Thank you, Manfred, the heading guidance now seems to work perfectly and I think the PAR controller's rather less frequent calls are good too. The flight shown here was done entirely manually with the gauge hidden. I am still not getting the turns quite right and might like a little more space on downwind legs between the reciprocal path and the heading for the runway if that is possible and consistent with the practice of the period. I am not quite sure whether that is what Tom is discussing. Still, this is a pretty good approach as it is and I look forward to trying a flight in the poor visibility for which all this was intended. Thanks again, Ken
Last Edit: Oct 21, 2019 3:23:34 GMT -5 by connieguy
Post by Tom/CalClassic on Oct 20, 2019 14:44:15 GMT -5
Ken, I'm not having this problem at all. I can make the turns in plenty of time. How far is APC putting you away from the runway centerline? (bottom right number when abeam of the airport). I am at 4-6 NM, which is plenty of time to make two 90 degree turns. I can't imagine that they were further away than this back then, and often much closer. Heck, I think my Southwest 737 makes a downwind approach at SMF no further away than that.
How fast are you going when you make the turn to base? I'm usually at around 150 kts using pattern flaps, but I've been able to make these turns in a DC-7C going a bit faster. How steep is your bank? Is the pointer near the white dot on the turn coordinator? I don't normally need to get close to the dot though. Are you starting the turn to final at no more than 150 kts (try 130-140 kts) and immediately after Alice makes the call? Are you turning through about a 45 degree bank?
Post by Tom/CalClassic on Oct 20, 2019 15:03:33 GMT -5
Here is an image of the approach of a DC-7C at a 5.5 NM intercept setting (~1800 ft AGL). I was 5 NM away from the airport when abeam. I made the turn to base at 170 KIAS with flap 1 extended just before the turn, and the turn to final at 150 KIAS with flaps 1. The turn to base was made at about a 15 deg. bank (not near the dot of the turn coordinator) and the turn to final was at about a 25 degree bank (at the white dot of the turn coordinator). I probably could have made this approach when only ~3 NM away.
Hope this helps,
Last Edit: Oct 21, 2019 11:11:27 GMT -5 by Tom/CalClassic: Changed bank angles to reflect reality. 30 deg to 15 deg, 45 deg to 25 deg.
Thanks for testing guys, I am very happy with the results shown.
Tom, yes, as you have found, I rather arbitrarily restricted the intercept distance to 6-12 miles. You can redefine that margin in the apsmall code itself, as you have done, or you can even do it against the Manual while Alice does her stint, except that you need to also reset INT height, but between you and me, there is a trick (R-click on blue Int distance figure and you get it), just as there is a trick to set reciprocal runway heading or the 90-degree turn to base (that angled arrow). I guess you are right that closer distances are viable (aircraft permitting) so I guess I'll redefine the margins, and add a caveat in the Manual.
Many thanks for your comments on the turns, Tom. I am between 5 and 6 miles away from the centreline before turning, which from what you say is clearly correct and in line with real practice. Turns banked as steeply as this have not been what I have done in the past, but I simply need to get used to them; and I wasn't too far off in the last flight. The point you make about airspeed is also very useful. I have carried out all these tests in the Lockheed L049, where the airspeed will only be below 150 kts at Flaps 60. Therefore I clearly need to trim the aircraft for Flaps 60 and perhaps lower the gear as well before Alice instructs me to make the turn. I guess this might also allow me to use a shorter intercept distance, but I look forward to experimenting further, Ken
If it helps the USAF C-121A (the L749) manual shows t/o flaps setting and 130 kts downwind, then gear down and 120kts on base, with approach flaps not until finals. That's a visual approach 'though but should work for IMC too.
45 degree bank on a 7C? Surely hard to maintain stall speed margins or happy passengers?
Post by Tom/CalClassic on Oct 21, 2019 9:23:08 GMT -5
True, typical bank angles are up to around 30 degrees. I will limit myself to that, which just means I need to be a bit slower for a standard rate turn. Note that on my steeper turn I rolled out a bit early, so I could lower that to a 30 degree turn and still be OK.
Post by Tom/CalClassic on Oct 21, 2019 11:08:12 GMT -5
I tried it again with a less than 30 degree bank angle turn to final at 150 KIAS and the flight trace looks about the same as it does above, the intercept leg is just a bit shorter. No problems here.
Edit: It turns out that my "45 degree bank" (from cockpit view) isn't really 45 degrees. In a DC-7C at 107,000 lbs and 140 KIAS and flaps 1 (10 deg) at 1900 ft MSL if I make a turn such that the turn coordinator is at the white dot (standard rate turn) it looks like this in the cockpit:
In my inexperience that looked to me to be about 45 degrees. (Yes I could have figured this out from the artificial horizon but I wasn't that smart.) However, the plane is actually banking like this:
As you can see that's only about a 22.5 degree bank angle (look between the vertical tail and the 90 mark on the protractor), so I was WAY overestimating my banks. So I have edited my posts above to reflect the actual bank angles.
Remember, I'm an FS developer, not a precision flyer.
Ok, gentlemen, thank you very much for your valuable comments and here is the latest. I set the weather in FS9 to a visibility of 2 nautical miles. Here is the breadcrumb trail of the flight and the point at which I saw the runway - it looks rather less than 2 nautical miles somehow.
I got myself into position turning with altitude hold on but switched the autopilot off just before contacting Alice, after which I also closed the gauge and was guided entirely by the voice instructions. With intercept distance set at 8 nautical miles I was at Flaps 60 with gear down and doing about 130 knots before doing the 90 degree turns, which as you can see were much more successful. PAR delivered me to exactly the right point by the time the runway came into sight, although I wandered about a little before that. He was telling me that I was above the glide path as the runway came into sight but in fact I landed easily and smoothly. Another thing one can bear in mind when doing these things is the known altitude of the airport when cross-referenced with the altimeter reading. As PAR tells you the distance you still have to travel you are not likely to be far off with a runway at 288 feet (LFPO) if you are at 1000-1500 feet 2 nautical miles away.
I know I have linked to 'In on the Beam' before, but I do find it fascinating and here it is again - it is the final section which deals with GCA at a stated visibilty of 800 yards.
Post by Tom/CalClassic on Oct 21, 2019 11:24:27 GMT -5
Now you've got it. Your base and intercept legs look just like mine, glad we're getting the same results now. I've recently tried 1 mile visibility (but I still had the AP handle the glideslope - not enough practice yet for that) and made it down OK. I'm impressed you could handle it all - that's tough.
Hi Tom, Many thanks. I think it is partly because I have always done manual landings and in the past I have been fairly successful with ILS landings at a visibility of less than a mile. The really crucial thing is knowing what engine and trim settings will fly the aircraft level at the various stages of descent. Once you don't have to work all that out on the hoof it all gets a lot easier. It is also crucial, of course, to be flying something with a proper flight model which always behaves in the same way, as the Connies do, and your DC-6B and DC-7C.
Last Edit: Oct 21, 2019 11:35:57 GMT -5 by connieguy
Post by Tom/CalClassic on Oct 21, 2019 11:54:41 GMT -5
Yes, there is nothing like experience to help you nail the numbers. I find when switching aircraft it takes me several flights to get those kind of settings down in my (feeble) brain so these approaches become smooth and not me flailing around in the sky... I just tried it without any AP help (I used AP ALT hold until final descent) in the CV-340 with 1 mile visibility - first time was a disaster, the second time not so bad but I still wouldn't pass a check ride.
Bill I've never claimed to be a good flyer, so any help I can get is welcome.