Flight Dynamics experts...I need help

F

Felixthreeone

Charter Member
Ok here is my issue:

I have a tweaker's mentality when it comes to flightsim, and have learned my way around things pretty well over the few years I have been into it. One pesky problem seems to keep creeping up and ruining my tweaking life, and it is the #@#! stalling issue that I seem to have with certain addon aircraft, both payware and freeware. I will elaborate.

I recently set out to modify the FS-KBT super hornet to add some different effects and tweaks (I know my way around the aircraft config fairly well), and have been successful adding the mods I wanted. When I get into the flight dynamics, however, i run into a 'stalling' issue. Now as a real-world pilot, I am familiar with AOA, airspeeds for safe operation, and MOI and the like. This aircraft, like a few others in my hangar, exhibit behaviour that is uncharacteristic for the flight envelope they are supposed to mimic. For example, at 250-350 knots, any stick deflection (pull) that i feed into my X52 beyond, say, a third of the stick range, almost instantly throws the stall flag, and the aircraft begins to depart controlled flight. Now, I have some fast jet experience IRL, so i can attest to the fact that this is not the case with the real thing; speaking to some super hornet pilot friends of mine, I have gleaned some very good info on the handling characteristics of the real jet.

Another example is the Dave Garwood Hunter. It flies beautifully...whereas my Alphasim Hunter has the same stalling issue as my KBT Superhornet.

I have AirEd, but am not too familiar with the settings inside of the .air file, so i am not sure if the solution to the problem lies in the .cfg, or the .air file itself. These aircraft shouldn't throw a stall flag under the circumstances that they are. But if anyone here can help me solve this issue, It would be a fantastic leap that would allow me to remove from mothballs a few aircraft that I really enjoy outside of this issue. I thank you guys in advance for your time and knowledge.
 
Hi,

Dunno if you know this small tutorial .. it's useful infos there:

FS2004 (ACOF) - Misc. FS2004 How To Tweak Flight Dynamics
[SIZE=-1] [ Download | View ] [/SIZE]
Name: howtweak.zip Size: 47,722 Date: 09-12-2005 Downloads: 1,785
[SIZE=-1] FS2004 How To Tweak Flight Dynamics. This pdf file is for people who want to learn, or learn more, about updating the flight dynamics of FS2004 aircraft. It won't tell you everything, but it will tell you some things the majority of flight simmers don't know about updating flight dynamics. By Bob Chicilo.[/SIZE]
Click to expand...
 
I updated the flight dynamics for this some time ago. I'll review what I did and see if it does what you say yours does.
 
aeromed202 said:
I updated the flight dynamics for this some time ago. I'll review what I did and see if it does what you say yours does.
Click to expand...

....thank you very much; I downloaded the tutorial claudius pointed me to, and went about a few tweaks, but it didnt seem to have an effect on the issue...
 
Fly by wire aircraft are particularly frustrating to deal with in FS. The reason bering they react as their computer says they should, not as one would expect the airframe to fly by raw data. I am afraid that you will need to start mucking about in trhe .Air file. Aircraft Airfile Manager is a usefull utility and does provide a small number of hints at what each parameter does. AirEd is another useful tool once you have some idea what is going on.

By stall flag you mean the small red message at the bottom that says "stall" as opposed to the break? You can specify the AOA at which this occurs.

Good luck: T
 
Thanks, T...when you say you can specify the angle, how do I do it? I tried what I thought was that exact thing in AirED, and increased the angele, but it had no noticeable effect....what am I missing?
 
Lots of things can impact this issue and here are a few to look at attached.

See highlited section near top to adjust angle.
 
Thank you very much, Milton. I had seen one or two of the lines you pointed out, but you also pointed out a few I hadn't looked at....I will mess with 'em a bit and see what happens....

