tag:blogger.com,1999:blog-5821522320379987891.post1203087849324803622..comments2023-11-11T18:21:04.799+01:00Comments on Shrediquette - the award-winning multirotors by William Thielicke: Aerodynamics in racing multirotors! Part 2.William Thielickehttp://www.blogger.com/profile/01217178163189555726noreply@blogger.comBlogger12125tag:blogger.com,1999:blog-5821522320379987891.post-29314520989922579602016-11-21T23:41:33.000+01:002016-11-21T23:41:33.000+01:00I would love to see some drag data on something ne...I would love to see some drag data on something newer than the ZMR250 (Luminere QAV-X https://goo.gl/0pQAVD or kraken https://goo.gl/C2FHgN or Shuriken X1 https://goo.gl/mlHKk0).<br /><br />I'm also very curious what's the Derbe weight (without the LiPo)<br /><br />Anonymoushttps://www.blogger.com/profile/04868807392564284525noreply@blogger.comtag:blogger.com,1999:blog-5821522320379987891.post-1977705673838538872016-10-11T21:53:52.576+02:002016-10-11T21:53:52.576+02:00An issue I have with the test setup is you fixed t...An issue I have with the test setup is you fixed the Prop speeds as all equal. By using a BlackBox logger that data shows that when a quad is in forward flight the rear motors run at a higher speed. I think this does create lift, downward thrust vector, else the quad would not hold a forward pitch angle and must rotate back to level.<br />Interesting data and flow measurements.<br />I would like to see those done with an active Flight controller. Maybe mount the quad on a pivot to allow it to rotate in pitch. Then use the RC controls to command the FC to pitch into forward flight. My bet is that you will see an different flow.<br />waltr on RCgroups forumAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-5821522320379987891.post-72559210836197860912016-02-03T17:16:30.647+01:002016-02-03T17:16:30.647+01:00it has no effect, it's that I started sketchin...it has no effect, it's that I started sketching frame design over your images. I will need to change the image around to start sketching again. Basically, I put the arms in the red area and not the green.Jerome Demershttp://www.jeromedemers.comnoreply@blogger.comtag:blogger.com,1999:blog-5821522320379987891.post-48662610649420060482016-02-02T07:14:14.124+01:002016-02-02T07:14:14.124+01:00Yes, I think my props all spin in the other direct...Yes, I think my props all spin in the other direction of what is "standard". But I don't think that this has an effect.William Thielickehttps://www.blogger.com/profile/01217178163189555726noreply@blogger.comtag:blogger.com,1999:blog-5821522320379987891.post-13295485626778570662016-02-02T01:23:34.993+01:002016-02-02T01:23:34.993+01:00is your quad motor layout orientation different fr...is your quad motor layout orientation different from Naze or CC3D?<br />From that image it seems yes. That might explain why your say this in image #8: "this is only true for the propeller rotational directions shown in this image. If all propellers<br />rotate in the other directions, then red and green areas need to be inversed."Jerome Demershttp://www.jeromedemers.comnoreply@blogger.comtag:blogger.com,1999:blog-5821522320379987891.post-16481918151531634072016-01-11T22:01:42.583+01:002016-01-11T22:01:42.583+01:00Hi Mario, thanks for your feedback! I am currently...Hi Mario, thanks for your feedback! I am currently also flying with a conventional design, but I don't like it. I simply cannot 'accept' that a standard racing multirotor looks almost symmetrical, but flies everything else than symmetrically: It goes forward all the time.<br />There simply must be a good solution for a racing copter with an aerodynamically good body... I'll keep on trying to make something like this despite my limited time.William Thielickehttps://www.blogger.com/profile/01217178163189555726noreply@blogger.comtag:blogger.com,1999:blog-5821522320379987891.post-41039106711504027662016-01-11T19:38:15.520+01:002016-01-11T19:38:15.520+01:00hi William, huge compliments for your professional...hi William, huge compliments for your professional works and measurements here! We need better highspeed copters! I love to dive fast in the alps (dont know if you know my RCSchim videos). I cant do as much diving as I want to - but this is the best part in FPV for me ;-) Last time I had a crash with my Black Bullet (esc burnt) but the bullet (fwd tilted arms) had some issues for me in the beginning. mainly the sudden 90 degree yaw issues on fast forward were terrible. I got it down to flyable behaviour but never 100% rid of it. I used cleanflight on the naze32 with luxfloat - that made the quad behave better, and I also had better results with bigger props (going from 5x4.5 to 6x4.5 gave more yaw stability were everything else failed).