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Thread: Flight dynamics (important issues)

  1. #1

    Flight dynamics (important issues)

    These are the real issues plauging the flight model IMO. I am stealing the first part of this from my other post.

    My impression so far is as follows:

    Light and medium helos. In expert mode, with everything mapped except throttle, I feel like the helicopter wants to float. Full down collective and the helicopter settles at a very very reduced rate from the real thing. Lowering the collective in a real helo gives you a descent rate of 1500-2000 FPM. I am getting maybe 500 FPM in TOH. Also, the stability dynamics seem backwards. By this I mean that, a helicopter fuselage dangles from the rotor system, which is supporting it as it is the part that is actually flying. So imagine holding a pendulum from your hand. As you move your hand, the pendulum responds, this is the kind of motion that should be depicted in a hover. It seems opposite to me, more like trying to balance a pencil on your hand. It wants to fall over, whereas a pendulum wants to dangle directly below you and is trying to find its equilibrium. When you tilt the rotor disk in a helicopter in a hover, you slide in that direction, not roll over, because the airframe wants to stay DOWN. In order to roll the helicopter over, you need a pivot point, like a skid touching the ground, or a rock or a grass patch. It needs to GRAB something in order to give it that rolling moment. You cant just roll the heli over by applying lateral cyclic in the hover, you will just take off in whatever direction you pointed the cyclic until you correct it, or hit something. Not to say it WOULDN'T roll over if you completely rediculously overcontrolled the thing. But it doesn't inherrently WANT to do that.

    How to fix it: Increase the descent rate to 2000 FPM with full down collective. Reduce the "ground effect" present in the game. It's totally overdone. The medium helo feels better about this than the light helo. I would recommend you make the light helo feel a little bit heavier. Reduce the rolling moment with cyclic input. Cyclic input should give the helicopter a directional movement over the surface without wanting to flip it over. Basically, stabilize the body of the helicopter a bit. The rotorsystem is tilting, not the airframe (at least, not as much, there is still some banking, etc, but it's way overdone here).

    Regarding the throttle.... I have a full helicopter control set with a twist grip throttle on the collective. Is there any way you could assign an analogue setting for those of us that have the hardware to simulate a roll on/off throttle? This also may be helpful to people who have a HOTAS joystick. Being able to control the throttle is key to starting, shutting down, simulating power failures and dealing with things like governor failures (manually controlling the throttle setting for a given pitch setting). This would definitely make the pilot types happy.

    Dyssemetry of lift: Modeled on the wrong side of the helicopter. The helicopter seems to have a tendency to roll right, and when I deliberately got over VNE to test retreating blade stall, the helicopter did what it was supposed to, except in the wrong direction.

    How to fix it: Get rid of the rolling tendency in forward flight. Real helicopter rotor systems have the ability to flap which nulls the rolling moment. Basically, the dyssimetry is there, but the pilot can't tell because the rotor system is doing the fixing on it's own. Retreating blade stall happens when the dyssimetry of lift becomes too great for the flapping hinge to overcome, THEN you get the rolling/pitch up tendency, but it will roll to the LEFT on counter-clockwise turning rotor systems. So get rid of the rolling tendency below VNE, and then, when VNE is exceeded, have the helicopter roll to the LEFT.

    Torque effect: Not present? Very limited? I can't tell because the slip ball does not seem to work. In any case, I get almost no feeling of torque in a hover on Expert settings. No left pedal required.

    How to fix it: As torque is applied to the rotor system, the helicopter wants to yaw in the opposite direction of the blades rotation. In counter clockwise turning rotor systems, it wants to yaw right, so the pilot needs to add left pedal. I am not seeing this in game, although I saw it in the Community Preview. Keep in mind that as forward airspeed increases, less left pedal is required due to a combination of increased tail rotor efficiency as well as the vertical stabilizer becoming effective.

    That's all I currently noticed.
    Last edited by nightsta1ker; Oct 30 2011 at 06:27.

