Removed

[SilentEagle]

I've been looking at mixing flaperon and elevon (stabilizer) control for roll command: since the stabilizer can work both symmetrically (elevator) and differentially (aileron) mixing that for both flaperons and elevons can be tricky.

 

It is essential to have but means changes to both flight control and aerodynamics: old aero code assumes always symmetrical deflection for flaperons and elevators and does not calculate separate lift and drag for different sides of aircraft.

 

Yes, the NASA aerodynamic data does not account for differential elevon in the rolling moments, so I also don't have that affect in my model. However, I do visually animate the elevon mixing and do use their differential positions for affecting pitching moments and drag.

[kazereal]

Yes, the NASA aerodynamic data does not account for differential elevon in the rolling moments, so I also don't have that affect in my model. However, I do visually animate the elevon mixing and do use their differential positions for affecting pitching moments and drag.

 

Either way, that is something that needs to be handled at some point to make it fly correctly..

 

I'm not at that point yet but I'm reading more about it when I have a chance.

Before then I'm making other changes in splitting fcs command logic from actuator code and aero code so the mixer (blending) of commands can be easier to add.

 

Likely changes to aero code need changes into equations of motion too since they are no longer symmetric effects around center of gravity. I'll need to look into that too at some point.

[SilentEagle]

Either way, that is something that needs to be handled at some point to make it fly correctly..

 

Actually, I found that the aircraft rolling speeds are dead on with the real aircraft without adding differential elevon affects. There is no PID in the roll axis, so you won't get any instability by adding additional rolling power, but I don't think it is really necessary. I'm thinking the NASA data just accounted for the affect in the aileron rolling moments, but did so with the current flaperon to elevon ratio at the subsonic speed they chose. Anyway, the thing already has such a quick roll rate acceleration and deceleration that it almost always looks horrible over multiplayer. When viewing the aircraft from external view (not over multiplayer), it looks very crisp like the real thing.

 

Before then I'm making other changes in splitting fcs command logic from actuator code and aero code so the mixer (blending) of commands can be easier to add.

 

Yes, this would be a good step in organization.

[kazereal]

Actually, I found that the aircraft rolling speeds are dead on with the real aircraft without adding differential elevon affects. There is no PID in the roll axis, so you won't get any instability by adding additional rolling power, but I don't think it is really necessary. I'm thinking the NASA data just accounted for the affect in the aileron rolling moments, but did so with the current flaperon to elevon ratio at the subsonic speed they chose. Anyway, the thing already has such a quick roll rate acceleration and deceleration that it almost always looks horrible over multiplayer. When viewing the aircraft from external view (not over multiplayer), it looks very crisp like the real thing.

 

I don't know about roll rate, that might be accounted for in the data already like you said.

 

I'm thinking mainly of things like near-stall or other rare cases where it might make a difference. I don't know how much of effect that might be in things like recovering from some situations. But we'll see..

 

There's part of the changes uploaded now, of course I'll need to revisit the changes and recheck everything afterwards but it is in progress.

 

Anyway, good to know that it compares well so there's way to check effects :)

[kazereal]

Some changes to leading edge flaps schedule (and more to do).

 

Should handle cases where they are locked in place (not in automatic mode), weight on wheels, transonic speed adjustment (needs improvement still).

[kazereal]

Simple oxygen pressure added so pilot stays alive in high altitudes.

 

No big changes now, looking at documents and planning for next set of changes.

 

I was testing some flight conditions, cases where it is near stall and close to losing control can be managed by use of airbrakes and flaps (with the alternate flaps switch). The documents mention this to be helpful so I thought of checking that.

 

Interesting to see what it will be like when planned changes to code are complete..

 

Edit: fixed a bug in LEF handling on takeoff, should give smooth transition from takeoff position now. 3D model animation does not handle -2(deg) upwards angle for both sides so that is a known thing..

 

Also found a forum post saying that TEF come down below some speed even if wheels are up.

Need to find another source to verify that and more details about speed and if there's other conditions (is it really automatic or just manual with the alternate flaps switch?).

Edited September 15, 2016 by kazereal

[kazereal]

Center of lift is now calculated as function of mach number.

 

Unlike traditional aircraft designs, F-16 has "relaxed static stability" which mean center of lift is a bit forward from aircraft reference center. Also the lift position moves backward as speed increases. This gives better agility but has downsides as more complexity in flight control system.

 

Reference point is 0.35 percent from mean chord length and actual position can change from 0.30 to 0.39 (0.35 at mach 1).

 

The change in lift position must be counteracted by trimming or by flight control system automatically (working on changes there still..)

 

Try it out. Other changes still in progress as mentioned before..

 

Edit: old code had a constant difference there which was for low speeds (max. front) and did not change it for higher speeds.

Edited September 18, 2016 by kazereal

[mvsgas]

For what is worth, thank you for all your hard work

[kazereal]

For what is worth, thank you for all your hard work

 

Thanks :)

 

There's still a lot to do and I'm waiting for a couple of books to arrive learn more about stuff that is waiting.

[Sierra99]

Guys this is really amazing...but I have to ask...what's it good for? Since nobody will confirm or deny a Falcon in the works and from what I've gotten from others, the only falcon currently in the wild is a private build for the virtual thunderbirds...what's the purpose of this.

 

Sierra

[kazereal]

Guys this is really amazing...but I have to ask...what's it good for? Since nobody will confirm or deny a Falcon in the works and from what I've gotten from others, the only falcon currently in the wild is a private build for the virtual thunderbirds...what's the purpose of this.

