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Post by Erik on Aug 11, 2020 17:06:12 GMT -5
Great info John, thank you.
Ken, outstanding post once again, including the images. You could rename this thread into 'Adventures of a trained navigator', at least for the enroute part if I go by your information! And I consider flying within two minutes of published schedules ridiculously on-time.
Well done. Erik
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Post by connieguy on Aug 16, 2020 5:29:37 GMT -5
Thank you very much, Erik. There are often times when flights with the Air France L 1049G are uncannily close to the published schedules, but I have always thought that principally a reflection of the Connie Team's wonderfully accurate flight model. I always go straight in and land, so there is no replication of the flying of holding patterns which if implemented would have a significant effect on timing, but nor do I know whether airline schedules made any allowance for the likelihood of these. I believe they were in use at London Heathrow from a fairly early date and I know that the New York terminals were extremely busy in the late 1940s, but this may not have been so in many other places.
Rangoon to Bangkok was an exciting flight because it was the first to make full use of John Hewson's oriental airways charts from 1962. Here is the one relevant to this flight.
As it shows there were NDBs at Rangoon and Bangkok which created a connecting airway on a heading of 126 degrees. The Bangkok one on 345 was the hub of a number of airways, but there was another such hub just to the north of it centred on a VOR on 113.1. Both these seem to have been in line with VTBD runways 21L and 21R and would therefore have facilitated lining up on those runways. Below are navaids as they are now in my FS9. I have assumed that the modern VOR is in the same place (but this was not true at Saigon) and have been happy to use the modern frequency. The NDBs on 293 and 276 I ignored during the flight.
Once again, I had the guidance of a log entry on a previous flight, when for the distance of just over 300 nm I cruised at FL9 and arrived comfortably within the schedule. On this occasion there was rain and some thunder before take-off, but both stopped very soon after it as I manoeuvered to establish the rmi needle tuned to the Bangkok NDB on the reciprocal of 126, that is 306. I had expected a strongish south-westerly wind on the basis of the previous flight and sure enough in order to keep the needle pointing at 306 I needed to actually fly a heading of 135. I have always thought the visibility of the gauges on this panel excellent, but this kind of exercise needs the accuracy of a considerably magnified rmi and I have now provided myself with that for the next flight.
Cruise was at 1700 BHP in low blower with a mixture of 20% and an OAT of 13C. Cylinder head temperatures were much lower in this situation and I was able to close the cowl flaps fully, which with a light fuel load produced a KTAS of 249, only about 10 knots lower than flying at FL190 in high blower with cowl flaps partly open. Just a few minutes after losing the Rangoon NDB I picked up the one at Bangkok. I do not have DME but knew that it would take 18 minutes to halve the distance of 150nm to Bangkok and once my elapsed timer showed that time began to descend for Runway 21R. The night was as black as pitch but fortunately visibility was good and I made a good approach and landing. Having taken off 3 minutes late landing was 19 minutes ahead of schedule, at 04:41 local time (UTC+7).
Only a few seconds to go. Full flaps, gear down, landing trim and manifold pressure reduced to 20 inches to produce a gentle flare and touchdown as I pull back on the yoke. Contact with the runway is so gentle it is hardly noticeable at a speed of under 100 knots. After the bounce on the last flight this is reassuring. The rmi needles tuned to the VOR and the NDB on 345 point dead ahead.
Even on landing, the night was as black as pitch, but as the main wheels touch the nose wheel is exactly where it should be.
Bangkok. Scenery by Cal Classic. Next stop Saigon.
And the Plan G breadcrumb trail. An interesting feature of this flight was that as I crossed the high ground west of Bangkok the behaviour of the radio altimeter showed me that I was doing so. This too could have been used to roughly estimate distance had it been necessary. My thanks once again to John Hewson for the invaluable charts, which together with the period navaids make all this seem so much more realistic.
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Post by connieguy on Aug 18, 2020 11:21:04 GMT -5
Before I go any further with this I would like advice on the possible implications of one aspect of the 1962 charts. The airways contain triangles sometimes solid and sometimes in outline, sometimes with Lat and Long coordinates sometimes not, and what appear to be distances between them. Does this imply that aircraft were expected to have DME? On the face of it apparently not, because the mid 1950s airways charts on the Military Airfields site also have these distances, and as I understand it DME was not around then. Perhaps they are no more than a rough guide?
