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Post by connieguy on Feb 16, 2019 2:47:02 GMT -5
In the thread Adventures of a Trainee Navigator I raised some time ago the matter of the range of NDBs in the classic period. Thanks to Bill, I am now reading P.G. Taylor's Frigate Bird, and have got to the section on his flight to Easter Island. It contains the following passage:
"Ask Angus to let me have the folder with the radio details" ... There was a full page of information on Easter Island. Mr Goddard, the Department of Civil Aviation officer who had prepared this list of possible facilities across the South Pacific, had produced some valuable information for the flight. Under "Radio Facilities" I read: Communications: Easter Island provides Communication. Call Sign. CCY. Transmits/Receives 4335 kcs (Night) 11400 (Day). Note: This station works with the mainland at 01:30 GMT daily for weather and routines on 11400 kcs. I ran through that. Angus had the island, on communication. It was the beacon information below that interested me now. Radio Aids M/F Homing Beacon 500 kcs. Identification: CCY (Manual) Type of Transmission: A.I. (Range in worst conditions- 300 miles) No D/F facilities.
Being within this range they try it and there is no reaction from the needle on the radio compass. They switch it off, try it again when they are closer and this time the needle does react, but it wanders round the gauge without giving a definite heading, whereupon they switch it off for good. This is similar to other accounts I have read of the unreliability of radio beacons in the early 1950s. Nevertheless, the supposed range of the beacon is of some interest - 300 miles in the worst conditions - because the longest range I have come across in FS is 112.5 miles. The beacon information looks as though it came from some publication. Has anybody any idea what it was?
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Post by Defender on Feb 16, 2019 4:26:00 GMT -5
Hi Ken,
You can get up to 147-148nm range from FS9 NDB's if you create your own with ADE etc. Not sure if you can edit the range on the default ones. In the real world the longest range is at the lower range of MF frequency. As far as I know the wandering needle was either a weak signal, interference from other powerful transmitters close to that frequency or atmospherics. Or all of these.
Bill
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Post by connieguy on Feb 16, 2019 5:37:28 GMT -5
Thanks, Bill. They had relied on star shots from the sextant and had flown through the night with the attention of arriving just after dawn, so they could land (sic) in daylight. Taylor comments of the beacon 'I treated this with suspicion because this beacon had never been used by aircraft', which I take to mean tells us that it was intended for shipping. He and his flight engineer were convinced it wouldn't work, but politely kept their doubts from their radio man. When they thought of trying it at about 300 miles he says 'But bad conditions around dawn' (the clarity of his writing lapses occasionally) and then when they got no reaction 'Too far out, anyhow, for dawn conditions'. Thus, there seems to have been something about dawn. Taylor gives a lot of interesting detail about the star shots taken that night and it will be possible to recreate the night sky of that location on 23rd March 1951 in Stellarium, but I will leave that for another time.
Ken
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Post by Tom/CalClassic on Feb 16, 2019 11:09:01 GMT -5
I assume this kind of beacon was similar to an AM radio station. While taking trips across the country we found that the range of such stations was much further at night, and sometimes you could get a very long range due to “skips” which I assume was the signal bouncing off the atmosphere. So indeed this type of beacon would have a variable range due to day/night and weather conditions. I have also read about HF signals getting lost in rain and other weather conditions.
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Post by Deleted on Feb 18, 2019 2:34:13 GMT -5
Connie Guy - I grew up with NDB's and because of where I spent my flying career Australia Pacific etc the NDB has been the staple navigation aid for a long period of time and still is.
