Helicopters jump in and out of ground effect when near raised platforms, the CFD is not calculating the drop

Bug Reporting Hub Aircraft & Systems
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1

H125 in tags because it needs at least one, but this applies to all helicopters in the game.

Description of the issue:

The ground effect is calculated when the center of gravity or mass passes over a physical object.

When the helicopter passes this point, the ground effect is instant, meaning if you are hovering out of ground effect, and then are instant on with ground effect, you get an increase in lift and drag, causing the aircraft to instantly twist on its vertical axis. This will sometimes cause the helicopter center to then move off the raised platform, causing an instant loss of ground effect, which then leads to a very bad oscillation and loss of control.

If you watch the video included at the end of this post, it shows how the CFD (computational fluid dynamics) is not interacting with the raised planform until it under the aircraft., and then even the part of the rotor that is not supposed to be in ground effect now has an invisible “floor” that it is interacting with.

Video was done with all aids on to film in external view with CFD display on

If applicable, which aircraft is experiencing this issue:

All Helicopters

[PC Only] Did you remove all your community mods/add-ons? If yes, are you still experiencing the issue?

Nothing in community folder, unmodded game

FREQUENCY OF ISSUE

Always

REPRODUCTION STEPS

1.Fly a helicopter to a raised platform. A fuel truck, a oil rig platform, a tree, building top, anything where there is a sharp drop off.
2.approach where you go from out of ground effect to in ground effect.
3. Notice that the change in effect is instant, and not gradual as the CFD of the aircraft is not interacting with the raised object until it gets close
4. Notice that the CFD display of the downwash is not gradual, but instantly switches around a center ppoint under the helicopter. It is not caculating gradual transtion for partial ground effect on one side of the helicopter, only a flat plane under it, so it is on or off, no in between.

YOUR SETTINGS

If the issue still occurs with no mods and add-ons, please continue to report your issue. If not, please move this post to the User Support Hub.

What peripherals are you using, if relevant:

[PC Only] Are you using Developer Mode or have you made any changes to it?

No Dev mode

[PC Only] What GPU (Graphics Card) do you use?

4090

[PC Only] What other relevant PC specs can you share?
N/A

MEDIA

Please add a screenshot or video of the issue occurring.

For DEV staff, these bug reports are related to this, just using wording that is describing what is happening when the above happens, but not pointing out the root cause of the problem:

https://forums.flightsimulator.com/t/ground-effect-is-too-strong-on-helicopter-approach/670011

https://forums.flightsimulator.com/t/behavior-of-helicopters/672749

[END OF FIRST USER REPORT]

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Do you have the same issue if you follow the OP’s steps to reproduce it?
•

Provide extra information to complete the original description of the issue:
•

If relevant, provide additional screenshots/video:
•

17 Likes
2

Do you have the same issue if you follow the OP’s steps to reproduce it?
• Yes.

Provide extra information to complete the original description of the issue:
• This is the exact same issue that was reported for 2020 and fixed in SU15, for more details, see [Helicopter] Abrupt induced yaw when flying over edge of elevated helipad and Helicopter ground effect transition is abrupt and requires large inputs to recover - Aircraft - MSFS DevSupport.

This bug was frustrating the first time in 2020, but that the fix did not make its way into 2024 is even more frustrating, we are back to square one after almost two years. This was reported in January 2023 first on DevSupport, it took a year for Asobo to fix it.

This bug is pretty much kills all the fun of helicopter flying. Wondering if anyone ever tried to land on that spray truck shown on the trailers…

If relevant, provide additional screenshots/video:
• Video showing the bug: https://youtu.be/Zp-MR0cti24 (thanks @hhelikopter4891)

Duplicate here: Problem with Heli Pads on Tall Structers MSFS2024 - #2 by pvaiko1203

9 Likes
3
13 Likes
4

Same problem here. Its nearly impossible to perform a smooth landing on the spray tanker platform with the H125. You just can hit the chopper fast on the platform an hope you naild it on the exact position. But the platform is so small its nearly impossible…
Version 1.1.9.0
Platform PC
MS Store

4 Likes
5

ISSUE DESCRIPTION

Description of the issue:

The helicopter behaves unrealistically:
(Fresh boot, fresh installation, no addons, no mods)
The helicopter tends to drift to the left when hovering in an open field without wind. To keep it still, I have to keep it to the right with a roll angle of approx. 3° to 5°.

