Chirping bouncing aircraft

[papab]

I posted this on one other forum and I thought I would post here as well:

A hand full of my aircraft A2A B-17, Capt Sim B-52, Lionheart Kodiak and several more act strange when the loaded filght opens. Every 3 or 4 seconds ths plane bounces up and down once and the wheels make a chirping sound. Even on takeoff roll, it might bounce once before lift off.
Does this have something to do with "contact points" and if so can some one explain a fix

Thank you in advance

PS: I looked for previous posts and could not find any to address this issue

Rick B

 

[RudiJG1]

I've experienced this with the RealAir Duke and suspect a hardware issue...my CH Rudders include a toe brake that seems to be sending an intermitent signal even when not being pressed. When I deleted the toe brake axis assignment via CH Manager, I no longer had the "chirp".

I'm interested in your thoughts and the experiences of others on this.

 

[papab]

I've experienced this with the RealAir Duke and suspect a hardware issue...my CH Rudders include a toe brake that seems to be sending an intermitent signal even when not being pressed. When I deleted the toe brake axis assignment via CH Manager, I no longer had the "chirp".

I'm interested in your thoughts and the experiences of others on this.

Thanks for the reply-
I am using Saitel X52 with no rudder peddles

I also experience this with the real Air Duke as well......

Any one else?

Rick

 

[srgalahad]

Does it happen all the time ( with those a/c)?
Is it on initial load or only if you switch a/c during a session?

It's happened to me in FS9 (but not yet in FSX) and seems to be that the sim is finding a conflict - like trying to display the new a/c while still 'using' cached data from a previous one if a/c are switched after startup or after a crash recovery.

The 'chirp' is likely the sim sensing the 'touchdown effect' parameters. As for the brake issue, most stick/pedals are not that perfect in sensing the null points at rest so you may not have to remove the command, but a simple tap of the brakes may clear any 'sticky brakes'.

Not that I have a clear cut answer...I usually just suffer it until it quits or I try something else

 

[papab]

Does it happen all the time ( with those a/c)?
Is it on initial load or only if you switch a/c during a session?

It's happened to me in FS9 (but not yet in FSX) and seems to be that the sim is finding a conflict - like trying to display the new a/c while still 'using' cached data from a previous one if a/c are switched after startup or after a crash recovery.

The 'chirp' is likely the sim sensing the 'touchdown effect' parameters. As for the brake issue, most stick/pedals are not that perfect in sensing the null points at rest so you may not have to remove the command, but a simple tap of the brakes may clear any 'sticky brakes'.

Not that I have a clear cut answer...I usually just suffer it until it quits or I try something else

Yes, all the time..they bounce and chirp about every 5-8 seconds

I will try the tap on the brakes to see what happens

Thank you for your reply!

Rick

 

[Milton Shupe]

Historically, chirping tires has meant the suspension is too stiff. This may mean that the static compression and max to static ratio together representing total suspension movement is very small as defined in the contact points. The max-static ratio should not be above 2.5. Hopefully static compression is at least 4-6" on smaller GA aircraft. This is shown as feet in the contact points. A .4 represents 4.8" of static compression (.4 X 12" = 4.8). A max to static ratio of 2.0 would mean that the total travel of the suspension (hanging versus fully compressed) is 9.6".

A screenshot or list of your contact points for one of the problem aircraft may help.

Ideally, the modeled movement of the suspension matches the contact points definition of the suspension.

If you change either of the number sets, you must ensure that total suspension travel remains the same to avoid visual tire on tarmac issues.

Determine total suspension travel by multiplying static compression by the ratio as I did above. ( 4.8" x 2 = 9.6").

To soften suspension, decrease the ratio, and increase static compression.

When you do this, you must also reset your wheel distance to ground because you allowed more suspension sitting statically. Decrease your distance to ground in the 4th parameter.

While this corrects stiff suspension (by effectively decreasing spring rates), it may not be the problem you are experiencing here in FSX.

 

[Snave]

Before you change anything, CHECK THE LOADOUT. If you have full fuel and full pax you will be overweight, and the `suspension` response in the sim will do exactly what you are describing.

The common factor of the problem across several different very highly regarded aircraft, whcih no others report acting similarly is the clue that there is something amiss locally, not with the .air or .cfg files of these aircraft.

 

[papab]

Historically, chirping tires has meant the suspension is too stiff. This may mean that the static compression and max to static ratio together representing total suspension movement is very small as defined in the contact points. The max-static ratio should not be above 2.5. Hopefully static compression is at least 4-6" on smaller GA aircraft. This is shown as feet in the contact points. A .4 represents 4.8" of static compression (.4 X 12" = 4.8). A max to static ratio of 2.0 would mean that the total travel of the suspension (hanging versus fully compressed) is 9.6".

A screenshot or list of your contact points for one of the problem aircraft may help.

Ideally, the modeled movement of the suspension matches the contact points definition of the suspension.

If you change either of the number sets, you must ensure that total suspension travel remains the same to avoid visual tire on tarmac issues.

Determine total suspension travel by multiplying static compression by the ratio as I did above. ( 4.8" x 2 = 9.6").

To soften suspension, decrease the ratio, and increase static compression.

When you do this, you must also reset your wheel distance to ground because you allowed more suspension sitting statically. Decrease your distance to ground in the 4th parameter.

