+logan4 847 Posted January 31, 2013 Hello Gents! I'm working on a Mig-Ye8 - which progresses a bit slowly - and during test flights I run into some FM and visual issue I'm not sure with what data modification I can solve. few of the symptoms: - Autorotation during take of at around 154km/h, it already wants to raise nose up even when still bellow take off speed. - during flight canard and stabilizator are not in a "straight" position (see top pic in level flight), not sure which of the followings I have to change. Did some up and down changes but no visual difference so far. CL0,CLa,CD0,CDL,Cmq,Cmad,Cyb,Clp or Cnb parameter. Stabs use the standard TW mig21 stab data, canards set somewhat similar to the f31 canard (due to position and size similarities) Although this angle problem not exists on the ground (see second pic) during high speed run or taxi. This is the canards data: (Most of the data is wild guess to start out from something, so do not look for accuracy.) [LeftCanard] ParentComponentName=Nose ModelNodeName=Canard_L DestroyedNodeName= ShowFromCockpit=TRUE DetachWhenDestroyed=TRUE DamageRating=DISABLED MassFraction=0.005 HasAeroCoefficients=TRUE LiftSurface=TRUE CL0=-0.0198 CLa=0.1450 CD0=0.0006 CDL=0.0002 Cmq=-2.1048 Cmad=-1.1198 Cyb=-0.0087 Clp=-0.0061 Cnb=0.0042 CL0MachTableNumData=9 CL0MachTableDeltaX=0.40 CL0MachTableStartX=0.00 CL0MachTableData=0.972,0.984,1.000,0.763,0.534,0.387,0.205,0.169,0.086 CLaMachTableNumData=9 CLaMachTableDeltaX=0.40 CLaMachTableStartX=0.00 CLaMachTableData=0.934,0.979,1.000,1.070,1.208,1.983,1.588,1.284,0.976 CD0MachTableNumData=9 CD0MachTableDeltaX=0.40 CD0MachTableStartX=0.00 CD0MachTableData=1.494,1.120,1.000,0.962,1.343,1.601,1.371,1.288,1.226 CDLAlphaTableNumData=15 CDLAlphaTableDeltaX=4.00 CDLAlphaTableStartX=-28.00 CDLAlphaTableData=31.000,25.000,20.000,13.000,9.000,4.400,1.200,0.070,1.000,3.800,7.200,16.000,21.000,29.000,37.000 CmqMachTableNumData=9 CmqMachTableDeltaX=0.40 CmqMachTableStartX=0.00 CmqMachTableData=0.972,1.000,1.042,1.108,1.196,1.112,0.896,0.708,0.642 ClpAlphaTableNumData=15 ClpAlphaTableDeltaX=4.00 ClpAlphaTableStartX=-28.00 ClpAlphaTableData=1.474,1.361,1.264,1.182,1.121,1.068,1.034,1.012,1.000,1.015,1.034,1.079,1.134,1.208,1.285 XacMachTableNumData=9 XacMachTableDeltaX=0.40 XacMachTableStartX=0.00 XacMachTableData=-4.849,-4.852,-4.858,-4.876,-4.921,-5.024,-5.084,-5.136,-5.184 CheckStall=TRUE CLmax=0.2977 AlphaStall=43.87 AlphaMax=48.64 AlphaDepart=54.41 StallLiftTableNumData=30 StallLiftTableDeltaX=10.00 StallLiftTableStartX=-180.00 StallLiftTableData=0.000,-0.014,-0.026,-0.044,-0.059,-0.049,-0.034,-0.015,0.000,0.021,0.054,0.107,0.152,0.220,0.266,0.370,0.577,0.882,0.494,0.288,0.182,0.096,0.041,0.000,-0.015,-0.034,-0.051,-0.028,-0.014,0.000 StallDragTableNumData=30 StallDragTableDeltaX=10.00 StallDragTableStartX=-180.00 StallDragTableData=0.001,0.012,0.043,0.082,0.152,0.221,0.294,0.408,0.564,0.795,0.937,1.018,1.142,1.122,1.000,1.122,1.142,1.018,0.937,0.749,0.562,0.451,0.367,0.292,0.201,0.123,0.062,0.026,0.008,0.001 StallXacShiftTableNumData=30 StallXacShiftTableDeltaX=10.00 StallXacShiftTableStartX=-180.00 StallXacShiftTableData=-0.324,-0.322,-0.275,-0.248,-0.235,-0.219,-0.202,-0.178,-0.161,-0.144,-0.120,-0.103,-0.087,-0.077,-0.074,-0.047,0.000,0.000,0.000,-0.047,-0.081,-0.103,-0.132,-0.168,-0.202,-0.224,-0.245,-0.275,-0.322,-0.324 DownwashAlphaTableNumData=30 DownwashAlphaTableDeltaX=10.00 