On final approach to a raised platform, it spontaneously turns 90° to the right. For no apparent reason. No winds, no gusts, no rudder pulses. Regardless of the approach direction, regardless of the approach speed.

If applicable, which aircraft is experiencing this issue:

It has occurred most strongly with the H125 and somewhat more moderately with heavier helicopters such as the Skycrane
[PC Only] Did you remove all your community mods/add-ons? If yes, are you still experiencing the issue?
No mods. No addons

FREQUENCY OF ISSUE

permanently

REPRODUCTION STEPS

Start free flight. Set the H125 Helicopter to any location. Set wether to no winds, clear sky. Start hovering. Try to hold still. Drifting occurs.
Approach any platform, while sth like 10 to 30 ft above, the heli turns right as if gusts cought it.

YOUR SETTINGS

If the issue still occurs with no mods and add-ons, please continue to report your issue. If not, please move this post to the User Support Hub.

What peripherals are you using, if relevant:
Titanwolf Hotas

[PC Only] Are you using Developer Mode or have you made any changes to it?
no dev mode, no changes

[PC Only] What GPU (Graphics Card) do you use?
RTX 4070

[PC Only] What other relevant PC specs can you share?
AMD Ryzen 7 5700X3D, Win11, 32 GB Ram @3200 MHz, VR Mode using HP Reverb G2 (btw bring back the Windows VR Portal!!!)

MEDIA

Please add a screenshot or video of the issue occurring.

[END OF FIRST USER REPORT]

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Do you have the same issue if you follow the OP’s steps to reproduce it?
•

Provide extra information to complete the original description of the issue:
•

If relevant, provide additional screenshots/video:
•

3 Likes
6

That sounds very much like translating tendency, or put more simply the thrust generated by the tail rotor will cause the helicopter to drift. It would therefore be correct that you would use the cyclic to counteract this by effectively rolling the helicopter slightly to maintain your position.
Much the same as how you use the pedals to counteract the torque generated by the main rotor. In a hover you would apply a left or right input depending on the direct the rotor spins.
It is therefore not a bug but helicopter physics being modelled.
I you don’t like the realism you may want to check the assists in the options - like wise, you may also want to turn them off if the helicopter is not reacting as it should be expected to.

4 Likes
7

On this point I believe the sim is known to be a bit bugged in this respect. Not tried it myself yet, but it may be the sim is reacting to abruptly to the change in ground effect as the helicopter suddenly gains ground effect as it passed over the raise platform.

1 Like
8

Same issue here, also to add:

=General Issues:
*H125
-NG reading unrealistic,
-FLI gauge not accurate based of the first limiting indicator (NG,TOT,TQ)

=Flight Model:
*H125
-Autorotative flight, from 200ft 60 kts beginning flare as per flight manual, as intensifying the flare airspeed rapidly drops and so the vertical speed rapidly increases? VS should in theory and practicality should slow down, RPM needs to rapidly increase (It Doesn’t). therefore no energy there to arrest the fall, once touchdown initiated, collective adjusted the slightest allows for a full climb while engine out, this is also wrong.

1 Like
9

The cyclic to the right is normal. It is supposed to be that way due to translational drift. Tailrotor thrusts to compensate for torque, and you need to compensate for that.

This is also why the cyclic is slightly placed left of the center of the seat. Fun tidbit!

6 Likes
10

Please add and vote on this bug report, it goes more into the root cause of the issue you are describing:

11

Sounds reasonable to me. I was just wondering since in the 2020 did not show this behavior with this heli.
The only helicopter I have experience with in real life has a twin Rotor and no tail rotor and didnt behave like this, too - which makes sense.
Nevertheless. Hovering in ground effect has never been that challenging in the fs2020 in this heli. But i would let convince myself thats a feature and not a bug… :smile:
Assists to make it easier? No. Never. I love the challenge…

12

The comparison to behaviour in 2020 probably shows Asobo are improving the flight model for helicopters - a good thing!

