TURNING MANUEVER at that speed. Of course that's just my "Armchair Pilot" opinion today. Others may "agree" or disagree.

I hope I answered your questions SO... Sorry about the Advanced "ground school lesson".
Go to the top of the page
 
+Quote Post
rob balsamo
post Jan 22 2011, 06:42 PM
Post #7



Group Icon

Group: Admin
Posts: 9,744
Joined: 13-August 06
Member No.: 1



QUOTE (IslandPilot @ Jan 22 2011, 02:15 PM) *
SO, you say you don't want a "flying lesson", then you ask questions requiring an advanced "course" of instruction to answer properly. I'll try my best to provide the answers I think you are "looking" for.

Autopilot systems have been used in large (and small) aircraft ever since WWII.



lol... when i first saw this thread,,, i thought the same exact thing...and this is loosely portrayed in "Memphis Belle" as well... then thought... wow... i'll be typing forever.

Thanks for helping out IslandPilot et al.

SanderO, try google please.

I didnt see it skimming the thread and if i missed it... also google LORAN to understand the evolution of Navigation and differences with GPS.
Go to the top of the page
 
+Quote Post
aerohead
post Jan 29 2011, 05:30 PM
Post #8





Group: Core Member
Posts: 327
Joined: 13-July 09
From: State of Heightened Awareness
Member No.: 4,476



Im sure most of you have seen this but im gonna post it anyway.
1984 NASA 720 Remote Control Crash Test. But as stated in this thread,
AutoPilot and Remote Control have been alive for a very long time.
Btw guys, didnt Hitler toy around with it ?

"Pay no attention to that man behind the curtain........"




And i cant help but wonder if this next "test" wasnt a dry run to see how
much evidence would be left after a 500 mph crash into a concrete/steel building.
Pretty obvious if you ask me. F-4's have long been a favorite of the old school gang.
And there in lies the "why" for the excessive speeds that day, imo.




And dont forget the chiefs little Northwoods plan of 1962 to remote fly
a plane over Cuban airspace and detonate it, claiming it was shot down
by a Cuban MIG, after a mid-air plane swap near Eglin, where the passenger
plane (carrying CIA operatives posing as college students) would land and the
remote controlled drone would take off and continue the illusion. This plan was
WRITTEN AND APPROVED by the Chiefs of Staff and appoved by the Chairman of the JCS- Lemnitzer.
The only obstacle was McNamara, JFK's Secretary of Defense.

Clicky- If you can handle the truth about how far the Machine
will go



This post has been edited by aerohead: Jan 29 2011, 05:31 PM
Go to the top of the page
 
+Quote Post
SanderO
post Jan 29 2011, 06:07 PM
Post #9





Group: Troll
Posts: 1,174
Joined: 23-December 09
From: NYC
Member No.: 4,814



Island Pilot,

Thanks for the lesson... Very comprehensive, understandable and informative. One point I feel was perhaps incorrect, though minor.

LORAN C and GPS do not supply position beacons if understand them correctly. They send out THEIR position and with use of a precise clock and several different "stations" or satellites the onboard computer "does the math" and computes the crossing arcs of distance to each signal.

In celestial navigation we used three stars and get what's called a three cornered hat if my dim memory is correct ...your position is inside of that triangle... smaller the triangle more precise your sightings were and your math.

Fast moving objects don't have a position because it's changing very rapidly so this is where computers do some "predicting" by comparing a series of computed positions to determine speed, heading and even rate of turn and so forth...something that a human could not do in real time.

Sailboats move slow enough that loran C and GPS are extremely accurate for their motion. Planes seem to be a whole level of more complexity especially when you add the 3rd axis into the motion computation.
Go to the top of the page
 
+Quote Post
amazed!
post Jan 30 2011, 06:17 PM
Post #10





Group: Extreme Forum Pilot
Posts: 4,017
Joined: 14-December 06
From: Fort Pierce, FL
Member No.: 331



Don't give up your day job, SanderO rolleyes.gif

Loran was decommissioned a few years back, and your view of GPS seems grossly inadequate--at least the language you use to describe it.

