Unpopular opinion in your viewer base, but as a guy who just spend the entire weekend repairing and improving just 4 quads, I would love for your setups to be available as prebuilt versions. Tuned and ready to go.
The curve "recruits" more air, actually sucking more air in which is then added to thrust propellers create, provided that the propeller blades are very close to the inside of the duct.
Thanks for sharing Bob! Love those kind of videos you make. If there were more technical videos like these in the FPV community, improvements in certain areas would be quicker and people should not reinvent the wheel every time. Much like open-source communities work.
I used to work in a manufacturing environment where we used air knives to blow downward on products. The air knife employed compressed air that came out of a nozzle and blew across the flat surface of the knife creating a sheet of air that was moving about 40 mph. At the end of the knife was a 90° down facing curve and nothing else. As the air passed over the curve it did not continue out into space, but rather, it turned and followed the curve, thus blowing straight down. At the bottom of the curve, the flat flowing air was moving 90 mph and was thin and long. Hence the term, air knife. The real beauty of this was that it didn't take more energy to make 90mph air. By sucking a large volume of air into the duct, you are causing the air at the edges to flow over the curve and speed up. If you keep the inside of the duct straight and smooth, the faster air should stay along the edges and blow straight down causing more thrust. And I think, that because the faster air is in a ring it will cause the flow of air to act more like a column of smooth air and be less turbulent. I think that what you need to do to get the best effect, is to top mount the motors so that the frame, hardware and motors are all above the column of air so as to not disturb the column and make it turbulent.
This is all assuming that there's a very high amount of pressure behind the column of air and the duct is acting like an actual duct meaning there's no gaps all around the column of air. Unfortunately neither of those are true. There isn't much pressure created by the prop and the duct is very inefficient.
Three words Wind Tunnel Smoke Understanding that we use “propellers” in hybrid as a bit of a“rotor” in flight. Thrust and Lift blend Hover is pure thrust Flight is a gradient of marginal lift and trust. So its mostly vectored thrust, more stuff pushed through a medium is an exercise in drag , the drag smooths. Nice to play and watch.
I've also done a lot of duct optimization. For me, the ultimate goal is to get longer flight times. My recent testing showed that my 3D printed ducts, which weigh just about the same as the stock ducts, give about a 10% increase in flight times. I'd be interested in seeing how they stack up against the ones you're using. One thing to note is that mine are tightly matched to the diameter of the gemfan 5 bladed props. To do this I embedded nuts in the print rather than pressing in threaded inserts, which I found to be too variable in position. I then adjusted the ID of the duct by .5mm steps until fresh ducts matched fresh props. I also designed in tabs which can be used to connect the fore and aft ducts, resulting in a much stiffer airframe.
To get maximum flight time and efficiency, you'll need to do as you did and tune the duct ID to the prop but also tune the lip on top of the prop disk. The prop should sit just below the vertical point of the lip curve and you gotta play with how drastic or gentle of a curve you design into it. Too gentle and you're not getting enough air passing quickly over the curve. Too sharp and you're just causing more turbulence. The curve on my duct design is actually limited by the print. Because we print the mounting side first, we can only do so gentle of a curve. Since I have a very serious powertrain, I didn't find the curve design variation to make too much of a difference in my testing however it should be a bit more of a gentle and longer curve than what I've got on my design.
@@Kababa lot of suggestions you presented here are proven by stuides like Jason L. Pereira 2008 and these ideas mostly generate from them. People like Capolight actually tried to get as close as possible to their recommended optimal duct design and saw 40% efficiency increase. The reason people having better results with cut squirt ducts from the original one is a great example if done wrong, they stray away from optimal. You still see the benefits if the weight to gain ratio is still good but not as much as 40% of course. Duct height, diamater related to prop, gap between duct inner wall and prop tip (%0.1 of duct diamater), inner wall curvature angle, top lip radius related to duct height and optimal tip for the props are all tested in that study and they even give you the optimal design so you can fit them to your prop diamater. Your video is amazing and explains a lot. Can there be better ducts? Yes. As I said there are people out there claiming 40% efficiency increase which is close to the claims of 46% in the study. All that said, itnis of course harder than it looks. We do not all have machine shops and access to exotic materials to make a hobby craft perfect. All these rtf drone companies long gave up from an optimal duct and went to prop guards because newer generation motors can compensate a lot and bring up the efficiency. But if you manage to make the perfect duct for your size and match it with these motors, you can see a lot more benefit.