Totally with you regarding the assist thing - not for me!

2 Likes
13

:white_check_mark: SIM INFORMATION

This is vital information for our test team, please do not skip it or your issue may not be able to be reproduced or fixed.

  • Microsoft Flight Simulator 2020 or 2024:
    MSFS 2024

  • Version Build Number (Where do I locate that?):
    1.1.7.0

  • Game Platform (Steam, Xbox, MS Store):
    MS Store

:white_check_mark: ISSUE DESCRIPTION

  1. Description of the issue:
    On MSFS2024, with a helicopter (whatever the model), there’s a sort of “bounce” when I get a few meters above the ground (when landing)… I get thrown into the air. It usually starts with a hard left (as if I were pushing hard left), and then I’m thrown 10-20 meters as if by the wind…
    General handling is fine, but as soon as you approach a platform, Ground effect takes over way to strong and bounces you around.
    This issue occured on MSFS2020 but was fixed in SU15. Apparently it has found its way back to the surface on 2024.

  2. If applicable, which aircraft is experiencing this issue:
    All Helicopters from the game

  3. Did you remove all your community mods/add-ons? If yes, are you still experiencing the issue?
    Yes, No add-ons installed

:white_check_mark: FREQUENCY OF ISSUE

How often does this occur for you? (Example: Just once, every time on sim load, intermittently)
Everytime you get close to the deck

:white_check_mark: REPRODUCTION STEPS

Please list clear steps you took in order to help our test team reproduce the same issue.

1.Get in a helicopter
2. get up in the air and approach the ground, preferrably a raised platform like a rooftop pad or an oil rig
3.approach the pad and as soon as you get above the pad you’ll bounce up way to strong

:white_check_mark: YOUR SETTINGS

If the issue still occurs with no mods and add-ons, please continue to report your issue. If not, please move this post to the User Support Hub.

  1. What peripherals are you using, if relevant:
    not relevant

  2. [PC Only] Are you using Developer Mode or have you made any changes to it?
    nope

  3. [PC, MSFS 2020 Only] Are you using DX11 or DX12?

  4. [PC Only] What GPU (Graphics Card) do you use?
    4070Ti

  5. [PC Only] What other relevant PC specs can you share?
    7800X3d 32GB Ram

:white_check_mark: MEDIA

Please add a screenshot or video of the issue occurring.

[END OF FIRST USER REPORT]

:loudspeaker: For anyone who wants to contribute on this issue, Click on the button below to use this template:

Do you have the same issue if you follow the OP’s steps to reproduce it?
•

Provide extra information to complete the original description of the issue:
•

If relevant, provide additional screenshots/video:
•

3 Likes
14

yes, I also think so

15

Do you have the same issue if you follow the OP’s steps to reproduce it?

• Yes

Provide extra information to complete the original description of the issue:
•

If relevant, provide additional screenshots/video:
•

16

Do you have the same issue if you follow the OP’s steps to reproduce it?
• YES

Provide extra information to complete the original description of the issue:
• Helicopters are close to uncontrollable when near an elevated platform. Yawing, getting suddenly pushed up at same engine settings. This doesn’t feel right

If relevant, provide additional screenshots/video:
• none

17

Do you have the same issue if you follow the OP’s steps to reproduce it?
• Yes

Provide extra information to complete the original description of the issue:
• Approaching the ground in any situation the effect is too strong. Elevated helipads are very difficult to land on due to this issue

If relevant, provide additional screenshots/video:
• none taken

18

Do you have the same issue if you follow the OP’s steps to reproduce it?
•

Provide extra information to complete the original description of the issue:
•

If relevant, provide additional screenshots/video:
•

19

Yup, this happens to me also

20

Please add and vote on this bug report, it goes more into the root cause of the issue: