beroun Posted November 13, 2022 Share Posted November 13, 2022 Hi, curious why most of the TDS Boeings have CG way forward (see picture). This seems to cause unnatural down pitch after take off during climb. I did some tweeks in aircraft GFGs to alter this but only marginally. Actualy when I moved back static pitch in contact points too much, the aircraft fell on its tail. But somehow I believe that TDS have a reson for this since most of their Boeings look like this? Just curious if any clues. Peter Bendl ex. British Airways Link to comment Share on other sites More sharing options...
johnhinson Posted November 15, 2022 Share Posted November 15, 2022 The static_pitch= setting in the [CONTACT_POINTS] section relates to how the aircraft sits on the ground. It won't affect in-air performance. The place you need to start to move the COG is in the [WEIGHT_AND_BALANCE] section but you will almost certainly have to fiddle with a lot of settings elsewhere too. It isn't a five-minute job, and I would recommend much reading up on the subject before spending hours tearing your hair out. John http://www.adventure-unlimited.org My co-pilot's name is Sid and he's a star! Link to comment Share on other sites More sharing options...
ViperPilot2 Posted November 15, 2022 Share Posted November 15, 2022 Question... is the case with all of TDS' offerings? Sounds like major tweaking of the FDE, and it's hard to tell if any of the FDE tweaks in the File Library addresses this issue. "I created the Little Black Book to keep myself from getting killed..." -- Captain Elrey Borge Jeppesen AMD 1.9GB/8GB RAM/AMD VISION 1GB GPU/500 GB HDD/WIN 7 PRO 64/FS9 CFS CFS2 Link to comment Share on other sites More sharing options...
beroun Posted November 15, 2022 Author Share Posted November 15, 2022 Thanks Gents, I can get by, by setting the trim to offset CG, also loading the back, so that the take-offs are reasonable. Descent and landing is a different story and usually have to adjust the pitch scalar in flaps settings to offset this, but all is just not realistic. As opposed to many of my other aircraft perfectly in balance. Therefore I am trying to avoid TDS and raised this post just as a curiosity to see what others think. Peter Bendl ex. British Airways Link to comment Share on other sites More sharing options...
johnhinson Posted November 16, 2022 Share Posted November 16, 2022 Have you considered using a comparable Boeing's flight dynamics for the aircraft you are having issues with? John http://www.adventure-unlimited.org My co-pilot's name is Sid and he's a star! Link to comment Share on other sites More sharing options...
ViperPilot2 Posted November 16, 2022 Share Posted November 16, 2022 It just might be time to make some Space in the FS9 aircraft Folder, and move some TDS heavy Iron to the Boneyard. That'll free up a couple gigs of Storage! "I created the Little Black Book to keep myself from getting killed..." -- Captain Elrey Borge Jeppesen AMD 1.9GB/8GB RAM/AMD VISION 1GB GPU/500 GB HDD/WIN 7 PRO 64/FS9 CFS CFS2 Link to comment Share on other sites More sharing options...
GKKnupper Posted November 20, 2022 Share Posted November 20, 2022 Hi, [ATTACH=CONFIG]231696[/ATTACH] curious why most of the TDS Boeings have CG way forward (see picture). This seems to cause unnatural down pitch after take off during climb. I did some tweeks in aircraft GFGs to alter this but only marginally. Actualy when I moved back static pitch in contact points too much, the aircraft fell on its tail. But somehow I believe that TDS have a reson for this since most of their Boeings look like this? Just curious if any clues. @Peter Bendl Please see the line : wing_sweep [airplane_geometry] wing_area = 1341 wing_span = 117.5 wing_root_chord = 25.8 wing_dihedral = 6.2 wing_incidence = 1 wing_twist = -0.5 oswald_efficiency_factor = 0.68 wing_winglets_flag = 1 wing_sweep = 0 //25 !!! The CG Forward has to do with the Wing Sweep ... It must be OFFSET accordingly , NOTHING else wing_pos_apex_lon = 15.0 wing_pos_apex_vert = 0 Sincerely G.Kirschstein Link to comment Share on other sites More sharing options...
GKKnupper Posted November 20, 2022 Share Posted November 20, 2022 @ViperPilot2 Please see the line : wing_sweep [airplane_geometry] wing_area = 1341 wing_span = 117.5 wing_root_chord = 25.8 wing_dihedral = 6.2 wing_incidence = 1 wing_twist = -0.5 oswald_efficiency_factor = 0.68 wing_winglets_flag = 1 wing_sweep = 0 //25 !!! The CG Forward has to do with the Wing Sweep ... It must be OFFSET accordingly , NOTHING else wing_pos_apex_lon = 15.0 wing_pos_apex_vert = 0 The TDS planes are excetionally WELL designed !! Your comment: "and move some TDS heavy Iron to the Boneyard." is NOT deserved for this very good designer. Sincerely G.Kirschstein Link to comment Share on other sites More sharing options...
