Device: Samsung Galaxy S23 Ultra Operating system: One UI 7.0
Hey! I think IF may have made a mistake in calculating the Mach speeds in game. I find that the KIAS (Knots Indicated Airspeed) in game corresponds to a higher TAS (True Airspeed) and Mach speed than what would be expect in the real world at specific altitudes. For example, if you fly the A320 in IF at 300 KIAS, 28,000 feet (Mach transition altitude for IF), at around -40 degrees Celsius you would hit 473 KTAS, or Mach 0.80. In actuality, this would be approximately 452 KTAS, or Mach 0.76. There was a very good website mentioned by another person in A220 Autopilot Speed that peaked my interest and I used it for this claim. I’ll save you time and link the actual website here: https://aerotoolbox.com/airspeed-conversions/. Based on the website, my guess is that IF is likely going off of EAS (Equivalent Airspeed) instead of IAS (Indicated Airspeed)/ CAS (Calibrated Airspeed) suggested. If you use EAS, then you get a Mach speed of 0.796 or approximately 473 KTAS, which would round up to 0.80 in IF. To further prove my point, I headed to Youtube and looked at this video to confirm the calculator’s accuracy: https://www.youtube.com/watch?v=n3TJMro_NzA. The pilot reached 19,000 feet, 457 KTAS at Mach 0.719. Plug that into the speed calculator mentioned (change the temperature offset to get KTAS), and you get an IAS reading of 339.581 or roughly 340 knots. This matches what we see on the pilot’s PFD (Primary Flight Display) screen for IAS. In IF, that’s like 474 KTAS, or Mach 0.75. If you tried the EAS using the calculator, you would get 0.743, which is still less than what IF has, but that could just be internal rounding in IF since it’s hard to get exact values in temp because IF displays whole numbers. My hand may have adjusted the slider slightly on the higher side. I know that looking at something like this right now would possibly change a lot of stuff and cause more bugs, but it would provide correct speed guaging, which I see as an improvement for the sim. Thank you for reading this.
I did test in Solo. I didn’t see that as a problem since I adjusted the temperature sliders till I reached the suggested OAT temperature that the calculator said. This puts them at the same conditions. There, we can see the difference in readings between IF and what the calculator has to say.
Ehm… are you referencing the calculator logic or IF? By default the calculator is set to ISA at MSL. It’s temperature reading is 7°C at 4,000 feet. I just plugged the ISA in Solo and got 7°C as well at 4,000…
I meant in solo in IF, this morning. I did notice it was wrong. I am gonna check again tomorrow, live and solo. But I also believe someone in the staff said something about temps in IF not being quite as right in solo as in live mode.
Maybe you could just hop on an a320 in casual and climbs to 28000ft or more, then check with the live temp if the speeds are right. I believe they are.
Okay, I brought the A320 to 28,000 feet, -28 degrees Celsius, 500 KTAS, Mach 0.82 on the causal server. IAS is around 309 knots. According to the calculator, you should be at approximately 326 KIAS with a KTAS of 500 (Mach 0.819, which rounds to Mach 0.82 in IF) for those conditions. Funny enough, the EAS is registered as 309 knots, which confirms my claim that IF is actually using KEAS and not KIAS.
But in the thread about the a220 stuck under M0.78, where I posted a link of the aerotoolbox page, it appears that the IAS is displayed. So why would the A320 and the most recent A380 display the EAS, and the A220 the IAS?
Tbh, the most important is to have the Mach and TAS right, which they are, and when IAS matters (low and slower), EAS is nearly equal to IAS.
For that, you didn’t change the temperature offset. If you look closely, the OAT in IF doesn’t match what’s on the calculator. If you change that, then the speeds won’t be the same and/or correct.
Still wanted to double check the numbers, because I still think this is on all aircraft. The numbers match at 38,000 feet for those parameters, but what about other altitudes? Again, I repeated at the IF Mach transition altitude (28,000 feet). Chose this because it’s easier to see when and which IAS switches to a certain Mach speed. I aimed to maintain mach 0.80 on the autopilot. The actual was Mach 0.79. At -28°C, the plane used approximately 299KIAS to maintain that Mach 0.79. With the calculator, it claims that approximately 313 KIAS is needed for that Mach speed at said altitude and temp. That’s around 298 KEAS, which again is closer to what’s reflected in IF. I’m not sure how to explain how the A220 matched the calculator at 38,000 feet and I have no idea on how IF guages. I assumed it was EAS because the numbers are oftly closer .
Edit. It is not weird at all! IF uses EAS and not IAS, you are right.
For the A220, I had deduced the altitude (not given by the OP and not visible from the picture given) and found the Mach/IAS relationship between about IAS 243 and about M0.77 to happen at 38000ft… because I was searching for an IAS value. But he was probably flying at about 36000ft, where the same Mach correspond to about EAS 243…
On a side note, temps have no effect here on IAS/EAS, only on TAS.
We indeed show the EAS as the IAS which in our case where there’s not really position errors or anything, is the same as EAS.
The only thing we do is adjust for cross winds but you shouldn’t see this in normal coordinated flight.
If we were to show the IAS for each plane, we’d need to get the correction tables for each plane, which is not really doable, so when this was designed, we just went with EAS.
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