......*edit*....also, Milton, one other interesting phenomena I notice: I can put this aircraft into a shallow dive, picking up speed; during the descent, if i quickly apply a brief 'pull' on the stick, the stall flag shows on the screen, but only for the split second that I applied the excess backpressure....its almost like a 'switch' in the travel of the controls is triggering the stall signal from FS. Since I have essentially no positive AOA, why on earth would that happen? This is something I am determined to fix...and I appreciate the feedback very much.
 
Thanks Milton, was gone for a bit, but that was what I was looking for!

As to the brief stall, my guess is that it is sensing (developing) an instantaneous G load. Aerodynamically this is not correct, but the interaction between the elevator and the wing is one of the more approxiamate areas of FS.

Cheers: T
 
You might compare some of the key values to an air file of a similar aircraft.

Optionally, you might post the air and cfg file here so that we have something to look at. Darkness hides the obvious.
 
Hmm, never bothered to look at the FM for that plane as I stripped the bird of panels and scrapped the rest. I'll compare the C and D models from [SIZE=-1] Areal Foundry to your pic and see what their numbers indicate (as those AF Hornets don't show stall warnings like you indicate)
[/SIZE]
 
Sadly NONE of the A/C I looked at have those circled items in sec 1101: Not the Abacus F-18, neither of the aerialfoundry hornets V2 or V3, not my gripen C, not the Viperden F-16, Eaglesoft Citation X, vistaliners 727, CLS DC-10, POSKY 757, nuthin.

You sure thats the FS9 model ? The KBT F-18F doesn't have them either, weird.
 
Maddog, I believe the values are there, they are just labeled differently than in Milton"s example; I still don"t have a clue what to do with them really, other than changing them and going in-sim to see what happens
 
well, I'd assume Miltons aired is a later version than I'm running. I'm looking at airwrench with V2 aerialfoundry hornet C, in the scaler section and the descriptions are close to miltons pic, and my values are as follows:
stall warning stick shaker= 140
stall warning body AoA=17.25
*cl adop lift AoA rate=2575
*Cmo pitch= -10
*cm adot pitch moment AoA rate= 24000
*cm de pitch moment elevator= -1200

Hope that helps, but like I said I've never had that problem with the AF hornets, and I don't fly the KBT one (I don't like the superhornets- I'm a 'C' guy)
 
While you are coming at the issue from one direction you can try the mods I made for the 'E'. With this cfg it will do a stable mach 1.4 (still working on 1.9), dirty approach speed to the deck of 138-144, and fly crisply. Had problems with the contact points and do justice to the nice gear animations and still be less drunken on the ground but I think it's better. Make a backup of your CFG first and note that this one starts after [General] so be careful to only drop that much in. Made from trial and error, videos, and spec sheets. I use the panel hudhrnt.zip by Scott Printz.

[flight_tuning]
cruise_lift_scalar=0.700
pitch_stability=1.400
roll_stability=1.101
yaw_stability=1.000
parasite_drag_scalar=0.700
induced_drag_scalar=1.000
elevator_effectiveness=1.10
aileron_effectiveness=1.10
rudder_effectiveness=1.100
elevator_trim_effectiveness=1.000
aileron_trim_effectiveness=1.000
rudder_trim_effectiveness=1.000
[weight_and_balance]
// ACM V2.3
max_gross_weight = 65918.138
empty_weight = 29119.8618
reference_datum_position = 0, 0, 0
empty_weight_CG_position = 0, 0, -1.20
empty_weight_pitch_MOI = 400385
empty_weight_roll_MOI = 98000
empty_weight_yaw_MOI = 250000
empty_weight_coupled_MOI = 1300
max_number_of_stations = 1
station_load.0 = 400.00,-3.000000,0.000000,0.000000
//[lights]
//Types: 1=beacon, 2=strobe, 3=navigation, 4=cockpit, 5=landing
//light.0 = 4, 14.950, 0.000, 2.619, fx_vclight
//light.1 = 1, -18.330, -6.400, 7.131, fx_beaconb
//light.2 = 1, -18.330, 6.400, 7.131, fx_beaconb
///// NOTICE NO STROBES ? NOT ON THE REAL AIRCRAFT EITHER
///// CAUSES PROBLEMS WITH THE VAPOR FX DISPLAY
//light.3 = 10, -10.0, 0.0, 0.0, fx_RCB_machenvlop,1
//light.4 = 7, -13.00, 22.0, -1.00, fx_contrail_s_short
//light.5 = 7, -13.00, -22.0, -1.00, fx_contrail_s_short
light.6= 5, -28.0, -1.6, -1.2, fx_F14_Burnerflame , // Eng1 Afterburner Flame
light.7= 5, -28.0, 1.8, -1.2, fx_F14_Burnerflame, // Eng2 Afterburner Flame
light.8= 5, -27.0, -1.6, -0.9, fx_F14_Blueflame , // Eng1 Blueflame, when engine running
light.9= 5, -27.0, 1.8, -0.9, fx_F14_Blueflame , // Eng2 Blueflame, when engine running
[LIGHTS]
//Types: 1=beacon, 2=strobe, 3=navigation, 4=cockpit
light.0=4, 14.950, 0.000, 2.619, fx_vclight
light.1=1, -18.330, -6.400, 7.131, fx_beaconb
light.2=1, -18.330, 6.400, 7.131, fx_beaconb
light.3=2, -22.208, -6.146, 8.095, fx_strobe
light.4=2, -22.208, 6.146, 8.095, fx_strobe
light.5=10, -10.0, 0.0, 0.0, fx_RCB_machenvlop,1 // SonicBoom effect
light.6=8, 13.5, 0, 0, fx_vapor_fa18
light.7=7, -13.00, 22.0, -1.00, fx_contrail_s_short
light.8=7, -13.00, -22.0, -1.00, fx_contrail_s_short
light.9= 5, -28.0, -1.6, -1.2, fx_F14_Burnerflame , // Eng1 Afterburner Flame
light.10= 5, -28.0, 1.8, -1.2, fx_F14_Burnerflame , // Eng2 Afterburner Flame
light.11= 5, -27.0, -1.6, -0.9, fx_F14_Blueflame , // Eng1 Blueflame, when engine running
light.12= 5, -27.0, 1.8, -0.9, fx_F14_Blueflame , // Eng2 Blueflame, when engine running
[GeneralEngineData]
//0=Piston, 1=Jet, 2=None, 3=Helo-Turbine, 4=Rocket, 5=Turboprop
engine_type = 1
fuel_flow_scalar = 0.800000
engine.0 = 0.000000,0.000000,0.000000
engine.1 = 0.000000,0.000000,0.000000
min_throttle_limit=0.000000
[effects]
wake = fx_wake
water = fx_spray
dirt = fx_tchdrt
concrete = fx_sparks
touchdown = fx_tchdwn_s, 1
[smokesystem]
smoke.0 = -27.0, 0.0, -0.9, fx_smoke_rx
[fuel]
//Longitudinal (feet), Lateral (feet), Vertical (feet), Usable(gallons), Unusable (gallons)
fuel_type = 2
number_of_tank_selectors = 1
LeftMain = -1.3, -3.75, 0, 1075, 0
Center1 = -1.25, 0, -2.8, 480, 0
RightMain = -1.3, 3.75, 0, 1075, 0
electric_pump=0
[contact_points]
static_pitch = 0
static_cg_height = 7.282
max_number_of_points = 8
//0 Class
//1 Longitudinal Position (feet)
//2 Lateral Position (feet)
//3 Vertical Position (feet)
//4 Impact Damage Threshold (Feet Per Minute)
//5 Brake Map (0=None, 1=Left, 2=Right)
//6 Wheel Radius (feet)
//7 Steer Angle (degrees)
//8 Static Compression (feet,0 if rigid)
//9 Max/Static Compression Ratio (higher=less springy)
//10 Damping Ratio (0=bouncy, 1=Stiff)
//11 Extension Time (seconds)
//12 Retraction Time (seconds)
//13 Sound Type
point.0 = 1 16.19, 0.00, -8.52, 1781, 0, 0.79, 44, 0.60, 2.80, 1.84, 3.8, 4.0, 0.000, 0.000, 0.000
point.1 = 1, -4.23, -7.30, -8.96, 1974, 1, 0.63, 0, 1.87, 1.70, 1.94, 3.8, 4.0, 2.000, 0.000, 0.000
point.2 = 1, -4.23, 7.30, -8.96, 1974, 2, 0.63, 0, 1.87, 1.70, 1.94, 3.6, 4.0, 3.000, 0.000, 0.000
point.3 = 2.000, -7.591, -16.090, -1.010, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 5.000, 0.000, 0.000
point.4 = 2.000, -7.591, 16.090, -1.010, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 6.000, 0.000, 0.000
point.5 = 2.000, -20.250, 0.000, 0.000, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 9.000, 0.000, 0.000
point.6 = 2.000, 19.099, 0.000, -2.343, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 4.000, 0.000, 0.000
point.7 = 5.000, 13.192, 0.000, -6.300, 1600, 0, 0.00, 50.0, 0.0, 0.0, 1.00, 3.0, 3.0, 0, 0.0, 0.0
gear_system_type=0
[keyboard_response]
elevator = 150.000000, 250.000000
aileron = 150.000000, 250.000000
rudder = 150.000000, 250.000000
[forcefeedback]
gear_bump_nose_magnitude = 6000
gear_bump_nose_direction = 18000
gear_bump_nose_duration = 250000
gear_bump_left_magnitude = 6000
gear_bump_left_direction = 35500
gear_bump_left_duration = 250000
gear_bump_right_magnitude = 6000
gear_bump_right_direction = 00500
gear_bump_right_duration = 250000
ground_bumps_magnitude1 = 3250
ground_bumps_angle1 = 8900
ground_bumps_intercept1 = 5.0
ground_bumps_slope1 = 0.48
ground_bumps_magnitude2 = 750
ground_bumps_angle2 = 9100
ground_bumps_intercept2 = 0.075
ground_bumps_slope2 = 1.0
crash_magnitude1 = 10000
crash_direction1 = 01000
crash_magnitude2 = 10000
crash_direction2 = 9000
crash_period2 = 75000
crash_duration2 = 2500000
[airplane_geometry]
wing_area = 450.000000
wing_span = 40.000000
wing_root_chord = 10.833333
wing_dihedral = 2.142334
wing_incidence = -0.494385
wing_twist = -1.1563
oswald_efficiency_factor = 3.195582
wing_winglets_flag = 0
wing_sweep = 0.000000
wing_pos_apex_lon = 0.000000
wing_pos_apex_vert = 0.000000
htail_area = 230.000000
htail_span = 22.500000
htail_pos_lon = -21.250000
htail_pos_vert = 0.000000
htail_incidence = 0.000000
htail_sweep = 0.000000
vtail_area = 270.000000
vtail_span = 18.734994
vtail_sweep = 0.000000
vtail_pos_lon = -13.333333
vtail_pos_vert = 8.333333
elevator_area = 50.000000
aileron_area = 16.080000
rudder_area = 34.000000
elevator_up_limit = 16.501974
elevator_down_limit = 12.626481
aileron_up_limit = 15.480565
aileron_down_limit = 15.896903
rudder_limit = 23.491270
elevator_trim_limit = 19.480565
spoiler_limit = 25.988681
aileron_to_spoileron_gain = 0.000000
min_ailerons_for_spoilerons = 0.000000
min_flaps_for_spoilerons = 0.000000
spoilerons_available = 0
[electrical]
max_battery_voltage = 24
generator_alternator_voltage = 28
max_generator_alternator_amps = 60
electric_always_available = 0
[Flaps.0]
type=1
span-outboard=0.500000
extending-time=5.000000
