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pellebus

taxi speed in turboprop to fast!

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I have the AFG Beech 300, and still, even how I try, the plane keeps "running" down the taxiway even when I have all the levers in the right configuration for taxi.So, my question is... could I go and do some fixing/tweeking in the cfg to slow the plane down a bit during taxi?And if thats the case, were do I change the cfg parameters?RegardsP.

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Guest belga1

Hello,

This topic is very interesting technically and show some knowledge how real aircrafts throttles and engines interact .. but in no way it will be a answer to the OP question.I never go deep in the prob .. but I think it can be solved by some modifications in the Aircraft.cfg and maybe more importantly in the air file.You can also try to use a addon gauge like the taxi speed one .. but the results are not perfects as alway the plane during taxi try to accelerate (on iddle) and the gauge try to slow down him to respect the taxi speed set.The result is a non stop visible dow-up movement of the nose due to damping.Regards.bye.gifGus.

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Here are some ways keep a turboprop aircraft slow for ground taxiing when the idle condition lever is set to ground idle and it is still too fast.Taxi with one engine running (the one supplying any needed system hydraulics, bleed air, and/or generator power). At the low power needed for taxi speed asymmetric thrust should not be a problem. If you need auxiliary system services from both engines running see if you can feather one engine prop.Run the prop rpm levers at the bottom. That puts quite a load on the engine and in real world conditions is not done. It's kind of like trying to go from a stopped stick shift vehicle in third gear.As a diagnostic check pop up the throttle quad window and insure the thrust levers bottom when you controller lever, wheel, etc., is at bottom. Hit the throttle idle button (F1 default) and if any levers drop visually then you need to use the Gaming Options applet to calibrate your throttle control.


Ron Ginsberg
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Guest napamule

It's not like 'real', but since most turbo props have 'some' reverse thrust ('min_throttle_limit = -0.25' in GeneralEngine section of config), doing the equivalent of 4 or 5 taps of F2 enables you to slow down the taxi speed. If you can see how much reverse thrust you are using you will find that -0.07 should be sufficient. At -0.25 you will (maybe) move in reverse from a stop. I use a USB keypad for throttle control, and have panel with digital read out, which makes it easier to 'gauge' how much rev thrust I am using. I also find that some rev thrust will help set up a sharp (90 degree+) turn, or even a doughnut, without using braking. Hitting F1 allows me to then 'resume' normal engine rpm to finish turn, or continue taxi. My 2 cents.Chuck BNapamule

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Guest belga1

Hello,I have the best result with this modification in the aircraft.cfg of the AFG Kingair:[propeller]thrust_scalar = 1propeller_type = 0propeller_diameter = 8.75propeller_blades = 4propeller_moi = 25.6beta_max = 65beta_min = 18min_gov_rpm = 17958 //22447.5prop_tc = 0.01gear_reduction_ratio = 17.6056338fixed_pitch_beta = 25low_speed_theory_limit = 80prop_sync_available = 1prop_deice_available = 1prop_feathering_available = 1prop_auto_feathering_available = 1min_rpm_for_feather = 700beta_feather = 79.5power_absorbed_cf = 0.9defeathering_accumulators_available = 1prop_reverse_available = 1minimum_on_ground_beta =2 //10 //5 //1minimum_reverse_beta = -14rotation = 1, 1With this it's possible to manage a very slow taxi speed when you move very slightly forward the throttles.Regards.bye.gifGus.