Now the thing about NDB's is twofold firstly they effectively are on the AM band and the signal is a 360 degree radiation, acutally if you see an NDB site there are two towers with aerial wire strung in a series of runs between the two towers, generally about 3 or 4 and the transmitter shed nearby. Pre digital and modern electronics most NDBs require a high degree of skill, firstly you had to tune them properly and then they had what is called a loop antenna (literally like a hoop ring on the roof) you had to turn the antenna to pick up the signal and then find what is called a null zone and so forth to get the best fix and hence the pointer in the cockpit would wander a lot. The other thing is that NDBs are subject to a wide variety of issues which produce limitations on their accuracy. If the NDB is on the coast then you get Coastal Refraction where the wave bends by up to 20 or 30 degrees where the signal crosses the coast, giving you a false bearing indicator. Then at night they are like all AM radios subject to changes in the ionosphere and hence may skip long distances or you get signals from other NDB's a long way away skipping and causing interference and inaccurate signals or at times the needle would just wander all over the place as good as useless. If they are situated near mountains the signals can be bent by the hills as well, again giving you a false bearing at times. Then atmospheric electricity, ala thunderstorms play havoc with the ADF/NDB in fact they were good at finding a thunderstorm because the needle would swing and point to the lightning or storm not at the NDB on the ground.
So you can be thankful that in the sim these issues are not reproduced at all. You got used to wandering NDB's but it was another reason that good navigation required a positive station passage and it was very hard to use cross position lines at times to get a fix. There is a whole variety of navigation techniques you can use to work out Ground Speed, drift and track keeping with an NDB but that would take a whole book but it is remarkably good once you understand these issues and these techniques. So older drivers like myself got to know the NDB very well in fact for an instrument rating in this country it is still mandatory to fly an NDB approach to hold the rating and you can hold an instrument rating with only an NDB endorsement on the license. A real challenge used to be doing an NDB approach where the beacon was near the coast with mountains on one side and at night, that kept you on your toes, now was that hazardous, yes if you ignored it but the rule was you flew what the needle said because the approach profile designers had already built into the buffers these vagarities even if they werent specifically stated on the chart. The other thing was this when you flew and NDB approach you were required to keep the morse ident on and listen to it throughout the whole approach until safely at minima or the circuit area, that was a real pain, the ADF wandering all over the place with you chasing it and the morse bleating in your ears, engine noise and then general radio and so it went. Makes you really respect the older guys who flew range nav with these things basically keeping track by a change in the dots or dashes to tell you if your were left or right, that took some doing, let me tell you.
Now as to range. Basically the NDBs range was determined by the transmitter power (the power was not published but the range of the NDB was, you will find it in what is called the En Route Supplement or ERSA which lists all the aids for the relevant country), they put low powered transmitters as airfield beacons and for example as marker beacons. Generally the range of such low powered beacons was considered to be a maximum of 50 nn (on a good day). Then they had moderate powered beacons which they used on airways (The could go to 120 nm) but these have been mostly phased out by VORs a long time ago. Finally there were high powered NDB's that were sited near major terminal areas (capital cities) and they went in before the days of LORAN, INS and GPS and they were considered good for about 400 nm. They were primarily sited at coastal places where inbound or outbound traffic traversed a lot of ocean before coming in range such as Easter Island or Australia, Hawaii and parts of the US had them as well. Generally they were pretty good, I can recall you could get the Sydney NDB as far as as Lord Howe Island (over 400 nm from Sydney) The other thing every NDB had to have a morse ident, no ident then you considered the aid to have failed and be unusable. So tune, identify, test was the golden rule and still is.
You get an idea from PG Taylors account of how unreliable these aids could be at times.
Hope this explains. I do not see why you could not add in an NDB via ADE that had long range (I have not checked what is the maximum you can go to) but the few I have done I tweak up to 50 nm standard aerodrome distance and leave marker beacons etc at 30 nm the default.
Hope this helps understand the NDB a bit better.
A quick postscript while I think of it, spare a thought for the aviators of the Cal Classic Period. Noisy pistons, appalling weather down to the minimums, flying an NDB approach, morse on and the final pain HF radio not VHF with it crackling and hissing and crashing in your ears as well. Very different to todays modern jetliners and pressurised aeroplanes, you worked for your money and you slowly went deaf. Until the invented SELCAL you had to listen to HF for hours and hours on end constantly chasing the frequencies up and down to get a message through or to receive a message, same frequencies as Taylor was using. Sunspots basically caused radio blackouts and the changing ionosphere day to night produced some interesting outcomes. Nothing as amazing with HF radio as to be trying for 10 minutes to get a position report across to the relevant centre you were working and to have say Honolulu answer you clear as bell across thousands of miles of ocean and relay the position on. The way it was so in the sim I am glad it is not reproduced in fact I dont use ATC either, I enjoy the peace and quiet.
