Weird behaviou at rolling... Just before takeoff.



  • @Delta558 Do you have any idea why this problem suddenly appeared following one of the recent updates either 0.4 or 0.5? Also the pitch stability is pretty bad. Excessive rates of climb and decent with very small pitch change. Very difficult to climb at constant rate do to pitch oscillation. Yet difficult to achieve a full stall landing without running out of elevator authority and dropping the nose.



  • Actually I don't - as I think I mentioned elsewhere, it's very difficult to track down a problem that I don't see myself and which has not been reported in extensive testing but is obviously affecting a few users. There have been adjustments made to try and alleviate some of the core sim's awful ground handling and transition to airborne, but nothing that stands out as "this will cause a sudden yaw", it's generally been rebalancing rather than introducing anything new.

    That's also the first anybody has mentioned to me about pitch stability or oscillation, as well. It's actually been remarked how easy it is to trim the aircraft, are you trimming for the climb or just using aft pressure on your controller? (and have you set the control forces as shown previously?)



  • @Delta558 Yes I do always attempt to trim but in a climb it is almost impossible because with hands off the nose will rise slowing descent and then it will fall increasing descent. I just can't recall the term for this kind of oscillation. Please tell me about setting control forces because I have done nothing of the sort.



  • Sensitivity - 0%
    Sensitivity + 0%
    Dead Zone 1%
    Neutral 0%
    Extremity Dead Zone 0%
    Reactivity 100%

    You can set up a profile for these, use them for all three primary axes as that is the settings the aircraft was developed with.



  • @Delta558 Oh yes I do remember doing that but I will check it again. Except for the ground handling issues and sudden excessive yaw the aircraft feels very realistic on takeoff which really impressed me from the beginning. It also handles well straight and level. I can get it trimmed fairly well in a descent but cruise climb would bust a check ride. It is really hard to understand how performance can very so much from one user to another.



  • @sdvpilot: longitudinal phugoid oscillation



  • @sdvpilot said in Weird behaviou at rolling... Just before takeoff.:

    @ViniciusQdrs Yes not a skid but a sudden yaw left or right just reaching takeoff speed on some but not on every takeoff with no significant crosswind. Don't know what the cause might be but it was not always that way until one of the latest updates. It is like a sudden wind gust hitting the vertical stabilizer just when you leave the ground.

    I seem to be experiencing this as well.



  • There is one thing I can't understand. In flight-model.cfg for c172 moments of inertia are 3 times grater than in case of arrow - but both planes have similar mass. Is such a difference really possible or maybe default planes have this paramer tuned up to get more stable behaviour? Am I missing something here?



  • I cannot speak for what was done with the default aircraft, but the Arrow's MOIs have been calculated as per standard aerodynamic convention.





  • @ViniciusQdrs And that first video - I have seen that behaviour in default aircraft, I actually have not seen it to anywhere near that extent in the Arrow except for when I adjusted the yaw stability setting to =1 (as recommended above).

    It is a problem with the sim.
    The weather builds the crosswind effect from nothing when stationary to full effect at about 50kts. Unfortunately, you are also entering the transition period in this aircraft between the sim's ground handling and airborne handling, which also deal with weather seemingly differently. There is a lot going on in the core sim at around that speed.

    A quick search of the MSFS forums throws up thread after thread about this, virtually every aircraft is affected by it (some say not the airliners, others say even they are). Until the core sim is sorted, anything we try and do is going to be at best a botched job that may have detrimental effects elsewhere.



  • @Paul-J Yes that is it, and it is quite bad on initial climb. Greater than +/- 500 FPM, but it does seem to eventually settle down.



  • @Delta558 Good to know it is in the sim. It gets almost uncontrollable with any kind of crosswind.



  • @Delta558 I think it is better with sensitivity settings you recommended, but still you cannot stay on the ground any moment longer than nesessary. I tried also yaw stability set to 0.05 and I think it helps, but i did only few takeoffs with this setting yet, so I have to do more testing. It was ok, but maybe wheather was too mild.



  • Have the same issues, also when doing a Touch&Go, totally uncontrollable as soon as I'm touching the ground, sliding left and right.
    Control sensitivity is on default, no issues hand-flying or taxiing at all, only at high speeds.
    And since this has not been the case before the recent updates, I don't think this is just a MSFS issue.



  • @copper It really is a sim issue. Been having it for ages now on the DA-62.



  • @Cristi-Neagu said in Weird behaviou at rolling... Just before takeoff.:

    @copper It really is a sim issue. Been having it for ages now on the DA-62.

    But didn't have it with previous versions of the Arrow, there was defintely some change in the recent updates that made it far worse. Never had such big issues to counteract wind on takeoff roll. Doesn't happen on other aircraft this way to me, so there certainly is a way to avoid this.



  • @copper There have been various issues with the rudder through development, testing and with all versions released so far. Each attempt to improve things seems to throw up or increase another problem area.

    Let me be clear, I am not happy with it.

    I do not rate the core flight model at all - I think it started with good intent but the implimentation is poor. Within that, I think that the yaw axis is by far the weakest of the primary axes. The problem is, the same issues occur in the default aircraft, and we seem currently unable to just 'make it all work', we can fix some but not all. That is down to a poorly implimented core sim flight model which is brand new but has no worthwhile documentation .



  • @Delta558 said in Weird behaviou at rolling... Just before takeoff.:

    Let me be clear, I am not happy with it.

    Fair point, neither am I and I understand that tweaking one thing will break something else.
    Just wanted to say that the issue discussed here definitely changed to the worse for me in the last few updates (probably with 0.5.0).
    If that's the state that you think is the best compromise for now in terms of other effects, I can't contradict since I don't have all the insight 🙂 But at least it's good to know that these issues are seen by the devs.



  • @copper I am in complete agreement with you that something has changed. I do not understand why it is not also obvious to the developers. While it may not happen on every takeoff, it does happen most of the time in fair weather with very light winds reported. I would go back to 0.3 to check but I really don't want to mess things up in doing so. It seems that I am spending most of my flying time just keeping up with updates and chasing bugs.