  2. #2
    agreed to OP, but you forgot the stupidly annoying overly exaggerated ground effect. the ground effect ballooning of the helicopter is still there but it's not as bad as before, i don't think they understand when we tell them it's a cushion of air when we're IGE and that it requires LESS collective/blade pitch to hold a steady hover. i do agree that there is a ballooning effect in helicopter flight during hovering but it's not caused by ground effect. this is the only reason that i have encountered the ballooning effect. say if we do a left pedal turn and do not add more collective which means more power is transferred to the tail rotor to rotate the helicopter and there's less power available for the main rotor so we slowly descend, and when we see that descend we add more power but add too much and now we're gaining altitude and we just keep chasing the collective up and down. same thing for right pedal turns and not decreasing collective because we're using less power on the tail rotor so the main rotor has more power so we raise up a little bit and forget to lower collective, then we lower the collective when we realize we're ascending and we lower too much and we drop down again etc. however none of that is a big springing effect that bounces the helicopter back up 20ft when we're coming to IGE while descending down to the ground. how it should look like is we're descending and maybe 25ft above ground and we slowly increase collective to arrest the descend, as we're coming near the ground but still descending we stop adding collective at around 10ft or so and let the helicopter settling itself into IGE and that extra cushion of air will arrest our descend and we come into a hover. what it does NOT do is bounce us back up into the air unless we've added too much collective in the descending process which would result in us flying straight and level instead. it's not so bad when we're landing into solid ground but when you're trying to land on top of a building it gets ridiculous and totally throws you off your approach. i've landing on top of a building before in real life and there's no bouncing up when you get close to the top of the roof.
    Last edited by MD500Enthusiast; Oct 30 2011 at 07:35.

  3. #3
    Totally agree. I hope BI listens to OP.

  4. #4
    It's really cool to read real Life pilot feedback. Keep giving us your impressions guys

  5. #5
    I guess we need some Flight Data to compare this Sim against... That is usually very exe.... Run a few FAA/EASA test.
    Intel Core i7 980X EXTREME, 24 Gig RAM, 240 Gig Revo x 2 SSD, 2 X EVGA (SC) 680GTX's, Win 7 64 Pro,
    Single 27 inch Monitor, Oculus Rift V 1.0, Track IR 5, HOTAS Warthog, SIMPEDS Pedals..Arma3 Ready... not....

  6. #6
    also totally agree +1
    thanks for these very very great feedbacks
    it should be help BIS or some modders to improve the FM a lot

  7. #7
    Second Lieutenant
    Join Date
    Jun 3 2003
    Hong Kong
    Yeah, the ludricously over exaggerated Ground effect is by far the most annoying thing.
    I don't use a pump to scare somebody. I use a pump to shoot somebody.
    -Travis Haley - Magpul Dynamics - Art of the Dynamic Shotgun

    1911 mag, twinkie, twinkie, cupcake, primary weapon magazine... OH! There it is!
    -Christ Costa - Art of the Art of the Tactical Carbine 1

  8. #8
    Things that I know from flying real RC helicopters...

    1. Ground cushion goes at least as high as 1 rotor diameter.
    2. 2 Degree down pitch (full down collective)is not much when you are wanting to loose altitude. 2 degrees is best for keeping the head speed up for auto rotation landings.
    3. There is no rolling right or left when increasing or decreasing collective.
    4. In an auto rotation landing (no power and thus no torque from then engine) when you apply up collective to flair, you don't get torque from the engine that needs countering.
    5. Retreating blade stall can cause a boom strike.
    6. The Chaos and Piro-Flip are the hardest stunts to do. Uhh, maybe that doesn't apply here.

  9. #9
    Yes, you really have to fight/work your way through the GE for sure, as OP said, should be more of a cushoning effect, not ballooning effect that is currently the case.

  10. #10
    Second Lieutenant
    Join Date
    Jun 3 2003
    Hong Kong
    Quote Originally Posted by Bothersome View Post
    6. The Chaos and Piro-Flip are the hardest stunts to do. Uhh, maybe that doesn't apply here.
    Well given enough AGL you can do it in the game as well(if the main rotor or the tail did not break off)

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