system_type=0
lift_scalar=0.81
drag_scalar=0.700
pitch_scalar=0.03
flaps-position.0=0.000000,0.000000
flaps-position.1=10.000000,0.000000
flaps-position.2=43.00000,0.000000 //// 50.992454,0.000000 ON THE gEh MODEL
flaps-position.3=58.467895,0.000000
flaps-position.4=70.467895,0.000000
[jet_engine]
thrust_scalar=0.9
[TurbineEngineData]
fuel_flow_gain=0.004500
inlet_area=11.289500
rated_N2_rpm=29920.000000
static_thrust=18000.000000
afterburner_available=1
reverser_available=0
[Reference Speeds]
flaps_up_stall_speed=145.000000
full_flaps_stall_speed=116.000000
cruise_speed=380.786348
max_indicated_speed=1500.000000
max_mach=2.500000
[Views]
eyepoint=13.95, 0, 1.619
[autopilot]
autopilot_available=1
flight_director_available=0
default_vertical_speed=2000
autothrottle_available=1
autothrottle_arming_required=0
autothrottle_takeoff_ga=0
autothrottle_max_rpm=93.000000
pitch_takeoff_ga=8.000000
max_pitch=10.000000
max_pitch_acceleration=1.000000
max_pitch_velocity_lo_alt=2.000000
max_pitch_velocity_hi_alt=1.500000
max_pitch_velocity_lo_alt_breakpoint=20000.000000
max_pitch_velocity_hi_alt_breakpoint=28000.000000
max_bank=25.000000
max_bank_acceleration=1.800000
max_bank_velocity=3.000000
max_throttle_rate=0.100000
nav_proportional_control=9.000000
nav_integrator_control=0.250000
nav_derivative_control=0.000000
nav_integrator_boundary=2.500000
nav_derivative_boundary=0.000000
gs_proportional_control=9.520000
gs_integrator_control=0.260000
gs_derivative_control=0.000000
gs_integrator_boundary=0.700000
gs_derivative_boundary=0.000000
yaw_damper_gain=0.000000
default_pitch_mode=0
default_bank_mode=0
[pitot_static]
vertical_speed_time_constant=99
[direction_indicators]
direction_indicator.0=3,0
[brakes]
toe_brakes_scale=0.900000
parking_brake=1
[hydraulic_system]
electric_pumps=0
engine_map=1,1,0,0
normal_pressure=3000.000000
[stall_warning]
type=0
[attitude_indicators]
attitude_indicator.0=1
[turn_indicators]
turn_indicator.0=1,0
[folding_wings]
wing_fold_system_type=4 ;0=None
fold_rates=0.12,0.11 ;Percent per second
[TailHook]
tailhook_length=6 ;(feet)
tailhook_position=-15.0, 0.0, -1.0 ;(feet) longitudinal, lateral, vertical positions from datum
cable_force_adjust=1.0
[exits]
number_of_exits = 2
exit_rate.0 = 0.4 ;Percent per second
exit_rate.1 = 0.4 ;Percent per second
[Radios]
// Radio Type = availiable, standby frequency, has glide slope
Audio.1=1
Com.1=1, 1
Com.2=1, 1
Nav.1=1, 1, 1
Nav.2=1, 1, 0
Adf.1=1
Transponder.1=1
Marker.1=1
[gear_warning_system]
gear_warning_available=0
pct_throttle_limit=0.000000
flap_limit_power=0.000000
flap_limit_idle=0.000000
 
Don't be confused by my post above; I was simply showing an example air file to show where the AoA could be changed. That air file was from my AC520 I think. :)
 
Milton Shupe said:
Don't be confused by my post above; I was simply showing an example air file to show where the AoA could be changed. That air file was from my AC520 I think. :)
Click to expand...


...Thanks for clarifying, Milton. I will be messing around with it and see what i get...as soon as I make (positive) progress, i'm throwing a party and you are all invited!!!!!!!!!
 
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