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Airfile Adjustment Questions

L

Lionheart

SOH-CM-2014
Hey guys,

Being that things are slow in other forums and alot of developers hang out here, I thought I would ask a couple of questions, if I could, concerning airfile and config file tuning.

Question 1: What department will cause the tail wheel (tail dragger) to raise sooner or later (slower speeds or at higher speeds)? I have a plane I am making that raises its tail up a bit soon. I would like to raise the speed at which this occurs and cannot seem to find the tune that does this.

Question 2: I cannot seem to find the tune that causes 'climb/descent' to occur during a banking turn. For instance, my present project does not lose any altitude when banking. The wings are thin and narrow, so it 'should' lose altitude in a steep 45 degree bank. What might effect this? I tried perhaps 10 sections in the AIR file today trying to get this to 'effect' properly, but nothing seemed to work.

oops.. one last question...

Question 3: I changed out a different aircraft AIR file template from a 'set' (different plane, Cessna config with a Lockheed Vega AIR file). I suddenly had issues with the engine stalling at idle and not being able to restart. Before, with a pair of Cessna files, the engine was fine, but the Vega AIR file seems to cause this anomolly. Any ideas? I tried increasing idle to .10 but that didnt work..

Many thanks for any input on these. Sorry for all the questions...


Bill
 
Speaking about q.1: does it have fixed pitch prop or constant speed prop ? I am asking because you could increase prop pitch value a bit and this should slower the take off a little bit. It is the combination of prop pitch, take off/landing speed, mass, drag and few more. The position of the CoG can also affect the plane (if the plane is nose heavy on neutral trim).

Lucas
 
Hey Lucas,

Roger that. Actually, accelleration and speeds are perfect and right on the numbers. The lifting of the tail a bit early is the only odd thing.


Bill
 
Bill:

Early tail lifting is not usually an issue. Several things affect this, COG vrs the wheel longitudinal position, verticle location of the COG, Airfile pich moment from thrust (under pitch in Primary aerodynamics) , angle of incidence of the horizontal stab and (most importantly) the max CL of the wing. The visual aspect of this can also be affected by the contact point configuration of the tailwheel. Most planes that I have seen that have such an issue have a very high CL max and a slow takeoff/landing speed.

Good Luck: T.
 
Thanks Fliger,


I'll give CL and GG a try and see if that helps. Since its a fast bird, perhaps Steve moved the CG forward for better flight handling.

Many thanks for the advice.



Bill
 
I am still getting an engine stall at idle.

I just cant figure this out...

I tried raising the fuel flow to 2.0, the output to 1.2 (originally at .092), etc. The engine runs fine if I keep the idle up. But if it idles for 10 seconds, it dies.

Here is the data if anyone is curious.


(I couldnt find anything related in the air file. This is a Cessna 182 config coupled with the Lockheed Vega 'air' file).





[GeneralEngineData]
//0=Piston, 1=Jet, 2=None, 3=Helo-Turbine, 4=Rocket, 5=Turboprop
engine_type = 0
fuel_flow_scalar = 0.6
min_throttle_limit = 0.15
engine.0 = -0.06, -0.03, 0,


[piston_engine]
power_scalar = 1.0 //Piston power scalar
cylinder_displacement= 90.3 //Cubic inches per cylinder
compression_ratio= 8.0 //Compression ratio
number_of_cylinders=6 //Number of cylinders
max_rated_rpm= 2850 //Max rated RPM
max_rated_hp= 300 //Max rated HP
fuel_metering_type= 0 //0=Fuel Injected, 1=Gravity Carburetor, 2=Aerobatic Carburetor
cooling_type= 0 //0=Cooling type Air, 1=Cooling type Liquid
normalized_starter_torque= 0.3 //Starter torque factor
turbocharged= 0 //Is it turbocharged? 0=FALSE, 1=TRUE
max_design_mp= 0 //Max design manifold pressure, (inHg)
min_design_mp= 0 //Min design manifold pressure, (inHg)
critical_altitude= 0 //Altitude to which the turbocharger will provide max design manifold pressure (feet)
emergency_boost_type= 0 //0=None, 1=Water Injection, 2=Methanol/Water injection, 3=War Emergency Power
emergency_boost_mp_offset= 0 //Additional manifold pressure supplied by emergency boost
emergency_boost_gain_offset= 0 //Multiplier on manifold pressure due to emergency boost
fuel_air_auto_mixture= 0 //Automixture available? 0=FALSE, 1=TRUE
auto_ignition= 0 //Auto-Ignition available? 0=FALSE, 1=TRUE
max_rpm_mechanical_efficiency_scalar= 1.0 //Scalar on maximum RPM mechanical efficiency
idle_rpm_mechanical_efficiency_scalar= 1.0 //Scalar on idle RPM mechanical efficiency
max_rpm_friction_scalar= 1.0 //Scalar on maximum RPM friction
idle_rpm_friction_scalar= 1.0 //Scalar on idle RPM friction


[propeller]
thrust_scalar = 1.0 //Propeller thrust scalar
propeller_type= 0 //0=Constant Speed, 1=Fixed Pitch
propeller_diameter= 6.2 //Propeller Diameter, (feet)
propeller_blades= 3 //Number of propeller blades
propeller_moi= 5.9 //Propeller moment of inertia
beta_max= 34 //Maximum blade pitch angle for constant speed prop, (degrees)
beta_min= 17 //Minimum blade pitch angle for constant speed prop, (degrees)
min_gov_rpm= 1400 //Miminum governed RPM
prop_tc= 0.1 //Prop time-constant
gear_reduction_ratio= 1.0 //Propeller gear reduction ratio
fixed_pitch_beta= 0 //Fixed pitch angle of fixed pitch prop, (degrees)
low_speed_theory_limit= 80 //Speed at which low speed theory becomes blended in (feet/second)
prop_sync_available= 0 //Prop synchronization available? 0=FALSE, 1=TRUE
prop_deice_available= 0 //Prop de-icing available? 0=FALSE, 1=TRUE
prop_feathering_available= 0 //Prop feathering available? 0=FALSE, 1=TRUE
prop_auto_feathering_available= 0 //Prop auto-feathering available? 0=FALSE, 1=TRUE
min_rpm_for_feather= 0 //Minimum RPM for prop feathering
beta_feather= 0 //Feathering pitch angle (degrees)
power_absorbed_cf= 0 //Coefficient of friction for power absorbed by propeller
defeathering_accumulators_available= 0 //Defeathering accumulators available? 0=FALSE, 1=TRUE
prop_reverse_available= 0 //Prop reverse available? 0=FALSE, 1=TRUE
minimum_on_ground_beta= 0 //Miminum pitch angle on ground, (degrees)
minimum_reverse_beta= 0 //Minimum pitch angle in reverse, (degrees)
 
Bill:

With regards to idle, the 509 table which sets the engine friction vrs RPM will have big effect on the idle (most FS planes idle too fast) and the rate at which the engine spins down. The various versions of FSX seem to impliment this differently, so what works in Accel may not work with SP2. It is even possible to have a prop that turns forward or backwards with the engine shut down! In your case it may be necessary to reduce the idle friction value, paying attention to where the curve croses the origin. For Supercharged engines, increasing the min MP value might help.

Good Luck! Tom
 
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