OAT Question at altitude

[ddewees]

I am having problems flying turboprops at altitude due to the sim keeping the ground temps while flying at altitude. For instance, I departed the airport with an OAT of 29C deg (near 90F). While climbing to 19,000 ft, I could not keep the TOT below redline (800C) even with power at 50%. I noticed that my OAT was still showing 29C when passing through 16,000!

Does anyone know how to change the sim to show temps at altitude, or why this would be happening? Thanks.

[JSkorna]

Hi,

What are you using for your weather program?

[mrzippy]

I just took a quick test fight in a King Air and OAT changed with altitude. Are you using real weather with/without 15 minuet updates? I saw on a few other forums about temps actually increasing with altitude because of temperature inversions.

[MoeWoodworth]

Yes. Temperture inversions can and do happen. As general rule OAT drops about 2 deg C for every 1000ft but an inversion may cause it to get warmer. I have seen this in real flying and in FSX. It happens. Now as to why you have High TOT at altitude with only 28C. That sound odd. OAT changes might make up to 100F difference in TOT but that should not gimp you to less that 50%. Look to other sources of you high TOT. The change in pressure altitude should not be a factor in temps in your TOT.

Moe

[ddewees]

Thanks for the info...Currently, I fly the "Real Air" Beech turbine Duke online with FSInn. It might have something to do with the setup for FSInn's weather interface??
I know that when I used to fly with Squawkbox, that program would take control of the weather generator for FS, so maybe I need to do something in FSInn.

I will fly again and see if I'm getting the same problem.

[CaptainTower]

I am having problems flying turboprops at altitude due to the sim keeping the ground temps while flying at altitude. For instance, I departed the airport with an OAT of 29C deg (near 90F). While climbing to 19,000 ft, I could not keep the TOT below redline (800C) even with power at 50%. I noticed that my OAT was still showing 29C when passing through 16,000!

Does anyone know how to change the sim to show temps at altitude, or why this would be happening? Thanks.

If you are talking about TAT (Total Air Temperature), that is a measure of the temperature of the skin of the aircraft, not OAT, the Outside Air Temperature. In jets (and I suppose Turbo Props to some degree), at very high speeds, the skin of the jet becomes hot. The Concord used to develop enough TAT (Total Air Temperature) to fry eggs! It sometimes had a TAT of 200 degrees Farenheit or more.

Thanks,

Tim

[torkermax]

for our purposes. OAT is all that matters and modeled.

[CaptainTower]

for our purposes. OAT is all that matters and modeled.

OK. I thought you might have been confusing the two. Some FSX AC have a readout of TAT.

Tim

[btwilks]

ddewees

As the problem you're describing occurs when using FsInn, it seems you're encountering the traditional high-altitude temperature phenomenom mentioned in the FsInn Troubleshooting thread in the VatSim Forums at

http://forums.vatsim.net/viewtopic.php?f=43&t=56205

The specific bit that'll interest you is

Weather Bug in FSInn/FSX (affects Speeds, Temperatures, and Climb [above FL245])

This is an issue with FSX/Simconnect/weather. When flying at high altitudes (above FL245) there's a miscommunication between FSX and FSInn concerning the temperature. This TAT problem isn't experienced when flying below FL245.

The resolution is to turn off FSInn's weather when flying above FL245 and use an alternate such as FSX's weather. There are two ways.

■Turn the weather off by default (Inn Control Panel -> Set -> Weather [Check/Uncheck]). With this option You will in effect use whatever alternate weather you already have in effect with Flight Simulator.

■Or (what I consider preferred) turn it off or on on-the-fly by clicking the CAVOK bottom to turn FSInn's Weather off or clicking the VATSIM cloud to turn it on. When you turn FSInn's weather off, use FSX's download real weather +15 minute option. To resume FSInn's VATSIM weather, just click on the cloud next to VATSIM

Hope this helps.

Brian