Bouncing aircraft..

Hello

Bouncing aircraft.

Many years sim flying, but still don't understand why some aircraft are bouncers.

I downloaded a rather nice looking South A.As Posky A340 the other day.

On my first flight unfortunately this aircraft turned out to be a bouncer.

This is a really irritating phenomenon.

Can someone tell me why certain aircraft do this

Is it anything to do with the airport scenery itself and not necessarily the plane?

If the cause of the bouncing is something to do with the aircraft's cfg;could I copy and paste the details from another Posky a340 non bouncer and maybe resolve the issue that way.

If not then I will delete this particular model and look for another.

PS I will try another non bouncing Posky a340 at my new airport scenery of FACT just to see if it is anything to with the scenery itself.

 

Cheers Andy

I've had this lots of times, before you blame the aircraft does it bounce at another airfield?

 

 

If so then you need to eliminate one thing at a time, try a different air file.

 

Remember to keep aback up copy first.

 

Then if that doesn't work alter the aircraft.cfg by as you said copy from another same or similar aircraft, my first thought is it could be the weight, compare the original with another same type, if the other is different try those weights and or the moi settings etc.

 

Remember to keep the contact points and lights settings of the original as well, if you really like the aircraft then it is worth doing.

This happens with some of my own models! I now test them at 20 fps rather than unlimited. I usually find that can stop them bouncing (increasing ones frame rate).

The other thing that can help is to increase the pitch MOI in the aircraft.cfg, if the frame rate doesn't do the trick.

Good luck

Keith

Could be the contact points, these are from a POSKY A340-313X and they don't bounce:

 

[contact_points]

 

//0 Class

//1 Longitudinal Position (feet)

//2 Lateral Position (feet)

//3 Vertical Position (feet)

//4 Impact Damage Threshold (Feet Per Minute)

//5 Brake Map (0=None, 1=Left, 2=Right)

//6 Wheel Radius (feet)

//7 Steer Angle (degrees)

//8 Static Compression (feet) (0 if rigid)

//9 Max/Static Compression Ratio

//10 Damping Ratio (0=Undamped, 1=Critically Damped)

//11 Extension Time (seconds)

//12 Retraction Time (seconds)

//13 Sound Type

//14 Airspeed limit for retraction (KIAS)

//15 Airspeed that gear gets damage at (KIAS)

 

//Nose Gear

point.0= 1.000, 68.443, -2.000, -12.200, 1181.102, 0.000, 1.590, 72.000, 2.200, 2.400, 0.510, 7.000, 9.000, 0.000, 280.000, 300.000

point.1= 1.000, 68.443, 2.000, -12.200, 1181.102, 0.000, 1.590, 72.000, 2.200, 2.400, 0.510, 7.000, 9.000, 0.000, 280.000, 300.000

 

//Main Gear (Left)

point.2= 1.000, -17.067, -20.500, -12.300, 1574.803, 1.000, 2.000, -8.000, 0.700, 0.800, 0.550, 10.900, 11.900, 2.000, 280.000, 300.000

point.3= 1.000, -17.067, -15.000, -12.300, 1574.803, 1.000, 2.000, -8.000, 0.700, 0.800, 0.550, 10.900, 11.900, 2.000, 280.000, 300.000

point.4= 1.000, -10.667, -20.500, -12.300, 1574.803, 1.000, 2.000, -8.000, 0.700, 0.800, 0.550, 10.900, 11.900, 2.000, 280.000, 300.000

point.5= 1.000, -10.667, -15.000, -12.300, 1574.803, 1.000, 2.000, -8.000, 0.700, 0.800, 0.550, 10.900, 11.900, 2.000, 280.000, 300.000

 

//Main Gear (Right)

point.6= 1.000, -17.067, 20.500, -12.300, 1574.803, 2.000, 2.000, -8.000, 0.700, 0.800, 0.550, 10.900, 11.900, 3.000, 280.000, 300.000

point.7= 1.000, -17.067, 15.000, -12.300, 1574.803, 2.000, 2.000, -8.000, 0.700, 0.800, 0.550, 10.900, 11.900, 3.000, 280.000, 300.000

point.8= 1.000, -10.667, 20.500, -12.300, 1574.803, 2.000, 2.000, -8.000, 0.700, 0.800, 0.550, 10.900, 11.900, 3.000, 280.000, 300.000

point.9= 1.000, -10.667, 15.500, -12.300, 1574.803, 2.000, 2.000, -8.000, 0.700, 0.800, 0.550, 10.900, 11.900, 3.000, 280.000, 300.000

 

// Main Gear (Center)

point.10= 1.000, -17.067, 2.200, -12.300, 1574.803, 0.000, 2.000, -8.000, 0.700, 0.800, 0.550, 10.900, 11.900, 3.000, 280.000, 300.000

point.11= 1.000, -17.067, -2.200, -12.300, 1574.803, 0.000, 2.000, -8.000, 0.700, 0.800, 0.550, 10.900, 11.900, 2.000, 280.000, 300.000

 

 

//Scrape Points

point.12= 2.000, -14.167, -84.717, 0.000, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 5.000, 0.000, 0.000

point.13= 2.000, -14.167, 91.817, 0.000, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 6.000, 0.000, 0.000

point.14= 2.000, -120.667, 0.000, 6.500, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 9.000, 0.000, 0.000

point.15= 2.000, 88.417, 0.000, -3.750, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 4.000, 0.000, 0.000

point.16= 2.000, 14.167, -99.917, 0.000, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 7.000, 0.000, 0.000

point.17= 2.000, 0.000, 44.750, 0.000, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 8.000, 0.000, 0.000

 

static_pitch= -2.000

static_cg_height= 11.560

gear_system_type=0

Hello

I tried some of my other 340s at the airport where I noticed the bouncing originally.

This at airport FAOR Oliver Tambo.(actually FAJS in fs2004)

Unfortunately they too joined the dance and bounced with vigour.

I am sure I haven't seen this at other airports with Posky 340 but will experiment further.

Interesting that Keith mentions restricting frame rates to 20 to stop bouncing as I have recently switched to unlimited .Will check this out as well.

Thanks all for your suggestions.

 

Andy

Check the bathrooms. Sounds like a couple (or several) are trying to join the "mile-high club" a bit early!

:D ;D ;D

Pat☺

Hi,

 

To my understanding the problem is in the main landing gear definitions. The site if Jerry Beckwith explains the issue. See http://www.mudpond.org/contact_points.pdf

The static compression should be a positive number (of feet). Not too small to my experience. In this case it is 0.7 (parameter 8) for the main landing gears. The maximum compression should be bigger than static compression. So the parameter 9, Max/Static Compression Ratio should be bigger than one, but it is 0.8 in this case. The model designer has defined the Max compression, but we (I) do not know it. You could try 1.05, which is 1.5 times 0.7. So you could try to change all the values of 0.8 to 1.5. Note, that there are ten values of 0.8 to be changed. I do not know if the possible conflict with the Max compression defined by the model designer is a problem or not.

 

Best regards,

Juha

Test at more than one airport.

 

Some runway textures are bouncier than others.

 

peace,

the Bean

Are you using the aircraft as a flyable or an AI?

Andy,

 

In my previous post I studied your non-bouncing aircraft and gave advice. Sorry about that. The error I found may not cause any bad behavior. I don't have a bouncing A340 but I have a similar non-bouncing A340 than you have. I made some experiments. I changed the static compression to 0.1 and when landing the aircraft bounced a while after touchdown but ended bouncing when the airspeed reduced. Then I changed the static compression to 0.01 and the aircraft bounced badly on ground even at zero speed. So the static compression should be close to 1 feet as it was originally.

 

Juha

Test at more than one airport.

 

Some runway textures are bouncier than others.

