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Forum Index : Microcontroller and PC projects : GPS clocks to roll over on 6 April 2019
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| Paul_L Guru  Joined: 03/03/2016 Location: United StatesPosts: 769 |
The pause in the launch of the weather balloons will cause some inaccuracies in the charting of jet streams which will cause airlines to load more fuel for all long duration flights. Back in the day when I was still playing with Boeings the FAA didn't trust GPS for primary navigation. Pan Am 747s depended on two GM Delco INS computers for navigation so GPS was not an issue. I guess there are more GPS satellites up there now and the reliability has been demonstrated so the FAA has approved GPS for navigation. Which explains why the 787s are grounded in China. Paul in NY |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 4044 |
Sort of the opposite of Y2K. With Y2K lots of work was done ahead of the deadline to make sure bad things didn't happen. With GPS often no work was done for old systems and now we see the result. Just buy newer units? John |
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9610 |
@ Paul_L - I guess you will be following the issues with the Boeing MAX aircraft systems that seem to be fighting the pilots. .....but I digress, sorry. Smoke makes things work. When the smoke gets out, it stops! |
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| isochronic Guru Joined: 21/01/2012 Location: AustraliaPosts: 689 |
NeoBlox-6 gps module looks like it is working ok. |
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| ajkw Senior Member  Joined: 29/06/2011 Location: AustraliaPosts: 290 |
I have newer units but l also like my old one and don’t wish to simply put it in the bin for want of a software update. Anyway, I have received a nice reply from Magellan saying they hope to have a solution soon so hopefully that will happen. |
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| robert.rozee Guru Joined: 31/12/2012 Location: New ZealandPosts: 2442 |
the VK16E (sirf III) units i use also still work fine. checked a couple of nights ago and one of the modules was able to pinpoint my location within a couple of metres, as well as returning the correct time and date. cheers, rob :-) |
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| Paul_L Guru Joined: 03/03/2016 Location: United StatesPosts: 769 |
Hey .... a sudden left turn in the topic!!! OK with me. The 707, 727, and 737 aircraft were designed as cable controlled aircraft. When the pilot twists or pushes or pulls on the yoke loops of stainless steel wire rope hundreds of feet long run over a rube goldberg assembly of many pulley sheaves and apply force to the trim tabs via levers which then cause the ailerons or rudders to deflect. https://aviation.stackexchange.com/questions/46179/why-do-flight-control-cables-not-slacken-during-the-cold-temperatures -at-cruise They didn't need amplifiers, motors, or hydraulic actuators, they were controlled by human muscles. When the 747 showed up in 1969 the forces needed to move the much larger control surfaces were too high for human muscles. The control cables were run to hydraulic valves in the wings and empennage which then apply hydraulic pressure to the control surfaces. Redundancy was required so four independent hydraulic systems were designed into the 747 in such a way that the total failure of any two of the systems would leave you with all control surfaces working, and the failure of three systems would leave you with 50% of the surfaces working. Now the 707 and 727 aircraft have largely disappeared but the 737 remains. Somewhere along the way the engineers decided that all that wire rope in the 737 was too heavy so they substituted amplified electrical servo mechanisms operating the hydraulic valves. Then they started putting computers in between the pilot and the servo mechanisms. Guess what ... if the software has a bug the aircraft becomes an agricultural plow! Sometimes computers are a very very very bad idea! Especially when the computer has to function at high altitude where high energy incoming gamma particles pierce narrow lands in an IC. So they make these gizmos using MSI CMOS and TTL chips in MIL spec MU metal shielded DIP packages ... the weight and cost go up ... and pretty soon you realize that all that wire rope wasn't really that heavy! KISS! Keep It Simple Stupid! Paul in NY |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9610 |
[Quote=StarTrek TNG]PICARD: He proposes to turn total control of the ship over to the computer, as IT is capable of making quicker adjustments then any Human being. RIKER: Computers have always impressed me with their ability to take orders. I'm not nearly as convinced of their ability to creatively give them. PICARD: You know, number one, you missed something not playing with model ships. They were the source of imaginary voyages each holding a treasure of adventures. Manning the earliest spacecraft. Flying an aeroplane, with only one propeller to keep you in the sky! Can you imagine that? Now the machines are flying us.[/Quote] - From episode six, season three, "Booby Trap" Smoke makes things work. When the smoke gets out, it stops! |
