I tried with 32-inch propeller frame. I think it is out of the audible zone (<=20Hz). It just appears when I looked at the log file.
I guess we need to use some experimental methods on large frame to figure out what the resonance is.
I was absolutely fascinated by the speaker approach and tried measurements on all of my copters. I got what looked like definitive results on each, but after chatting with Andy, I’m convinced it’s not quite as useful as it first appears for the reasons he described above.
The resonance peak from such testing will also wander a lot with very minor changes to physical configuration, so it’s only a slight indicator rather than something to trust and tune to, implicitly.
I suspect the speaker test might be more successful on larger frames, but I have no data to support the assumption.
What do you think about the hammer excitation metheo on this study? https://past.isma-isaac.be/downloads/isma2016/papers/isma2016_0797.pdf
hello! can you describe why 40/10? why not 52/13 or 64/16?
Its the ratio and the absolute value of the frequency that matter. The ratio determines the notch width. The absolute value determines the lowest frequency that the notch will be active at. So in your examples the ratio is the same but the notch will only go to a higher frequency - this may or may not matter - you would have to get a log of throttle drops to figure it out. I use 40 as a rul of thumb as its about as low as you want to go while still mostly staying out of control bandwidth.
The documentation says that ins_hntch_freq should be lower than the revs of the motors when hovering. Would you like to know how much lower? From your answers it follows that above 40 it makes no sense to raise ins_hntch_freq? Did I get it right? That is, ins_hntch_freq is suitable for both 3 inch toothpicks and 7 inch quads?
This is all true as long as you are using ESC telemetry to drive the notch
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Great build thread!
May I suggest the next standard build to be something smaller with extended range capability? Not everyone has large enough field to fly 7" frames. Something like Flywoo Explorer 4LR which are 4 inch capable of 30 minutes flight time on 4s Li-Ion packs would be an excellent choice.
Or has it been done already?
…
There is a 5" LR. Enter “5” long range" in the search box above.
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Thanks for that. 5" is nice, but 4" is the sweet spot since it’s right below the 250g weight limit. Plus it can carry goodies like GPS/compass and DJI video system, while still maintaining good performance over 30 minutes duration.
Just a suggestion. Thanks again for the response!
I have done 4" racers but not LR. Would be a nice project, I might try it. But under 250g is a stretch with all of the goodies.
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My 3" arducopter sub 250 gr (gps, compass, baro, optical flow, fpv 400mW analog) has been flying for about 3 years. With 2s Li Ion it flies almost 20 minutes. I had proposed an advanced version with DJI digital, but it is not was never approved. I also built a 5" and a 4", but with the 4" with normal frames, you need to use 3s Li ion to have a decent flight time (15 minutes 3s 21700 liion) but the weight is much higher than the 250gr (on my 4" I also have lidar and sonar rangefinder).
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A Flywoo frame and motors (their electronics are rubbish though even if you could get a stack with 1MB flash, so I would use other electonics) with a Visa Air Unit or even a O3 Air Unit will get at or under 250g with a Runcan Thumb or a Naked GoPro with a 4S 850 mah LiPo. I fly usually fly mine with a 4S 3000 mah LiIon, which makes them over 250g.
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If you want such a frame and motors I have an un-used one I could pop in the mail to you as i will be in the UK next week. It is an analog Flywoo LR4 whose stack just failed on the bench spontaneously. Replaced FC and it failed again so I think the ESC BEC is faulty. Needs a 20*20 stack. That would mean you could use the installed Runcam Ant. The VTX may be fine. Not sure. It has a working crossfire nano on it. I currently fly a DIY DJI digital version of same using iNav. I like 4 inch LR as it is quiet enough to use without disturbing people.
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That would be great! I have plenty of flight controllers and probably an ESC as well
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Do you use Crossfire? Are you analog or digital?
Yes I mostly use crossfire, I have both analog and digital setups
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Ok then. I will get it to you with the crossfire installed. I really think the Flywoo stack needs to go though and some 20*20 stack with 1mb flash needs to be found. I would not even trust the 4-in-1 ESC. Your address is the same?
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