DownwashAlphaTableStartX=-180.00 DownwashAlphaTableData=0.000,0.000,0.000,0.000,0.000,0.000,0.000,-0.004,-1.642,-3.229,-4.715,-6.050,-7.210,-8.151,-8.844,-4.737,0.831,6.428,9.837,8.241,5.677,3.883,1.961,0.000,0.000,0.000,0.000,0.000,0.000,0.000 Chord=1.18 Ymac=-0.94 MovingSurface=TRUE ControlSystemID=1 MinExtentPosition=-1.36,4.718,0.043 MaxExtentPosition=-0.485,6.096,0.15 CollisionPoint[001]=-0.537,5.279,0.091 HasVortexEmitter=TRUE VortexEmitterName=WingtipVortexEmitter VortexPosition=-1.3,4.77,0.09 VortexG=3.5 SystemName[001]=LeftElevator [RightCanard] ParentComponentName=Nose ModelNodeName=Canard_R DestroyedNodeName= ShowFromCockpit=TRUE DetachWhenDestroyed=TRUE DamageRating=DISABLED MassFraction=0.005 HasAeroCoefficients=TRUE LiftSurface=TRUE CL0=-0.0198 CLa=0.1450 CD0=0.0006 CDL=0.0002 Cmq=-2.1048 Cmad=-1.1198 Cyb=-0.0087 Clp=-0.0061 Cnb=0.0042 CL0MachTableNumData=9 CL0MachTableDeltaX=0.40 CL0MachTableStartX=0.00 CL0MachTableData=0.972,0.984,1.000,0.763,0.534,0.387,0.205,0.169,0.086 CLaMachTableNumData=9 CLaMachTableDeltaX=0.40 CLaMachTableStartX=0.00 CLaMachTableData=0.934,0.979,1.000,1.070,1.208,1.983,1.588,1.284,0.976 CD0MachTableNumData=9 CD0MachTableDeltaX=0.40 CD0MachTableStartX=0.00 CD0MachTableData=1.494,1.120,1.000,0.962,1.343,1.601,1.371,1.288,1.226 CDLAlphaTableNumData=15 CDLAlphaTableDeltaX=4.00 CDLAlphaTableStartX=-28.00 CDLAlphaTableData=31.000,25.000,20.000,13.000,9.000,4.400,1.200,0.070,1.000,3.800,7.200,16.000,21.000,29.000,37.000 CmqMachTableNumData=9 CmqMachTableDeltaX=0.40 CmqMachTableStartX=0.00 CmqMachTableData=0.972,1.000,1.042,1.108,1.196,1.112,0.896,0.708,0.642 ClpAlphaTableNumData=15 ClpAlphaTableDeltaX=4.00 ClpAlphaTableStartX=-28.00 ClpAlphaTableData=1.474,1.361,1.264,1.182,1.121,1.068,1.034,1.012,1.000,1.015,1.034,1.079,1.134,1.208,1.285 XacMachTableNumData=9 XacMachTableDeltaX=0.40 XacMachTableStartX=0.00 XacMachTableData=-4.849,-4.852,-4.858,-4.876,-4.921,-5.024,-5.084,-5.136,-5.184 CheckStall=TRUE CLmax=0.2977 AlphaStall=43.87 AlphaMax=48.64 AlphaDepart=54.41 StallLiftTableNumData=30 StallLiftTableDeltaX=10.00 StallLiftTableStartX=-180.00 StallLiftTableData=0.000,-0.014,-0.026,-0.044,-0.059,-0.049,-0.034,-0.015,0.000,0.021,0.054,0.107,0.152,0.220,0.266,0.370,0.577,0.882,0.494,0.288,0.182,0.096,0.041,0.000,-0.015,-0.034,-0.051,-0.028,-0.014,0.000 StallDragTableNumData=30 StallDragTableDeltaX=10.00 StallDragTableStartX=-180.00 StallDragTableData=0.001,0.012,0.043,0.082,0.152,0.221,0.294,0.408,0.564,0.795,0.937,1.018,1.142,1.122,1.000,1.122,1.142,1.018,0.937,0.749,0.562,0.451,0.367,0.292,0.201,0.123,0.062,0.026,0.008,0.001 StallXacShiftTableNumData=30 StallXacShiftTableDeltaX=10.00 StallXacShiftTableStartX=-180.00 StallXacShiftTableData=-0.324,-0.322,-0.275,-0.248,-0.235,-0.219,-0.202,-0.178,-0.161,-0.144,-0.120,-0.103,-0.087,-0.077,-0.074,-0.047,0.000,0.000,0.000,-0.047,-0.081,-0.103,-0.132,-0.168,-0.202,-0.224,-0.245,-0.275,-0.322,-0.324 DownwashAlphaTableNumData=30 DownwashAlphaTableDeltaX=10.00 DownwashAlphaTableStartX=-180.00 DownwashAlphaTableData=0.000,0.000,0.000,0.000,0.000,0.000,0.000,-0.004,-1.642,-3.229,-4.715,-6.050,-7.210,-8.151,-8.844,-4.737,0.831,6.428,9.837,8.241,5.677,3.883,1.961,0.000,0.000,0.000,0.000,0.000,0.000,0.000 Chord=1.18 Ymac=0.94 MovingSurface=TRUE ControlSystemID=1 StructuralFactor=1.5 MinExtentPosition=0.486,4.718,0.043 MaxExtentPosition=1.36,6.096,0.15 CollisionPoint[001]=0.537,5.279,0.091 HasVortexEmitter=TRUE VortexEmitterName=WingtipVortexEmitter VortexPosition=1.3,4.77,0.09 VortexG=3.5 SystemName[001]=RightElevator Also anyone has info that this bird had a second airbreak like the fishbed front of the ventral fin? I can't find any info or photo which says it had. Thank you any info and advice in advance. Share this post Link to post Share on other sites