@@fpvosman The latest ducks that we have are a much shorter duct design that tends to have the aerodynamic benefits as well as the lower weight we prefer. This entire duct apparatus is not really a duct. It's sort of a pseuduct that happens to work because it has the aerodynamic shape of a duct and there is some air flowing through it in the correct direction. If you have a perfect system that is sealed and functional then you can see those high efficiencies but it's unreasonable to strive for that on something so rudimentary as what we are doing here. I have actually created a duct that the props extend into the duct. The duct has a channel for the end of the props such that there is no gap between the duct wall and the prop. It is essentially 100% closed because of the overlap. In that particular instance, the noise was insanely loud but the efficiency did go up a bit at the expense of response performance because of reasons I cannot even explain
hmm... I would fit one of these to my new micro, but there's maybe a 2mm gap between the prop swings. I somehow managed to cram 4 inch props on a 130mm frame.
I recently switched to stan fpv ducts from stock could 149 ducts based on your recommendation probably months ago and the difference in performance way significant, more precise control and smoother operations.
I think in general cinewhoops are just gonna be heavy and inefficient. I think you should also consider weight added vs efficiency gains when you test cinewhoops because I find everything about their design adds weight at the sacrifice of efficiency - the ducts, bigger battery, deeply pitched props, gopro - all of these are fighting the added weight while contributing more weight. Do you think an asymmetrical duct design would help with lift generated? You don't really need the lip around the whole duct, just the front part.
Free zillion has recently tested the asymmetrical duct. Some interesting results but he hasn't shared on his channel unfortunately. But yeah it flies like a plane but doesn't really go slow. Every bit of weight matters on a cinewhoop. The CineSplore frame is overall a low weight frame with low weight ducts. It's not efficient but 3-4min from a 4s 1100mah and a hero 8 is till pretty decent
SO awesome! The airfoil aspect that tends to 'tip' the kwad verticle is more accentuated on the squirt because the front and back ducts are one piece, and so the airfoil edge creating lift is only at the very front of the frame and doesn't balance out as it might with two separate ducts and an airfoil at the center as well as at the front.
My understanding of the primary benefits of ducts in a hover state is the that reduce tip losses separating the high and low pressure zones. The second benefit which is only really applicable to the ducts with the smaller exit is that by reducing the area of the exit it increases the velocity of the airflow. This ultimately reduces the static pressure of the airflow coming off the prop reducing the apparent disk loading. Quick disclaimer I'm only an engineering student so there is a decent chance I'm wrong
In this specific case, what we're running aren't true ducts. Even if the prop tip is scraping the walls. The prop tips would need to sit inside a very closely fit channel in the wall of the duct to actually have true duct performance. This isn't practical for our purposes however. There are some benefits to ducts that can be explained but the end result is that it needs to be tuned right and it flies great when it is
@@Kabab i agree with you that the ducts aren't true ducts, however I'm am if the opinion (note I haven't flown any quad with ducts this is purely from my understanding of the aerodynamics) that whilst many of the benefits of ducts aren't particularly prevalent in the ducts that people are using they are still in effect. furthermore the stanfpv ducts really do seem to have some of the benefits of ducts despite their imperfect fit. all in all I'm still not a huge fan of ducts but I'm curious to see what benefits could be had from making ducts with a better fit and props to match.
@@robinbiskupic2639 if you fly something with ducts that actually work, you can very very easily feel the benefits. Super smooth, slow, controlled flying.
Smaller outlet means nozzled, bigger means diffused. Nozzle increase exit speed, diffuse reduce them. Make the bottom bigger and add a fix prop at the exit (act as counter rotating). So that the driving props lift the drone, the fixed props lift the ducts. Taller stator motor always better, wider stator reduced props efficiency. Ducts surface are smooth and glossy, sturdy not flexi. Monocoque is the best. - 2 cents
The theory of lift that Kabab talks about here is based off Bernoulli’s principle using conservation of energy. But there are two other theory’s, the Newtonian theory using conservation of momentum and the coanda effect which basically uses an attached flow to redirect the flow off air to produce lift. As for the exit hole smaller than the prop you will have an increased air velocity at the point of exit with a lower static air pressure this can be calculated using Bernoulli’s equation
I like the short ducts that are on my ET Max. You get some of the benefits of the duct with creating drag in flight. I thing that they also make for smoother yaw spins as wind isn't hitting the prop from the side as you rotate. They allow for smooth, fast flight down low and aren't bothered much by side winds. The ducts also come in handy when blasting your way through scraggle.
