Queries on the Constellation

[McDonnell-Douglas]

Currently I have around 200 hours on the Constellation. I have a few queries based on my experience so far.

Cruise Speed – 313mph. When using the Operating Data Power Settings, I am able to achieve the quoted IAS e.g. 173 kts IAS at 76,000 lbs weight, 2,080 RPM and 125 BMEP. What are the official power settings required to achieve the official cruise speed of 313mph? Did Lockheed provide this or was it kept intentionally blank? I usually find it at around 140-145 BMEP.

RPM. In my eternal quest for maximum fuel efficiency I have realised that I can lower the RPM to a certain point without losing speed at a constant BMEP. The aircraft in my experience tends to reach its best cruise and maximum speed at around 2,000-2,100 RPM. As I adjust RPM it actually slows down slightly in level flight. For climbing I tend to lose climb rate as I adjust RPM downwards so I leave it at the recommended setting. Can I confirm what I am doing is logical? I am interested in how the propeller angle of attack influences this and the RPM can someone explain this?

Automatic Pilot. I set the attitude. I set the heading. As the aircraft turns I turn the rudder heading control to match the changing actual heading (continuous operation until heading is established) Is this correct operation?

Flaps. I use landing flaps for landing. Is this correct or can I use approach flaps depending on the weight?
Landing Speed and Flare. In my experience the actual landing speed is closer to 90mph rather than the 100mph stated in the manual, the aircraft tends to float indefinitely at 100mph to 110mph depending on weight. I use the throttle to adjust the sink rate and/or pitch. Is this correct procedure?

Oil Dilution System. I either can’t get it to work or it did work but I was surprised by the oil pressure which was relatively high for one minute. Any ideas what I could be doing wrong? I followed the manual to the letter.

Thank you in advance.

Colin

[flapman]

Here's my attempt to answer some questions.

What are the official power settings required to achieve the official cruise speed of 313mph?

The easy answer is there are none. 313mph is not an "official" number, but a promotional one. The only thing 'official' about it is that it originated from Lockheed's marketing department, who asked the engineering department one day "so how fast can this thing go?"
Max cruise speed (the manual quotes 313mph is achieved at FL200) requires max cruise power (which is an "official" power setting), and reading between the lines we can determine this setting.
Note 1 on the power settings charts instructs us not to exceed 34" MAP or 140psi BMEP in High Blower Cruise, while the constant power cruise chart defines 2300RPM as maximum for cruise. Thus, 34" or 140psi at 2300RPM will be max cruise, and is your best chance to reach 313mph at FL200.
A quick spin on the computer reveals that 313mph is ~271KTAS, which at FL200 gives a KCAS of 198 KIAS which you read on the gauge. 198 is your target airspeed.

Can I confirm what I am doing is logical?

Sounds like the simulation is functioning properly. You have to make choices on appropriate RPM for each phase of flight, and while accepting the compromises which must be made.

Is this correct operation?

Yes, if you're using the rudder knob above the double-barrel compass to control heading. Also remember to periodically disconnect the autopilot and retrim the aircraft (this relieves accumulated forces within the control linkages).

Is this correct procedure?

I have seen no references to normal (non emergency) landings being made at any flap setting other than full down. In addition to charts in the manual, there is a placard on the Captain's instrument panel which specifies the appropriate reference speed (speed over the airport boundary fence) for given weights of the aircraft. Use this information+ your current weight to determine the correct landing speed. You will find it very closely parallels what you have discovered is "best." For the most part, throttle for glidepath and pitch for airspeed.

No idea about Oil Dilution procedures... I never use them.

[Jacques]

Dilution time is determined by temperature:

4 to -12 C requires 4 minutes of dilution
-12 to -29 C requires 6 minutes
-29 and lower requires 9 minutes

Hold dilution switch on for indicated time, stop engine, release switch.

Operate propeller increase and decrease switches several times during the period to ensure prop domes are replenished with diluted oil.

The propellers should be feathered and unfeathered several times towards the end of the dilution period to ensure the feathering lines are flushed with diluted oil.

The last two items were required in the real Connie, I can't say how far A2A went in modeling cold soaked oil. But you might as well complete the entire procedure!

To make this all work, I believe you need to then save the flight as I don't think it carries over if you turn off the computer or change planes and then come back to the Connie. Perhaps someone could confirm this?
Maybe Lewis?

I did do this with the B-17 once while overnighting in Keflavik and it worked perfectly- engines fired right up in sub-zero temps no problem the next night (having loaded the saved flight).


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[McDonnell-Douglas]

Hi Flapman, Jacques.
Thanks for the input.

Is this correct operation?

Yes, if you're using the rudder knob above the double-barrel compass to control heading. Also remember to periodically disconnect the autopilot and retrim the aircraft (this relieves accumulated forces within the control linkages).

Just to be clear, I don't use the rudder knob to control the heading. I use it to control the rudder. I keep it aligned with the changing heading.
I has been my experience that if you use the autopilot rudder control to turn the aircraft you end up with sideslip.