GKKnupper Posted November 20, 2022 Share Posted November 20, 2022 Hi, [ATTACH=CONFIG]231696[/ATTACH] curious why most of the TDS Boeings have CG way forward (see picture). This seems to cause unnatural down pitch after take off during climb. I did some tweeks in aircraft GFGs to alter this but only marginally. Actualy when I moved back static pitch in contact points too much, the aircraft fell on its tail. But somehow I believe that TDS have a reson for this since most of their Boeings look like this? Just curious if any clues. @ Peter Bendl Dear Sir, please see line "wing_sweep" [airplane_geometry] wing_area = 1341 wing_span = 117.5 wing_root_chord = 25.8 wing_dihedral = 6.2 wing_incidence = 1 wing_twist = -0.5 oswald_efficiency_factor = 0.68 wing_winglets_flag = 1 wing_sweep = 0 //25 wing_pos_apex_lon = 15.0 wing_pos_apex_vert = 0 The "Problem" has to do with the WING Sweep and must be corrected accordingly and NOTHING else. NO fussing with the CG , Contact Points .... in the CFG- or even ANYTHING in the AIR-file. Sincerely G. Kirschstein Link to comment Share on other sites More sharing options...
GKKnupper Posted November 20, 2022 Share Posted November 20, 2022 Hi, [ATTACH=CONFIG]231696[/ATTACH] curious why most of the TDS Boeings have CG way forward (see picture). This seems to cause unnatural down pitch after take off during climb. I did some tweeks in aircraft GFGs to alter this but only marginally. Actualy when I moved back static pitch in contact points too much, the aircraft fell on its tail. But somehow I believe that TDS have a reson for this since most of their Boeings look like this? Just curious if any clues. @ Peter Bendl Dear Sir, please see line "wing_sweep" [airplane_geometry] wing_area = 1341 wing_span = 117.5 wing_root_chord = 25.8 wing_dihedral = 6.2 wing_incidence = 1 wing_twist = -0.5 oswald_efficiency_factor = 0.68 wing_winglets_flag = 1 wing_sweep = 0 //25 wing_pos_apex_lon = 15.0 wing_pos_apex_vert = 0 The "Problem" has to do with the WING Sweep and must be corrected accordingly and NOTHING else. NO fussing with the CG , Contact Points .... in the CFG- or even ANYTHING in the AIR-file. Sincerely G. Kirschstein Link to comment Share on other sites More sharing options...
mikeandpatty Posted November 20, 2022 Share Posted November 20, 2022 (edited) The diagram for loading can be misleading - it is relative to the reference_datum_position, which must be taken into consideration. All the various loading, contact points and other measurements are relative to it, and does NOT have to represent a real life cg position. I usually modify my fore/aft loads to a point slightly forward of the reference datum, make them all the same and see how it goes. Try starting out at the empty weight cg longitudinal position. That way you just increment that one longitudinal value (same for all load positions) for further improvement. I look for good flying qualities, not particularly interested in loading up 250 seats etc. in a real life scenario. I typically just combine everything in about 3 to 5 positions: crew (pilots/ cabin) 1st class pax total coach pax total baggage split fore /aft if applicable cargo as desired I use 170 lbs per pax, 40 lbs baggage each; 250 lbs total per pilot, 200 lbs total per flight attendant. Others use 175 /55 etc. As an example, a 5 person crew of 2 pilots / 3 cabin crew would be 500 +600 = 1100 lbs for my station.0 = 1100, x, y, z , crew (2+3). Anyway, whatever. You can use the same technique with fuel tanks if you care to. It is very easy to vary your loading when starting out - your setup will be default, but changing your loading values is quick and easy in the fuel/payload screen using your assumed weight values for pax, baggage, crew. Regarding flap pitch - too often the designer just uses the default value of 1, which is lazy or an oversight because some pitching moments are absurd. I flew for the Navy for over 20 years, including test pilot school and have an FAA ATP - never saw anything like some of the flap pitch up changes I.ve seen in some FltSim models. In fact, some military and civil aircraft have a minor nose down pitch tendency. Admittedly, there are some designs that have had a flap / elevator interconnect scheme to counter a nose up pitch. Edited November 20, 2022 by mikeandpatty Link to comment Share on other sites More sharing options...
beroun Posted November 22, 2022 Author Share Posted November 22, 2022 Hi Mike, all good points. On the flap pitch up/down changes, I am changing this in almost all the aircraft I got by adjusting the Flaps pitch_scalar and lift_scalar in aircraft cfgs. Reducing figures pitches aircraft up, increasing down. Also Flight Tuning cruise_lift_scalar has a similar effect. So just keep landing and adjusting these to the most realistic levels. Obviously loads have a lot to do with this also. So bit of a sciance but one eventually gets it right. As we know the old props almost nose dive to the runway as opposed to the newer jets landing pitched up. Peter Bendl ex. British Airways Link to comment Share on other sites More sharing options...
Downwind66 Posted February 5, 2023 Share Posted February 5, 2023 Two good posts Mike and Patty & Peter. I think I will print these to have when I get an aircraft that acts up with the first flight after downloading! Thanks Mike and Peter 1 Link to comment Share on other sites More sharing options...
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