Carbon Cub

Jet-Pack (IPACS) · Feb 20th 2023

To set up a jointmulti first check that the R0 of the two referenced rigidbodies are set correctly and the Pivot of the joint (R0). R0 of the rigidbody is the center of mass and if your rigidbody is very light and very far from the joint's R0 position and the Kp/Kd are high then the physics can explode numerically. So you want to make sure that the R0s are set correctly before you continue.

In the second step I'd reduce the damping and spring constants (Kd, Kp) by a factor of 10 until it no longer explodes. The gear may collapse at this point and the prop may hit the ground and cause a reset but that is not as critical - it's the instant reset or glitching/jittering that needs to be taken care of first.

You can do this for one gear at a time.

aenbacka · Feb 20th 2023

Some interior modeling progress from the team😀 Still some texturing, then progressing to do some rigging.

Tomfa · Feb 20th 2023

You have made a good choice regarding the panel, apparently the WORLD VFR model with a Garmin aera796, as shown below at the bottom of the first page of this link.

Carbon Cub SS | CubCrafters

aenbacka · Feb 20th 2023

Quote from Tomfa

You have made a good choice regarding the panel, apparently the WORLD VFR model with a Garmin aera796, as shown below at the bottom of the first page of this link.

https://cubcrafters.com/carboncub/ss

Thanks, hopefully it will be possible to implement the modern avionics as well. First step will be to get the basic aerodynamics working in Aerofly FS4, and then iterate on the systems etc.

Jet-Pack (IPACS) · Feb 21st 2023

Awesome, that looks great!

Tomfa · Feb 21st 2023

Quote from aenbacka

Thanks, hopefully it will be possible to implement the modern avionics as well. First step will be to get the basic aerodynamics working in Aerofly FS4, and then iterate on the systems etc.

Good luck to you for the rest and your excellent work!

aenbacka · Feb 21st 2023

Concerning the R0 for multibody joint, based on the attached screenshot, what should be the defined joint point, which connects fuselage and the front wheel(hull)?

Jet-Pack (IPACS) · Feb 21st 2023

I would use these for the R0 of the joints between the gear and the fuselage. The wheel attachment point is defined in the wheel itself.

aenbacka · Feb 21st 2023

Quote from Jet-Pack (IPACS)

I would use these for the R0 of the joints between the gear and the fuselage. The wheel attachment point is defined in the wheel itself.

Thanks a lot, will try with those points.

aenbacka · Feb 21st 2023

Jet-Pack (IPACS) Should the value for R0 be the same for both the rigidbody and wheel elements, e.g. as in the following example. I also found in the tmd file an extra multibody_joint element which pointed to an entirely bogus location, maybe that could have caused some of the issues?

<[rigidbody][RightGear]

<[tmvector3d][InertiaLength][ 0.420624 0.2 0.8 ]>

<[tmvector3d][R0][ 0.3046 -0.3654 -0.646 ]>

<[tmmatrix3d][B0][ 1.0 0.0 0.0 0.0 0.70711 -0.70711 0.0 0.70711 0.70711 ]>

>

<[wheel][RightWheelHull][]

<[string8][Body][RightGear]>

<[tmvector3d][R0][ 0.3046 -0.3654 -0.646 ]>

Jet-Pack (IPACS) · Feb 22nd 2023

No, the rigidbody R0 should be where the center of mass of the gear is located, the R0 of the joint should be where the hinge is located and the R0 of the wheel is where the wheel rotates about.

aenbacka · Feb 22nd 2023

Quote from Jet-Pack (IPACS)

No, the rigidbody R0 should be where the center of mass of the gear is located, the R0 of the joint should be where the hinge is located and the R0 of the wheel is where the wheel rotates about.

Thanks for clarifying these things, it helps a lot👍

aenbacka · Feb 22nd 2023

So now I have gone through all R0s and Kp/Kd values for the multibody_joints, and finally it seems to stand quite steady on the ground. Attached is a link to a short demo video from within the simulator (still with the old texturing).

Carbon Cub demo

jayeye2011 · Feb 22nd 2023

Wonder if there is an easy way to test how well your gear Kp and Kd setup handles shock absorption, like some kind of drop test from a small preset height above the ground.

aenbacka · Feb 22nd 2023

Quote from jayeye2011

Wonder if there is an easy way to test how well your gear Kp and Kd setup handles shock absorption, like some kind of drop test from a small preset height above the ground.

Good question, I guess when we get it up in the air it will be possible to test landings on different types of surfaces. These parameters are difficult to know ideal values before proper testing has been done. First challenge was to get the ground contact to work, so the rest can easier be tested.

Jet-Pack (IPACS) · Feb 22nd 2023

If you adjust the contact points you can perform a little drop test. Adjust the last values in the contact points to adjust the contact point size and thus height above ground upon initialization.

jayeye2011 · Feb 22nd 2023

Contact Point? Before anyone else asks, I Googled it and found Jet-Pack's explanation from 2017

Post

RE: Setting up Landing Gear so the plane sits on the Tarmac

The "contact points" a bit different in the Aerofly FS 2 and are defined in the tmc file of the aircraft. The contact points are the positions that are placed on the runway surface at initialisation, those don't have to be the wheels but they ususally are. They are just used to calibrate the orientation of the aircraft (e.g. tail down for a taildragger).

The wheelhull2 R0 parameter is the center of the wheel, the contact point would be one "Radius" distance further down in the z-axis.
R0 =…

Jet-Pack (IPACS)

Mar 28th 2017

aenbacka · Feb 22nd 2023

Will make a small test then to see whether the drop will be suitable damped.

jayeye2011 · Feb 23rd 2023

Not sure if you have already done the airfoil setup in the your tmd file yet, if not here is a link to Jet-Pack's description of how to do this for FS 2 back in 2016

Post

RE: How to create an Airfoil (MH 30)?

No the airfoil.tmd file does not have any affect on the flight phyics of the individual aircraft.
You will need to edit the .tmd file of the aircraft itself with a text editor like Notepad++. Create a backup of that file first, than find the "AirfoilRoot" and "AirfoilTip" in the code.

Here is a quick version of how I'd generate the desired airfoil...
For more information about the aerofly airfoil visit the wiki: http://wiki.aerofly-sim.de/bin/view/Main/Airfoil

To change the airfoil you first need…

Jet-Pack (IPACS)

Feb 26th 2016

Helps clarify some of the nitty-gritty of the tmd.airfoil wiki page

aircraft:tmd:airfoil [Aerofly FS Wiki]

Hopefully this is still the same for FS 4 (as the existing aerofly wiki is only for FS2, at least as far as the tmd file goes) .

aenbacka · Feb 23rd 2023

I did some quick tests with the gear by editing the ContactSpheres in the tmc and trying to drop it down on the runway. With the Kp/Kd values for the joints for which the plane stands steady on the ground it seems to reset simulation when touching down (it jumps up and down a few times first, as seen in the vide below). How to see what is the cause for the reset?

Gear testing

Carbon Cub

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