Wheel sinking into the ground ...?

[visade]

Whenever I land a particular plane and then brake the front wheel sinks into the ground... is there anything I could do to fix this?.

Regards

[wdscobie]

and the aircraft is ...


--

[visade]

POSKY B-767 v4 (a wonderful plane).

Regards

[datatrain]

Aircraft.cfg look under contact points. first 3 in list are the wheels use 4th number up or down. You'll find which is the nose wheel soon enough.

DAve

[visade]

Thank you.
Regards

[napamule2]

Not sure if values are exactly the same, but here is a rough guide.
There are other things that will affect nose wheel compression (fuel tank locations, load out, and CG_position. If the contact pt values are as below:
pt.0=nose,1=type, -25.000=Lon, 0.000=lat, -17.500=vert pos, or height.
point.0 = 1, -25.000, 0.000, -17.500,

change CG_pos value for Longitudal from -90.5 to -120.5, like this :
empty_weight_CG_position = -120.500, 0.000, 0.000
//empty_weight_CG_position = -90.500, 0.000, 0.000

If it still sinks on braking try this:
point.0 = 1, -25.000, 0.000, -17.880 //(or, even 18.000)
//point.0 = 1, -25.000, 0.000, -17.500

This should fix it. Let me know if it worked.
Chuck B
napamule

[visade]

It's better than before.

Thank you.

[napamule2]

So which parameters did you change? If you don't mind telling. Doing both things will surely cure it, unless model wheel compression is too 'loose' in which case you can change the compression values (pt 8, 9, 10) from '0.500, 3.500, 0.900' to '0.250, 2.500, 0.990' (but for the NOSE wheel ONLY). Try that.

You might have to change height to what it was before. Or, look, and if wheel is off ground, use a smaller number. If wheel is in the ground, use a bigger number. Say it's '-17.000'. A smaller number will be '-16.000', and a bigger number will be '-18.000'. You adjust using '0.300' increments, lower/higher. Ok?
Chuck B
napamule

[visade]

The plane tilted when I changed the CG position. So I only changed the nose wheel parameters (4th number).

Thanks again.

[fruitfly]

Check this out:

http://www.sim-outhouse.com/index.php?loc=articles&page=cp

;)

[visade]

A fantastic page. Thanks a lot!

Regards

[datatrain]

I also read this page and followed it to solve a major problem with nosing over on landing and braking.

The writer was correct about a lot of trial and error but I got the result I was looking for.

I seem to recall from the fs98 days that nosing over was due to misplaced wheels in the config file. They were too far back in the config although they looked fine on the screen.

This method fixed that by moving the wheel contact point forward about one foot ahead of the wheel.

[napamule2]

Well, that page is old, but still good. The problem is that the new programs used to built the models sometime leave the wheel compression too 'loose', where the 'normal' values in the contact points are no longer able to contain the 'nose over' (compression) on braking, etc.

Then is when the trial&error comes in. The adjustment to placement of contact point relative to actual wheel position IS one of the adjustments. But that don't compensate for model shortcomings. You must then adjust pt 8, 9 and 10 to something like 2.000, 4.3, 1.200, OR, 1.999, 11.5, 0.999, OR, 0.200, 3.1, 0.700, etc (etc=trial and error tests). Not all models are the same, either.

And you will notice that Center of gravity adjustments might have been necessary in 'Weight and Balance' and is usually done by the author of model (ck the default 747-400). Some of the Amphibs have a problem with it's water pts, which when on land CAN influence taxi behavior. Usually we don't notice anything as we start at end of runway, gun it, and are off and flying. And of those that do long taxi, turns, etc and do notice, they will not do anything (being afraid of messing it up worse-which can happen). You pay your moneys and you takes your chances. Modelers are the worst tweakers of cfg and/or air files (period!). They need to 'hire' a 'mechanic' to ck out (beta test) AC before they upload it, but they don't. Too bad, so sad.
Chuck B
napamule

[visade]

Thanks again. Regards.

[roln]

Hi everyone...
I have a similar problem only much worse. When appying brakes after landing, my plane bounces up and down like a yo-you....starting at around 60mph on down to about 20.
The nose wheel sinks into the runway during each nose bounce.
The plane is a Piper Cherokee Six.....from BobHolland.com and resembles his real plane.

A sim friend also downloaded the same plane and has the same problem with his.
I changed the value in the brake scaler. If I enter a small value like 2 or 3, the plane doesn't bounce too bad, but it takes forever to stop. I higher value makes the bouncing worse.
I like the way the plane flys, but the landing problem is ugly.
Any ideas what is causing the problem??

Roln

[IronmanMLR]

It is probably the same problem. The contact points are not set correctly, the center of gravity is too far forward, the static_pitch is incorrect, or static_cg_height is incorrect. It may take a lot of trial and error to fix it. Use the same procedures that Chuck and the others gave you should be ok. Going to the lights section and assigning a light to the same co-ordinates as the wheel contact points may help. You may have to off set them to see them, but it will give you and idea as to where they are fore and aft and left and right. Also you can use two different color lights for each wheel contact point. One would be set to the exact wheel co-ordinates and the other you can change the co-ordinates up till it appears at runway level and that will give you the compression you are getting. Now remember to offset the light either fore or aft or left or right in order to see it, otherwise it will just be inside the wheel. Generally I offset the light about one foot to the left for adjusting fore and aft settings. Then change the offset back to what it was and offset one foot forward of where I adjusted the fore and aft setting to and adjust the left to right settings. Another thing you can do is watch how the aircraft behaves when you first load the flight. If the aircrafts nose or tail drops, then the static_pitch is incorrect. The same is true if the nose or tail comes up. If the whole aircraft drops, then the static_cg_height may be too high. If the whole plane comes up, then the static_cg_height is too low. You may have to exit and reload the flight several times to get an idea what it is doing. You can also assign a button to reload the aircraft with out exiting. Becareful as you may un-assign another function you may want to keep. It isn't a problem to re-assign it back, so long as you know what it was that got re-assigned.

