Bouncy Carrier Planes

TARPSBird

TARPSBird

Moderator
Staff member
I wasted a lot of time last night trying to adjust the .cfg file for one of my carrier planes so I could fly a decent approach and not have the bird bounce up to the height of the mast when I try to catch a wire. :banghead: What are the magic numbers that need to be adjusted in the .cfg (or .air) files to cut down excessive bounce on landing???
 
Landing Gear Section of ***.air file

Its in the whateverplane.air file.................

I was just trying to get the AT-9 jeep to be able to trap........

Here is a shot of the Stock Hellcat next to the AT-9........

the AT-9 is very bouncy...........compared to the Stock Hellcat for a comparison on ........up or down number adjustment

So ......

Play with Center and Main Gear Spring Loading Factors and Center and Main Gear Damping factors
 
The B-24Guy's .cfg's

Hi Tarps,
I would try compression first.

point.0=1, -22.84, 0.00, -1.73, 1600, 0, 0.25, 30.0, 0.30, 2.5, 0.90, 3.5, 3.3, 0
point.1=1, 0.96, -6.42, -6.65, 2200, 1, 1.25, 0.0, 0.50, 2.5, 0.79, 6.5, 7.5, 2
point.2=1, 0.96, 6.42, -6.65, 2200, 2, 1.25, 0.0, 0.50, 2.5, 0.79, 5.0, 7.0, 3

This one shows the two main struts with no compression at all. The tail wheel at + 30.

Sometimes this pesky tail wheel will cause more bounce then the main gear. A lower number is stiffer.

Check out the .cfg files The B-24Guy has done for the Overhaul Planes. He has them dialed in perfecto.
Dave
 
Lemony ........indeed

Just a side note.........

If you do change landing gear with Abacus Flight Dynamic Editor.........

you will need to delete the contact points from the aircraft.cfg file to get the FDE to reset contact points.......that.....Dvslats is referencing.

However, be careful because........

when you use FDE and then delete out of aircraft.cfg text........you maybe loosing the numbers someone previously set for that aircraft by just editing the aircraft.cfg.............if you know what I mean.........

Either way.......it gives it that fresh......lemony effect
 
Rockster, were you able to tweak the AT-9 so it could trap?
I can see the compression number is very high compared to the Hellcat.
I've used the AirEd utility in the past to tweak various .air file values, but not the contact point info. I've always been confused as to which sets of contact point figures are the defaults used by the aircraft, the .air file or the .cfg file. MS did an outstanding job of making it difficult to figure out.
 
I touched down very carefully......

The AT-9 has a low glide to sink ratio......meaning I have to come in fast and flat........It's a very high stall aircraft............

So.......

no real drop..........

for a bounce.......

I did stall on an attempt to land just short of the cables.......and the AT-9 bounce like a pogo stick.

what you also didn't see is the negative G's ripped the tail off..............

when the cable grabbed......

AS for the aircraft.cfg and the ***.air file........

I always let the ***.air file do all the work.........

Get that right and then delete the contact points, view, and static angle out of the aircraft.cfg everytime I make a change.........

Delete the above and then save aircraft.cfg........then edit you air file with airwrench, aired, or FDE save .........then when cfs2 starts up..........it reads the air file and writes it to the aircraft.cfg........

The exception is .......

if you have a belly landing plane........or some other special adjustments that the ***.air file doesn't control.
 
So... you're saying that when the .air file values are adjusted via AirEd, FSE, etc. new values are written to the .cfg file next time CFS2 is started? Jeez, I've had CFS2 for nine years and I did not know that. :redf:

Edit: Just tried it and by golly it worked! Still haven't solved the bounce problem but it's good to learn something new. :)
 
Rockster234 said:
Its in the whateverplane.air file.................

I was just trying to get the AT-9 jeep to be able to trap........

Here is a shot of the Stock Hellcat next to the AT-9........

the AT-9 is very bouncy...........compared to the Stock Hellcat for a comparison on ........up or down number adjustment

So ......

Play with Center and Main Gear Spring Loading Factors and Center and Main Gear Damping factors
Click to expand...


One thing I see that cannot help is the distance between the main gear and CoG at 36". I would think that the main gear would be at or near the leading edge of the wing, and that CoG would be at or near 25% MAC of the wing. Certainly that is not 36". Probably more at 16"to28".

For the main gear setup, spring rates and damping is critical. See the below text written by Tom Goodrick.
-----------------------------------------------------------------
Flight Dynamics by Tom Goodrick

Brought to you by Flight Simulator World and Abacus "We Fly The World"
36

Stopping Hopping

Here’s the solution: First, figure the total weight by adding the fuel weight to the dry weight as found in the .air file. We’ll call that W. Then calculate and enter the following values in the Landing Gear Section of FDE:


Main Gear Spring Loading Factor = 2.72 * W
Main Gear Damping Factor = 0.34 * W
Center Gear Spring Loading Factor = 2.04 * W
Center Gear Damping Factor = 0.24 * W


You may want to adjust these values after trying some landings. However, these settings will be good enough for safe landings. These exact values were taken from the author’s Aerospatiale Trinidad. Factors from a heavier jet are: 2.01, 0.34, 0.86 and 0.11 which are the values for the 35,000 lb Galaxy jet. You have to watch for excessive compression or excessive stiffness. With excessive stiffness you will hear a series of strong chirps as the wheels barely touch the runway on a smooth landing. In bad cases the plane will bounce fore and aft or left and right (in roll) as the wheels chatter on the runway. With these good values, any landing with touchdown velocity between 0 and -400 fpm will look and sound smooth.
-----------------------------------------------------------------------

Of course you want to ensure that the contact points are precisely on the wheel touch points and that CoG is at 25% MAC.

Hope this helps.
 
These are for the FDG2 F4U. (ACM 1% mod.)

Aircraft.cfg
.
.
.
[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)

;--------0---1-----2------3-------4---5--6------7---8-----9---10---11---12-13-14- 15
point.0= 1, -18.00, 0.00, -4.10, 3200.0, 0, 0.50,180.0, 0.25, 2.5, 0.90, 1.0, 4.0, 0, 0, 360 //tail wheel
point.1= 1, 2.10, -5.93, -8.20, 3200.0, 1, 1.35, 0.0, 0.54, 2.5, 0.77, 5.5, 4.5, 2, 0, 360 //left wheel [10/0.76(early), 0.77(late)]
point.2= 1, 2.10, 5.93, -8.20, 3200.0, 2, 1.35, 0.0, 0.54, 2.5, 0.77, 6.0, 5.0, 3, 0, 360 //right wheel [10/0.76(early), 0.77(late)]
.
.
.


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

F4U-1 = 0.76 (stiff oleo's)
F4U-1A-1D = 0.77

To reduce bounce, INCREASE #10 value by +0.01 at a time until it feels right.

Enjoy.
 
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