Panama Red 22 Posted January 31, 2013 You might start with "fixing" the Canard location. I do notice that you tell the Canards that they are located back at the stabilizer area versus ahead of the Cockpit: "XacMachTableData=-4.849,-4.852,-4.858,-4.876,-4.921,-5.024,-5.084,-5.136,-5.184" Anything AHEAD of the CG is positive, behind the CG is negative. Share this post Link to post Share on other sites
Fubar512 1,350 Posted January 31, 2013 Panama red is correct. The Xmac table should start 1/4-1/3 of the way back from the leading edge of the surface, and terminate 1/2-2/3 of the distance back from the leading edge, which in the case of a canard, should be foreward of the model's center. Also, the Xmac tables should be applied at the mean chord of a given surface. Share this post Link to post Share on other sites
+logan4 847 Posted February 1, 2013 Thank you very much PanamaRed and Fubar512 the info, honestly I had no clue about the meaning of +/- values in those parts. Just to make sure I understand it right we talk about the grey masked area on the pic bellow. (a bit slow on grasping after my 4th 12 hour shift this week) Also I did a quick data change and correction, the good news it is now reverted in direction, so some fine tuning will still needed, the bad (at least for me) I will have to rewrite and change many things in the FM as now want to drop like a brick. Is there any other related parameter which has this +/- relation? Also points should be given from root side outward the tip of the canard or from tip inward to root? Thank you again! Share this post Link to post Share on other sites
Fubar512 1,350 Posted February 1, 2013 Canards provide postive lift, not the slight static (CL0) downforce that elevators and horizontal stabs do (you are using horizontal stab values for your canards). Change this value CL0=-0.0198 to CL0=0.0198 on both canards Share this post Link to post Share on other sites
+logan4 847 Posted February 1, 2013 Thank you Fubar512, the CL0 change solved the dropping. More fiddle and test will be after work. Share this post Link to post Share on other sites
+logan4 847 Posted February 7, 2013 I might need a little more help. I did calculate the new CLa(DW), Mac, ymac values using Fubar512's tutorial from 2k7 with the aeroconverter and would like to go further with all the other drag,alpha,etc calculations as simply changing Tk's data with my actual data, resulted in a "nose into ground" attitude above 130km/h. Is there a comprehensive guide about all related formulas or site which is preferable to use? Or should I buy a book about aerospace engineering? An other question would be if I want to give lets say 21 reference values, what determines the sequence or parameters those values should be originated or their intervals. I mean is it speed (mach value in 0,1 steps) or altitude (1000m steps), or weight (kg), or ........ Thank you in advance. note btw: With the exception of XB70, kfir and J10 all canard (rafale, tyhoon, viggen, gripen, F31, F29) planes use negative Xacmach position values even when the min/max extend is only positive in Y-axis for the given mesh. Share this post Link to post Share on other sites
