Aircraft mixture question

[rich12545]

I don't like fooling with the air-gas mix so I leave it on automatic. But there are a couple of planes that seem to ignore this and the engine stops at high altitudes - these are GA. So I'm wondering if there's some place maybe in the cfg (I looked but couldn't find anything) where I can change a y to n or whatever.

 

[Motormouse]

I don't like fooling with the air-gas mix so I leave it on automatic. But there are a couple of planes that seem to ignore this and the engine stops at high altitudes - these are GA. So I'm wondering if there's some place maybe in the cfg (I looked but couldn't find anything) where I can change a y to n or whatever.

Depends on if its' 'turbo' or not; IIRC most non-turbo run out of puff @ 8,000ft-11,000ft due to density altitude changes;
'turbo' charged or supercharged can go higher.

Try changing the .cfg line turbocharged=0 to turbocharged=1
The section below is from default c182.

[piston_engine]
power_scalar = 1.0 //Piston power scalar
cylinder_displacement= 90.3 //Cubic inches per cylinder
compression_ratio= 8.5 //Compression ratio
number_of_cylinders=6 //Number of cylinders
max_rated_rpm= 2400 //Max rated RPM
max_rated_hp= 230 //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


ttfn

Pete

 

[rich12545]

Ach. It was there and I didn't see it until you posted. Fuel Air Auto Mixture. I changed it and now it's fine. Thanks very much.

 

[Sunny9850]

fuel_air_auto_mixture= 0 //Automixture available? 0=FALSE, 1=TRUE

Adding a Turbo will require many other changes to not alter the over all dynamics too much and will still require adjustment of the mixture as you climb.

Turbo is not equal Turbo in any case. Some aircraft are TurboNormalized....and others are TurboCharged.
The first maintains a maximum MAP to a higher altitude but does not give more power at low altitudes than a normally aspirated engine would. The second does just that but then looses some of that additional power as you get higher and higher.

Cheers
Stefan

 

[racartron]

The C-182, usually sporting a Continental O-470-L piston engine, has a service ceiling of 18,000ft. But to get there you do have to "fiddle" with the mixture controls. A small price to pay for the view -- IMHO

 

[srgalahad]

Rich, I agree. It's much easier to use FS' auto-mixture to keep things simple. However, there are a couple of reasons to learn about manual leaning etc. Other than the obvious one of expanding horizons and increased knowledge, manually leaning the mixture can give a significant gain to your range in a decently modeled aircraft if you "fiddle". The optimum F/A mixture is that 0.083 set in FS but managed correctly even real engines can be run leaner under the right conditions.

Since Rich's question about auto mixture has been answered and "service ceiling" has been brought up I thought I'd throw this out for the entertainment/education value...

absolute ceiling n (Engineering / Aeronautics) the maximum height above sea level, usually measured in feet or metres, at which an aircraft can maintain horizontal flight.

service ceiling n (Engineering / Aeronautics) the height above sea level, measured under standard conditions, at which the rate of climb of an aircraft has fallen to a specified amount (most commonly = 100 ft/min)


The two are parameters used for certification, not "normal operating". They are also based on engineering data and a 'factory-fresh' and/or prototype test aircraft, not the 1600 hr beast approaching major overhaul . The normal operating altitude of a non-turbo C182 is 8-12,000 ft. Sure, in FS, you can hack the cfg. file to add turbocharging (thank goodness you aren't simulating the $10-20K cost) but then you'd better remember to add the Oxygen kit and be conscientious about using it abv. 12,500' (or 10K after 30 minutes). The C-182 POH only has performance charts up to 12,000 ft which is a pretty good idea that's what the manufacturer deems 'normal'.
Since time-to-climb shows 20-24 minutes to 12,000' and one can project another 20-24 min for the remaining 6000, I guess one has to ask "Why bother?"

In addition, flight characteristics are affected once you exceed the normal range (somewhat modeled in FS). I only had a real C-182 up to 11,000' ONCE (density alt. was probably 12.5-13K) and was very glad to get back to some thicker air. 15* bank angles were enough to start feeling mushy and the rate of climb starts to deteriorate significantly. In fact the Rate of Climb chart in the POH shows 320-385 fpm at 12K depending on temperature (see ref. below Pg 77.)

More than you ever wanted to know dept.: a full C-182Q Pilot's Operating Handbook in PDF format -- http://axenty.com/resources/PIM/Cessna 182QM (1979).pdf

 

[fliger747]

Some FSX aircraft, not GA types, such as the DC2 require manual mixture adjustment. This replicates the engine, which did not have an auto rich and lean range which new radials often featured. FS calculates the stoichometric ratio, a ratio at which most aircraft engines do not normally operate, the mixture being intentionally rich for cooling, especially at high power settings. Typically one does not gain much range wise by leaning in FS as compared to auto. However we did set the DC2 up such that CHT was tied to teh mixture, such that for takeoff and climb, a rich of peak mixture was very desireable.

Cheers: T

 

[Motormouse]

Turbo is not equal Turbo in any case. Some aircraft are TurboNormalized....and others are TurboCharged.

Cheers
Stefan

Hey I was using common terminology there! Its' been years since I had a fiddle with (RW) GA piston engines.

ttfn

Pete

 

[rich12545]

I plan to add more realism when I get around to it. So far there's been no ambition to do so although I have moved the sliders about halfway and introduced realistic damage. I want to learn about the air/gas mixture and ifr and other stuff. I fly only GA aircraft mostly from small airports. Just found out about VIVA and might join them. Looks nice. My largest aircraft is the DC-3. More typical is the Cessna (172 & 185), Scout, Super Cub and Beaver.

 

[tgibson]

I once circled over the peak of Mt Whitney in a Cessna 150, but it was a very cold day.