Grand Duke TAS discrepancy
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I noticed a rather big discrepancy between POH values and actual TAS cruising at FL290.
TAS according to:
GTN 750 -> TAS 256kts
ASI -> 266ktsFL290, 1kt TW, -43°C SAT (so pretty much ISA) at 55% Power should result in a TAS of ~216kts (interpolation).
Assuming the lowest TAS calculated by the GTN there's still a 40kt discrepancy.Either I'm missing something or there's indeed something off.
If more information is required for reconstruction just let me know!First time crusing that high, in the region of FL200-FL240 numbers were pretty much spot on every single time. Really enjoying that piece of art!
Cheers,
Max
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Im pretty sure the GTN750 displays speed over the ground or GS and not TAS. The only time TAS=GS is with no wind. TAS can not just be read off the ASI unless of course you move the card then I don’t believe it to be an accurate indication close but I wouldn’t say it’s spot on. TAS= IAS corrected for nonstandard temperature and pressure.
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Im pretty sure the GTN750 displays speed over the ground or GS and not TAS. The only time TAS=GS is with no wind. TAS can not just be read off the ASI unless of course you move the card then I don’t believe it to be an accurate indication close but I wouldn’t say it’s spot on. TAS= IAS corrected for nonstandard temperature and pressure.
@xXCaveDwelerXx GTN is indeed able to calculate TAS which can be looked up under the "Utilities" tab.
ASI card's been moved with FL290 below -43°C SAT. I know it's not gonna be 100% exact but that's why I listed both: ASI TAS and GTN TAS. So taking either one we still end up with a 40kt-50kt discrepancy on pretty much ISA Temperature. -
I’m gonna have to check to see if I get same result on next flight.
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This is what I was just indicating.
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This is what I was just indicating.
@xXCaveDwelerXx hm okay but apparently these numbers aren't comparable at all. You're at FL260 where TAS is supposed to be higher than at FL290. Also look at the difference between Pressure Altitude and Density Altitude, temperature's gotta be a lot higher than ISA compared to my flight at almost ISA conditions. And what Powersetting did you use to reach 180kts IAS at FL260?
But thanks for trying to help. I'll try to reproduce it myself again.EDIT: Disregard everything I've just said, just noticed you were using the TURBINE Duke, I was talking about the GRAND Duke so comparability is out of question now hahah...
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@xXCaveDwelerXx hm okay but apparently these numbers aren't comparable at all. You're at FL260 where TAS is supposed to be higher than at FL290. Also look at the difference between Pressure Altitude and Density Altitude, temperature's gotta be a lot higher than ISA compared to my flight at almost ISA conditions. And what Powersetting did you use to reach 180kts IAS at FL260?
But thanks for trying to help. I'll try to reproduce it myself again.EDIT: Disregard everything I've just said, just noticed you were using the TURBINE Duke, I was talking about the GRAND Duke so comparability is out of question now hahah...
@mxqn haha I should’ve read the title! I’ve been flying the turbine so much lately I forgot there was two other variants! I know there was some issues when released with performance in all three of the dukes but I thought Nick got those sorted. I know for the Grand Duke it is tough to find an actual POH with the correct numbers. Where did you get the POH for the Grand Duke?
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@mxqn haha I should’ve read the title! I’ve been flying the turbine so much lately I forgot there was two other variants! I know there was some issues when released with performance in all three of the dukes but I thought Nick got those sorted. I know for the Grand Duke it is tough to find an actual POH with the correct numbers. Where did you get the POH for the Grand Duke?
@xXCaveDwelerXx no worries! I just used the numbers of the tables provided in the manual.
I'll try another flight in the higher levels later on and have a look at the results again.(but tbh I really don't mind flying faster than advertised...)