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Post by Deleted on Feb 18, 2019 2:45:57 GMT -5
Thanks, Bill. They had relied on star shots from the sextant and had flown through the night with the attention of arriving just after dawn, so they could land (sic) in daylight. Taylor comments of the beacon 'I treated this with suspicion because this beacon had never been used by aircraft', which I take to mean tells us that it was intended for shipping. He and his flight engineer were convinced it wouldn't work, but politely kept their doubts from their radio man. When they thought of trying it at about 300 miles he says 'But bad conditions around dawn' (the clarity of his writing lapses occasionally) and then when they got no reaction 'Too far out, anyhow, for dawn conditions'. Thus, there seems to have been something about dawn. Taylor gives a lot of interesting detail about the star shots taken that night and it will be possible to recreate the night sky of that location on 23rd March 1951 in Stellarium, but I will leave that for another time. Ken
Ah Connie guy let me explain re the dawn thing, one, they were waiting for the sun to come up because once the stars faded it would be the only celestial body available to get a sextant shot, so with a good sun shot and time the could get a line of position longitudinally so have a pretty good ideas where they were distance wise from Easter Island, trouble is without a another different body to take a position line from you would not know for certain whether you were north or south on that line. This was the predicament that Amelia Earhart and Fred Noonan had, they got a dawn sun shot and hence a line of position and then the began searching for Howland Island, problem is did they turn north or south? you see the problem, one way might take you away the other might take you to where you want to go but it was the best you had. In Fred and Amelias case they may have turned the right way but have drifted so far off track (the weather was pretty awful for celestial nav in the last stages so they would have been desperate for that sun shot) that they ran out of fuel before getting to where they needed to go. Two, the ionosphere changes between night and day so basically the rule was at night you went down to lower frequencies because they skipped a long long way, then by day as the ionosphere becomes energised by the sun there is more absorption of the radio wave so you need a stronger or higher frequency to get the bounce and skip, which is the way HF works by basically bouncing of the ionosphere across the globe in a wave like pattern. They used to publish ionospheric prediction charts for a flight like Honolulu to Sydney and it would give your a graph of the time versus the frequency most likely to work so you if your were having issues you would pull out the chart and see what would probably be best. That service and those charts have gone by the bye now as well. Taylor may not have had one but his radio operator may have.
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Post by connieguy on Feb 18, 2019 10:08:23 GMT -5
Mike, Many thanks for two very informative posts. There is nothing like listening to the experiences of those who actually did these things, and although one day they will be history at the moment they are still within living memory. Taylor says of the Easter Island radio - 'The presence of this radio aid was a big safety factor in navigation for the island, and I wanted it to work. At the same time I undertook the flight on the assumption that it wouldn't, and, as far as was humanly possible, covered the situation for that eventuality.' After speaking of dead reckoning and astro navigation he also says that because of 'the obvious difficulties and occasional weather effects... aircraft on regular routes and services are directed by various simple forms of radio aids, which have in fact passed the status of "aids" and in most cases are the basic means relied upon for direction on the route, and approach to the destination.' He flew during the night and landed after dawn partly I think because landing on the sea near an island that had no lagoon required visibility as good as possible. I suspect that he was far too good a navigator to be caught by not knowing which way to turn along a line of position, and this seems to be implied by 'If something happens and the island isn't there, take a line from the sun, run it up through the island and turn down it to make contact'. Still, I get the impression that he was worried about the possibility of very poor visibility, hence the need for working radio. In fact they found the island and landed without any problem. Hair-raising problems then arose when a rough sea arose of the type the Catalina was never intended to withstand. Some would say that Taylor's determination to carry on reached the point of foolhardiness, but carry on they did and got away with it. I will experiment with NDB ranges in FS9. The only way of replicating the uncertainties I can think of is to turn the morse identifier on but throw dice as to whether one then sees where the needle is pointing. Many thanks again. Ken
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Post by Deleted on Feb 20, 2019 4:18:28 GMT -5
Yes fascinating man PG. He was a bit of a stiff backed character, not a great sense of humour but a perfectionist and very determined. His copilot was Harry Purvis also another Australian aviator with a fascinating life story. Purvis has a good account of the flight from his perspective in his memoirs. Harry found airline so boring he chucked it and went off to fly in central Australia. His recollection was that flying the Cat was a chore, no Autopilot and hours and hours of endless adjustments to keep straight and level. PG was the man who went out on the strut of Smithies Fokker in flight across the Tasman to put oil in the engine, not once but 6 times. I have all his books all are a good read. Tried his hand at building up a flying boat airline later after this but it never did any good. We are lucky the aeroplane survived and Frigate Bird hangs in the PowerHouse Museum in Sydney.