With the stanfpv ducts, the bottom portion having a smaller diameter actually creates a nozzle rather then disrupts the air flow. So the air leaving the duct is actually traveling faster then a duct with a straight wall design. However, that doesn't necessarily add to the benefit of the prop because props pull rather then push. If the thrust was generated by a jet or rocket engine then the nozzle would aid in the thrust, (up to a certain speed cause then a reverse nozzle actually aids in thrust for the rocket.) Since the nozzle isn't really helping the prop what it is doing is causing unnecessary pressure inside the duct, which could affect prop efficiency. With the short duct height you are really just getting rid of unnecessary friction. Which would effect efficiency probably more then the weight savings. I'm sure you tried multiple different heights but I'm curious how short of a duct you tried. Your final duct was probably the threshold of duct benefit and losses due to friction.
The smaller exist causes obstruction. These aren't jets. They're weak motors spinning props. The motor and prop is still doing 95% of the work. The duct needs to get out of the way.
Bernouli principle is not related to the wing lift, but it is a common myth :) there are numerous demonstrations on youtube. It is more of a reactive thing, you go up about as much as you push air down
yeah I knew it was something about Bernoulli but also not. I left out attack angle here because it doesn't apply but I know attack angle is probably more than half of how a wing works.
@@Kabab In case you wana know a quick rundown There are two (one) kinds of lift, Newtons and Bernoulis (and Bernoulis one is not really a thing, and that was demonstrated) Newtons lift is bassically you chosing a optimal shape to push the air down, or to curve the airflow. And then you are taking into consideration all sorts of things like flow separation, drag, lift Bernouli assumes that two particles that start at the start of the wing reach the end of the wing at the same time. And that was even demonstrated to be false in a wind tunnel. There is a demo and some egeneral lift physics here: ua-cam.com/video/w78JT6azrZU/v-deo.html Have fun :)
I loved my 2203 2800kv motors on my 6s taycan dumptruck, but i smoked 3 of them trying to turtle mode when the battery strap let loose. are the 23xx 2350kv motors the only ones that can run 6s or are the 3450's ok to run 6s full crank like the 2800's? or is hte 2350kv verison basically the same thing as the old 2800kv versio? if not do i need to get the 4s version and just run a 33% throttle cut when flying 6s on it?
Thanks for the insights! I am just gonna keep the StanFPV ducts I have on my Cinesplore right now. It has been flying well and it took me a while to get the StanFPV ducts.
I bought standfpv ducts long time ago but never installed. accidentally bought 3" that mount 2.5" props. Wanted 4" for 3".. so it worth putting on even if I go down a half a inch
Very interesting video, thank you for sharing the explaining everything. One question I did have around the 18 minute mark you are talking about constricting the air inlet, and I believe you mentioned it reduced noise but you lost the benefit of the added lift from the lip. Have you tried to design a duct that does both? So in the picture in the video keep the inside edge the same but the outside edge get flared out to give you the lip too. Not sure if that makes sense or if it would work/give you the benefit of both or not.
In general, multirotors with these rings around the props that have some duct-like effect benefit most from not being restricted any more than they need to be in order to get that duct-like effect
9:04 i don't think front and back cancel completely back has a shorter lever to the cg a large part of the lift generated by a wing comes from deflection, how else would a plane fly upside down? thats also why props aren't flat airfoils something interesting to try would be small wings sticking out from the ducts, at the normal cruise angle +3° another thing would be to make a frame to hold normal edf's, especially the penta props make them seem similar
Both have been tested by Free Zillion. link to his YT in the description but he doesn't make videos about all the things he tests. He's a bit of a madd scientist
@@Kabab you know, far back in 2013-14, i was thinking that quads should be ducted to cruise into environment without breaking props at every shock (props were so brittle at that time). when the FIRST 4in1 esc came out, I built a "tootpick quad" (yes yes) thanks to a toy grade quad and included it in TWO plastic frames. you don't believe me ? here it is ! ua-cam.com/video/nHQEET41fKA/v-deo.html
I think for the notched duct doesn’t work because when the blade comes swinging the air inside the notch (small but significant) has barely any space to go, and the notch creates turbulence due to flow separation and collision. We don’t see our commercial jetliners’ a turbofan engines have those for the same reason I imagine.
Hey Kabab. I've got a question/Problem I wonder if you can help me with? I've trawled the internet for answers but can't find any. I've printed and added some half ducts/prop guards to go on my 5 inch. But when I arm and then hover, the throttle increases slightly on its own. Which is obviously not ideal. Especially for flying indoors and in tight spaces. It happens with airmode on and off. Any ideas? Prop guards would really help for what I'm using my drone for atm.