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TassyJim Guru Joined: 07/08/2011 Location: AustraliaPosts: 6283 |
Thanks for the confidence boost. I will be flying on a 737 in a couple of months. (Hopefully not a MAX) Jim VK7JH MMedit |
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| Boppa Guru Joined: 08/11/2016 Location: AustraliaPosts: 814 |
Thats if the MAX class is even flying again by then, which seems unlikely- outside of the US at least (theres a couple of EU airlines have already struck them off their summer roster, which doesn't bode well for it) Means they have to organise replacement airframes and rated crews for them, and they are just coming into their summer season- which means they suspect that the MAX family wont be flying for at least that long... It's an expensive move for an airline to make- the fact that at least two have done it means they are leasing aircraft, while their own planes are sitting on the ground- not a move that shows they have confidence in the MAX's flying again soon...  |
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| BrianP Senior Member Joined: 30/03/2017 Location: AustraliaPosts: 292 |
Paul_L wrote For a long time I've been pondering on the greater vulnerabilities of the increasingly lower voltage operation of our digital toys (& our not-so-toys). The so-called "cosmic rays" have enough energy to penetrate many metres underground & many layers of metal. With the low voltage chips we have now it doesn't take much to flip a bit or two - "unexplained" computer crashes can have an explanation... @Grogster -  |
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| Paul_L Guru Joined: 03/03/2016 Location: United StatesPosts: 769 |
@BrianP ... It's not the low voltage, it's the land width inside the CPU. @Boppa ... There are no available replacements. Boeing has a 7 year order book now. Airbus is nearly 5 years. All of the older cable controlled airframes are flying. They are only scrapped when they reach their estimated life in pressure cycles. The 747 fuselage expands its diameter between 7 and 11 inches and its length by 11 to 18 inches for each pressure cycle. How many times can you squeeze an accordion before the bellows fail? @TassyJim ... You're welcome. Ask them if it's an older cable controlled aircraft or a new fly by wire aircraft. If it's fly be wire cross your fingers! @Grogster ... Picard lives on but the computer crashed! Paul in NY |
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| isochronic Guru Joined: 21/01/2012 Location: AustraliaPosts: 689 |
There are benefits though.. even allowing for the frothy PR, the 787 direct flights sound better than the wait-transit-change-wait-again-etc slog |
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| Boppa Guru Joined: 08/11/2016 Location: AustraliaPosts: 814 |
They aren't replacing the planes themselves, they are replacing them on their rosters with whatever they can hire/ divert from other routes In many cases the will be using either larger planes at less capacity usage or older planes with higher operating expenses (which is what got Boeing in this trouble in the first place- they WERE the older plane with higher operating expenses with the 737 original) Neither of which is going to make the airlines happy if the grounding continues on, higher operations costs and frame hire is going to eat into their budgets significantly, may send some smaller operators under... They will be looking at Boeing for compensation, I think that will be a certainty, especially the longer the groundings continue And given the unhealthily close relationship between the FAA and Boeing, other regulators are going to be understandably skeptical of any 'quick fix' and may not take the FAA's 'word' for it and may want their own testing done... |
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| Paul_L Guru Joined: 03/03/2016 Location: United StatesPosts: 769 |
@Boppa -- there are basically no older replacement aircraft to hire or charter. Profitable airlines don't keep less useful aircraft standing around just in case someone wants to charter one. They try to load all of their aircraft with passengers and fly them as continuously as possible. Using larger aircraft is usually not possible. The 737s can operate from 4500 foot runways and often have self contained boarding stairs and so do not always need mobile stairs or fingers. The larger aircraft have a higher boarding floor height above ground. Smaller airports sometimes do not have fingers or boarding stairs which will mate with bigger aircraft. The earlier aircraft are not necessarily more efficient unless they have really old engine types installed. The high bypass carbon composite engines began showing up in the 1990s and the fuel savings were significant. Most older 737s have had the newer engines installed. It's just too expensive to buy fuel and to maintain the old ones with all of their titanium blade high pressure stages. Most of the Boeing sale contracts do not provide for remuneration due to operational problems, except for the US Air Force. That's why the Air Forces doesn't get the latest improvements