I guess the Easter Island encounter while route proving was to prove it was not for Flying Boats the lack of shelter and sea state indeed to this day makes it a hazardous place even for boats. Still once you have flown all the way from Tahiti at 105 knots, there is nowhere else to go.
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Post by connieguy on Jan 6, 2020 11:13:47 GMT -5
In the classic period flights across the Pacific from Australia/New Zealand to the west coast of the U.S.A. via Fiji, Canton Island and Honolulu were offered by at least three airlines - Pan Am, British Commonwealth & Pacific Airlines and Qantas. BCPA used DC-6s (after I think DC-4s), and Qantas, who took over the BCPA routes in April 1954, Super Constellations. Their original L-1049Cs stopped at Canton Island eastbound but not on the return trip; when they eventually acquired Super Gs with tip tanks it was dropped eastbound as well. These flights offer tempting possibilities to the classic flight simmer, because there is Cal Classic scenery all the way and a good BCPA repaint of Tom's DC-6 by Wayne Tudor available on the Cal Classic website and a number of paints of Qantas Super Constellations by Tim Scharnhop on Flightsim. I shall be doing it with a L-1049C, VH-EAH. In preparing the first leg I have been a little exercised by the matter of navigation, and also by time zones. FS9 has Sydney 10 hours ahead of UTC and Fiji 11. BCPA and Qantas timetables give only local times, while a PanAm one suggests that Nandi (now Nadi) in Fiji was in fact +12 hours, and I believe this to be correct. The Qantas timetable for November 1955, the one available on the timetable website, says that their First and Tourist Class service left Sydney at 11:00 Local Time on Tuesdays and arrived at Nandi at 19:50, leaving it at 20:15. The flight from Auckland was done by a Teal DC-6 and left there at 13:15, with a scheduled arrival at Nandi of 18:30, where the passengers evidently joined the Qantas flight. I assume that this timing was largely dictated by a desire to be able to use astro-navigation during the coming night, departure from Canton Island being at 3:55 LT. However, this meant that the first leg to Fiji was done entirely over water during the day - with direct distances of about 1,717 nm from Sydney and 1,163 nm from Auckland - and this raises the question of the probable use of radio aids. That is why I have added this post to this thread rather than creating a new one, because this thread already contains a number of valuable contributions, not least by MikeH, who had first-hand experience of these things. I have also benefited greatly from the help of John Hewson, who has supplied me with important evidence on radio aids at Fiji, Canton Island, Honolulu and elsewhere. Although Radio Range stations are best known for their use within the USA they were likely to spring up during the Second World War wherever US forces operated, including the UK, France and Italy. John's evidence shows that there were also Ranges at Sydney, Nandi, Canton Island and Honolulu, the site of the one at Canton Island still being clear on satellite photographs, while that at Honolulu was just west of Pacific Heights in an area which is open ground even now. Following Bill's suggestion earlier in this thread, I have compiled these stations into a single bgl which has no impact on existing FS9 navaids and can be installed in the Add-On Scenery folder. In some cases I have had to change the original frequencies, because FS9 already uses that frequency at that location. This bgl can be uploaded to Flightsim if there is sufficient interest in it. There is also the matter of range, upon which valuable contributions were made earlier in this thread. P.G. Taylor in 'Frigate Bird' speaks of the Range and homing beacon at Aitutaki in the Cook Islands:
Here there was a radio range, a beacon and airadio communication, originally established during the war... We were able to receive the range on the radio compass receiver, using it in the 'aerial' position. A hundred miles from Aitutaki, I tuned into the 320kc frequency [the one still used in FS9] of the range and received the 'on-course' signal of the west leg with a faint A in the background... We checked the homer too, and found a good reaction on the radio compass needle.