This is called air mode. It's normal and is what allows the quad to actually perform well in the air. You're not supposed to sit on the ground armed for long.
I believe the "prop obstruction" you talk about with having the ducts longer at the bottom is essentially a pressure issue. By boxing in the thrust it creates a higher pressure downward of the prop reducing it's efficiency. It's worth noting that whilst you might have an issue with prop obstruction with a properly designed jet (which is where you are headed) the nozzle is what is actually producing the thrust. In a true jet the propeller doesn't really accelerate the air, it creates pressure which is then focused with a nozzle. Our props are bad for static pressure.
The main thing we discovered is that hover state and constant motion state is drastically different with the use of ducts. There's just about nothing a jet duct shares with a quadcopter duct. I do understand what you mean however it doesn't seem to apply here. Regarding the obstruction, jets don't generally change their output several times a second in order to fly. Obstruction there is actually beneficial as you describe but not here.
@@Kabab I'm not suggesting that the prop obstruction is good I'm more just pointing out that you are starting to change the nature of the system. Certain prop designs are much better at static pressure and might improve the effect. I wonder if a computer fan would hold up to cinewhoop rpm.
Chord length and angle of attack. Have played with them a bit on my own builds between 10deg and 15deg angle of attack. But things were not equal because for one duct setup I had to make a spacer to mount the motor higher to raise the prop line to match the edges of the duct. My interest is to see how much change in effect there is between a prop pushing air at the top of the duct versus a prop pulling air from the bottom of the duct. Firsy set I ever build had prop line at around the 1/2 way point of the airfoil but the 2nd set(15deg) forced me to have prop line at top of the duct. Biggest difference I noticed between the two was with first set I could still turtle mode. 2nd set I could no linger turtle.
I already commented this couple of times to other people but you will not see them so check out Jason L. Pereira 2008 study for answers to your questions.
Ducted fans in a static condition are extremely inefficient. They are using a lot of energy to squeeze that air through the duct which is why they are so loud. The bell mouth shape with the lip helps smooth the airflow coming into the duct. Maybe a more rounded inlet lip such as on a CF6-80C2 or any modern turbofan engine would help. Not really sure what the advantage is of a ducted fan on a drone though.
It's not truly a duct in this situation. It does genuinely give more thrust and more importantly, it slows down movement a lot. That's the key. Moving slow.
You said that the most important factor in performance is the motor-prop combination. Ok, but can you get that smooth low-altitude of your intro, without the ducts?
Hi! Can I ask question? Just got my fpvcycle 2204 2800kv motors and mounted it right away to my cloud149, but my motor jitters while hovering. Im using betaflight 4.1.7 with everything stock, Iflight aio f4 fc, gemfan 76mm 5 blade props. May I know if i'm missing something that causes the jittering? Thank you.
Trouble with the slotted duct design, is that any efficiency gains have to overcome the loss of efficiency you get by effectively reducing your propeller size. Most of the lift is generated at the tip, and you just hid it. It's worth remembering that some of these ideas work GREAT in the full-scale aviation industry because you can have a 5ft rotor and 3mm slot for the tip, whereas you are working with a 5inch rotor and still using a 1mm slot... same goes for the gap between blade-tip and edge of the duct. It should be 0.1% of the propeller's diameter. The bigger you go, the easier that is to achieve. I also suspect that on this tiny scale, fluid dynamics work differently: Air is effectively thicker on a smaller scale thus it's hard to know how beneficial they will be.
@@Kabab I agree, but wouldnt using low kv motors with the same style props as the DJI drones, make our freestyle drone fly the same as theirs? Cancelling out the need for a duct to make it fly "cinematically"?
I have a weird and repeatable thing happen to my Tina Whoop when I put on some ducts I designed for them out of curiosity. I flew up high, tilted forwards a little to go forwards, then (not fast, not slow) dropped the throttle to 0 and with no throttle it kept its orientation because of airmode, but instead of dropping fast straight down, it carried on gliding forwards and down. I'm guessing that happens because the ducts trap air under them?
Y'all can take really fine powdered salt and make packed molds with your 3d prints(not tpu) and remedy the plastic into a solid piece. Check out tutorials for better idea of this.
This makes me curious, what would be the difference between to the iflight ProTek25 ducts in which is half octagons and the circular ducts? I am more confused than ever.