Fubar512 1,350 Posted February 7, 2013 Then the planes you listed have incorrect values. If you add a lift surface forward of the model's centerline, it should positive positional values. As I often work 16-hour days, I cannot get back to my notes and test models until Friday evening at the earliest. When I do, I will post the canard values that I'm using for the as yet unreleased Su-33. But keep in mind that in the Sea Flanker's case those are movable surfaces, whereas (if I recall correctly) the Ye-8's canards were fixed, like the Mirages and the Kfir. Share this post Link to post Share on other sites
+logan4 847 Posted February 7, 2013 Based on the data I read actually the canards were movable and locked above 1Mach due to unsolved controlling issues, but could be fix locked from the start too or any time if there were some complications. In the FM I use about 1,25M for lock-out speed. Tanks for the info and kindness for your offer, do not worry I can't get to it before friday evening either. Share this post Link to post Share on other sites
Fubar512 1,350 Posted February 8, 2013 Here you go, Logan: [LeftCanard] ParentComponentName=Fuselage ModelNodeName=canard_left DestroyedNodeName= ShowFromCockpit=TRUE DetachWhenDestroyed=TRUE DamageRating=DISABLED MassFraction=0.007 HasAeroCoefficients=TRUE LiftSurface=TRUE CLa=0.043 CD0=0.0004 CDL=0.0012 Cmq=-0.7825 Cmad=-0.2818 Clp=-0.0025 Cnb=0.0055 CLaMachTableNumData=5 CLaMachTableDeltaX=0.40 CLaMachTableStartX=0.00 CLaMachTableData=1.001,1.000,0.979,0.910,0.938 CD0MachTableNumData=5 CD0MachTableDeltaX=0.40 CD0MachTableStartX=0.00 CD0MachTableData=1.825,1.000,1.028,2.494,2.773 CmqMachTableNumData=27 CmqMachTableDeltaX=0.10 CmqMachTableStartX=0.00 CmqMachTableData=0.868,0.872,0.897,0.937,1.000,1.095,1.240,1.475,1.904,2.935,7.322,-0.000,-0.000,0.246,1.152,0.121,0.494,0.568,0.599,0.609,0.598,0.591,0.578,0.558,0.529,0.495,0.464 ClpAlphaTableNumData=15 ClpAlphaTableDeltaX=4.00 ClpAlphaTableStartX=-28.00 ClpAlphaTableData=1.474,1.361,1.264,1.182,1.115,1.063,1.027,1.006,1.000,1.009,1.034,1.074,1.129,1.200,1.285 XacMachTableNumData=5 XacMachTableDeltaX=0.40 XacMachTableStartX=0.00 XacMachTableData=3.856,3.664,3.185,2.976,2.836 Chord=1.03 Ymac=0.983 MovingSurface=TRUE ControlSystemID=1 StructuralFactor=1.00 MinExtentPosition= -1.2907,1.6681,0.600 MaxExtentPosition= -0.8907, 1.1481,0.600 SystemName[001]=LeftCan HasVortexEmitter=TRUE VortexEmitterName=F16LexEmitter VortexPosition=-3.0007,1.1381,0.6000 VortexG=6.5 VortexUseNodeOffset=TRUE [RightCanard] ParentComponentName=Fuselage ModelNodeName=canard_right DestroyedNodeName= ShowFromCockpit=TRUE DetachWhenDestroyed=TRUE MassFraction=0.007 HasAeroCoefficients=TRUE LiftSurface=TRUE CLa=0.043 CD0=0.0004 CDL=0.0012 Cmq=-0.7825 Cmad=-0.2818 Clp=-0.0025 Cnb=0.0055 CLaMachTableNumData=5 CLaMachTableDeltaX=0.40 CLaMachTableStartX=0.00 CLaMachTableData=1.001,1.000,0.979,0.910,0.938 CD0MachTableNumData=5 CD0MachTableDeltaX=0.40 CD0MachTableStartX=0.00 CD0MachTableData=1.825,1.000,1.028,2.494,2.773 CmqMachTableNumData=27 CmqMachTableDeltaX=0.10 CmqMachTableStartX=0.00 CmqMachTableData=0.868,0.872,0.897,0.937,1.000,1.095,1.240,1.475,1.904,2.935,7.322,-0.000,-0.000,0.246,1.152,0.121,0.494,0.568,0.599,0.609,0.598,0.591,0.578,0.558,0.529,0.495,0.464 