stupid question time..

[+sophocles 1,345]

Hello all,

 

sorry for a couple of stupid questions but I'm trying to get my F-5a into the game starting on the runway, but it just blows .. I mean "up" I figure the aircraft is sitting too low on the ground .. so on to the question..

 

 

Is the ground in strike fighters at z =0? Like, at which position should the bottom of my wheel be in max for them to be on the ground in-game? (does this make sense?)

 

.. and, which in your experience would be the ideal stock aircraft.ini/data files to start with (I'm only just getting my head around these files .. so any help would be greatly appreciated.

 

 

 

regards

[+RAVEN 414]

In max the center of the AC (Waterline) should be at Z=0.0 , Pivot point for the fuselage should be at a percent of MAC (I can't find the ref. so you'll have to search) All the landing gear Parts should be "Reset XForm"'ed in the fully extended position and exported Retracted - Frame 0,This is what I did for my Hurricanes. For the ini stuff take a look at the data.ini's for the TMF F-5's as Refrence.

Edited July 12, 2012 by RAVEN

[+sophocles 1,345]

In max the center of the AC (Waterline) should be at Z=0.0 All the landing gear Parts should be "Reset XForm"'ed in the fully extended position and exported Retracted - Frame 0,This is what I did for my Hurricanes. For the ini stuff take a look at the data.ini's for the TMF F-5's as Refrence.

 

 

 

Thanks for the tips RAVEN; just to be clear, what do you mean exactly by "waterline" .. a line running parallel to the ground, but centred along the aircraft? If so, where does the game place the aircraft .. at 0 + something?

[+RAVEN 414]

You'll have to find a ref. drawing for the waterline, if the aircraft is exported with the waterline at Z=0.0 then the game will set the aircraft on the wheels acordeing to the "RollingRadius=0.??" Bottom Pic The Hurri Fuselage PivotPoint is at X 0.0, Y 0.0,Z 0.0

Edited July 12, 2012 by RAVEN

[+russouk2004 6,958]

The "waterline" or centre of the whole model (xyz axes)is set then to 0.0,0.0,0.0 then the game engine knows where parts are in game "world",ie,wheels etc.

either your not setting the Parent mesh to 0.0,0.0,0.0

or your meshes are actually not correct size,reset xform resets the true size of the mesh ,each time you scale a mesh you need reset it when its correct dimensions.

I always use a drawing thats set to the models real scale,I use a square set to ...Height,wingspan,and length of real model.then create the model to the exact size if possible,wheels etc easy to scale when you create the cylinder etc,or I make it close as poss to the scaled rawing,then when happy its ok,I reset xform the mesh,before animating or linking etc.

Edited July 12, 2012 by russouk2004

[Fubar512 1,350]

What ever you do Do Not set the longitudinal center (y-axis pivot point) at anything other than the centerline of the model. The game engine calculates parking revetment clearance (and several other things), based on the Y-axis center being at the physical center of the model.

[+sophocles 1,345]

Thank you all so very much I'll check everything and see it is in order.

 

 

Regards

[+russouk2004 6,958]

If u want a model thats done to look at for the above,let me know.

[+sophocles 1,345]

If u want a model thats done to look at for the above,let me know.

 

 

Russouk, that would be great I've been fumbling along trying the get the animations working.. and its really disheartening.

 

 

 

Sophocles

[+russouk2004 6,958]

Sophocles

check ur pm

[+sophocles 1,345]

Sophocles

check ur pm

 

Checked .. and hat's off to you! You're a real gentleman

[+russouk2004 6,958]

np,anytime.

[+baffmeister 1,205]

What ever you do Do Not set the longitudinal center (y-axis pivot point) at anything other than the centerline of the model. The game engine calculates parking revetment clearance (and several other things), based on the Y-axis center being at the physical center of the model.

 

One of the many things I don't understand. By centerline do you mean waterline as per the previous reference? If I apply FastCargo's ruler tool at the 0.0,0.0,0.0 point and it centers aft of the cockpit, does that mean the Y axis is too far aft? This is an area I have had some problems with regarding positioning the XAC points in a few FM's.

[+baffmeister 1,205]

I will attempt to answer my own poorly worded question. The airplane I'm working on is a single engine propeller fighter and the fore/aft zero point is behind the wing, but at the center of the model. [equal distance to the nose and tail] I did a quick ruler check on the ThirdWire Spitfire and the fore/aft zero point is about where I would estimate the Spitfire main wing spar is located, quite similar to Raven's Hurricane. With my project, if I place the XAC points at about 1/3 of the way aft of the leading edge of the wing, it won't fly due to the large leverage effect caused by the present fore/aft zero point. [it goes uncontrollably nose up] So, if I want to place the XAC points at the correct spot on the model I will have to use a CofG setting something like 0.0,1.7,0.0 This will move the "Pivot Point" [good description Raven] forward so I can place the XAC entries at the correct position. One of the problems I had on a previous airplane with an aft pivot point was a strong nose down force when carrying external stores, due to the leverage affect. Adding a forward CofG solved the problem and also improved taxi behavior. One thing to remember, if you change the CofG you will have to adjust the cockpit position. Probably lot's of other things affected as well, such as nose down force when extending the landing gear, behavior when extending/retracting flaps etc.

[+russouk2004 6,958]

set cog position,THEN centre the model to world.ie,0.0,0.0,0.0 then create all the points for pilot etc etc.

[+baffmeister 1,205]

set cog position,THEN centre the model to world.ie,0.0,0.0,0.0 then create all the points for pilot etc etc.

 

Unfortunately, I have no idea what that means. If it has something to do with editing the model Lod I can't do that. If it has something to do with the data.ini, I may be able to do something. Here is the edit I have done with the data.ini:

[AircraftData]

EmptyMass=4190

EmptyInertia=13191,8709,20184

ReferenceArea=26.0

ReferenceSpan=11.7

ReferenceLength=10.6

ReferenceChord=2.22

CGPosition=0.00,1.80,0.00//0.00,-0.10,0.00..........edited so I can place the XAC data at the correct spot. Also to avoid problems with external stores.

 

I have set up the XAC points for wings and tail based on this adjustment and it seems to work OK. Cockpit had to be repositioned but no problem with the pilot position. I think when adjusting the CofG this way it only affects positioning data for the cockpit, the "pivot point" for aerodynamic forces and the lever arm [much reduced]for the external stores. This is only the second FM I've done from scratch and I want to avoid some of the problems/errors I made on the first one.

[Fubar512 1,350]

One of the many things I don't understand. By centerline do you mean waterline as per the previous reference? If I apply FastCargo's ruler tool at the 0.0,0.0,0.0 point and it centers aft of the cockpit, does that mean the Y axis is too far aft? This is an area I have had some problems with regarding positioning the XAC points in a few FM's.

 

Yes, the physical center of the model in all axis. Any issues with weight distribution should be handled in the data.ini by the "massfraction" entries. For example, the mass fraction entry for the nose on a (single) piston engined fighter, would be understandably much greater than that of a jet-powered fighter.

[+baffmeister 1,205]

Mass fractions, something else I haven't been paying enough attention to. Probably would me a good thing to set those up early in the FM development.