So that means quads like the wingsuit s are just prop guards? I read what you said about narrow lower ducts being in the way cos I just noticed my racewhoop 30 frame has narrower ducts at the bottom.
Like I've said - if you're going to run defaults or a preset, then Emuflight is arguably the best firmware. For limited tuning, KISS takes the cake, and if you want to spend time dialing in a tune BF still carries a slight edge... but the EMU presets are so good, this makes sense.
@@tehllama42 I even tuned betaflight and it was ok but still had some bobbles. Emuflight took all that away and the quad doesn't feel like it's stuck in place like it did with betaflight. I've tried emuflight on 5" and didn't like it but that was about a year ago now
Is the duct even useful? I find I flights protek 35 interesting, where its just a guard not a duct, also 3.5 inch props feels like a better idea that trying to hail a hero 9 on a 3 inch ducted whoop. I see they're using the short wide motors also!
the protek 35 doesn't have ducts. Those are just prop guards. Actual ducts that have been tuned are very very good. If they're not tuned or poorly designed they're awful.
I really love your testing approach! Do you have any info on the curvatures? What’s the most efficient? Like what if one makes the lip more like the edge of a wing and the rear piece thinner... like a wing?
you can't make it a 90deg joint but also making it too gentle of a curve won't do anything. It doesn't need to be a huge saucer. Anything in between those two seems to work similarly.
I so want to build a cine quad but I’m so damn broke right now it’s pitiful. The bs lockdown straight up murdered my bank Accts this year 😢. I’m lucky tho that I do still have a couple 30x30 and a couple 20x20 escs and 5-6 revoltosd’s and a few sets of 2207’s for repairs on my race rigs or even my 2 freestyle rigs. But till about 3 weeks ago haven’t flown much at all the last 6 months. The one time I did fly during the last 6 mths I blew up my Falcox gtb339(from the first batch Fl1 sent out and it last me much longer than I expected) lol, but it went thru 4 races and tons and tons of practice. If my notes are right I got 150+ 525mah 3s and 300+ 525mah 2s packs thru it(left a 85% throttle cap and never changed it). But I found it weird that out of all of the crashes and hitting race gates and trees head on at full clip, it was clipping a tiny branch that took out either the motor or esc, haven’t had time to put another motor on and see which is dead(betting the esc). But I’m back to flying 5” and posting on here and Instagram 👍. Kinda wanna get some ducts for my dolphin1 and use it for some cine.
@@Kabab I’ve always said at least since my wreck in 2001 that left me in a coma for 3 months that it would be the slow crash that kills me. Funny but not funny. I used to race with the uscca and got into a wreck at the road course in Atlanta, got pushed into a wall doing 140mph... fractured c6, tiny crack in my skull, and then had an extreme fear of driving for 3 years. Not fun especially being a car guy. But I can say that was the one and only wreck I’ve ever been in and no speeding tickets in 20 years. Lol.
@@archer4922 I had a similar wreck that wasn't even my fault. I was stopped and someone decided to drive on the wrong side of the road. Barely recovered from that one. Cheers 🍻
This is what I used to believe as well until I flew a duct that actually performed right. Without ducts, cinewhoops fly poorly for their intended use and I might as well just use a 5" quad. I understand completely what you're saying but I would bet your mind will change if you flew one that worked right just like my mind did.
@@Kabab your good looking footage doesnt have the audible noise.. am happy with my "cinema" rigs but the environments where i can and like to fly are just not going to take it - people will apporach and complain. all the things i did to reduce the noise were like 10% in the end. this is not going to change significantly except by magic. noise level is a very important part for my expectations in terms of performance.
Na, noise doesn't change. Unless you drastically increase the prop size and keep the weight the same, you get the same noise output for any given AUW within an inch or two prop size change.
I flights protek 35 does basically this, it has solid injection moulded skinny prop guards, but no ducts. Looks like its a great evolution on the cine whoop platform
@@cinialvespow1054 prop gards are not much use in flight performance. They actually make performance worse. Actual ducts are a very notable improvement in performance
Gemfan has. Their 3 blade 75mm and 5 blade 76mm. Ducts come in all shapes and sizes and you also don't want a perfect fit prop or as soon as you touch something it could bind and you'll fall out the sky
If you mean props that have ducts built into them, I think that would be a good way to go too. Sure the wright is gonna be annoying to have spinning but with a 2305 motor or something it won't be an issue and the whole system will be lighter despite the bigger motors
@@Kabab That's exactly what i meant. Question would be how the spinning duct would affect the aerodynamics, yet still, while they would be safer than regular props, they might cause some trouble when bumping into things, not to mention people. Guess when it comes to safety the basic cinewhoop design is still unbeatable.
