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VeryBumpy

Catalina X barely flys

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Flying from Alaska airport, day raining, 4 degrees C, 8 knot cross wind. Takes off fine, throttle back to 30inHg and feather prop to 2.3k rpm. Shortly after this dusty bird starts dropping, pitching more elevator or trim doesn't help. Nears stall point. Throttle up the 35inHg, same prop rpm, better but can barely get to 1000feet altitude and that is using mountain ridge lift. Got prop deice on and set carb heaters to about 30 degrees C. Full rich was on the whole time too.

 

This thing was barely flying. I did have 1/2 the cargo bay full (doing an Air Hauler run) but fuel was very little at 300gallons.

 

I did eventually make it to my destination but it was a struggle the whole way avoiding backside of mountains and barely staying above 500ft much of the way. I was tempted to just plop it down in the water, shut it down and restart again.

 

If I throttled up to full throttle the plane would climb ok, not great, and I could fly normally but that would only last a few minutes before the cyl head temp would get too high forcing me to throttle back again.

 

Any idea what was happening? Does this plane get badly affected by wing ice? I did not have that on.

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This is from the Aerosoft product page for the Catalina X:

 

Non standard and far more realistic calculations of engine temperatures, taking cowflap position, ambient air temperature, fuel/air mixtures setting, airspeed and engine heat generation into account.

Accurate electrical load and hydraulic pressures calculations.

Realistic cold engine startup, requiring use of engine primers and fuel boosters.

Realistic auto mixture that controls auto rich and auto lean.

Realistic carburettor icing that takes moisture and carburettor air temperature into account.

Structural icing that will accumulate ice on the structure, adding weight until the aircraft becomes unflyable.

Non standard engine failure module that includes sparkplug fouling, damage caused by excessive cylinder head or oil temperature, shock cooling and more.

Power reduction due to excessive carburettor air temperature.

 

 

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Great simulation of a fantastic aircraft this, but I haven't flown her for ages since she's much too slow. :D

 

Was the Cylinder Head Temperature OK? Did you warm her up properly before you went? Pulled the (enormous) cowl flaps back to decrease drag? Did you at any point chop the power too fast (carburetor icing won't go away even at full throttle)?

 

And I can't remember with these engines, but have you tried leaning the mixture a bit?

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From an original PBY-5a, with P&W 1830-92 Engines,

For Climb at Maximum Continuous Power (60 minutes), 2550RPM, 42 Inches Boost Pressure (From Sea Level to 7,000 feet - Earlier in the manual it states 41.5 from Sea Level to 5,700 Feet, and then 39.5 Inches from 5,700 to 7,500 Feet), Maximum Cylinder Temperature 260 Degrees C., Auto Rich.

 

Once up at cruise speed try Auto Lean Setting (From an original PB4Y-2, P&W 1830-94 Engines Manual),

Cruise Maximum 2250RPM, Mixture Auto Lean, Oil Pressure 65-95 P.S.I., Oil Temp. 60-75 Degrees C., Cowl Flaps Closed, With Blower On Low (Can't remember if this is selectable in FSX) 735BHP 56 U.S. G.p.H., with Blower on High 675BHP 55 U.S. G.p.H., Maximum Cylinder Head temp. 232 Degrees C.

 

For the PBY-5A it's almost identical, P&W 1830-92 Engines, 2170RPM, 33.5/30.5 Inches Boost Pressure.

From Sea Level to 10,000 feet.

 

Bear in mind, that's the Military Rating for climb above.

In the P&W 1830 Engine Operators Hand Book......

The Standard climb is 75% Power, very close to what you had, 2325RPM , 31.5 Inches to 12,000 Feet, Auto Rich, This setting is the next down from the Maximum Continuous Power (Rated Power in the Engine Manual), but does clearly state that Military requirements may be different.

 

Cowl flaps open as required during climb.

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Regarding the heating system, Prop, Wings, Tail,

It essentially says to put it on before you think you will need it,

there is very little else on this in the manuals.

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Well maybe the plane must loosely emulate wing icing while on the ground because it behaved like a lead sink soon as it left the runway. I just wouldn't think the wing should ice up in 4 degrees C on the ground. Or maybe the ice built up REALLY fast once airborne.

 

I'll have to play and try to recreate the same situation.

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Not sure if this helps but I had some trouble with the Catalina when i first tried it. I scratched my head a few times and read the manual and saw that this aircraft don't need manual mixture use.

So I figured It could be some spikes in my mixture throttle that caused the weird behavior so I disabled mixture in FSX settings and set all controls via FSUIPC and made sure this aircraft don't have any mixture axes assigned. It fixed all my issues..

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Bah, happened again. Started raining mid distance of my flight and the plane lost a lot of power and behaved like it was vastly over weight. I ended up overheating the RH engine and had to put it down in the water. I immediately put all anti ice switches on this time soon as the rain started. Carb anti-ice was definitely working since the motors cleared up and came back to life; they were choking down fast as I didn't set the temp high enough initially.

 

But just could not maintain altitude with normal throttle amounts, the seeming added on ice weight brought me down, down, down.

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When flying the Catalina it's imperative to understand that its carburetor heat isn't a simple On/Off system as in most aircraft. And, as opposed to what is written in the manual, it's advisable to use it all the time, because flying the aircraft by the book might not work, depending on the conditions.

 

The carb heat switches are three position switches:

 

Up = raise temperature

Down = lower temperature

Center = maintain current temperature.

 

You need to maintain the correct carb temperature with these switches at all times.

 

Ideally you need to keep the carb temperature between 32° and 38°. If it falls below that value you can lose power due to carb icing, but if the temperature increases well beyond 38° you will lose power as well, because of the lower oxygen content in hot air.

 

It's a continuous balancing act that can be a bit tricky during take-offs and landings, because the carb temperature increases quickly when opening up the throttle, which consequently can cause a power loss during take-off if it gets too hot. Likewise, when you close the throttle in preperation for the landing the carb temperature might fall below the critical limit and cause carb icing, also causing power loss.

 

So, long story short: always keep an eye on the carb temperature whenever you make power changes, and adjust the carb heat accordingly. Whenever the carb temp is in the correct range, center the switches to maintain it. It's a tricky bird, but very rewarding once you master it.

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