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Post by Jorge on Aug 18, 2020 11:49:03 GMT -5
John, The triangles, like today, represent intersections. The lat/lon for some was given in order to enter them in the primitive INS boxes that existed at the time, usually on military aircraft. The lat/lon was not something that was required, but it helped the navigators without having to look through a book for a reporting point's lat/lon in order to put it on the flight plan, log, or the box. Which brings us to the second part: solid vs. open triangles. The solid ones were mandatory reporting points (if I'm remembering my initial IFR training from the '90's correctly) while the open ones were not. In other words, when crossing the solid ones you were supposed to tell ATC where you were, your altitude, and your speed, since it usually meant you were changing airspace and would have to change frequencies to another controller as well. You can tell this by the dotted lines that are close to the solid line in the area near those points. Close by you can see the label for FIR Boundary (Flight Information Region). Again, some have lat/lon while others don't and this was more for the INS or similar equipment. Considering that many aircraft were using sextants and such for navigation, my guess is that you would also be able to use the lat/lon as a quick reference for the sextant as well. I believe you're supposed to enter lat/lon in order to use that properly, but you would know more than me on that one! I'm no expert on the older systems or maps by any means, but their representation on the maps is fairly similar to the stuff we're using these days. I thought I'd throw in my two "Lincolns" into the fray. As Tom says, Hope this helps! Jorge Miami, FL PS: The distances were to aid the crew in determining how far they had traveled or how far between checkpoints (intersections). This was more for flight planning and in flight would help with fuel consumption among other things (X number of minutes from A-B intersection means Y airspeed and a consumption of Z fuel, etc.). It help more when you're planning a flight between airports that are "off-airway" that may be close to the intersection. It gives you a "generic" sense of the distances without having to pull out the calipers or the ruler. Just by looking at the picture the trip should be about 310nm between beacons with a fix 100nm from Rangoon, boundary penetration at 166nm (about 45 minutes or so at 200kts), with 105nm to the 100nm fix (Bangkok is 205nm inside the boundary), and a final fix at 50nm to the beacon. At 200kts it would probably take a little over an hour and a half. Add taxi and takeoff and landing and you can add another 15min each end. Total trip should be about two hours. Let me know if I'm close!
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Post by connieguy on Aug 18, 2020 12:47:48 GMT -5
Jorge, Many thanks indeed. This does clarify it immensely. I wrote an earlier post thanking you which seems to have disappeared. However, I pointed out that real pilots have significant advantages over armchair ones when it comes to this kind of thing! I am not sure, by the way, how far military aircraft used civilian airways. You cannot use a sextant to get a definite fix during the day unless another heavenly body is visible to provide a second line of position, and very often this is not the case. Ken
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Post by Tom/CalClassic on Aug 18, 2020 13:43:16 GMT -5
Regarding the distances - while DME was not common until the mid-1960s - I believe it was required on US commercial airliners sometime around 1964. United added a mention of a panel rearrangement that would be required in a 12/63 update to the DC-6/7 manual. BTW, transponders were added at the same time. Earlier than that the distances would be needed for an earlier technique. You knew your airspeed and had an idea of the wind (usually), and thus could estimate your ground speed. With this information you would know the approximate time to reach the next waypoint (and sometimes require a course change), as well as using it to advise ATC of the estimated time to the next reporting waypoint.
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Post by connieguy on Aug 28, 2020 11:27:14 GMT -5
The contributions by Jorge and Tom have added significantly to my understanding of these things and I hope that this will now be reflected in rather more accurate simulation of 1950s navigation in so far as FS9 can support it. Bangkok to Saigon was another shortish flight with take-off just before dawn early in August. I give below the relevant charts from John's collection.
