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DC-4 "floating" on final?

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I really like the DC-4 by Jens Christensen, but I noticed that on my machine, on final approach, the airplane starts a rise at 1000 fpm when I start setting up for final approach, and that's with the nose pointed DOWN. Very odd.Anyone else notice this strange behavior?RhettAMD 3700+ (@2310 mhz), eVGA 7800GT 256 (Guru3D 93.71), ASUS A8N-E, PC Power 510 SLI, 2 GB Corsair XMS 2.5-3-3-8 (1T), WD 250 gig 7200 rpm SATA2, CoolerMaster Praetorian case

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Umm, I've noticed this behavior several times on final with different planes. Threads on this forum refer to it as a bug in FSX that needs fixing. So I'm not sure what you have experienced is specific to the DC-4.Cheers,Noel.

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I have never experienced it with any other aircraft in FSX.It's way more than a thermal.Almost as if the flaps lift variable is out of whack, but it seems like it did it with flaps up, too.RhettAMD 3700+ (@2310 mhz), eVGA 7800GT 256 (Guru3D 93.71), ASUS A8N-E, PC Power 510 SLI, 2 GB Corsair XMS 2.5-3-3-8 (1T), WD 250 gig 7200 rpm SATA2, CoolerMaster Praetorian case

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I've had this happen to me twice in FSX, both times in the DC-3 but in two completely different locations. The first was coming in on final to KBED for rwy 29. As I was slowing down for the approach to 85Kts crossing the FAF, the aircraft suddenly started climbing at 1000fpm, despite full flaps, gear down and throttle full back! I had to abort the landing as I was too high, and as I came for my second pass of the FAF, the same thing happened again. I immediately cleared the weather and the issue went away.The second time was out in the boonies crossing Western Canada, when the level cruise that I had so beautifully trimmed using the sperry autopilot suddenly changed to a climb and with increasing speed. Rather than clear the weather this time, I went into my weather settings and turned on thermal visualisations and sure enough I was smack bang in the middle of one. As I exited the thermal, my airspeed returned to normal and my climb ceased.So I actually think it is being caused by thermals that should not be pushing aircraft as heavy as a medium loaded DC-3 around like that. Whatever it is, I hope it gets tamed down for non-glider aircraft in SP1.Gary

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Wow, that's so unreal, that I thought there was no possible way it could be a thermal.At one point, I had the nose pointed DOWN 10-20 degrees at least, gear down, flaps down, and yet the aircraft still rose at nearly 2000 fpm.If this is in fact a bug with thermals, then I hope they fix that. If this is a flaps lift scalar issue, then that's different. Has anyone pointed it out to Microsoft via tell_fs@microsoft.com? Are they aware of it?RhettAMD 3700+ (@2310 mhz), eVGA 7800GT 256 (Guru3D 93.71), ASUS A8N-E, PC Power 510 SLI, 2 GB Corsair XMS 2.5-3-3-8 (1T), WD 250 gig 7200 rpm SATA2, CoolerMaster Praetorian case

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>If this is in fact a bug with thermals, then I hope they fix>that. If this is a flaps lift scalar issue, then that's>different. Has anyone pointed it out to Microsoft via>tell_fs@microsoft.com? Are they aware of it?>As the OP, I think you just volunteered. ;-) Just send them this thread!Gary

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I want to see it happen with the DC-3. I want to see if I get the same thing as you did.there are a lot more weather-related bugs. For one, the upper air winds can shift rapidly and suddenly, sometimes pushing you to overspeed condition. I wonder if it's related to the thermals thing...RhettAMD 3700+ (@2310 mhz), eVGA 7800GT 256 (Guru3D 93.71), ASUS A8N-E, PC Power 510 SLI, 2 GB Corsair XMS 2.5-3-3-8 (1T), WD 250 gig 7200 rpm SATA2, CoolerMaster Praetorian case

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Anyone who wants to see this try Andrewsfield in the UK (EGSL). There are some ponds to the east of the field that are used as landmarks on a right circuit oriented to the north of the field, as you fly over these you will hit the effect as you turn for finals. I just floated along on finals then over the runway in the standard 172 with the engine at idle and 35 degrees nose down and was still gaining height. I remembered this thread and switch on visual thermals, totally surrounded LOL, now they are switched off circuits are a little easier to say the least.Is there a way to tone down the thermals as I miss the turbulance, I think that is modelled quite well and makes circuits a bit more fun?

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oops, I just thought the ponds may not be there in the standard scenery, as this is occurring with modified photoscenery, might still be worth a right hand circuit to the north though to see if it does it.

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It happened again to me today and this time, even after four attempts, I couldn't get my DC-3 down at all on the approach end of rwy 25 at CYQL due to ridiculous lift being generated. Again I had chopped throttles, full flap, gear down, and I was climbing at about 500-100fpm on "descent". If I went to the other end of the airport, descent returned to normal.I managed to get a top down screen shot of the thermal positions, and they correlate perfectly with areas I experenced ridiculous lift as you can see below:http://forums.avsim.net/user_files/167802.jpgI am going to send this in as a bug report to MS, but in the meantime is there anyway to turn off or tone down this excessive thermal effect for when I am flying non-glider aircraft?Gary

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Hi Gary,Settings - Display - WeatherUnder the heading 'Simulation Settings' there are a couple of tick boxes, check **Disable turbulence and thermal effects on aircraft**That will kill the thermals, but unfortunately also the turbulence.There must be a fix to just tone down the thermals, anyone?

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Thanks for the suggestion. Yes, it would be good to tone down thermals only - I like bouncing around in turbulent air!Gary

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In the root folder of FSX is a XML file ThermalDescriptions.xml. There you can lower the values for the thermal core rate. You have to increase the core turbulence values since these depend on the core rate.I set my values as shown below:CoreRateMin: 0.5CoreRateMax: 2.5CoreTurbulenceMin: 0.14CoreTurbulenceMax: 0.28This way you still have the turbulence but the updrafts are gone. The values in this file are documented in the SDK.Don't go on a soaring mission after these changes ;-)Alex

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A quick update, as I have been able to turn off thermals completely without affecting turbulence by renaming the file ThermalDescriptions.xml in the FSX root directory to something else (eg. like .bak). No more super climbs!An alternative is to download the file thermaldescriptions_11.zip here in the Avsim library and use the alternative ThermalDescriptions.xml file it provides. I just gave this a quick go and while the thermal lift effect is still there, it is neither as extreme or lasts as long as the default thermals. In fact, I was able to manage a mild descent in the stock DC-3 while passing through one!Gary

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Thanks Alex, looks like we cross posted. It is interesting that turbulence values are set in ThermalDescriptions.xml, yet I was still getting good turbulence when I renamed this file completely. Anyway between what you and I just posted, there are at least a few work arounds to this issue. Thanks for your input.Gary

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