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trimanted

C172 G1000 Unrealistic Flight Performance

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I’m using Carenado’s C172 with the G1000 glass cockpit and Prepar3d v4.2. 

I fly this plane in real life, so I know what the performance is supposed to be like according to the Vref numbers.  The Carenado version isn’t close, so there must be something wrong.

Im not talking about computer frame rates, but aircraft performance.  It seems better on the ground than airborne.  The takeoff roll is accurate and reaches Vr (55kts) easily. I rotate and shoot for Vy (75kts), but I don’t get anywhere near that speed or angle. I’m lucky to get 60kts and climb 100fpm. It never gets better until I’m high enough to decend and finally get some airspeed  

To eliminate software/hardware issues, I few A2A’s C172 and Carenado’s Barron G1000 in the same flight scenario by simply changing ‘vehicles’ in flight. The other planes perform as expected. 

Im hoping someone has had a similar problem and can offer some advice 

Thanks in advance. 

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I have Carenado planes they are great looking but can be unrealistic to real life performance as you already know.
You might try to change the values in the Aircraft configuration file under the following headings to the more realistic ones which I copied from the RealAir 172 I fly it with passenger weight and it always performs well in climbs.

[piston_engine]
power_scalar = 1.063    

[propeller]
thrust_scalar = 1.2 

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6 hours ago, trimanted said:

The takeoff roll is accurate and reaches Vr (55kts) easily. I rotate and shoot for Vy (75kts), but I don’t get anywhere near that speed or angle. I’m lucky to get 60kts and climb 100fpm. It never gets better until I’m high enough to decend and finally get some airspeed  

This doesn't make sense if you can normally accelerate to 55kts and suddenly acceleration stops at 60kts.

Just tested at ISA, S.L. with 50% fuel, one pilot on board and I get just a tad over 1000ft/min at 75kts. RPM is 2500. Static RPM is 2400. 

Takeoff roll was less than 900ft.

If you are not testing at S.L.Did you lean? Since the leaning simulation is totally wrong in FSX/P3D you need to lean as soon as you are 500ft above S.L.

@pcmill,  randomly mixing FDEs isn't a good idea.

edit: out of curiosity I've tried the 'modified' FDE and ROC increases from 1000ft/min to 1100ft/min, so this will definitely not solve the 100ft/min ROC problem. 

 

Edited by FDEdev

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Here is what I have done to my 172n and it works very realistic now and is fun to fly there is no autopilot so I test and fly it manually to it' ceiling here is how.

The following tips for the Carenado 172n which I have. I use fs9 but it is a Carenado plane . above 5 ,000 ft it starts to lag and se climb ability so I changed the Thrust Scalar value to 1.2 instead of 0.83 probably 1.0 would improve this rate of climb but I haven't tested that.

Of course altitude, temp and air density would change the rate of climb as well.

[piston_engine]

power_scalar = 1.063 //Piston power scalar I changed this value from 1.0

cylinder_displacement= 88.0 //Cubic inches per cylinder

compression_ratio= 8.5 //Compression ratio

number_of_cylinders=4 //Number of cylinders

max_rated_rpm= 2650

[propeller]

thrust_scalar = 1.2 //0.81 //Propeller thrust scalar is the value I changed

propeller_type= 1 //0=Constant Speed, 1=Fixed Pitch

propeller_diameter= 6.3 //Propeller Diameter, (feet)

propeller_blades= 2 //Number of propeller blades

propeller_moi= 5.5 //Propeller moment of inertia

beta_max= 0 //Maximum blade pitch angle for constant speed prop, (degrees)

beta_min= 0

ETC.

After this I changed yaw_stability = 1.0" to 3.0 resolves the problem of needing to constantly correct rolling to the left or right. This is found in the flight Tuning section.

[flight_tuning]

cruise_lift_scalar = 1.0

parasite_drag_scalar = 1.0

induced_drag_scalar = 1.2

elevator_effectiveness = 1.0

aileron_effectiveness = 1.0

rudder_effectiveness = 0.8

pitch_stability = 1.0

roll_stability = 1.3

yaw_stability = 3.0 //1.0 I changed this value to 3.0

elevator_trim_effectiveness = 1.8

aileron_trim_effectiveness = 1.0

rudder_trim_effectiveness = 1.0

I got these tips from https://www.braybaroque.ie/cloudy/cloudy_tips/tips.htm

It applied to the Carenado 150 but I used it on my 172n. Above 3000ft I ajust the mix to about 75%- 42% you can play with it but I leave it at that. Also ajust your trim to keep climb rate around 5 to 700 ft per min.

With the above setting changes at 13,000 I am slowed to 80kts and a climb rate dropping because I am reaching the airplanes ceiling. I find this realistic compared to default values.

What I changed was only 3 values.

1. Under fine tuning

yaw_stability = 3.0 //1.0 I changed this value to 3.0 =no more wild roll

2. Under propeller

thrust_scalar = 1.2 //0.81 //Propeller thrust scalar is the value I changed was 0.81

3. Under Piston Engine

power_scalar = 1.063 // was 1.0

 

 

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Ooops. You can't do that!  The C172N has an almost 10 year old FDE, it has been designed by a different FDE designer and is heavily based on the default 172.

The C172S has been only released a year ago and has a completely new FDE by a different designer. Easy to recognize because it e.g. slips and spins.

Furthermore the FDE consists of the air and the aircraft.cfg file. You definitely shouldn't make changes to the cfg file which has been designed for a different air file, since the outcome of this hybrid FDE will be completely different.  

Concerning yaw stability in your above example; You have increased the yaw stability by 300% because this stopped the wild roll but by doing this, you have most likely significantly removed the ability to yaw the airplane (and to e.g. slip and do crosswind landings).

The rolling moment is being  caused by the yaw and to 'fix' that, you need to edit the airfile since nothing in the aircraft.cfg file can do this….without seriously affecting other important FDE items.  

 

Edited by FDEdev
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