Simviation Forum - Project Opensky B767-300

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Project Opensky B767-300 (Read 186 times)

Mar 23^rd, 2004 at 8:55am

Poseidon Offline
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Has anyone flown the B767-300 of Project Opensky? I takeoff and start my climb at 1800 FPM, The airplane accelerates well and maintains speed up to about 20000 (0.7 mach) and then starts losing airspeed even if I reduce the climb rate to 1400 or even 1200. As a result it stalls before FL350 which I believe should not be a problem for this airplane. No need to say that spoilers, flaps, landing gear are clean. Has anyone experienced the same problem?

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Reply #1 - Mar 23^rd, 2004 at 8:58am

ozzy72 Offline
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It sounds like you're maintaining to high an angle of attack. Try lowering the nose a tad, and you should gradually float up to the required flight level Wink

Ozzy

There are two types of aeroplane, Spitfires and everything else that wishes it was a Spitfire!

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Reply #2 - Mar 24^th, 2004 at 3:33am

Poseidon Offline
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I tend to believe FL370 may be too much for 767. I tried again and made it to FL350 with 8 degrees angle of attack and 1000-1200 FPM. I reached FL350 just above the stall airspeed and then the cruising (level) had to be continued with a 3-4 degrees nose up.

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Reply #3 - Mar 24^th, 2004 at 4:49am

microlight Offline
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May be a dynamics issue - I'll have a look.

BAe ATP for FS9 now available! www.enigmasim.com

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Reply #4 - Mar 24^th, 2004 at 7:16am

Nexus Offline
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FL370 is not too much for a 767.
Heck, some years ago I was onboard a 767 that cruized at FL390

I know you're very knowledgable about the 737, but the 767 is a different cookie. On longer routes, you'll often use step climbs. Because of the high TOW, the aircraft is not capable of cruising at maybe FL370. So wait some hours until you've burned some fuel, and then climb to your desired cruise level.

Last night, I made a flight between Montreal and Paris. My final cruise level was FL370, but I had to maintain FL310 for some hours before I could further climb to 370.
Firstly, I was of course too heavy for a direct climb to FL370, and even if I did reach that altitude, the engines would not be enough to maintain an economical speed.
A deck angle at 3-4 degrees is not abnormal, infact I can assure you that a 767 never cruises with a 0 degree pitch. However, as the flight progresses the upward pitch will be reduced, but it will not be 0

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Reply #5 - Mar 24^th, 2004 at 7:34am

Poseidon Offline
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Ok, that makes sence now. Thanks Nexus.

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Reply #6 - Mar 24^th, 2004 at 11:46pm

Selbio Offline
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I have experienced the same problem. But I realized that I was taking off with the fuel tanks at 100% capacity. You actually need the amount of fuel required for the flight + some for holding time and all that.
What I do before I start the flight is use the MS flight planner to see how much fuel I would need for the flight, then I'd add around 2000 gallons(add them evenly) and I would have enough to take off and ascend without any loss of speed and to be able to land without a lot of weight.
After I did this I noticed that the plane flew much better. I have also noticed that using the PIC panel wil cause the aircraft to lose power on take off. However; there is a merge for Posky and PIC 767 that you can use that eliminates all these problems.

Best Regards,&&Selby&&

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Reply #7 - Mar 25^th, 2004 at 5:24pm

microlight Offline
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BA take 767s to places like Phoenix AZ from Heathrow, so they must be capable of taking off with a full fuel load! I think that the .cfg file for the Posky 767 overdoes the drag element, making it almost impossible to reach cruise speed (at FL310, I've managed to get to M0.72 with the default Posky settings) instead of M0.83-ish. If you cut and paste this into the .cfg file, replacing what's there (back up the original first!):

[flight_tuning]
cruise_lift_scalar    = 1.00
parasite_drag_scalar = 1.00
induced_drag_scalar = 1.00
elevator_effectiveness = 1.00
aileron_effectiveness = 1.00
rudder_effectiveness = 1.20
pitch_stability    = 1.20
roll_stability    = 1.00
yaw_stability    = 1.00
elevator_trim_effectiveness = 1.0
aileron_trim_effectiveness = 1.0
rudder_trim_effectiveness = 1.0

and then add this as a new section:

[jet_engine]
thrust_scalar=1.05

This should make it behave a little better. You will still need to burn off fuel at FL310 as otherwise the nose gets too high, and once the fuel level is down, you can climb and get a more reasonable attitude.

BAe ATP for FS9 now available! www.enigmasim.com

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