I use the heading knob to set the heading and turn the aircraft. I keep rudder knob aligned with the changing heading to ensure a coordinated turn.

To make this all work, I believe you need to then save the flight as I don't think it carries over if you turn off the computer or change planes and then come back to the Connie. Perhaps someone could confirm this?
Maybe Lewis?
I did do this with the B-17 once while overnighting in Keflavik and it worked perfectly- engines fired right up in sub-zero temps no problem the next night (having loaded the saved flight).

That could explain it. I typically don't save my flight. I just shutdown. I assumed that the effects/outcome of the oil dilution system would be carried over to the next flight as with other aspects of the living aircraft in Accusim.

[flapman]

MD, that does not sound like the procedure I use, or the one described in the manual. What control are you using to initiate heading changes with the autopilot?
The manual describes autopilot operation on page 129.
Step 10 instructs you to use the rudder knob to initiate course changes. Make sure you properly set the 3 "speed control valves" to have the AP use proper proportional aileron and elevator inputs as it seeks to correct heading errors.

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[WB_FlashOver]

I have found that the prescribed oil dilution times are a bit excessive at times. My procedure has been to open cooling flaps in effort to get oil temps as low as possible so fuel is not burnt off while in the process of diluting. Once oil temps are down I turn on dilution switches and watch oil pressures. It may be necessary to increase RPM to 1100 near end of dilution to maintain proper pressure. Cycle props as mentioned and feather.

My experience has been that the diluted engines are persistent without saving flight. However, I do not fly other aircraft much so I was always coming back to the Connie on next flight.

Cheers
Roger

[McDonnell-Douglas]

MD, that does not sound like the procedure I use, or the one described in the manual. What control are you using to initiate heading changes with the autopilot?
The manual describes autopilot operation on page 129.
Step 10 instructs you to use the rudder knob to initiate course changes. Make sure you properly set the 3 "speed control valves" to have the AP use proper proportional aileron and elevator inputs as it seeks to correct heading errors.

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Hi Flapman,
You are absolutely correct. The procedure does indeed instruct you to use the Autopilot Rudder Knob to initiate course changes. Slowly and smoothly. I used to follow the procedure.
However, when I am cruising and initiating turns I find the method too slow to change course particularly when changing VOR radial; as it must be done slowly and smoothly.

If you set the rudder knob more than 20-30 degrees than the current heading it will turn more quickly however it imparts an unacceptable level of sideslip into the turn. Changing the speed control valves appears to have little effect.

I have found that my preferred methodology was to use the Autopilot Aileron control to initiate a left or right turn with the desired bank angle, then as the heading indicator changes I continuously rotate the Autopilot Rudder Knob to match the heading to ensure there is no sideslip. This method ensures an appropriate and timely heading change with no sideslip.
I was asking whether this was either correct procedure or an acceptable alternative. I would highly recommend it, even if it is not to procedure.

I appreciate your input.

Best Regards,
Colin

[McDonnell-Douglas]

I have found that the prescribed oil dilution times are a bit excessive at times. My procedure has been to open cooling flaps in effort to get oil temps as low as possible so fuel is not burnt off while in the process of diluting. Once oil temps are down I turn on dilution switches and watch oil pressures. It may be necessary to increase RPM to 1100 near end of dilution to maintain proper pressure. Cycle props as mentioned and feather.

My experience has been that the diluted engines are persistent without saving flight. However, I do not fly other aircraft much so I was always coming back to the Connie on next flight.

Cheers
Roger

Hi Roger,
Thank you for the input. I will do some Oil Dilution practice sessions and follow your advise. It is possible fuel was getting burnt off instead, I'll keep the cowls open.
I'll double check the oil temps and pressure before I start the process.

I always start Prepar3d with another aircraft switch to the L-049. I remember there being a good reason for this.

Best Regards,
Colin

[WB_FlashOver]

It's been a while since I flew the Connie so I spawned in her (might even fly her this morning ) to check something. I was curious about Auto Cold & Dark. I have AC&D enabled so the dilution seems to be persistent with that enabled too. I also load with stock AC and switch for flight. The plane status is written to the L049log.dat file so in theory the dilution should be persistent no matter what. When the Connie is loaded, so is the .dat file.

I re-read the manual on diluting this morning, yes it has been a while, and see that it says to shut engine down then turn off dilution switch. I must have missed this sentence or just flat out forgot it. I have read somewhere that the procedure is to dilute the oil for the desired time, turn off dilution switch, then run engine for another minute or so while you are cycling the prop and feather functions to make sure oil is fully diluted. This is the method that stuck with me so this is what I have been doing. I've been South to McMurdo Station and North to Alert with the Connie. I've been in -45C temps on startup and only had issues once when I got impatient after landing and just shut things down without diluting.

Sometimes the hardest part is getting the oil cold enough to start the dilution process.

Cheers
Roger