So you basically reinvented original tiny whoop ducts, just for 3" props xd That final design is basically it www.rcgroups.com/forums/showatt.php?attachmentid=10048654
@@Kabab Yea, some people do mods to these ducts, when they cut off pieces of duct's bottom part but I noticed worse performance after doing this, even when the whoop was a touch lighter than before
Without RSGo the quad flies like it has RSGo applied. You can see my previous videos at the link in the description about the build. I use RSGo to change the file from 4:3 how I shoot to 16:9 with the lens distortion improved. The warping is from that lens distortion adjustment. This video has RSGo applied at the lowest setting which is almost off but it still does a very little bit.
@@Kabab oh ok . I actually like that look that rsgo does. That why I'm about to have to buy a new computer to use 64bit programs like rsgo. It wout help my vids so much. I already got it locked In with your 2203 motors, just need that last little bit out of it lol.
@@cinialvespow1054 not really warping like alot of other stabilizer apps but it does make for a slightly different looking video. And the lens distortion fix adds to that look.
There is a complete research paper on the Drone duct design. I guess you would find this extremely helpful. ninum.uit.no/bitstream/handle/10037/9982/thesis.pdf?sequence=2&isAllowed=y
The research paper that you linked to provided only measurements from static testing which may give us a good idea of how these duct designs perform in hover mode, but I did not read anything that might simulate flight tests at various flight speeds. Motor efficiency while hovering may be much higher than it would be in the typical flight plan of these small FPV quads. I have never seen any wind tunnel testing of ducted propellers in the 4 inch or 5 inch range. I think the best tests for efficiency would factor in the full range of flight speeds and the angle of flight incidence of the quadcopter to evaluate the air resistance of the duct while in typical flight. a wide range of various flight maneuvers that are the core flight regime of these small FPV quads may also not be significantly more efficient with the duct. There are a number of papers that have been written about the improved overall efficiency that can be high enough to offset the added weight of the duct. That improved efficiency in hover mode would definitely lend itself to slow flying multi-rotors where extended battery life would prove beneficial to the flight plan. But more research in high speed FPV flight is needed.
Random ducts or cylinders or prop guard designs will hurt flight performance quite a bit. A duct design tuned for the prop and frame can significantly improve the ability to fly smoothly and slowly as well as increase the efficiency of the quad because of the lift effect.
@@Unnaymed this video is 30fps. The blur is intentional. The frame rate doesn't really have much to do with the blur but it does have a lot to do with the iso and the way the aperture works.
Coming from a life long RC "everything" guy. For God Sake man! Get yourself some MIP drivers and be gone with that knock off hex driver that looks like the tip got ran over! amzn.to/3oEkQoi But in all seriousness. If you've never used MIP stuff, you're missing out. Get them and you'll understand immediately what I mean. They are that good. Worth every cent
CineSplore Parts, build, Recommendations: bit.ly/31Wv3Ts The motors that will make any cinewhoop fly way better: bit.ly/2JI2R1k Table of Contents: 00:00 - Intro 01:46 - Motor update 04:54 - Hover vs constant motion 05:30 - How a wing works 06:09 - How a duct is like a wing 08:05 - The drive train is more important 08:31 - How ducts help fly slow maybe 09:49 - Thrust obstruction effects 11:13 - Ways to optimize 16:16 - Effects of hiding the blade tip 17:55 - Design that reduced noise but performs bad Music: UA-cam.com/UDACHINYC Specific song: Udachi - Sky Limit This was a super duper basic duct discussion. For much more insane and amazing duct design and testing, check out and talk to this guy: ua-cam.com/channels/xOnKMnYqgzDE8A_LQIKRFQ.html Camera is a Hero 8 with this ND filter: bit.ly/36IjSkN Stay tuned to www.FPVCycle.com. We've been working extremely hard on a bunch of new things. ▼Join the FB group for more discussion: FPVCycle - Kabab FPV facebook.com/groups/379155946182689/ ▼ Tips? Patreon: bit.ly/2oGLP9b $1/mo from 1/4 of my subscribers will make me almost quit my job. Thank you -PayPal: www.paypal.me/kababfpv -Bitcoin: 1E4XZXoD4rS6MYWVWuenY7Kw2M1YgyNpoQ -Nano: xrb_1188ek5bd7tb9kw67asnp9o65byuoaxbtpxuznx1ribf75x78awywmakj55f -ETH: 0xD067F93811f2eC31CB1928901002dfdf9A492EF5 -LTC: La2KWYAjp4VT2Lq2M76pbjzXWvRyjpfCtG
If you want to brush up on how wings work: here is a short paper: www.longdom.org/open-access/calculation-of-the-air-displaced-by-a-wing-2168-9792-1000204.pdf Hint: fighter jets can easy fly upside down ;)
Here's some research that has been done, and gives a solution capolight.wordpress.com/2015/01/14/quadcopter-rotor-duct/ what this does NOT take into account however, is the weight of the material used. So the ideal duct design on paper might actually add more weight than thrust in the real world which is what I think you are finding with shorter duct height and a smaller lip proving to be the most practical.
