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davux3 avatar image
davux3 asked SJK91 edited

Helicopter ground effect transition is abrupt and requires large inputs to recover

With the new SU11 helicopter flight model, operations on elevated platforms suffer from what appears to be a lack of a transition in handling ground effect. This effect seems to be worse for heavier helicopters.

When approaching a platform horizontally, the helicopter will get a huge kick of energy exactly when the RADIO HEIGHT value rapidly decreases, as the center of the model crosses over the threshold of the elevated platform. This "kick" seems much worse for a heavier helicopter, and in ours it is also from the left (as opposed to simply rapidly rising upward). Users don't like this behavior, our pilots are saying this isn't correct and the physics of the rotor disc will have the behavior spread out over time. It's not that the effect is wrong, but the transition case is abrupt which results in behaviors that aren't realistic.

We're wondering if there may be some way to stop this from happening? We have dialed in our flight model now and have it working well but we can't find a solution to this ground effect behavior.

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FlyingRaccoon avatar image FlyingRaccoon ♦♦ commented ·
Hello @davux3

Can you make a video demonstrating the problem with CFD particle visualisation enabled please?

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davux3 avatar image davux3 FlyingRaccoon ♦♦ commented ·

Hi Sylvain - thanks for the quick reply. I have included a video with the CFD visualization turned on. Note that the helicopter is in hands-off AFCS modes since it's too difficult to fly precisely otherwise, so the kick here isn't representative of how jarring it is for somebody actually flying (as I said the ground effect overall increasing is expected and isn't the direct problem). The video is at a third party scenery but you can get the same effect on the built-in US Bank tower.


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ChokDK avatar image ChokDK commented ·

I agree totally on this.
Too aprupt and not what is happening on any real life approach videos either, not even when coming in "hard and flat".

The "kick" is somehow exaggerated for "anything" that is higher than plain ground (roofs, helipads )

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FlyingRaccoon avatar image
FlyingRaccoon answered

Hello @davux3 @ChokDK

The developers acknowledged this issue. It's tracked and will be addressed in a future update.


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RoscoHead avatar image
RoscoHead answered

There is also a very abrupt change in behaviour for fixed wing craft when transitioning between land and water - even at high altitudes the turbulence increases dramatically and suddenly when flying between water and land.

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SJK91 avatar image
SJK91 answered SJK91 edited

What I have experienced is a bopping effect where you are in a hover and the helicopter bops up and down slowly. In DCS I can hold the Huey in a hover at a specific height lets say 5 or 8 feet, only adjusting the collective maybe once whereas in MSFS I try to use a limited amount of collective but with the bopping up and down I find myself having to increase and decrease collective all the time, sometimes requiring large inputs which results in overshooting the desired power setting. To put it in common words its like the chopper goes in and out of ground effect constantly to which I have to "catch" it from falling or from jumping into the air further aggrevated by collective overshoots.

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