The first shows that the airway left Bangkok on a reciprocal bearing of 295 from the Bangkok NDB until it reached a reporting point on the Thailand/Cambodia border whereupon the heading changed from 295 reciprocal to 119 direct when tuned to the NDB at Phnom Penh. After passing over the Phnom Penh NDB the heading then became 115 when tuned to the Saigon NDB on a frequency of 305; this lay to the south of the airport and was an airways hub. The aircraft proceeding from Phnom Penh knew it was at point 0-7 when the beacon at Binh Long bore 081 degrees and that it was at point M-7 when it bore 051 degrees. It also knew that it was then 50 miles from the Saigon beacon (20+9+21). Also significant for landings on Runway 25 were two further beacons. The one on the frequency of 285 lay just off Runway 25 and was itself an airways hub as well as providing a way of lining up on that runway, while the Bien Hoa beacon on 272 was a good aiming point before turning for runway 25, as well as being yet another hub. This flight therefore required the creation of a fair number of period navaids, and I also created the VOR XVH on 115.5 but did not use it; it may in any case not have existed in 1957. In addition to those I added a period NDB at Phnom Penh, though there is reason to believe that this was on the site of the present VOR. The Saigon radio aids are shown on the chart below: There was also a modification to my panel, which to my surprise turned out to still contain the standard FS9 GPS. This has therefore been replaced by an enlarged rmi which makes it easier to see what is happening and can be summoned by means of the gps icon. Heading out from Bangkok tuned to the Bangkok NDB on a reciprocal of 295 degrees. It is known from the weather forecast that there is a following wind almost directly behind us, so a heading of 115 keeps the needle in the correct place. Meanwhile dawn is breaking in the eastern sky.
The route crosses high ground not far from the border between Thailand and Cambodia and as the sun rose and the light improved this was clearly visible, as well as causing a reaction on the radio altimeter. Here is the Open Topography map of that area and the co-pilot's view of it.
There is a period without radio assistance between losing the Bangkok NDB and picking up that at Phnom Penh, and it may be that in reality these beacons had sufficient range to overlap. However, Phnom Penh is easily dealt with once contacted and here the needle is just beginning to move rapidly as an indication that the aircraft is about to pass overhead, while the waterways outside confirm that this is indeed Phnom Penh.
Binh Long bears 051 and by this time we have been informed that the landing will be on R25. The descent from FL9 begins and Bien Hoa is tuned and the heading adjusted so that it is dead ahead. There is now dense cloud and navigation without the radio aids would have been rather testing.
One rmi needle still points straight at Bin Hoa but the other is now tuned to the Tan Son Nhut runway NDB on 285 and the ILS to a heading of 249. Visibility is 4 nm and there is occasional light rain, but Saigon is below.
It is a decent approach. And the runway is fortunately visible at a reasonable distance. Here the aircraft is shown as it turns for the runway and we see the cockpit view as it is near to the flare, which will reduce touchdown speed to about 100 knots.
Touchdown. We took off a minute early and land 14 minutes early, at 07:26 local time. Another fair landing, I am pleased to say.
And finally the Plan G breadcrumb. John's charts and the period navaids have increased the authenticity of the simulation of this flight, as it is to be hoped will have become clear, although ATC would have played a part in the real world which cannot be recreated. My thanks to all contributors and to Mike Stevens for the Cal Classic scenery.
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Post by Erik on Aug 30, 2020 16:07:44 GMT -5
Nice, nice, the enjoyment continues. Well-described and well-illustrated as usual, thank you Ken!
Erik
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Post by Jorge on Aug 31, 2020 9:52:47 GMT -5
Extremely wonderful flight Ken!
Glad I was able to help out!
Jorge Miami, FL
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Post by connieguy on Sept 1, 2020 6:08:31 GMT -5
Many thanks, gentlemen. Your help has been invaluable, Jorge, and Erik's on other occasions. People keep on looking at this thread, so it must be doing some good.
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Post by warbaby on Sept 2, 2020 7:22:14 GMT -5
This is a fascinating thread.
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Post by connieguy on Sept 8, 2020 7:07:15 GMT -5
Thank you, Allen.