<br />Ultimately however the props killed the ESCs ;-) <br /><br />So not sure atm. what's better, tilted arms, or conventional...<br />Vortex 250pro, which is looking good, is back at conventional; some others hop on the train of fwd tilted quads...<br /><br />However, keep researching!<br />Greetings,<br />Mario / RCSchim from AustriaRCSchimhttps://www.blogger.com/profile/04091288589574071797noreply@blogger.comtag:blogger.com,1999:blog-5821522320379987891.post-33544086129169321352016-01-08T21:46:01.524+01:002016-01-08T21:46:01.524+01:00I simply prefer the Graupner props... I also could...I simply prefer the Graupner props... I also couldn't measure any differences in flight speed when comparing them to 5045 bullnose props. These props turns at lower RPM, so there might be no advantage of the larger propeller pitch.William Thielickehttps://www.blogger.com/profile/01217178163189555726noreply@blogger.comtag:blogger.com,1999:blog-5821522320379987891.post-54369948205448451662016-01-08T12:16:23.158+01:002016-01-08T12:16:23.158+01:00Thanks for your information and research! :-)
I a...Thanks for your information and research! :-)<br /><br />I am just wondering why use 5.5x3 prop at 30m/s? Why not usual 5045 or 5045BN for example?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-5821522320379987891.post-80320796471552259882016-01-06T08:08:21.081+01:002016-01-06T08:08:21.081+01:00Yaw outs did not happen in fast flight, because in...Yaw outs did not happen in fast flight, because in that case, the flow was pretty much parallel to the arms. But in turns, when throttle is reduced but the forward speed is still high, the flow hits the arms almost perpendicular. And that creates too much (asymmetric) force on the yaw axis and could sometimes not be compensated anymore.William Thielickehttps://www.blogger.com/profile/01217178163189555726noreply@blogger.comtag:blogger.com,1999:blog-5821522320379987891.post-4910934009666024702016-01-06T08:04:56.233+01:002016-01-06T08:04:56.233+01:00Dear Alex,
I agree that they're flat plates wi...Dear Alex,<br />I agree that they're flat plates with a l/d of maybe 1... I guess mounting the arms the way I did makes sense from the aerodynamic point of view, but it is very bad for yaw control (because this axis is soooo weak...). There should be as little area in the "yaw plane" (the plane parallel to the motor axes) as possible, otherwise the copter might experience yaw outs in some situations. The DERBE had this when doing fast turns (but never in straight forward flight).<br />I did not test the airbrakes yet. In my next design, I'll try to make the arms as aerodynamically passive as possible.William Thielickehttps://www.blogger.com/profile/01217178163189555726noreply@blogger.comtag:blogger.com,1999:blog-5821522320379987891.post-45620275383099486772016-01-02T00:05:52.790+01:002016-01-02T00:05:52.790+01:00Looking at the Derbe in Forward Flight with a leve...Looking at the Derbe in Forward Flight with a level body, it looks like the arms are effectively flat plates (ignoring motor wires) with a high Angle of Attack. Wouldn't traditional flat arms have a similar frontal area but providing down force rather than, albeit with a terrible lift to drag ratio, positive lift? Are you suggesting that the rear arms should maybe be parallel to the FF flow (or with a slight AoA) rather than vertical or horizontal?<br />Did you ever manage to test the air brakes? I wonder if control surfaces could also prove useful for better yaw authority in FF. Have you noticed yaw issues with Derbe in actual flight?Alex Geenoreply@blogger.com