ClpAlphaTableNumData=15 ClpAlphaTableDeltaX=4.00 ClpAlphaTableStartX=-28.00 ClpAlphaTableData=1.474,1.361,1.264,1.182,1.115,1.063,1.027,1.006,1.000,1.009,1.034,1.074,1.129,1.200,1.285 XacMachTableNumData=5 XacMachTableDeltaX=0.40 XacMachTableStartX=0.00 XacMachTableData=3.856,3.664,3.185,2.976,2.836 Chord=1.03 Ymac=0.983 MovingSurface=TRUE ControlSystemID=1 StructuralFactor=1.00 MinExtentPosition= 1.2907,1.6681,0.600 MaxExtentPosition= 0.8907, 1.1481,0.600 SystemName[001]=RightCan HasVortexEmitter=TRUE VortexEmitterName=F16LexEmitter VortexPosition=3.0007,1.1381,0.6000 VortexG=6.5 VortexUseNodeOffset=TRUE Share this post Link to post Share on other sites
+76.IAP-Blackbird 3,557 Posted February 8, 2013 That looks impressive, was long time thinking about to build this plane, but yours looks realy great! Share this post Link to post Share on other sites
+logan4 847 Posted February 9, 2013 Thank you very much Fubar512! Based on the first comparison I seem to try give a lot more of the various "things", many which might not belong to this object properties. Like CdL tables, drag and stall values etc. Also if I make my calculated Cla (not the one above shown from me) to it's 1/10th value than the flips and autoroll stops. Actually the plane takes an auto roll above 214km/h (but keeps an 4,5deg attitude which I set for the AI for take off roll) and if throttle is given than auto rises to the air at around 324km/h. The stab and canard positions during flight seem to straightened out. It was a great help. Now I going to fiddle around some of the values. @Blackbird: Thank you. To be honest this is my second take on it also, and since last summer hardly had time to do much on it, but slowly going to make it complete. Recently only the FM got "worked" on it and if time allows it than going to make some parts mapping also tomorrow. Share this post Link to post Share on other sites
Fubar512 1,350 Posted February 9, 2013 Auto roll? Sounds as if you given both sides the same Ymac coordinates. Left is always a negative value (ie, Ymac=-0.935), while the right surface is always postive. Share this post Link to post Share on other sites
+76.IAP-Blackbird 3,557 Posted February 9, 2013 Your models looks very good, nice attention to details! Im a big fan of prototypes ,specialy the soviet ones. We have enough western targets around, for our new toys! Expect another MiG Prototypes this summer too from my end ;) Share this post Link to post Share on other sites
+logan4 847 Posted February 10, 2013 Auto roll? Sounds as if you given both sides the same Ymac coordinates. Left is always a negative value (ie, Ymac=-0.935), while the right surface is always postive. Sorry my "miss-labeling" about autoroll I meant when the plane lifts it's nose up automatically due to sufficient lift characteristics on certain parts. Probably there is a better term for it (autorotate?), it doesn't meant the roll condition during flight. @blackbird: yes we do have little to beat the blueforce with. I planed 4 versions for this bird which might be its evolutionary road given the time - no 2seater though. I do have an other one in the works. Found a drawing in one of the aviation books about the mig29 when there was very little to know about, but probably it is just a hypothetical drawing. 1 Share this post Link to post Share on other sites