 

peace,

the Bean

 

Hello

I had thought about doing that, as i hadn't noticed the a340s being particularly bounce inclined before.

PS The FAJS airport were bouncing has occurred was a stock FS9 airport.

 

Cheers Andy

If by "bouncing" you mean the plane judders and dances around while stationary, I had a Ryan PT-16 that did that a few years ago and I got this forum reply which fixed it, it's something to do with editing the ground contact points; dunno if it'll work for other planes-

 

Kid,

Went and got the contact pts I used in both FS9 and FSX for you. Try them out. Hope this helps you solve the shaking.

 

[contact_points] //cb cnt pts as in FS9 AND FSX for Ryan PT-16.

point.0=1, -15.600, 0.000, 0.190, 1268.0, 0, 0.238, 45.000, 0.330, 2.5, 0.800, 0.0, 0.0, 0. 0.0, 0.0

point.1=1, 0.100, -3.300, -3.100, 1268.0, 1, 0.512, 0.000, 0.400, 2.5, 0.700, 0.0, 0.0, 2, 0.0, 0.0

point.2=1, 0.100, 3.300, -3.100, 1268.0, 2, 0.512, 0.000, 0.400, 2.5, 0.700, 0.0, 0.0, 3, 0.0, 0.0

point.3=2, -3.000, -1.500, -1.100, 1387.4, 0, 0.000, 0.000, 0.000, 0.0, 0.000, 0.0, 0.0, 5, 0.0, 0.0

point.4=2, -3.000, 1.500, -1.100, 1387.4, 0, 0.000, 0.000, 0.000, 0.0, 0.000, 0.0, 0.0, 6, 0.0, 0.0

point.5=2,-13.300, 0.000, 0.200, 1787.4, 0, 0.000, 0.000, 0.000, 0.0, 0.000, 0.0, 0.0, 9, 0.0, 0.0

point.6=2, 3.300, 0.000, 0.200, 1787.4, 0, 0.000, 0.000, 0.000, 0.0, 0.000, 0.0, 0.0, 9, 0.0, 0.0

//point.7=1,1.100, -14.420, 0.350, 1268.0, 1, 0.512, 0.000, 0.300, 0.5, 2.700, 0.0, 0.0, 2, 0.0, 0.0

//point.8=1,1.100, 14.420, 0.350, 1268.0, 2, 0.512, 0.000, 0.300, 0.5, 2.700, 0.0, 0.0, 3, 0.0, 0.0

static_pitch=12.000

static_cg_height=2.840

 

//Notice I changed tail wheel size (0.529 to 0.238). Just being thouroughlyexactomundo (ha).

 

//As you can see, I commented out the 'wing wheelies' in both FS9 and FSX. Did not effect

// performance. I believe this will not do any 'good' at ALL. (also has brakes?-no way!!).

Hello

I seem to have fixed the problem.

As Bean had suggested I moved the aircraft to another airport and voilà !

No bouncing.

I.E. I loaded Iberia a340 at FAJS (tried both heavy parking areas) and there was bouncing at both.

Moved same aircraft to heavy parking at LEMD (were iam flying from tonight) result no bounce.

So it does seem its some sort of scenery anomaly at FAJS itself.

So thanks to all (especially for all those detailed cfg contact point entries )

 

Cheers Andy

P S

Glad to say it wasn't rumpy pumpy goings on as suggested by Phantom.

Strange. I have just loaded the Posky SAA Olympic livery a340 and placed it at heavy gate 9 in Jo'burg and got no bouncing. same with another Posky SAA a340 at gate 5.

Strange. I have just loaded the Posky SAA Olympic livery a340 and placed it at heavy gate 9 in Jo'burg and got no bouncing. same with another Posky SAA a340 at gate 5.

 

That is strange.

Should be filed under weird things that fs9 does but that you have no knowledge of as to why.

 

Thanks Andy

Anomalies in mesh used? Slight variations in airport elevations?

I've seen it before on other airports.

So you tried it at another airport as I suggested in post number 2 lol.