I've read this and the papers it's based off of. They almost totally negate the motor and prop entirely. They exclusively look at the duct when 90% of the work and 100% of the control performance is being done by the motor and prop
This is what I used to believe as well until I flew a duct that actually performed right. Without ducts, cinewhoops fly poorly for their intended use and I might as well just use a 5" quad. I understand completely what you're saying but I would bet your mind will change if you flew one that worked right just like my mind did.
Iflight protek 35 looks very interesting. I'd love to try it. From videos it seems to fly way better than any ducted cinewhoop, including the cinesplore. Just solid injection moulded prop guards
@@Kabab Cool maybe some day.... Was told the drag from the radiator scoop/duct thing on a P-51 is cancelled out by it's design. Smaller opening in front larger in the rear.
@@fubar4fpv what you're thinking of is the Meredith effect (which works because the radiator heats the air and the duct converts the heat into thrust). Nothing to do with quad ducts.
those intro shots were outstanding.
And that synth
Unpopular opinion in your viewer base, but as a guy who just spend the entire weekend repairing and improving just 4 quads, I would love for your setups to be available as prebuilt versions. Tuned and ready to go.
In time it will be. I've gotta finish building out the lineup first. Almost done.
The curve "recruits" more air, actually sucking more air in which is then added to thrust propellers create, provided that the propeller blades are very close to the inside of the duct.
I appreciate the effort you put into your videos. A lot of perspective lies within
Thanks for sharing Bob! Love those kind of videos you make.
If there were more technical videos like these in the FPV community, improvements in certain areas would be quicker and people should not reinvent the wheel every time. Much like open-source communities work.
I used to work in a manufacturing environment where we used air knives to blow downward on products. The air knife employed compressed air that came out of a nozzle and blew across the flat surface of the knife creating a sheet of air that was moving about 40 mph. At the end of the knife was a 90° down facing curve and nothing else. As the air passed over the curve it did not continue out into space, but rather, it turned and followed the curve, thus blowing straight down. At the bottom of the curve, the flat flowing air was moving 90 mph and was thin and long. Hence the term, air knife. The real beauty of this was that it didn't take more energy to make 90mph air.
By sucking a large volume of air into the duct, you are causing the air at the edges to flow over the curve and speed up. If you keep the inside of the duct straight and smooth, the faster air should stay along the edges and blow straight down causing more thrust. And I think, that because the faster air is in a ring it will cause the flow of air to act more like a column of smooth air and be less turbulent.
I think that what you need to do to get the best effect, is to top mount the motors so that the frame, hardware and motors are all above the column of air so as to not disturb the column and make it turbulent.
This is all assuming that there's a very high amount of pressure behind the column of air and the duct is acting like an actual duct meaning there's no gaps all around the column of air. Unfortunately neither of those are true. There isn't much pressure created by the prop and the duct is very inefficient.
Three words
Wind Tunnel Smoke
Understanding that we use “propellers” in hybrid as a bit of a“rotor” in flight.
Thrust and Lift blend
Hover is pure thrust
Flight is a gradient of marginal lift and trust.
So its mostly vectored thrust, more stuff pushed through a medium is an exercise in drag , the drag smooths.
Nice to play and watch.
LOL I thought the grass in the ducts in the thumbnail was some kind of new duct coating for efficiency
Yea I thought he was going to say coat them to get smaller prop duct gap haha
i thought it was a landscape and someone put in white spots
didn't have my glasses on 😂
I'm glad to see I'm not the only one to own a 4-blade weed whacker! 😂
I've also done a lot of duct optimization. For me, the ultimate goal is to get longer flight times. My recent testing showed that my 3D printed ducts, which weigh just about the same as the stock ducts, give about a 10% increase in flight times. I'd be interested in seeing how they stack up against the ones you're using. One thing to note is that mine are tightly matched to the diameter of the gemfan 5 bladed props. To do this I embedded nuts in the print rather than pressing in threaded inserts, which I found to be too variable in position. I then adjusted the ID of the duct by .5mm steps until fresh ducts matched fresh props. I also designed in tabs which can be used to connect the fore and aft ducts, resulting in a much stiffer airframe.
