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About fppilot

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    10 Mi NW KESN

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    Former USAF meteorologist & ground weather school instructor. The technology of weather has changed, but the science and understanding of weather has not!

    Founding member and former Chief Pilot of Sunair VA, the original virtual airline, founded on Prodigy in 1992 and originally based in subLogic Flight Assignment:ATP.
    480 hours real life flight time. Multi and instrument rated but no longer active or current.

    MSFS enthusiast since V1.0 with 5,000+ total hours in FS versions, subLogic ATP, Fly! and Sierra Pro Pilot. Was the second owner of the original IBM PC in the USA state of Oklahoma (Computerland franchise owner was the first owner) and Microsoft Flight Simulator was was one of the first three computer programs I purchased!


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  1. FSX-MS

    Anticipate only. It can always change. Base it on the weather at the destination airport. Winds are the influence. There are a number of ways to determine the destination weather/winds when enroute.
  2. I'm just letting Windows 10 update itself, when it wants, and not screwing with it at all, and life if good..... Just saying.
  3. Doing some more studying. Can get confusing but I worked through it. From my flight yesterday, the Turbine Duke v2 was indicating TAS of 267 knots and -30°C for OAT/SAT. The RXP GTN750 was indicating -21°C for TAT. ---------------------------------------------------------------------- Most useful formula I found to determine TAT from SAT/OAT is this one. Example plugs in the values from my flight. TAT= SAT + (TAS/87.1) ² With my values: TAT= -30 + (267/87.1) ² (267/87.1) = 3.06544 (3.06544) ² = 9.3969 TAT = -30°C + 9.3969°C = -20.6031 (which the GTN obviously rounded to 21) ---------------------------------------------------------------------- So both the TDv2 and the GTN750 are correct. To each his own. TAT (GTN) or OAT/SAT (TDv2). And proper use of either TAT or OAT/SAT, with an E6B that allows one of the other, returns identical ground speed GS. Funny. I downloaded the Sporty's E6B iPad app this morning and it for the like calculation it provides entry option for only one temperature, True Temp. Based on my use True, SAT, and OAT appear to be interchangeable. There are other formulas out there but be aware that most require converting SAT °C to Kelvin then converting the result from Kelvin back to C°.
  4. The best and most complete description of Total Air Temp I found yesterday is on the Flying magazine site https://www.flyingmag.com/air-temperature-explained. One site I was on yesterday stated that the difference coefficient between OAT/SAT and TAT is called Ram Rise and starts coming into play at about 200 knots TAS. However other site say that starts to happen at mach 0.2, which is about 134 knots. Interesting subject. Would be interesting to observe the difference between a sim aircraft that provides a tooltip at the temp gauge, such as the TDV2-indicated OAT, and GTN-indicated TAT, as TAS increases from say 150 knots to 250 knots. I am still not convinced that groundspeed indicated in the GTN is off by any measure as in E6B calculations using the separate OAT/SAT temp input and then using instead the TAT temp input both produce the same.
  5. Still catching up with you. On this question understand that the OAT is what is being returned by the Turbine Duke v2. Perhaps RealAir chose OAT over TAT in terms of what to display, while GTN chose TAT. Don't believe there is a bug. Just one requests one thing and one requests the other.
  6. OH! I am using FSX Acceleration and trainer 6.41. Also something else I can check on next flight is that from what I read this afternoon Total Air Temp (TAT) reflects ram rise in temperature at or above 200 knots. OAT does not. That being true, OAT and TAT should be the same or nearly the same at or below 200 knots.
  7. Well I had to do some learning about TAT. More rooted in general aviation aircraft that fly at less than 200 kts I've always used OAT or SAT. So I read that TAT takes into account ram rise at TAS above 200 knots, and certainly I was well above that. So In my mind that explains the difference between the OAT indicated in the Turbine Duke v2 and the GTN. TAT should read lower... I also found that one function mode of my Sporty's E6B electronic calculator has alternate inputs for outside temperature, (I°C) and (T°C). The instruction manual simply calls (I°C) "Indicated" and calls (T°C) "True". So I was not familiar with the term "Total". If from my flight today I use 200 knots IAS, 20,000 for pressure altitude, and -20°C for the I°C (indicated) variable in the calculator, it returns true airspeed as 267 kts. Matches what I saw. If I instead input -29°C into the T°C variable (true) it also returns 267 kts. Funny, but that would then appear to use I°C for TAT, and T°C for OAT. Checked the calculator three or four times and clearly for the two results to match the lower value must be input into I°C and the higher into T°C. Seems to be the use of terms in the calculator.
  8. Not sure from both of the immediately previous messages if it is to be addressed, but the °F vs °C for OAT needs to be looked at. My TDv2 reported OAT again was around -29°C. The GTN reported OAT was -20°C. So if both are read from the sim then why are they different? I descended from 20,000 to 16,000. TDv2 OAT was -19°C. GTN was indicating -9°C. Both clearly indicated as °C. FYI, a temp of -29°C corresponds to a temp of -20°F. C vs F.