 

As said before a couple of times:

1) demonstration of how to implement external flight model in DCS

2) to learn how to make simulations

 

So the "demonstrator" part has been there quite some time, personally I'm interested in the second part now.

 

If it is useful for someone else too, all the better.

 

There is also: 3) share ideas and information, but that is not too large part.

 

One thing is that this is based on public information and so there is no problem in sharing the source code or the implementation.

 

Edit: as such, this is more oriented towards people who are interested in making a simulation module of some kind

 

Edit2: if you do enjoy flying some other mod more, go ahead. Approach might be different, results may vary and so on.

I am mostly trying to keep with A model information, that is actually easier to find and less guess-work about certain things.

If the more modern/advanced models are more interesting then some other mod might be more suitable.

Edited September 21, 2016 by kazereal

[kazereal]

Time for a short update..

 

I'm looking at implementing aircraft skin friction effect to the flight model.

That would need either friction coefficient (Cf) at various parts in the surface, or Reynolds number (Re): Cf = Re*M*a (where M is mach number and a alpha).

 

There seems to be way to calculate Reynolds number for various parts of surface according to airfoil shape, but that seems quite complicated and I'm not sure I can do that. For one reason, I don't have that detailed measurements of the aircraft body and airfoil shape.

 

So good sources of reliable public information is welcome as usual.

 

Edit: never mind, I think I've figure out (most of) the equations needed..

 

I'll be adding some code to test soon.

Edited September 25, 2016 by kazereal

[Tonio]

Hello, it's possible to have a link for download the F-16 ? It's for a new project : restart the Belgium F-16 Solo Display on DCS World 1.5 :)

[kazereal]

It is in the usual place for download:

https://github.com/ipr/F-16Demo/

 

Download that as-is to DCS mods/aircraft/ and should have it working with no extra steps needed.

 

Note that there are bugs and things that are in progress of being fixed, can't say timetable..

 

You can get older version(s) from the version control too if there's a reason to.

Edited September 27, 2016 by kazereal

[Tonio]

We can't delete the pylons.. ?

[SkateZilla]

I will be going back to the original source file and re-doing the external model to Current Standards (Lighting, Animation and Materials wise) later this year / beginning of next,

 

I have other projects that take priority.

 

Current model is from 2013, so Things have changed since then.

Edited September 27, 2016 by SkateZilla

[Tonio]

Copy' ;)

[kazereal]

Very simple inertia calculation added.

 

Basically, when object is moving it wants to continue moving so changes in direction need to overcome that. The more speed and mass you have -> higher the force to overcome.

 

It should consider mass of aircraft and fuel and velocity, which is a vector (direction and magnitude). I'll need to double-check the way to integrate with DCS and that calculations match etc.

 

But should be another step in looong way.

[kazereal]

A friend noticed that mod does not work when using mission editor to place the aircraft.

 

It looks like AI is fighting for control of the aircraft even when set to human control (client).

 

Any ideas?

 

Looking at the problem now but low on ideas what might be causing this..

[SkateZilla]

the version I have is a few months old but I dont have that Issue.

 

is this a new issue?

[kazereal]

the version I have is a few months old but I dont have that Issue.

 

is this a new issue?

 

Well, there has been plenty of changes..

 

Anyway, looks like bug was in throttle input handling where there's new and old code in progress.

 

Fixing that seems to have fixed the problem I was seeing too.

 

So, disregard previous post..

 

Edit: seems like problem is not entirely gone yet, sometimes you "fall out of sky" or "explode on runway" when spawning to aircraft.

Usually helps if throttle is somewhere above halfway when spawning but not all the time.

 

There's likely some division by zero somewhere in those situations but it seems to be harder to track down than I assumed.

 

In the meanwhile, you should now use "engine start" and "engine stop" shortcuts instead of just throttle: as part of tracking down a bug I made that to use explicit command now.

Edited October 7, 2016 by kazereal

[LJQCN101]

Hi, just a little info. In NASA TP-1538, Cl Cn CY coefficients are already accounted for differential deflection of horizontal stabilizers, since they uses a simplified (fixed) control schedule of 0.25 times aileron deflection. (In GD's control law, however, it has a dynamic schedule based on Qc/Ps, which can be found in http://i.imgur.com/nLkcuTR.png.) So it may be a little tricky to decide to what degree a reduction of the original value is appropriate for aero calculation on ailerons only.

Edited October 19, 2016 by LJQCN101

[kazereal]

Hi, just a little info. In NASA TP-1538, Cl Cn CY coefficients are already accounted for differential deflection of horizontal stabilizers, since they uses a simplified (fixed) control schedule of 0.25 times aileron deflection. (In GD's control law, however, it has a dynamic schedule based on Qc/Ps, which can be found in http://i.imgur.com/nLkcuTR.png.) So it may be a little tricky to decide to what degree a reduction of the original value is appropriate for aero calculation on ailerons only.

 

Thanks for that info.

 

I'll have to get back to it bit later, currently busy with another thing.

 

Also got info on couple of good books for CFD analysis since that has other things to consider comparing to "usual" aerodynamics.

I'm looking at more in-depth information at this point, learning more about aerodynamics and other things.

 

One source (free textbook):

http://web.mit.edu/lienhard/www/ahtt.html

 

Edit: values from windtunnel are different from experiments in real flight too, but calculations can be used to compensate some of that.

Supersonic flight changes things a lot: if subsonic flight can be considered mostly through a "solid", in supersonic flight you need to consider plenty more of the flow types involved.

Edited October 19, 2016 by kazereal

[joey45]

Thanks.

 

using mobile

[Robert31178]

the version on the front page still says March 2014? Maybe I missed something, I dunno.....

 

Does this work with the recent updates to 1.5?