Fast moving objects have a trajectory or a track, however you want to look at it.
Go to the top of the page
 
+Quote Post
SanderO
post Jan 30 2011, 06:23 PM
Post #11





Group: Troll
Posts: 1,174
Joined: 23-December 09
From: NYC
Member No.: 4,814



Heck I know loran was decommissioned and everything has a position. I was awkwardly describing the problem of obtaining a fix when you are moving very fast. I know tracks and CPA and so forth. But it seems moving at jet speeds and in 3 axis makes this a very complex problem not to mention that moving through the air is different than ON the water as there are more control surfaces and so forth.

I'm not quitting my day job, but I have sailed single handed from St Maarten to NYC.... and didn't hit anything either. hahaha
Go to the top of the page
 
+Quote Post
rob balsamo
post Jan 30 2011, 08:14 PM
Post #12



Group Icon

Group: Admin
Posts: 9,744
Joined: 13-August 06
Member No.: 1



QUOTE (SanderO @ Jan 30 2011, 05:23 PM) *
I'm not quitting my day job, but I have sailed single handed from St Maarten to NYC.... and didn't hit anything either. hahaha


Yeah.. me too.. .several times, even at speeds of over 450 knots where i couldnt see anything in front of my face till 100-200 feet above the ground.

Try navigating the Great South Bay of Long Island from the Hamptons to Jones Beach, at night. Then i'll be a bit impressed.

The above routes were weekend fun for us....

Some of us even did it in tow... wink.gif

Go to the top of the page
 
+Quote Post
amazed!
post Jan 30 2011, 10:19 PM
Post #13





Group: Extreme Forum Pilot
Posts: 4,017
Joined: 14-December 06
From: Fort Pierce, FL
Member No.: 331



How far is it to Jones Beach Rob? That's quite a feat at night. handsdown.gif
Go to the top of the page
 
+Quote Post
rob balsamo
post Jan 31 2011, 12:04 AM
Post #14



Group Icon

Group: Admin
Posts: 9,744
Joined: 13-August 06
Member No.: 1



QUOTE (amazed! @ Jan 30 2011, 09:19 PM) *
How far is it to Jones Beach Rob? That's quite a feat at night. handsdown.gif



Actually, the first time we navigated those waters through the Moriches were when we picked up our Boat in Southampton and sailed it to our slip in Patchogue. Took us about 4 hours during the day... without any training whatsoever.. except the training we had as pilots and a bit of studying the Nautical Charts before-hand. Lotsa fun.. .didnt hit anything.

After that, we navigated the Great South Bay almost daily. Watch Hill and Davis Park nightly, fog, rain... didnt matter, we went.

We did Nassau County a few times... the first time... we brought along a buddy who bragged about knowing the "waters" in that area (because it was night), and he almost beached us when i kept telling him the heading doesnt match... but he insisted.

I slowed from 35 knots on top to 'step down' into a crawl... and sure enough.. .we bottomed. We made him get out and push us off. smile.gif

I still wince if i would have kept it wide open on top into the beach if i followed his instruction. What a mess that would have been.

Fun times...

I actually had something similar happen to me on approach to ILS 14 FRG, at night.. .tower closed. PCL lights.

They were calling zero/zero. I picked up the rabbit at minimums streaming off the nose... couldnt see anything else... continued 100 below as allowed.

My "Co-pilot" was in control of radios.

He picks up the lights of Route 110 and declares "Runway In sight! Turn here!"
(almost a 90 deg turn to the right...)

"What are you nuts? Thats 110!" i reply...

I hit the mic 5 times and the runway lights up like a Christmas tree.

In such a scenario, had Legge-Stutt been correct in their latest "paper", I would be a dead man and so would my "Co-pilot", along with our pax. This was around 1996-97...

Needless to say, I never since went down into the soup without making sure the lights were on if the tower was closed, even when the PNF was in charge of such a duty.
Go to the top of the page
 
+Quote Post
amazed!
post Jan 31 2011, 08:45 PM
Post #15





Group: Extreme Forum Pilot
Posts: 4,017
Joined: 14-December 06
From: Fort Pierce, FL
Member No.: 331



Live and learn. Some don't get the chance.