first. It's been my experience that the FAA doesn't have enough really good engineers to even double check what Boeing develops. They always seemed to be very diligent at making sure all of the paperwork was filled out completely but they didn't really want to get into the technical nitty gritty. FAA regulations still require technicians to be proficient at repairing wood airframes, airframe fabric application and the application of paint and lacquer to fabric covered airframes. The 707 vintage fuselage, which the 737 shares, had a design life of 20 years or 51,000 flight hours and 75,000 pressure cycles. Extending it conditionally beyond that required x-ray, eddy current or Magnaflux zyglo examinations of the riveted lap joints for cracks which was very expensive. If cracks were found doublers could sometimes be installed over the cold lap joints which would increase weight. Aloha Airlines N73711 had 35,496 flight hours with 89,680 pressure cycles when it became a convertible on 4/28/88. Aloha's route structure involved a lot of short duration flights between islands where the maximum fuselage pressure differential was seldom reached. LINK SECOND LINK THIRD LINK THIRD LINK The third link shows some nice illustrations of how cold lap joints are riveted together. I read through these reports and more back in 1988 when they hit my desk but it didn't seem to be likely that this could have happened to Pan Am aircraft. Pan Am's aircraft did not spend most of their ground time at hot, humid, sea level airports with the attendant likelihood of increased corrosion and Pan Am's route structure was mostly very long distance flights with very few pressure cycles. In 1968 I had totaled up the flight time for our first five 707-121 aircraft which had been delivered in 1958. After 10 years of service they averaged about 31,200 hours with only 4,300 pressure cycles for an average of 7.25 hours per flight leg which was the exact opposite of Aloha's short flight high pressure cycle operation. I did have our inspection department do some additional Magnaflux zyglo inspections of the 707 lap joints which disclosed nothing. The really old fuselages are sometimes relegated to flying very short, low altitude hops which don't require pressurization. I remember riding the observers seat in a four engine Lockheed Electra owned by TTAS - Trinidad Tobago Air Service from Piarco - Port of Spain to ANR Robinson - Tobago. That route was 51 statute miles long with an operational ceiling of 4000 feet to clear the 2500 feet Blanchisseuse mountain ridge along the northern coast of Trinidad. The flight time was 14 minutes. This long range Elektra had had it's pressurization components removed to save weight and spent the last 12 years of its life making 4 round trips a day from POS to TOB instead of flying from JFK to LAX! Big aircraft and their operation is more complicated than it seems at first glance. Paul in NY |
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| Paul_L Guru Joined: 03/03/2016 Location: United StatesPosts: 769 |
YIKES! PER to LHR is 9700 miles directly over Iran, MEL to LHR is 10400 miles over Tibet. Diverting to overhead Saudi Arabi would add 800 miles. That would make me very nervous in a two engine aircraft. Paul in NY |
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| BrianP Senior Member Joined: 30/03/2017 Location: AustraliaPosts: 292 |
@Paul_L - thanks for the heads up on the airlines. We industry outsiders seldom get to know what is really going on with the machines we trust our lives to.  OK, I get it. But is it the same for the DRAM or static RAM memory - different architecture? B |
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| Boppa Guru Joined: 08/11/2016 Location: AustraliaPosts: 814 |
There are a lot of the older planes still available from charter airlines in many places (they often will rotate an aircraft out and sell it well before it's useful end of life, once its operational costs and maintenance costs start to rise enough that buying a newer, more efficient plane becomes a better proposition- onselling them to smaller airlines/charter operations)-question is enough to cover the MAX fleet? unknown... Worse for the airlines is that if the charter airframes aren't enough, that will drive hire prices up higher, further cutting their margins I am betting that even with any 'not our fault' clauses in the Boeing supply contracts, if this goes on, they will be tested in court.... when you are talking hundreds of millions of dollars in lost income (billions???) then they will be looking at getting some of that money back... |
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| isochronic Guru Joined: 21/01/2012 Location: AustraliaPosts: 689 |
IIRC Qantas got some hundred million plus ( 170 m ?) compo when the A380s (Airbus) had to be de-rated for the Pacific routes after the engine problems. The media photos of the disintegrated engine and subsequent wing damage were pretty shocking though. I guess qantas will use them for the indochina routes instead (?). I can still remember seeing Electras taxi and take off as a kid... impressive (but noisy as !!). |
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