Weird behaviou at rolling... Just before takeoff.



  • Did anyone else is have a strange/weird beahavior evererytime at rolling? just before taking off?

    I'm experiecing some skid movment...



  • From your reading your almost illegible post alone, it's difficult to decipher what the problem is. Make sure that the flight model is set to Modern in the settings.



  • @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.



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

    t 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 upd

    Exactly @sdvpilot! Although Leonard doesn't know how to read, you understood the issue.



  • @ViniciusQdrs it sure keeps you on your toes. Pun intended.



  • I have the same issue. It doesn’t matter how gently I feed in the power, or how dainty I am with rudder input. I hold the line perfectly well until about 60 knots, then it’s like getting a sudden puncture. Probably affects 90% of takeoffs. And, yes, I’m set to “Modern”.



  • For me it's single most annoying problem with this otherwise beautiful plane. Hope develpoers are looking for some solution here.
    I don't see any such problems with other planes, default or made by other parties, so probably it can be solved, even if a little artificially.
    Of course I use "modern" flight model.



  • I recommend using the following mod to the flight_model.cfg file to reduce this problem...

    [FLIGHT_TUNING]
    yaw_stability =1.0 ;0.1



  • Thanks for the hint. I was thinking of looking for temporary solution myself, so I will give it a try.



  • The yaw_stability suggestion above may help, it may not. I would strongly advise only trying it IF you already have the problem mentioned above. I have just tried it and confirmed my previous findings with a couple of aircraft - for me, it leaves the aircraft virtually uncontrollable in yaw when on the ground.

    The stability scalars appear to work in reverse to 'common sense' - the SDK specifically suggests starting at 0.1, the default light aircraft in the sim (C152, 172, Cap10C) have a setting of 0.25 and, when I initially started working in this sim I rather naively expected scalars to be set to 1.0 as default (i.e.that setting not adjusting anything, moving away from it in either direction would increase or decrease the effect). With those stability scalars set to 1.0, aircraft were uncontrollable, so from practical experience I find that increasing that scalar has the effect of making the aircraft uncontrollable.



  • @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.