What G loads do Q-500's pull?
04-13-2009, 07:03 PM
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RE: What G loads do Q-500's pull?
The pitch line. i.e. the chord line, not the zero lift angle of attack, thus the cambered wings are making some lift at zero degrees aoa.
04-14-2009, 02:50 PM
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RE: What G loads do Q-500's pull?
ORIGINAL: GSJames Here are some "pretty pictures". That's all they are at this point, until I integrate the pressure distributions, but what they show is the pressure distribution at zero degrees angle of attack over 3 common Quickie 500 wings.
Those are nice pictures. But can you elaborate on what exactly we are looking at here? I can’t make out the color scale on the right. I assume its amount or extent of (negative) pressure distribution at zero AOA? If so, what does that actually infer outside of what 2D Cl/Cd xfoil-type polar data shows? If the example wings are pulling different amounts of lift dictated by their particular Cl at zero AOA its kind of apples & oranges, no?
Coincidentally a similar topic came up (in a much diluted form) in the high perf section of ezone pertaining to F5D (electric pylon racing airfoils). Different flavour event, but presumably same methodology. I wont repeat my posts & attachments here, but Ill include the link:
http://www.rcgroups.com/forums/showthread.php?t=1029219
My thinking is, airfoils for the typical pylon flight regime needs to be evaluated in 3 basic ‘modes’: cruise (the relatively straightish long run between pylons), P1 turn (dictated by its particular trajectory radius) and P2-P3 turn (likely some larger radius). They each demand different lift requirements of the wing, therefore call on different degrees of section lift coefficients to handle teh g-load & fly the course, therefore create different amounts of induced drag dictated by the airfoil geometry. The ‘winner’ airfoil would be the one that accomplishes this combined role task with the least amount of cumulative drag, all other things being equal. At least that’s my story & Im sticken to it!
So now you have me real curious - Im guessing you import the dimensional 3D airfoil coordinates, specify airstream stuff (AOA, velocity, density parameters…) it spits out 3D lift & induced drag distribution? If so, please keep working & posting! I’m particularly interested in ‘pictures’ resulting from real life 3D stuff, like
- the protruding center section nubby thing on the upper surface we mount the wing bolts through. That will interrupt the smooth, lateral pressure distribution, presumably less of the less of the continous airfoil wing is wing is ‘working’ which means even higher Cl & AOA is required.
- 3D effects of the fuselage mounted to the wing underside
- Drag from the other stuff, fuselage, landing gear, tailplane
- The airfoil’s Cm (moment coefficient) & associated tail load drag implication as mentioned in the ezone post above
Also, here is some good reading if you haven’t already been on Hepperle’s site before.
http://www.mh-aerotools.de/airfoils/index.htm
Looking forward to where this goes!
ps - I cant help you on freeware 3d plotting, but worse case I know cheated with x,y,z data type importing into 3d cad packages. That can then be useful if you want to drape a surface on the data etc.