The flight from Saigon to Manila , at nearly 900nm, was significantly longer than both Rangoon to Bangkok and Bangkok to Saigon. John's chart shows that the airway left Saigon on a bearing of 085 degrees from the Saigon VOR and proceeded to the NDB at Phan Thiet. From there it went via a series of intermediate points to the VOR at Lubang, initially on a heading of 075 and then on 076. From Lubang the route lay on a heading of 053 to the NDB at Rosario. From that point I used a 1958 Manila airport chart from John's Flickr album on Manila. It should be noted, however, that since 1958 the NDB which is shown there as OL on the frequency 330 has changed frequency to 375, and is present in FS9 as that, while the original NDB on 375 shown on the 1958 chart has disappeared. So has the NDB IL on the frequency 320, but as this was necessary for the landing procedure I recreated it as IL RETRO. I also created a retro NDB at Dha Nang with a range of 150 miles, but at the point where the chart shows it being picked up on a heading of 276 it was in fact out of range and I had to use the Chlebowski-Jahn AILA/GCA gauge as a substitute. Approaching the Philippines the airways chart also provides for the use of an NDB near San Fernando airport at Poro Point on a frequency of 270. As this was approximately 375 nm from the airway there was no point in recreating it, but it does illustrate the point that radio beacons were in use at that date which had a far greater range than is allowed in FS9.
The airways charts for the sections from Phan Thiet to Manila.
The 1958 Manila chart
RPLL Navaids as they exist in my FS9 installation
The Plan G breadcrumb of the flight
There was dense cloud around the cruising height of FL170 for most of the flight, less so as we reached the Philippines. Here the cloud clears just enough to reveal the last of the coast of Viet Nam to port.
I realised during the flight that the reasons that the airways charts give Lat and Long coordinates for some points may have included the fact that it would often have been possible once the aircraft was on the radio line of position to take a sextant shot of the sun which could then be combined on a chart with the radio line to provide a definite fix. I did take a shot for the point marked 112E on the chart and after the flight worked Google Earth to provide a fix (112E is marked as PH02). This suggests we were just north of track when the Plan G breadcrumb shows we were about 2nm south of it, but there is uncertainty here because the position of the 1957 Nha Trang NDB may have differed from that of the airport picked up by the AILA gauge and because an error as small as this may have resulted from the known imprecision of sextant shots taken with the Beaumont Bitzer sextant, which reflects that of real world instruments.
Beyond that the main interest of the flight to me lay in the runway approach which involved a procedure which I believe was common at the time but which I have never done in quite this form - that is flying over the runway on a reciprocal heading and then turning 180 degrees to land (in this case) on Runway 24. After performing it I read the following passage in Thorburn C Lyon's Practical Air Navigation (11th edn., 1972), p. 267.
A "procedure turn" (unless otherwise specified) is always made at the standard rate of 3 degrees a second (360 degrees in 2 minutes). It requires first a heading change of 45 degrees (a timed turn of 15 seconds); then a 180 degree turn (one minute); then another 45 degree (15 second) turn... the maximum indicated air speed should not exceed 250 knots, and the turn should be made within ten miles of the facility.
The first screenshot shows the view approaching the airport. The coastal area shown on the 1958 chart can be seen on the right while the two NDBs are almost dead ahead. I began the turn after passing over the nearer one but in fact turned rather too tightly and ended up with the runway to starboard, although it was not difficult to make the necessary correction and carry out a good landing. Rather more practice would probably produce a better result. Visibility was 8 miles and there was light rain.
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Post by Tom/CalClassic on Sept 8, 2020 11:28:58 GMT -5
Hi,
Nice job. Yes, Procedure Turns were very common. My Jeppesen books are filled with them.
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Post by connieguy on Nov 24, 2021 11:53:29 GMT -5
Although there are several places where I could have placed this link this seems as suitable a one as any, as there is a navigational element to it. After something of a false start a little while ago I have recently been attempting to master flying the Stratocruiser, and with rather more success. I also have some experience as a film maker and have wanted to try my hand at a classic flight simulation piece for some time. This is the result. youtu.be/UKsHJqnGk1A
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Post by mrcapitalism on Dec 7, 2021 12:39:32 GMT -5
Connie,
That's a very nice video. Thanks for sharing it. The crew voices are a neat touch, and I'll have to read your thread on that next. Saw your video here first, figured I should reply here.
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