Good story.
Go to the top of the page
 
+Quote Post
SanderO
post Jan 31 2011, 08:57 PM
Post #16





Group: Troll
Posts: 1,174
Joined: 23-December 09
From: NYC
Member No.: 4,814



The great south bay is so shallow you can walk across most of it. YIKES. Did you try to follow east west channels? or did you have some really shallow draft? Not much to hit but I suppose a buoy of the bottom. Good show Rob! Hamptons to Patchogue could be 30-40 or more miles.
Go to the top of the page
 
+Quote Post
IslandPilot
post Feb 1 2011, 02:04 PM
Post #17





Group: Core Member
Posts: 170
Joined: 16-June 10
From: Western Lake Erie, Ohio, Michigan, Canada
Member No.: 5,099



QUOTE (SanderO @ Jan 29 2011, 05:07 PM) *
Island Pilot,
<snip>
LORAN C and GPS do not supply position beacons if understand them correctly. They send out THEIR position and with use of a precise clock and several different "stations" or satellites the onboard computer "does the math" and computes the crossing arcs of distance to each signal.

In celestial navigation we used three stars and get what's called a three cornered hat if my dim memory is correct ...your position is inside of that triangle... smaller the triangle more precise your sightings were and your math.

Fast moving objects don't have a position because it's changing very rapidly so this is where computers do some "predicting" by comparing a series of computed positions to determine speed, heading and even rate of turn and so forth...something that a human could not do in real time.

Sailboats move slow enough that loran C and GPS are extremely accurate for their motion. Planes seem to be a whole level of more complexity especially when you add the 3rd axis into the motion computation.

Au Contraire Mon Ami...SO:
Your first statement is correct; Loran and GPS systems use precisely timed signal TRANSMISSIONS from their "KNOWN" locations. The "navigation instrument" in the backpack, boat, car, or airplane is a RECEIVER, that determines its distance from multiple TRANSMITTING stations by measuring "speed of light" time delays. Once these "time delays" and "transmitter IDs" are "acquired"; they are sent to the PFMagic "microprocessing" circuitry, for some serious PFM "number crunching". After millions of tireless electrons "dance between (0) and (1) atoms to the GigaHertz beat"; when the music pauses for a microsecond, the "silicon dance hall master" records their "new seating positions", (returning them to the dance floor). Then he sends his "output" to your "cockpit" display unit.

I can use the word "cockpit" as a "Marine" term, as well as an "Aviation" term. HMMM? doh1.gif

The year before I became a "grunt" in the big "Port Huron to Mackinaw Island" sailboat race, our crew had used "Dead Reckoning" for navigation. (maybe 1979?)
But now we had "Loran C" for navigation. What an improvement that WASN'T! The little "white" box had a 10 digit(plus) LED display that intermittently gave us the 10+ digit TD Number, for at least two transmitting stations, in that particular Loran Station "chain". We then used our brand new Loran C charts, which had very light "TD lines of position", criss-crossing all over it. Then we would plot our position by "interpolating" our distance between two crossing TD lines on the map. We may have known our Lat/Long position more accurately; but it didn't keep the rest of the fleet from disappearing beyond our bow.
Eventually "Uncle Herman" got a "Basic GPS" for Christmas; no color, no moving map, just numbers, that were more useful... like, "computed Lat/Long", "heading", "bottom speed", "distance from course" (rhumb line), CDI (Course Deviation Indicator), ETA, and curiously "VMG" (Velocity Made Good).
It probably also had a "serial data port" connectable to a Laptop or autopilot we didn't have.

But NOW we can NAVIGATE! We can tell when we are stuck in dead air, if one sail, or one "tack" is ONE TENTH of Knot slower or faster. HALLELUYA!

The Loran C system, according to my memory, which may be "dimmer" than SO's; involved receiving at least 3 signals from a specific Loran C "Chain" of transmitters. One was a "Master", the others were "slave" stations. Since it "assumed" that you are on the Earth's surface, you could determine your "position" from a minimum of (2) TD readings, IF you could otherwise determine WHICH ONE of TWO valid TD solutions between Two stations APPLIED to you. If you are on a boat, the alternate "distance" solution, may very well be on land somewhere. OK?