While this corrects stiff suspension (by effectively decreasing spring rates), it may not be the problem you are experiencing here in FSX.

Thank you for your detailed answer-totaly lost! LOL

Here is what I think you were asking for, the contact points from the A2AB-17 that bouces all the time:

[contact_points]
static_pitch = 7.82
static_cg_height = 8.25
tailwheel_lock = 1
gear_system_type = 0
max_number_of_points = 21
point.0 = 1, -34.0045, 0, -4.0, 4000, 0, 1, 40, 0.3, 2.5, 0.7, 10, 8, 0, 135, 180
point.1 = 1, 1.85, -10.6, -8.45, 5000, 1, 2.3, 0, 0.5, 2.5, 0.8, 13, 10, 2, 135, 180
point.2 = 1, 1.85, 10.6, -8.45, 5000, 2, 2.3, 0, 0.5, 2.5, 0.8, 17, 12, 3, 135, 180
point.3 = 4, -5.4969, -51.5, 3.0514, 10000, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0
point.4 = 4, -5.4969, 51.3763, 3.0402, 10000, 0, 0, 0, 0, 0, 0, 0, 0, 6, 0, 0
point.5 = 4, -50.5669, 0, 0.8886, 1800, 0, 0, 0, 0, 0, 0, 0, 0, 9, 0, 0
point.6 = 2, 6.5245, 0, -3.2301, 1800, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0
point.7 = 4, 15.7277, 0, -2.0154, 1800, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0
point.8 = 2, 1.8808, 10.0932, -3.1317, 1800, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0
point.9 = 2, 2.0133, -10.217, -3.1321, 1800, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0
point.10 = 2, -43.38, -0.0001, 16.8214, 2300, 0, 0, 0, 0, 0, 0, 0, 0, 9, 0, 0
point.11 = 2, -5.5, -34.9953, 0.5331, 10000, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0
point.12 = 2, 2.1347, -21.659, -1.7824, 1800, 0, 0, 0, 0, 0, 0, 0, 0, 6, 0, 0
point.13 = 2, 1.8846, 21.4368, -1.5351, 1800, 0, 0, 0, 0, 0, 0, 0, 0, 6, 0, 0
point.14 = 2, -5.5, 34.8767, 0.6681, 10000, 0, 0, 0, 0, 0, 0, 0, 0, 6, 0, 0
point.15 = 4, 10.6948, -21.6112, -4.3741, 10000, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0
point.16 = 4, 12.636, -10.1983, -5.8823, 10000, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0
point.17 = 4, -15.0776, -0.3503, -4.9302, 10000, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0
point.18 = 2, -46.5092, -0.2859, -0.2301, 1800, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0
point.19 = 4, 12.5753, 10.2414, -5.803, 10000, 0, 0, 0, 0, 0, 0, 0, 0, 6, 0, 0
point.20 = 4, 10.586, 21.3647, -4.4484, 10000, 0, 0, 0, 0, 0, 0, 0, 0, 6, 0, 0

Thank you again for your response!

BTW: Love all of your aircraft!!
Thank you for all of your time that you have spent on the freeware you produce for the Sim Community. My hat is off to you sir!
Rick

 

[Milton Shupe]

Thank you.

The contact points look good to me. You have 6" of static compression(for an empty weight aircraft) and 15" of total travel. That should be plenty sufficient to carry the weight.


Do check to ensure you are not overweight as suggested by Snave.

 

[papab]

Thank you.

The contact points look good to me. You have 6" of static compression(for an empty weight aircraft) and 15" of total travel. That should be plenty sufficient to carry the weight.


Do check to ensure you are not overweight as suggested by Snave.

Thank you Milton...
Next flight I will empty some fuel and see if that works

Rick

 

[Railrunner130]

Not to hijack the thread, but I have the same issue with Tim Conrad's C-133 as AI. It jumps all over the place. Any idea how to fix it?

 

[heywooood]

in my experience - I have noticed this hop/chirp and even gotten the tire smoke effect whenever I have my texture resolution too high for a given aircraft/environment combo...

for instance - if I am using a graphically intense aircraft in Orbx FTX scenery...I can get the hops pretty bad...it happens on the ground, obviously, when the textures redraw.

If you land your offending aircraft and taxi in closeup external view, you can see the hop occur whenever the ground textures snap into full focus - and in some cases - you can park the plane and rotate the external view slowly around the plane - and see the effect as it occurs.

the grass or taxiway will snap focus and the plane will hop....it can happen on the water too the same way, as the water surface detail snaps into focus, the seaplane will hop on the water in the same way.

 

[papab]

in my experience - I have noticed this hop/chirp and even gotten the tire smoke effect whenever I have my texture resolution too high for a given aircraft/environment combo...

for instance - if I am using a graphically intense aircraft in Orbx FTX scenery...I can get the hops pretty bad...it happens on the ground, obviously, when the textures redraw.

If you land your offending aircraft and taxi in closeup external view, you can see the hop occur whenever the ground textures snap into full focus - and in some cases - you can park the plane and rotate the external view slowly around the plane - and see the effect as it occurs.

the grass or taxiway will snap focus and the plane will hop....it can happen on the water too the same way, as the water surface detail snaps into focus, the seaplane will hop on the water in the same way.

Thank you for your advice
I will try changing the settings tomorrow
Rick