Ground handling improvements for planes

[opjose]

The ground handling of the planes can be improved greatly with a few simple changes.

Here is the Extra 300L with a few adjustments.

Gone is the "sliding on ice" behaviour and ground loops are more realistic.

Note:

Another "bug" in G4 is that the stiffness parameter in the physics editor acts in reverse.

The HIGHER the number the more springy the gear becomes...

[dhk79]

To save the time of comparing the files line-by-line, what parameters did you adjust?

[opjose]

I adjusted the gear stiffness DOWN, to around 65% ( down increases it, go figure )...

The gear friction went up to around 200%, while the rolling resistance to about 140... or just enough to prevent the plane from nosing over too quickly.

[Gregg28]

Most of the planes that I downloaded bounce around on the runway when they are not moving. Any idea why and how to stop this?
Thanks,
Gregg

[opjose]

It's a problem with the collision mesh and the "engine" effect.

Kill the engine ( hit "K" ) and does the bouncing then stop?

[Gregg28]

It's a problem with the collision mesh and the "engine" effect.

Kill the engine ( hit "K" ) and does the bouncing then stop?


No, the bouncing does not stop. I was wondering if it had something to do with the landing gear stiffness, as stated above, but I do not see a variable for it in G4.

[opjose]

The Stiffness can cause this, and increasing the stiffness ( which causes the gear to become MORE "springy" go figure... ) to say over 160% causes the plane to flounder on the ground like a fish on dry land.

However it's likely a problem with the gear collision mesh on the particular model(s) you are looking at.

[Gregg28]

The Stiffness can cause this, and increasing the stiffness ( which causes the gear to become MORE "springy" go figure... ) to say over 160% causes the plane to flounder on the ground like a fish on dry land.


Where do you adjust the stiffness?

Thanks

[jim_ag3y]

My first post to this forum. Great simulator, I am having a ball!

However, I notice that I can change landing gear all day long, tail dragger to tricycle, CG and location changes, etc. But the planes handle the same as if the change had not been made.

I even took the nose wheel off the PT40 just to see what would happen ( it should drop down on the prop spinner. But the plane handled exactly as though I didn't make the change at all!

Any idea what I am missing? Do I have to use a different design program to make these kinds of changes?

I really dislike the ground looping tendencies of the Bulldog, for instance, but NOTHING I do makes any difference! HELP ! Jim S.

[jeffpn]

You probably saw in my other post that you cannot make visual changes to models witout the original 3ds file. But the changes you make in the editor should be reflected in the physics. In other words, if you change a tricycle to a tail dragger, it will still look like a tricycle, but handle like a taildragger, in theory. I wonder though, if the collision mesh of the front gear might get in the way.

[jim_ag3y]

Of course I realize that the appearance of the plane does not change, but that is a small problem as long as the physics react in the proper manner. In the situation with landing gears, they do not seem to.

I would appreciate it if you would try it and report your results. Remove All the gear from the plane and see as if the fuse is sitting on the ground. I would think it would be like the planes with the retracts in the "up" position.

I am very new to this, but I wonder if the gear thing does not perform properly, how many other things might be misleading, too? Have you had much success with different airfoils, wing sizes, etc. Those SEEM to be working OK, but since I have almost no actual RC flying experience, it is hard for me to say definately!

I could go out to the field and crash my baby unmercifly because I THOUGHT I was flying it correctly in the simulator!

:eek:

I see a "visual mesh" section, but not a "collision mesh" one. Where do you find that ?

Thanks again. Jim S.

[opjose]

Yes changing the physics of the plane permits the plane to react as per the changes IN THE AIR.

Landing gear blue this distinction however as Jeffpn said, the gear mesh gets involved.

So you can turn a tail dragger to a nose wheeled plane, but even though you may have a virtual nose wheel present, G3/G4 will still cause the plane to nose over.

G3/G4 has no way of determining the "contact point" of the gear with the ground, so it acts as if the gear is simply not there, and the nose of the craft tilt forward as if the gear are in the ground.

The Collision mesh is defined in the original 3D model, so you need 3Dstudio and the original model to edit this... which means that for the most part, you cannot.

[jim_ag3y]

OK, I can certainly understand this, but are any other functions seriously affected by this? A wing is a wing, etc. so I would guess that changing the airfoils, CG etc, still can be expected to work OK.

See one of the things I want to do is to change the size of the aircraft, if not the configuration. I scaled everything down to 75% of a model, and put a .25 engine on it instead of a .40 . It seems to fly like I would expect a smaller plane to fly, but when it lands, for instance, it still thinks the LG is in the original position, which now puts them ahead of the CG. The plane sits on its tail, in spite of my relocating the LG in the wire frame !

I would LOVE to do some serious airplane design/modifications, and was hoping I could do this with G4.

What software do I need to actually do this work? Tell me more about 3Dstudio. Thanks again for great answers! Jim S.

[opjose]

OK, I can certainly understand this, but are any other functions seriously affected by this? A wing is a wing, etc. so I would guess that changing the airfoils, CG etc, still can be expected to work OK.

See one of the things I want to do is to change the size of the aircraft, if not the configuration. I scaled everything down to 75% of a model, and put a .25 engine on it instead of a .40 . It seems to fly like I would expect a smaller plane to fly, but when it lands, for instance, it still thinks the LG is in the original position, which now puts them ahead of the CG. The plane sits on its tail, in spite of my relocating the LG in the wire frame !

I would LOVE to do some serious airplane design/modifications, and was hoping I could do this with G4.

What software do I need to actually do this work? Tell me more about 3Dstudio. Thanks again for great answers! Jim S.


You can adjust the physics in G3/G4, to work on the 3D model ( which also affects the gear ) you need both the original 3D model itself and a suitable editing program such as 3DStudio ( a cheapy at $4,000.00 USD ).

If you've resized a plane there are MANY things you must do to it.

I've posted other threads on this topic.

Simply changing it's scale is not enough.

You also must do things like MANUALLY reducing the weights of each of the components in a reasonable proportion, adjusting props, engines, etc.

When you resize a plane you are not moving the location of the LG.

It stays the same relative to the rest of the plane.

However a smaller plane now weights a LOT more ( it retains the weight of the original larger plane ) until you adjust the weights of the component parts.

Swap out the engine, as you did, and now the plane becomes tail heavy due to the disparity in the relative weights.

So there is more work to be done by you to fix this so to speak.