Downloading and installing 'Airwrench' by GW Beckwith and going to the 'Balance' tab will give you the location of the center of gravity in relation to the landing gear. If you adjust the center of gravity, you may change it's flight characteristics as well. Generally the center of gravity is close to the main landing gear. On tail draggers it is behind the main landing gear and in front of the main landing gear on the modern tricycle landing gear.

I have had aircraft start bouncing when sitting still and engines off. They would start to bounce so hard that they would over stess the aircraft and it would crash. No fun on around the world flights and you hadn't saved recently. No fun at all!

Mike

[roln]

Mike,
Many thanks for the nice explanation on where to adjust things. I have two copies of the original .cfg file, so if I mess up during adjusting, I can fall back on a good file.
When I first noticed this problem, I thot it was something on my computer causing the trouble. When I checked with another person using the exact same plane, he said his was working fine. Come to find out, he wasn't taxiing and braking the same as me. I sent him a short video of how mine was acting. When he duplicated my taxiing, he found out his plane was doing the exact same thing. This means the problem isn't inside my computer......
The Piper Cherokee Six is a FREE download from Bob Hollands web site. I love the way it flies and handles....except for the taxi/braking problem, of course. I'm hoping to find another one or two persons with the same plane and ask if they're having a braking problem too.
Thanks again, Mike...for your excellent help. Much appreciated.
Roln

[napamule2]

Roln,
I just uploaded modified cfg and air file (FDE's) here at FSCom, for Bob Holland's Piper Cherokee 6 (pichr6cb.zip) and it should be available tomorrow (Sat, Dec 8). Too many tweaks to post here, so had to uplaod files. Hope this helps you guys out, as this is a nice AC (which I did not have). Couldn't quit flying it and doing landings (just to make sure). I like the panel too. Cheers.
Chuck B
napamule

[roln]

Hi Napamule,
Wow!! Many thanks for solving the braking problem on the Cherokee Six.
I have a soft spot for a Cherokee Six...it was the first plane my wife got a ride.
I was working on my private license at the time and couldn't take her up. I did
take her for a ride a month later, however.
I really enjoy flying this plane. A simmer friend in Germany customized a plane from a Warrior for me. The cockpit resembles the Cherokee, has my name below the pilot's window and my pal Felix the cat holding a bomb on the engine cowl. There's a photo
of me and my wife on the instrument panel too, but I'd rather have a younger well-built bade instead. LOL

So, where am I spose to find the file you overhauled?
Roln

[roln]

Aha!! I found the file in the file library...under new files.
Will grab it and install it, pronto!
Thanks,
Roln

[roln]

Chuck,

The brakes work great....no more bouncy bouncy.....thanks to your fix.
If you still have the plane installed, try a few take-offs and landings at MHCA.
Take off heading 060 and land heading 240. You'll see how well this plane gets
in and out of tight places.
Many thanks for the fix.
Roln

[Foxtrot]

Check this out:

http://www.sim-outhouse.com/index.php?loc=articles&page=cp

;)

Good read. Very interesting. I am going to try this next time I have such a problem.

Cheers,

Keenan

[napamule2]

Roln,
It could use a couple of small tweaks here and there, but overall it's 100 percent improvement, IMHO. There was a day delay, probably due to heavy uploads, plus the extra workload of new site features. It's there now, just checked. Glad to hear you liked it for a personal reason. Makes my day to hear that. I can't stop flying it myself. Not too many AC have everything you want or need. This has it all, even if it's supposed to be a low polygon count model. Hey, it looks good, it fly good. What more can one ask. And it's free (yet priceless. Well, maybe 100,000 smackers?). Cheers.
Chuck B
napamule

[Thom_D]

I downloaded Frank Elton's Sopwith Triplane (triple.zip) to round out my Sopwith collection. I have an affinity for WWI fighters. When I loaded it up the plane was sunk up to the tops of its wheels and the tail was sunk down below the level of the rear skid.

I used the info in this thread to find the great Sim-Outhouse article on how to managet this and got the wheels and skid back above ground and level with the runway.

The problem I am still having is when I load up the plane it still starts out below ground and when I unpause the simulator it "Hops" up to ground level. Not sure what else in the cfg file to get it to start out at ground level.

[CPSBruce]

The problem I am still having is when I load up the plane it still starts out below ground and when I unpause the simulator it "Hops" up to ground level.

You should see what it does with retracts... hovers in mid air while the gear come down. :D

[IronmanMLR]

More than likely your center of gravity height is too low. Which starts you out under ground and pops you up to where the landing gear contact points are. If center of gravity height is too much, then you start out in mid air and the aircraft drops down to the landing gear contact points.

Mike