take off length problem

[UllyB 1,207]

I've download some F-5 Tiger old models and I noticed that my aircraft, if I let it to take off, with autopilot ON, somehow takes off late (it's almost to the end of the runaway sort of speak) and loses its landing gear in the process. On the other hand, I noticed that my AI F-5s wingmen have no problem to take off without damaging the landing gear. Unless I pilot it myself  as it takes off, I lose the landing gear. Is there a way to "tell" the autopilot (some file to modify, a parameter, something) which pilots, for the take off sequence, in my place, to get the plane in the air a little earlier, BEFORE it's critical (loses its landing gear) ? I guess it has to be some file which one can modify the take off distance on the runaway. I hope I made myself understood. Thank you in advance.

[+Cliff7600 1,163]

Is there a way to "tell" the autopilot (some file to modify, a parameter, something) which pilots, for the take off sequence, in my place, to get the plane in the air a little earlier, BEFORE it's critical (loses its landing gear) ?

 

-> No, there's no way to do so, the plane takes off as soon as it can. The wingmen don't use the flight model the same way the autopilot does.

 

I guess it has to be some file which one can modify the take off distance on the runaway.

 

-> No, you have to edit the whole flight model (wings and horizontal stabilisers) in the data.ini file.

Maybe just editing the Cl0 and Cla values and the Cl0MachTable and the ClaMachTable of the wings and stabs may be enough, but you have to know what you're doing.

If not, maybe you can lighten the plane with less ordnance and less fuel (and sometimes it's not enough)

 

ThirdWire FM Notes.rar

 

Have some fun

and the knowledge base of the forum is a nice place to learn (though sometimes it's not enough too, just like the F-5 trying to take off)

Edited July 16, 2016 by Cliff7600

[+Cliff7600 1,163]

I just took a look at the (old) F-5A data.ini file

 

The Left/Right stabs seem ok (though I wouldn't agree with the Mach tables, but my way would made the issue worse)

 

and to me the problem comes from the fact that the Left/Right wings and Left/Right outerwings don't have Cl0 values and Mach tables.

It works as it is, and if you really want your player aircraft to take off on autopilot (???), you have to add those Cl0 values and Mach tables (that don't exist).

 

Live with it, or waste a huge amount of time doing it, it's your choice.

 

OR maybe somebody already did it and is still here at CombatAce, you'd be lucky.

 

or somebody knows something I don't that could be useful... (?)

 

I don't have time enough to deal with the projects I'm already involved in, and I don't fly the F-5 (on autopilot), so I won't do it.

 

"Best call" (or not) would be downloading the lastest SF2 F-5 data.ini and trying to use the same values for your old SF1 F-5 (and sometimes it doesn't work at all)

(Don't use the SF2 file, you have to copy/paste or rewrite the entries to your SF1 data.ini file, and keep the original file, as SF2 and SF1/Wox files are not compatibles, at all)

Edited July 16, 2016 by Cliff7600

[UllyB 1,207]

ok, thank you for your precious insight. I will take a look and I hope I won't me messing those files /values up too much.

[UllyB 1,207]

I have three F-5 planes models, a F-5E Tiger II, a CF-5A and a F-5A one, all of them downloaded from here. The first works without crashing the gear (when taking off on autopilot), I just checked that few minutes ago, the latter two don't. I will try to match the F-5E data stab/wings coefficients, as you instructed me, with the ones of the other two planes and see what happens (maybe that way I might learn some things along the way) and I'll come back with the result. Thank you for inspiring me.

[+Cliff7600 1,163]

... I hope I won't me messing those files /values up too much.

You will, that's a part of the process 

 

If you take a comparison between aircrafts, be sure that all the parameters are equals : weight, loadout, flaps settings, thrust power, etc...

all parameters, check the whole data.ini file, even the things that may be not relevant (and maybe are actually not relevant, but only after you checked it) : landing gear, mass fraction, Xmac, all.

[UllyB 1,207]

I solved it. For CF-5 I matched the coefficient values, plus I had to match the engine power (F-5E has the strongest power for engines) and it was enough.

For F-5A  all these weren't enough so I had to reduce the payload (a small fuel tank here, a bigger one there etc) and it finally took off without crashing. Thank you once again for guiding me into the matter. I couldn't have done without your help. Thank you.