In the bgl I have given the Ranges in some cases a range of 200nm, but my experience so far with Nandi confirms those of Bill mentioned above - that FS9 NDBs do not work at such a range, and that 140nm-150nm is likely to be the limit. Nevertheless, it is clear that flights from Sydney to Nandi could have been flown direct using such radio aids as were available and probably sextant shots of the sun. Auckland to Nandi was different in being significantly shorter and without such radio aids as far as I can see, although I guess they may have deliberately offset the course to the west in order to avoid the danger of passing Fiji too far to the east. Thus (to return to Sydney-Nandi), we are indebted to MikeH for the information that the range of the beacon at Sydney was about 400 nm. Tracking out on the back-course of that should bring us abreast of Lord Howe Island, where I have added to the exisitng NDB with a range of 75nm another with a range of 150nm (75nm would not be adequate if we were slightly left of track). After that Norfolk Island is to the right, although even with a new NDB of 150nm range it would only be picked up if we were significantly off-course in that direction. After that we are approaching New Caledonia to the left and I have placed a 150 nm range NDB on the Ile des Pins (airport NWWE) which may be useful, although I have no historical evidence for this. However, it may well be that we shall then be within sufficient striking range of Nandi for this not be necessary. How do we track out on the Sydney beacon for 400nm when its FS9 range will be about 150nm? By using the relatively new Chlebowski-Jahn GCA gauge. This picks up airports at a range of about 250nm, although in densely occupied areas one at that range will not be visible on the Nearest Airports list, where others which are nearer have priority. In the vicinity of Fiji NFFN, however, it will be visible at that range because there are only about three others in the area. Moreover, the range can be even greater than that if desired. By entering the airport ICAO code into the ICAO box the gauge will pick up the airport no matter how far away it is, and the orange pointer will point at it like the needle of a radio compass. This should therefore allow a reverse course from Sydney of 400nm and also give the considerable range for the Range at Honolulu which MikeH's comments rather seem to suggest that it had. Any thoughts about this welcome, and information on Pacific radio aids in the 1950s even more welcome. And if MikeH is by any chance reading this, please come back.
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Post by Tom/CalClassic on Jan 6, 2020 11:51:03 GMT -5
Hi,
I find that extending the range of overwater NDBs and such is one of the most useful ways to use Manfred's gauge (Ocean Stations, for example). I monitor the distance and activate/deactivate it at the proper range.
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Post by connieguy on Jan 6, 2020 13:04:25 GMT -5
I thought it could only be used with airports. How do you get it to focus on an Ocean Station or other NDBs which do not have an ICAO code and are not associated with an airport?
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Post by Tom/CalClassic on Jan 6, 2020 13:54:52 GMT -5
My ocean stations do have ICAO codes. Type 4YN into the Go To Airport ICAO code box and you'll see the list of Ocean Station codes. Hope this helps,
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Post by connieguy on Jan 6, 2020 14:19:20 GMT -5
I am trying it on the ground with the battery on but the engines not yet started. I can only see one ICAO box which produces the goods with the 4 letter codes but nothing at all with 4YN... Please don't spend significant time on this...
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Post by Tom/CalClassic on Jan 6, 2020 16:04:13 GMT -5
Hi,
The one time I used it this way I chose it from the list. I didn't realize you couldn't search for a 3 letter code, a significant drawback...
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Post by Erik on Jan 6, 2020 17:59:22 GMT -5
Hi Ken, Regarding the time zones you mentioned, www.timeanddate.com confirms your data for 1955: Sydney at UTC +10, no DST observed and Fiji at UTC +12, no DST either. Enjoying this topic as always! Erik
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