posted 04-20- 04:10 AM               

Zur mentioned something about faking it with Inertia volumes. However in the Hurricane I am using seperate models for the fuel tanks (the plan being that they get hit seperatly, and also allows the fuel to be positioned). Do these fuel tank models need an inertai volume to have weight or does it fall out of the fuel load.

Second question: The Hurri has the main tank split between two wing tanks and the fuel is drawn from each in an equal manner. How is this represented in the SM file? especially in the engine which is using the fuel.

posted 04-20- 08:09 AM               

You specify a "primary" fuel source for your engine. Usually it's the fuselage, but it could be the wings (not sure exactly how the syntax works for specifying both wings as the primary fuel source--you may have to just list them in the order you want them used). In the object that has the fuel, you specify whether its a "main" tank or "aux" tank. You can even put both an aux and a main in the same object. So, you might have each wing contain a "main" obFuel property and the fuselage might have an "aux" obFuel property. In this case the weight of the fuel capacity is distributed evenly over your wings and/or fuselage--not good.

As I learned while setting up the Corsair last night, the engine will not recognize a separate fuel tank object if you still have obFuel properties attached to your fuselage or wings. The engine will look for any obFuel properties in the fuselage or wings EVEN if you've told it that it has a "dedicated" fuel tank object.

To add a fuel tank, you make the object (I just copied and pasted Laika's I-16 tank), position it in the model and assign it a capacity and a type (main or aux). You can make it self-sealing, and there may be some other properties you can give it. Then you give it a density and a C of G. Now, if I understand it correctly, the weight of the fuel will be evenly distributed throughout your tank object, which is obviously much smaller than the fuselage, and located in a specific point in relation to the aircraft's overall C of G. (This is where the FM benefit comes in, because you've "moved" about 1000 pounds or so to its "correct" location on the airframe) Then just assign the engineFuelSource property to feed off of your tank object(s) and you should be all set.

Make sure the only objects with obFuel properties are the tanks tho, by deleting the obFuel properties from the wing or fuselage objects, or you'll be running out of fuel with full "tanks."

The "inertia volume" of the tank I'm pretty sure just applies to the weight of the tank itself; i.e. it takes the phyRelDensity value and the size of the object and figures out what percentage of the aircraft weight that represents. But I'm not too sure of that one--take a look at the phyRelDensity of the tank object on the Jug and 1-16 to be sure. If it's a low number like 0.2, it's just "weighing" the tank walls. If it's 0.9 or 1.0 I guess that would mean the fuel is included there.

posted 04-20- 09:41 AM               

So if the phyLBS is 6532 and a part has a phyRelDensity of .1 the weight of that object is 65.32 lbs

In order to balance the DVII, I set up a spreadsheet to check all the weights and phyRelDensity. What I found was that If the total of all the weights is about or above the phyLBS it would make the plane shake at low speed. The lower (the combined weights) were from the (given total weight)the faster the plane could go before it would shake. Also if I increased the phyRelDensity of the wings to a higher number it would raise the speed it could fly before it would shake.

posted 04-20- 11:11 AM               

Yup you both got it right. The density just opproximates the physical tank weight ... the actual "fuels" weight will populate it when full ...

... Bryan,

posted 04-20- 12:05 PM               

I experimented with making the fuel tanks and pilots take damage by making low level collision LODs but couldn't get it to work right. I think it has something to do with what Laika discovered re: poly flags and collisions. Is there any way to have the .obj importer automatically set these flags?

posted 04-20- 02:24 PM               

TS

posted 04-20- 04:59 PM               

Either a very astute choice or a very foolish one, depending on one's point of view...

BTW what's the best way to test this stuff? Park a B17 next to the plane and wail on it from one of the turrets?

posted 04-20- 05:45 PM               

A better way to model this may be to use obprob to remove the tank from the list of fuel sources for the engine when the part is hit? Is that possible?

posted 04-20- 07:07 PM               

He's also got a damage obFunc in there that changes the engine fuel source to "none." Haven't played around with it enough to see how that works, but I CAN verify that the plane catches on fire quite well

I would think you could also give yourself a very small "aux" tank somewhere, and have the main tank obDetach after some damage. Since it's invisible, you wouldn't see it fall off, and presumably the engine would seek out the aux tank...and run out of gas a minute or two later. Think that would work?

posted 04-20- 08:41 PM               

and the only properties in FusAuxFuel are

(obFuel((CapacityGal 28 Type 'Aux)))

All the fuel tank objects are children of the main model.

The Engine has three properties of :

(engFuelSource 'PortWingFuel) (engFuelSource 'StarWingFuel) (engFuelSource 'FusResFuel)

As well as the others of course. So is this the right setup to draw fuel evenly from the wing tanks?

posted 04-21- 01:45 AM               

That was Jaguars (when I remember right) tip.

Hey jedi - nice to see that you like it I did DM testing with a parked B17 and 6-10 I16 around. Much fun

I never got a clue what I was doing, much trial and error..

Bryan -

if i.e. the StarWingFuel-Tank is gone (dmg to max) why not call a function wich sets your engine-fuel objects like this:

(engFuelSource 'PortWingFuel) (engFuelSource 'StarWingFuel_empty) (engFuelSource 'FusResFuel)

'StarWingFuel_empty ist just a name (could also be "none" or "anything" else), no really existing model. Now the 'StarWingFuel is no longer used by your engine and you can detach it for the correct cg of the Plane.

posted 04-21- 09:55 AM               

If you want to test it, set the fuel capacity in two of the tanks to 0.1 and leave the third tank at normal capacity. If the engine quits after a couple minutes, your tank isn't being recognized. If the engine runs normally, the tank with the fuel is "good." Switch it around so that each tank has fuel with the other two almost empty to make sure all the tanks feed.

Laika--

I installed your engine/fuel tank damage into the Corsair last night and set myself on fire a few times. Pretty cool! The one in the Jug is neat too, but I didn't understand exactly how that one was working, so I haven't experimented with it yet.