We all thought Loran C was the Cat's Meow back then.... a helluva lot better than ADF/RDF..
But it had it's "problems", and soon became "obsolete". Today the Low Frequency ADF, and "Outer Compass Locators" are still with us (thank God); even though I have an FAA document informing us they will be completely phased out by "1990 something."

Now back to GPS: The "BOAT" version of GPS, works EXACTLY THE SAME as the "AIRPLANE" version. I'm sure the PROCESSOR GUTS in your BOAT GPS, are an EXACT MATCH to the SILLYCON GUTS in my Airplane GPS... if they have similar physical capabilities and outputs.

The NUMBER CRUNCHING - NAVIGATION SOLUTION FINDING - GUTS (Hardware), if not IDENTICAL, still WORK EXACTLY THE SAME WAY. It's Pure Fn Magic, for sure!

The only difference between a handheld MARINE GPS and a comparable AVIATION GPS today, is in the INSTALLED or AVAILABLE SOFTWARE DATABASE MEMORY CARD of CHIP! I can add full MARINE Capability to my Airplane GPS by sliding the appropriate dinky SD Data card into a slot in the battery compartment, and choose between the two on the "MENU Page" of my GPS. And I can also "insert" Marine waypoints, ie buoys and channel markers, light houses, etc... onto my Aviation Moving Map displays... (sometimes this is VERY HELPFUL in finding one's way home in "low ceilings"; but don't tell anyone I said that!)

Our GPS positions are calculated from PRECISELY determined distances FROM at least 3 or MORE GPS SATELLITES in ORBIT above the earth. The GPS Satellites are NOT LOCATED in FIXED GEOSTATIONARY orbits, above the EQUATOR. They are in precisely determined orbits, that are continually being "updated" to maintain navigational accuracy.

Please REMEMBER that they are MOVING MUCH FASTER than MY AIRPLANE or YOUR BOAT!!
GPS satellite orbits are NEITHER CIRCULAR, NOR perfectly ELIPTICAL either.
But, to keep it simple (HAH-WRONG AGAIN) let's assume that at one "moment" in time, ALL the satellites, your boat, and my airplane become FROZEN IN POSITION... IN SPACE and in TIME..

To accurately determine your present position, you will need to determine your "intersatellite distance" from at least 4 satellites. Each "distance" measurement from a single satellite will define your possible "sphere of position" having a radius "r" from the satellite, as determined by your GPS.

If you receive distance signals from 2 satellites, your location will be located on a "circle of possible" positions, where the "spheres of Position" from both Satellites "intersect".

You need to have a THIRD intersecting Sphere of POSITION, to reduce the "common solution set" down to TWO possible POINTS of POSITION. This is similar to my discussion above when you are a KNOWN distance from 2 loran stations, and it's usually "trivial" to choose which one.

If you are sailing along HAPPILY in your sailboat, (not cold, wet, and miserable, as usual), you are also sailing on the surface of a "sphere" of position, provided for FREE, by good old MOTHER EARTH!

Lucky you! "sort of". Your "GPS" could "narrow" your position on the Earth's surface, down to TWO points, with information from only 2 satellites.... and then "pick" the best one for you. But, for all its SMARTS.... it hasn't a CLUE to choose which of those two points is "right" for you and your boat.

So, it won't even TRY to calculate a position "on the surface of the earth" for you, until it calculates your precise LOCATION IN SPACE, within the known distance spheres of location FROM AT LEAST 4 GPS SATELLITES! I hope you are still with me so far... ??

The Earth's Surface, even if you are in the middle of the OCEAN, is not a FIXED SPHERICAL DISTANCE from the "CENTER" of the EARTH. Our poor Earth, it turns out, has an irregular "pear" shape. In addition, it does not have a "uniform distribution of mass" throughout.

These "problems" with the irregular shape and non-uniform masses of Planet Earth were discovered by observing the "IRREGULAR" orbits of satellites.