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Guest napamule

Here is what I use with Milton Shupe's Dash7 (Army RC-7B ). Just for compare. Dummy down for taxi=performance hit while in the air-no way around that.[GeneralEngineData]engine_type=5 //0=Piston, 1=Jet, 2=None, 3=Helo-Turbine, 4=Rocket, 5=TurbopropEngine.0=0.0, -24.5, 0.500 //(ft) long, lat, vert dist from ref datumEngine.1=0.0, -12.5, 0.000Engine.2=0.0, 12.5, 0.000Engine.3=0.0, 24.5, 0.500fuel_flow_scalar=1.000 //Scalar for fuel flow efficiencymin_throttle_limit=-0.499939//[TurbineEngineData]fuel_flow_gain=0.011 //Gain on fuel flow //try .014 instead of .011 inlet_area=1.000 //Sq Ft, engine nacelle inlet arearated_N2_rpm=29920.000 //RPM, second stage compressor rated valuestatic_thrust=158.000 //Lbs //affects taxi speed?afterburner_available=0reverser_available=1//[turboprop_engine]power_scalar=1.0 //Scalar on Turboprop powermaximum_torque=4860.000 //max take-off rating is 4860 ft-lb at 1210 RPM//[propeller]thrust_scalar=1.0 //Propeller thrust scalarpropeller_type=0propeller_diameter=11.300propeller_blades=4propeller_moi=55.000beta_max=38.200beta_min=11.800min_gov_rpm=25520.000prop_tc=0.011 gear_reduction_ratio=22.787fixed_pitch_beta=0.000low_speed_theory_limit=80.000prop_sync_available=0prop_deice_available=0prop_feathering_available=1prop_auto_feathering_available=0min_rpm_for_feather=700.000beta_feather=83.200power_absorbed_cf=0.900defeathering_accumulators_available=0prop_reverse_available=1minimum_on_ground_beta=4.200 //o=8.300 //****NOT SURE***minimum_reverse_beta=-13.50Chuck BNapamule

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Guest belga1

Hello,

static_thrust=158.000 //Lbs //affects taxi speed?
I don't think so.By the Microsoft book:static_thrustMaximum rated static thrust at sea level (lbs).Regards.bye.gifGus.

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Guest napamule

You don't 'THINK SO'? Then change it to 1580 and see what happens, so you will KNOW what it CAN do to your taxi speed (and to your air speed). Simple as that. Nevermind that Microsoft MIGHT have said that 'it's nothing'. It's something. Of course you may need to enter the same value in the air file.Chuck BNapamule

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Guest over and out

Try just pressing F1. I have found that for some reason some planes dont reduce to full idle on their own and pressing F1 can sometimes fix it.

I have the AFG Beech 300, and still, even how I try, the plane keeps "running" down the taxiway even when I have all the levers in the right configuration for taxi.So, my question is... could I go and do some fixing/tweeking in the cfg to slow the plane down a bit during taxi?And if thats the case, were do I change the cfg parameters?RegardsP.

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Guest belga1

Hello,

(and to your air speed).
Indeed .. and that's the problem The problem to solve is to slow down the "Taxi speed" not the "Taxi speed" and the "Air speed" I have very good result with the modification of the propeller ground beta number (pitch angle of the blades)Regards.bye.gifGus.

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Guest belga1

Hello,

Didn't sim1.dll have something to do with taxi speed?
This library affect the ground friction.Indeed this can be useNevertheless this will affect the brakes efficiency (of all your planes) if you modify this DLL IMHOsome discussions:http://www.airsimmer.com/support/index.php?showtopic=3690http://www.simforums.com/forums/forum_post...=12079&PN=1Another one:http://www.leveldsim.com/forums/forum_post...7&PID=48355Regards.bye.gifGus.

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and you can also buy the Majestic Software Dash 8 or the Aeroworks B200,both seem to replicate turboprop operation very well,with the Dash 8 taking #1 if only for the sound.Off to fly some,cheersJP.


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Guest napamule

Press and hold F2 for a couple of seconds. (Or tap 4 or 5 times). (Is this a HUGE modification? What part of 'it's already there' do you not understand?)min_throttle_limit = -0.25; //Minimum percent throttle //(GET IT? THROTTLE, not pitch or N1 or N2 rpm, bla, bla, bla). Too easy?)I taxi 12 kts. I did not do any mods. I rest my case.Chuck BNapamulePS: if your t-prop does not have the '-0.25' value (ie: it's '0.00') then just enter it and save cfg. Done. No need to re-write SDK. No need to read manuals (for real planes?) or go hunting around internet, google, or read suspect advice on forums. It's THERE already. Cheesh.

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