How to get the right cruise lvl?

[Bazonka]

Hello!
I use the Performance tables for power settings and so on but how do I choose the right cruising level?

I ask because on my last flight I flew an about 600nm trip with about 1000gal of fuel and the heavy preset for pax. I choose FL200 for cruise and used the FSX standard Autopilot, not the sperry. In cruise flight I got this anoying pitching up and down on Alt Hold. It oscilated between 150fpm up and down. But I dont think I was too heavy for FL200? What do you think?

[EnDSchultz]

This is a "feature" of the default FSX autopilot. It will tend to get itself into pitch oscillations on some of the more pitch sensitive airplanes. I notice the same thing on the P-51 when in altitude mode with an aft CG. There might be a file to edit somewhere that will turn down the sensitivity but alas, I don't know what it would be.

[Tomas Linnet]

Did you check the manual for cruise levels? I'm pretty sure the performance charts include weights. I never had that problem, so yes, it could be because you were to heavy for that altitude.

[Paughco]

Try turning off the altitude hold, retrimming the aircraft, getting it spot-on to the correct altitude and pretty much stable "hands off," then switch the ALT back on. Maybe it'll work better. I've successfully done this once or twice.

Seeya
ATB

[flapman]

From the 2008 Propliner Tutorial,

OPERATIONAL CEILING.

The practical definition of operational ceiling when using a simulator is the maximum level to which the aircraft can climb, *using only climb MAP and rpm*, without the Vertical Speed Indicator (VSI) falling below 500 ft/min and without the Indicated Air Speed (IAS) falling below the mandated climb IAS.

And from "B-377 Mini-Tutorial,"

In real life we could inform our captaincy decision with forecasts of cloud and QNH and OAT and ice ahead. We would make a 'predictive' decision. In MSFS we must make a 'reactive' captaincy decision instead. Sooner or later our reactive decision will always be proven wrong by today's weather, but inside MSFS we have no other 'informed choice'.

The A2A Charts can be a little lacking in this department, but it's not that big of a deal. Deciding the current 'Operational Ceiling' is a skill that comes with a little experience, when given the correct information. I use the following segment of the freeware L-049 handling notes.. and find them perfectly acceptable for this payware example.

Climb stage 3: Climb power, high blower (1400 HP)
Note: HIGH supercharger gear not available in BA-1 engines
Plan 4 * 750 = 3000 lbs/hr and climb rate 500 ft/min
[ ] MAP 33" // for 144 BMEP
[ ] 2300 RPM
[ ] Cowl Flaps 20%, max. CHT 230°C
[ ] Mixture AUTO RICH
[ ] Altimeter ABOVE FL 180 set to 29.92 In. Hg.
[ ] Throttles Adjust to 144 BMEP if required
[ ] Maintain IAS=150 kts, If climb rate decays below 500 fpm, level off and begin cruise segment.

I've performed at least one transcontinental USA (JFK-LAX) with the default FSX autopilot, and had no pitch oscillation experiences like you described. Was it coupled with any rolling oscillations, indicating a "Dutch Roll"? Was there turbulence present? What was your IAS and pitch attitude in cruise?
I suspect your were going too slow, because my experience is that FL200 is perfectly achievable with the loading you describe. In fact, I often add extra cargo/bags on top of the "Heavy" preset....

[alan CXA651]

Hi.
On top of what has been said , what was your CG , to far FWD/AFT can cause issues with the auto pilot not being able to trim the aircraft , and as fuel is burned off this CG will change.
regards alan.

[Bazonka]

Wow, I thought I know the connie
CG was not the problem I think, as the load was distributed by the loader itself... I dont know the actual number, but it was in limits for sure.

Maybe I was too slow, I took the performance settings from the charts in the manual - they was 2080 RPM and 125 BMEP.
Unfortunately I dont remember the exact speed indicated or the wind at the time. Also Man Press... I quited the flight as it was annoying and I was unable to solve it. But I know there was no turbulence.

[alan CXA651]

Hi.
Had you had turbulance , then you would hear a lot of airframe rattling in the VC as well as the shakeing , plus the oscillations on your VSI and airspeed indicators , if you had none of these happening , then you had no turbulance.
regards alan.

[Bazonka]

Over on this site -
https://docs.microsoft.com/en-us/previo ... ocId942782

I found this part about the autopilot pitch mode:

default_pitch_mode This determines the default pitch mode when the autopilot logic is turned on.
0 = None
1 = Pitch Hold (current pitch angle)
2 = Altitude Hold (current altitude)
If no value is set, Pitch Hold will be the default.

I think I will look at this figures and trie if it works better with pitch hold.

[alan CXA651]

Hi.
The link you posted does not work , and i would strongly recommend that you do not mess with this part of the aircraft.cfg file , the only parts of the aircraft.cfg file that you can alter , is adding new paints , and if like me you have trackIR5 , and find the views in the aircraft are not correct for you , then try modifying these , but unless you know what you are doing in the .cfg file , you can seriously damage the flyability of the aircraft , the problem you have discribed is pilot error , due to not knowing the aircraft fully , please get to know this aircraft better , A2A go to great lengths to get the aircraft they produce to be as real as they can within the sim constraints.
regards alan.

[Bazonka]

Hi.
The link you posted does not work , and i would strongly recommend that you do not mess with this part of the aircraft.cfg file , the only parts of the aircraft.cfg file that you can alter , is adding new paints , and if like me you have trackIR5 , and find the views in the aircraft are not correct for you , then try modifying these , but unless you know what you are doing in the .cfg file , you can seriously damage the flyability of the aircraft , the problem you have discribed is pilot error , due to not knowing the aircraft fully , please get to know this aircraft better , A2A go to great lengths to get the aircraft they produce to be as real as they can within the sim constraints.
regards alan.

I know what you mean, but as I use the default Autopilot and not the sperry it is "semi realistic" I would say I thought maybe the issue is about this "cheat" that the default AP is not handling the realistic A2A flightmodel well enough.

It is hard to say what the error finaly was... I dont think I was too heavy, as I had not much fuel. CG I could not say, as I cant enter the 2D popup in flight. I dont think I was too slow, as I had set the power regarding the power tables for the altitude. There was no turbulence, I had not the typical signs of turb inside the cockpit and my active sky is relatively calm set for this.