If the GPS Satellite Navigational system was based on the assumptions of a spherical Earth Surface, and regular ELIPTICAL satelite orbits, and if you tried to navigate your boat back to your home harbor in a fog, YOU WILL HIT THE ROCKS! And there is NOTHING SCARIER than that, because the wave action keeps on LIFTING your boat up, to SLAM IT BACK DOWN ON THE ROCKS.... AGAIN and AGAIN!
[Don't ask me how I know, OK?]

So now back to the PFM of how GPS works in a boat, car, or plane. Several complicated "algorithms" and "computational adjustments" are applied to "raw distance from satellite" information, to determine your position within the Galaxy of those satellites.... and "that" information is "integrated" into the "known Kepplerian elements" of the satellite orbits you are "tracking", to find an "instantaenous fixed location" for you in "space" between the satellites... and then it has to calculate A POINT on the Earth's surface for you that corelates to that same point in space between the satellites... after applying all the known corrections..... WHEW!!!
and before it gives you a single position.... it's already doing calculations necessary for your next FIX!

It doesn't matter if you are BECALMED or if you are ANCHORED.... or if you are going 500 miles an hour, the satelite positions keep changing.... the Earth keeps turning (I forgot to mention the ROTATION of the earth! GEEZ!) the sun goes down the moon comes up... thousands of electrons keep dancing to a Giga Hertz beat.... One's and Zero's keep getting crunched.. until you turn it off.

The "normal" aviation GPS unit will probably do its number crunching and Display updates about the same as a Marine unit. High END GPS units for Military or Commerical Airliners, may be "faster", but not necessarily so.

Remember that everything is "relative". If I'm traveling at 6 Kts in my sailboat, the next waypoint will probably be less than 20 miles away... and if I stray from my course by half a mile, no big deal, that's when I'll start to correct it. If it updates the VMG by 1/10 Kt one minute after I establish my new heading after changing tacks, I'm happy with that...

If I'm flying in an airplane at 200 Kts, my next waypoint might be 100 miles away.... or the "range" of my display will be "100 miles", to keep the "clutter" down. My GPS will update about every 10 seconds or so... and if I change Heading, or Altitude, or power setting, I can see the benefit after about 1 minute of being "established" under the new conditions. As I get closer to a destination, my handheld GPS might give me a "descent profile" from its "altitude" calculations" if I select that option, the range of my "moving map display" will change automatically, if I selected "autoranging" from the setup menu. And if I am taxiing on the ground at a slow speed, I can follow taxiways if they are in the GPS data base.

PRECISION GPS Approachs to runways in Instrument Weather Conditions are now Legal and Approved at many locations.... and these usually require "signals" from Ground based "Differential GPS" transmitters.

Your BOAT GPS unit will have an ANCHOR ALERT capability... to warn you if your anchor comes loose while you are "resting" comfortably "below". I don't have that on my Airplane GPS, I don't think.

You are lucky that your boat GPS caculates a VMG for you. VMG is damn useful in a sailboat! It calculates a Velocity Made Good toward your waypoint, when you are "tacking" upwind to get there, on a heading, which at the moment is "hopefully" within 45 degrees of your "course line" to get there. And it also caculates your ETA from the VMG information.

Airplane GPS's DON'T know what a VMG is. Every one I've ever seen "ASSUMES" that you are heading DIRECTLY to your destination, on your present heading.... unless your "track" deviates more than 90 degrees from your "course to destination", then you'll get an error message.
Because, it doesn't consider your present "course track heading" to caculate a VMG, it uses your present GROUND SPEED information as the Divisor to Divide into the DISTANCE REMAINING to come up with its "Time Remaining" and "ETA" displays. And if you are heading 89 degrees off course, you ain't never gonna get there, no matter what kind of GROUND speed you are traveling.

And also, If you happen to be "FLYING BACKWARDS" against the wind; to "hone" your flying skills; DON'T even TRY TO LOOK at your GPS DISPLAY! It will blow your mind. {don't ask me how I know.}
Go to the top of the page
 
+Quote Post
IslandPilot
post Feb 1 2011, 03:52 PM
Post #18





Group: Core Member
Posts: 170
Joined: 16-June 10
From: Western Lake Erie, Ohio, Michigan, Canada
Member No.: 5,099



A picture is worth a thousand words:
Handheld GPS unit near Missoula Montana, with "terrain" display selected.