  9. I concur with Gregg. Thanks to FSUIPC auto saves, I was able to resume my flight after lunch. My wind arrow stayed fixed until I changed the map settings from Track Up to North Up. Then to Heading Up. The wind pointer changed each time I changed orientation. When I returned to Track Up the wind arrow started showing a direct cross wind. But the actual winds could not be cross winds. My IAS was 202 knots, TAS was 269 kts, and Ground Speed at only 223 knots. With the arrow showing a direct crosswind GS would have been the same or very very close to TAS. My actual TAS and GS were consistent with winds aloft in my FltPlan.com flight plan. Approx 300° to 310° and around 46 to 50 knots. At my indicated 269 TAS my and heading of 282° my indicated GS of 223 knots would have been realistic. Other than the °C vs °F OAT temperature issue I reported earlier, the calculations in the GTN appear accurate in regard to speeds and enroute times. i.e the wind arrow appears to be only a false indicator. My actual winds were accurate in regard to my plan and my chosen weather engine and actual performance.
  10. OK. Let's see how well I can write this. Am up in the Real Air Turbine Duke v2 (TDv2). Am at 20,000 feet (29.92). Pointing at the airspeed indicator in the TDv2 provides a tooltip showing both IAS and TAS. My IAS is 201 kts and TAS shown as 266 kts. Pointing the mouse pointer at the TDv2 outside temperature gauge shows OAT of -29°C/-21°F. The RXP GTN750 is showing 219 kts ground speed. Winds at 48 kts. My autopilot guided flight plan has vectored me around the Washington, DC protected airspace so I have been at various headings so far into my flight. My GTN indicated wind speed has changed several times. However the wind direction arrow has not changed at all. I am flying with a real world flight plan created at FltPlan.com and flying with weather infusion from FS Global Real Weather (FSGRW). My FSX/FSGRW departure weather at Easton was spot on with my FltPlan.com flight plan. My GTN indicated winds aloft have been in very close proximity to my flight plan. I believe my GTN indicated ground speed is off and I may have determined why. The GTN Map's User Fields (via Menu) include an option to show Outside Temperature (OAT). It is indicating -20°C. The OAT gauge in the TDv2 is as stated above showing -29°C/-20°F. So the GTN may be using the °F instead of the °C. Pulled out my trusty Sporty's electronic E6B calculator and calculated TAS from Pressure Altitude (20,000), Calibrated Airspeed (CAS or IAS), and OAT. I did this for the TDv2 °C reading of -29°C and for the GTN °C reading of -20°C and the differences in the two results, after subtracting the GTN indicated wind speed accounts for the difference. Yes, I used the indicated wind speed and did not convert it to true component vs my heading, but I did if the same for both the TDv2 and GTN OAT °C readings. The wind component would be the same for both. I did not get a chance to time any FSX enroute segments vs my plan to determie as my FSX just crashed, likely due to all my messing around and Alt-Tab's between other applications. In closing, my GTN wind direction arrow did not at any point change, and it may be that the GTN is using a °F reading for OAT instead of °C, which if true places TAS and thus GS off by a handful of knots. Perhaps 6 to 8 in the case of my flight.
  11. Ok. So here is my planned flight for tomorrow (If I can find time) from Easton, Maryland, to Spirit of St Louis, Missouri. Take a look at the wind component column I circled. Virtual headwinds so this should be a great determinate. My weather engine is Real World Global Weather, which I have high confidence in with over 1,000 logged hours using their weather feed. I have not yet logged a flight with the RXP GTN's so this should tell the tale if there is an issue. My flights with the v2 GNS gauges have been accurate. http://
  12. Not sure about my day tomorrow, but perhaps the resident meteorologist can take a flight and see what's up (or down). I am a stickler that my real world based flight plans be closely reflected when in the air with FSX, and winds aloft and enroute times are an important element of that as they dictate fuel burn. I have been too long in the hangar/shop the past several days so its time to catch some air...
  13. Do you need help? LOL!
  14. So does that mean that you uninstalled the TDv2, then reinstalled it, then configured it before firing up and looking at it? I would suggest you totally and completely without question uninstall it. Then reinstall. Do nothing else. No configuration other than default installation. Boot up P3D and look at the panel at that point since your other gauges and radios exhibit the same issue. Then take baby steps in the config process, firing up each time and looking to see when it first appears. Believe me I hate the painstaking element of the process, but I have been pulling my hair out the past few days while in my case making small mistakes of omission when configuring GPS models into panels and into popups. When I slowed down and created a checklist I found I could determine when issues arose and then recognize what I was doing or not doing. Not saying you are yourself making errors at all, that was my issue. But moving a step at a time only, and verifying, helped me overcome it. That type of process might help you identify better what is amiss in your case. The TDv2 is too valuable to be dissatisfied with. It needs to be totally enjoyed!
  15. So an obvious question is whether you have your GPS display track up, or if you have it north up? May not be the answer to the issue, but worth asking.