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Guest DSandberg

Realistic Simulation of Mountain Flying

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Overall I think Fly does a pretty good job of modelling the atmospheric effects on the flight model. One time I had a repeatable problem when I loaded a particular metar cycle file. As soon as I flew into an area between OKC and DFW all the A/C temp readings maxed out and the A/C would loose lift and spiral into the ground. At first I couldn't figure out what was happening with the sim. I finally determined the metar cycle was reporting from one particular station an ambient temperature around 400 degrees!

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That's been known to happen when a PK WND element is a part of the METAR report's comments section. If you use InfoMETAR to preprocess METARs before loading them into Fly!, you won't run into that problem anymore.Of course it's always possible it was just a different type of random METAR error, but by far the most common cause of wildly off temperature/dewpoint after loading METARs is the presence of a PK WND entry.[table cellspacing=0 cellpadding=0][tr][td width=320]http://www.usinternet.com/users/mystic/infomsig.gif[/td][td width=170 align=center]God wants Richard Harvey to be his copilot.[/td][/tr][/table]

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This is really a great discussion. Reading about hangliding is fascinating too. I'm amazed at all the other things Fly!2 community members are involved in.David...regarding Fly!2's weather simulation, can I assume that depending on the METAR information I download with InfoMETAR, Fly!2 may simulate conditions where my 172SP will have a harder time around 12-14K feet than at lower elevations? Or is it not that granular?

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I agree about the hangliding ... I'm sure it's safer than the idea seems, but I'm still amazed. The experience of hanging that high above the mountains, up in the rarified air, with only that tiny non-motorized wing to keep you there ... well, it sounds like an experience one would remember for a lifetime, at the very least. Just looking at Henri's picture confirms that much.There are two answers to your weather question. First, Fly II ought to be doing a reasonable job of simulating typical adiabatic lapse rates for temperature and dewpoint (and hence density altitude) as altitude increases, with associated changes in engine and wing performance. This should be true regardless of how the weather was generated (METARs, global weather setting, or whatever). How accurate the flight modeling is with regards to simulating the effect of those changes I can't say ... there are others better qualified to express an opinion about that.As far as specific layer information with METAR weather, this really doesn't exist as a part of METAR reports (outside of visible cloud layer information). METARs are surface observations only ... no balloon soundings or anything similar that would include information about temperature, dewpoint, or wind changes with altitude is present in METARs. There are different types of weather reports that include such information (FAs in particular), but those are not supported by Fly II (or any other sim that I'm aware of, for that matter).[table cellspacing=0 cellpadding=0][tr][td width=320]http://www.usinternet.com/users/mystic/infomsig.gif[/td][td width=170 align=center]God wants Richard Harvey to be his copilot.[/td][/tr][/table]

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David,This was definitely before I started using Infometar to process my metar files. I have never run into this type of problem again but it sure added a new element! First I noticed all the temp readings climbing to their max reading and then no more lift. Talk about an unexpected, unrecoverable in-flight emergency! BTW, what is a PK WND element?

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PK WND is a METAR comment element that indicates the highest winds recorded at the location during the cycle period, as you might expect. It only commonly shows up during windy events (I recall that we first encountered this problem with Fly! 1.0 when people tried to go flying in weather from an East Coast hurricane.)[table cellspacing=0 cellpadding=0][tr][td width=320]http://www.usinternet.com/users/mystic/infomsig.gif[/td][td width=170 align=center]God wants Richard Harvey to be his copilot.[/td][/tr][/table]

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