IAS mode

  • Please correct me if I make any mistakes, but IAS autopilot mode does not seem to work with me.
    TMS is in SYNC 1 mode, I engage IAS when approaching 220kts and the autopilot just flies through it up and beyond max speed. Only VS mode seems to work to manage the climb.

  • JF Staff

    Please get in touch with the support team so they can collect further information to identify the cause - https://support.justflight.com/support/tickets/new

  • @fly2belgium

    Try to hand over to IAS in a well trimmed state and try to reduce climb power a few %N1 below takeoff power.
    I got the impression with IAS the V/S gets limited to around 3000fpm and any excess power is put into speed then. With the above mentioned climb power reduction you can dampen this a bit.
    Currently it I somewhat unclear how to set climb power, with the TGT/Sync it doesn't really work, as the temperatures are too low. 780C would be somewhere above takeoff power. So I just guesstimate the climb power around 5-6 %N1 below takeoff power. At least for me the IAS Mode keeps it below 250kt then.
    Other than syncing the engines TMS in Sync1 mode does nothing for climb power setting. It just copies your actual N1 to the TMS display


  • @Mikealpha

    I just noticed, IAS Mode has definitely been improved in 1.06!

  • @Mikealpha and now FD doesn't want to work with IAS. Autopilot is ok, but FD shows to drop nose down.ekWWfPEFvyc.jpg

  • JF Staff

    There's been no changes to the FD logic but we'll investigate.

  • Just to clarify any confusion; the TMS and A/P IAS/Mach are in no way coupled. The TMS is purely controlling the Engines to a set parameter (N1/N2/TGT), it doesn't care what the A/P is trying to do. (although this doesn't sound like the issues you're reporting.

    Typical CLM Thrust is about 88% N1for the 502 Engine. But keep an eye on the TGT! It should be maintained below 820C till about FL150, then keep it below 840C.

  • @flightstrike said in IAS mode:

    But keep an eye on the EGT! It should be maintained below 820C till about FL150, then keep it below 840C.

    Thanks, that's very good advice.
    In the Justflight plane the EGT even at full thrust is way below these values though. I mentioned this already several times, but it is seems Justflight isn't interested anymore in fixing this.


  • JF Staff

    Was that mentioned on the forum and in a support ticket? The only other mention I can see is in the new thread regarding future updates?

    I'm seeing approx. 770c at take-off and initial climb with an OAT of 15c. That matches what I can see in videos such as the ITVV 146 DVD. I hit the EGT limit at OATs of above 25c.

    If we're able to get more data that clarifies where EGTs need to be modified then we're happy to make those changes.