Moving Map Display in late model Cessna 182

Same Cessna 182 at night.
Flight from Billings, Montana to Toledo, Ohio. Aircraft is over Iowa, next planned fuel stop is DSM- DesMoines , Iowa. Destination is Toledo, Ohio. Notice the "Fuel with reserve ring" (dashed green circle) at the far right in the display, is close to our Toledo destination.

You can see the Strong Low Pressure to the North, and also some "weather" north of us on this display. But, notice the GREAT, REAL TIME, WINDS ALOFT display...

Maybe if my pilot, Lucky Lindy Jon, reduces the power just a little bit; we can skip the fuel stop, and arrive home sooner. Let's see...

Closer to DesMoines, weather display in front of us
Destination at Toledo, KTOL is well within dashed green ring... weather at South Bend Indiana is good,
they have 24 hr. fuel, in case this good luck runs out.
We request an "ammended clearance" to Toledo at this time.

36 gallons of fuel remaining, buring 9.7 GPH...
We'll be picking up a 40 to 50 knot tailwind... Toledo is well within range.

We listened to "TUNES" coming down from the Satellite Radio, and ate some munchies...

Max groundspeed was 185 KTS for a few minutes. We shot an ILS Approach to RWY 25; it was "overcast" at about 1500 ft, 3 mile visibility on the ground.
Even though the ILS approach was in a direction opposite to our arrival heading... the airplane autopilot "acquired" the ILS within 90 degrees of the final approach course, and made smooth banked turns to "capture" and track the ILS; providing "anticipatory vectors" for its turning manuevers on the display screen.
All Jon had to do was to reduce power after "flaring" the airplane for landing, and taxi off the runway.

We were in the air non-stop for 7.6 hours, in that Cessna 182..... The longest time either one of us had ever spent in a single engine Cessna.

I think that helps to answer how GPS and Autopilots are USED today in small General Aviation Airplanes. The "Big Boys" have had it THAT GOOD... for decades...

We only felt tired after we put the airplane away, and unpacked all our stuff. Our "day" began in Bellingham, Washington, which is about as far as you can get from Toledo, Ohio within the continental United States. We flew to Seattle, Wa, and dropped off My good ole Cessna 207, the one we flew to Bellingham... using the handheld GPS.

We continued from Seattle in the Cessna I82, making only one stop in Billings Montana. The lady at the "COOKIE" FBO didn't have any cookies for US, so she gave us a car to get something to eat. We watched the sun go down while eating "Quarter-Pounders" at Mickey Dees. Then we departed from Billings, Mt to Toledo, OH shortly thereafter.
Go to the top of the page
 
+Quote Post
SanderO
post Feb 1 2011, 06:12 PM
Post #19





Group: Troll
Posts: 1,174
Joined: 23-December 09
From: NYC
Member No.: 4,814



Island Pilot,

Awesome description of GPS and LoranC. GPS is really like celestial naviagation using radio signals and a computer... By the way you failed to mention that the GPS satellites are also transmitting all sorts of "ephemris" type data which is why it takes some time to "break in" a new GPS as it downloads and stores this location data.

What I was really trying to learn about was not how GPS provides a position or a course made good... but how GPS drives the control surfaces and or "throttle" to "steer" the plane in 3 axis motion. My boat is pretty basic with a ram which drives the rudder.

I also realize that an AP makes very minor corrections once a course is set. But suppose you wanted to say... turn 135 (YIKES) and climb to 5,000 feet... how is this done and programed?

Can you/do program altitude waypoints as well as lat lon?
Go to the top of the page
 
+Quote Post
amazed!
post Feb 2 2011, 11:48 AM
Post #20





Group: Extreme Forum Pilot
Posts: 4,017
Joined: 14-December 06
From: Fort Pierce, FL
Member No.: 331



SanderO

The autopilot controls the airplane (flight control surfaces) and the nav system (including GPS if installed) controls the autopilot through an interface.
Go to the top of the page
 
+Quote Post

3 Pages V   1 2 3 >
Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 




RSS Lo-Fi Version Time is now: 22nd July 2018 - 08:15 AM