Seemingly no way to control the thrust of the C-310

[dokeefemain]

With the F-16 the thrust/throttle or whatever it's called is easily controllable via fcs/throttle-cmd-norm. What is the equivalent to this for the C310? I've tried adjusting the fcs/throttle-cmd-norm[0] and fcs/throttle-cmd-norm[1], fcs/throttle-pos-norm[0] and fcs/throttle-pos-norm[1], fcs/mixture-cmd-norm[0] and fcs/mixture-cmd-norm[1] and many other parameters and none of it seems to do anything.

[seanmcleod]

You haven't told us what you're doing. Do you have a script you're running? If so, share the script. Otherwise we're really making guesses in the dark.

So here is one guess. Are the engines running?

[dokeefemain]

Here's what I have:

import jsbsim
import math
lat = 0.6536054872462248
lon = -1.300833822119308
alt = 4000

dt = 1/60

plane1 = jsbsim.FGFDMExec('./jsbsim/')
plane1.load_model("c310")

plane1["ic/psi-true-deg"] = 180
plane1['ic/lat-gc-deg'] = lat * 180 / math.pi
plane1['ic/long-gc-deg'] = lon * 180 / math.pi
plane1['ic/h-sl-ft'] = alt
plane1['ic/vg-kts'] = 270
plane1.run_ic()
plane1.set_dt(dt)
plane1["fcs/mixture-cmd-norm[0]"] = 1
plane1["fcs/mixture-cmd-norm[1]"] = 1
plane1["fcs/advance-cmd-norm[0]"] = 1.0
plane1["fcs/advance-cmd-norm[1]"] = 1.0
plane1["propulsion/magneto_cmd"] = 3
plane1["fcs/throttle-cmd-norm[0]"] = 1.0
plane1["fcs/throttle-cmd-norm[1]"] = 1.0
plane1["propulsion/starter_cmd"] = 1

while True:
    plane1.run()
    # Need to control throttle here
    # For the F-16 I could just do:
    plane1["fcs/throttle-cmd-norm"] = 0.35
    # And that would do the trick but for the c310 that doesn't seem to work

This was based on c3105.xml

[seanmcleod]

none of it seems to do anything.
but for the c310 that doesn't seem to work

You'll need to be more specific.

i = 0
while True:
    plane1.run()
    # Need to control throttle here
    # For the F-16 I could just do:
    #plane1["fcs/throttle-cmd-norm"] = 0.35
    # And that would do the trick but for the c310 that doesn't seem to work
 
    if i % 60 == 0:
        print(plane1['propulsion/engine[0]/power-hp'], plane1['propulsion/engine[1]/power-hp'])
    i += 1

0.019801980198019802 0.019801980198019802
5.819465314851099 5.819465314851099
247.15813543345558 247.15813543345558
259.06507547732275 259.08049086426195
253.43959029151836 253.4406814542261
249.2824567813061 249.2823319668072
245.30864431024807 245.30830930396587
241.5871878321587 241.58871305573336
238.15918438870747 238.160411756084
235.08775511881737 235.08766251197966
232.3445025649813 232.34561014144919
229.97156308068023 229.97176616912392
227.92987810066364 227.93257682393758
226.22878719365448 226.2302664850349
......

[seanmcleod]

I was going to suggest that you also trim the aircraft to get a feel for the throttle input required for say straight and level flight. However I noticed that I wasn't able to get JSBSim to trim with your initial conditions.

First issue is the speed you've set via: plane1['ic/vg-kts'] = 270. Take a look at the readme for the C310 - https://github.com/JSBSim-Team/jsbsim/tree/master/aircraft/c310 and you'll see that the ground speed you've specified is way too high, especially with the gear down by default.

So I made the following changes:

plane1['ic/vc-kts'] = 120
plane1['gear/gear-cmd-norm'] = 0
plane1["fcs/advance-cmd-norm[0]"] = 0.3
plane1["fcs/advance-cmd-norm[1]"] = 0.3

# Trim
try:
    plane1['simulation/do_simple_trim'] = 1
except RuntimeError as e:
    # The trim cannot succeed. Just make sure that the raised exception
    # is due to the trim failure otherwise rethrow.
    if e.args[0] != 'Trim Failed':
        raise

Not sure what the issue with the fcs/advanced-cmd-norm is in terms of preventing a trim solution with the conditions I've used. Had to make it 0.3 or smaller, 0 also worked.

Which then results in the following trim solution, with the throttles at 0.56.

  Full Trim

  Trim successful
  Trim Results: 
       Angle of Attack:   2.91  wdot:  9.11e-04 Tolerance: 1e-03  Passed
              Throttle:   0.56  udot:  5.03e-04 Tolerance: 1e-03  Passed
            Pitch Trim:   0.08  qdot: -8.50e-08 Tolerance: 1e-04  Passed
            Roll Angle:  -0.00  vdot:  7.80e-04 Tolerance: 1e-03  Passed
              Ailerons:   0.03  pdot:  2.05e-05 Tolerance: 1e-04  Passed
                Rudder:  -0.00  rdot: -4.87e-19 Tolerance: 1e-04  Passed