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Post by anderscn on Feb 28, 2010 10:28:39 GMT
Thank you,
for all the thoughts. Well, during my flight home from Newark to Heathrow (on a B777), I could maybe notice a small difference in nose-up pitch between early and the end of the flight. It was however very small, if any.
On my own armchair flight with the DC8-50, I took it up to FL400, pushed the speed up to Mach 0,86 and burned the fuel down to 19%. Still there is some significant nose-up pitch, as the Attitude Indicator also shows a 3% pitch.
So this is probably a part og the DC-8´s aerodynamic design? I havent noticed so much pitch with other similar planes of the era, such as the Convair 990A or the Boeing 707 from this site, or the Vickers VC-10 (from another site) that I also like to fly.
Best Regards, Anders
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Post by Mike Monce - HJG on Feb 28, 2010 13:16:33 GMT
If you think it is a bit nose high, then go into the cfg and up the cruise_lift_scalar by about 10% and see if that helps.
Mike
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Post by christrott on Feb 28, 2010 16:57:50 GMT
Part of the problem is that you're too high. FL400 is above the max operational ceiling for the DC-8. If you brought it down to maybe FL350 or FL370 at the highest, you'd probably see quite a difference in pitch.
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Post by anderscn on Mar 1, 2010 16:58:53 GMT
Thanks both, for the suggestions. I cannot find the Cruise_lift_scalar in the CFG of the DC8-50. Maybe there is still some development work going on for the DC-8 model ? I have flown at both FL310 and FL400 (and even higher). In both cases there is around 3 degrees nose-up. Above FL400, the nose lifted further to 4 degrees. Now, that would be tough for the stewards to pull their waggons along the aisle, I would guess I will try somewhere in between, to see if there is an optimum. Best Regards, Anders
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Post by aerofoto - HJG Admin on Mar 1, 2010 19:39:00 GMT
Mike .... I've just sent you a PM regarding "ANDERCN's" DC8 difficulty ! Mark C AKL/NZ
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Post by Mike Monce - HJG on Mar 2, 2010 18:01:51 GMT
Anders, It appears the DC8's don't have a flight uning section in the cfg's If you want to add one, here's what to put in: [FLIGHT_TUNING] elevator_effectiveness =1.0 aileron_effectiveness =1.0 rudder_effectiveness =1.1 elevator_trim_effectiveness =1.0 aileron_trim_effectiveness =1.0 rudder_trim_effectiveness =1.0 pitch_stability =1.0 roll_stability =1.0 yaw_stability =1.0 cruise_lift_scalar =1.0 parasite_drag_scalar =1.0 induced_drag_scalar =1.0 then you can change the cruise lift scalar. I recommend small increments; say 5%; i.e. 1.05 to begin. Mike
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Post by anderscn on Mar 2, 2010 21:06:42 GMT
Hello Mike, Before I saw your post, I actually thought of copy/paste the Flight Tuning section from the B707 cfg into the DC-8 cfg.. But I did not. In stead I added your suggestion to the DC-8 cfg, and voilá, it levelled the plane up as can be seen in the attached picture. Now the AI shows a pitch of 2 degrees, which I assume is more realistic for the DC-8. I fly at the same altitude FL310 as in the first pic. At FL340 it is the same. However, going up to FL400, pitch goes up again to 4 degrees. And I haven´t even adjusted Cruise_Lift_Scalar yet; in this picture it is still 1.0 Thank you for the help, Anders
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