To get maximum flight time and efficiency, you'll need to do as you did and tune the duct ID to the prop but also tune the lip on top of the prop disk. The prop should sit just below the vertical point of the lip curve and you gotta play with how drastic or gentle of a curve you design into it. Too gentle and you're not getting enough air passing quickly over the curve. Too sharp and you're just causing more turbulence. The curve on my duct design is actually limited by the print. Because we print the mounting side first, we can only do so gentle of a curve. Since I have a very serious powertrain, I didn't find the curve design variation to make too much of a difference in my testing however it should be a bit more of a gentle and longer curve than what I've got on my design.
@@Kababa lot of suggestions you presented here are proven by stuides like Jason L. Pereira 2008 and these ideas mostly generate from them. People like Capolight actually tried to get as close as possible to their recommended optimal duct design and saw 40% efficiency increase. The reason people having better results with cut squirt ducts from the original one is a great example if done wrong, they stray away from optimal. You still see the benefits if the weight to gain ratio is still good but not as much as 40% of course.
Duct height, diamater related to prop, gap between duct inner wall and prop tip (%0.1 of duct diamater), inner wall curvature angle, top lip radius related to duct height and optimal tip for the props are all tested in that study and they even give you the optimal design so you can fit them to your prop diamater.
Your video is amazing and explains a lot. Can there be better ducts? Yes. As I said there are people out there claiming 40% efficiency increase which is close to the claims of 46% in the study.
All that said, itnis of course harder than it looks. We do not all have machine shops and access to exotic materials to make a hobby craft perfect. All these rtf drone companies long gave up from an optimal duct and went to prop guards because newer generation motors can compensate a lot and bring up the efficiency. But if you manage to make the perfect duct for your size and match it with these motors, you can see a lot more benefit.
@@fpvosman The latest ducks that we have are a much shorter duct design that tends to have the aerodynamic benefits as well as the lower weight we prefer. This entire duct apparatus is not really a duct. It's sort of a pseuduct that happens to work because it has the aerodynamic shape of a duct and there is some air flowing through it in the correct direction. If you have a perfect system that is sealed and functional then you can see those high efficiencies but it's unreasonable to strive for that on something so rudimentary as what we are doing here. I have actually created a duct that the props extend into the duct. The duct has a channel for the end of the props such that there is no gap between the duct wall and the prop. It is essentially 100% closed because of the overlap. In that particular instance, the noise was insanely loud but the efficiency did go up a bit at the expense of response performance because of reasons I cannot even explain
hmm... I would fit one of these to my new micro, but there's maybe a 2mm gap between the prop swings. I somehow managed to cram 4 inch props on a 130mm frame.
I recently switched to stan fpv ducts from stock could 149 ducts based on your recommendation probably months ago and the difference in performance way significant, more precise control and smoother operations.
I think in general cinewhoops are just gonna be heavy and inefficient. I think you should also consider weight added vs efficiency gains when you test cinewhoops because I find everything about their design adds weight at the sacrifice of efficiency - the ducts, bigger battery, deeply pitched props, gopro - all of these are fighting the added weight while contributing more weight.
Do you think an asymmetrical duct design would help with lift generated? You don't really need the lip around the whole duct, just the front part.
Free zillion has recently tested the asymmetrical duct. Some interesting results but he hasn't shared on his channel unfortunately. But yeah it flies like a plane but doesn't really go slow. Every bit of weight matters on a cinewhoop. The CineSplore frame is overall a low weight frame with low weight ducts. It's not efficient but 3-4min from a 4s 1100mah and a hero 8 is till pretty decent
SO awesome! The airfoil aspect that tends to 'tip' the kwad verticle is more accentuated on the squirt because the front and back ducts are one piece, and so the airfoil edge creating lift is only at the very front of the frame and doesn't balance out as it might with two separate ducts and an airfoil at the center as well as at the front.
My understanding of the primary benefits of ducts in a hover state is the that reduce tip losses separating the high and low pressure zones. The second benefit which is only really applicable to the ducts with the smaller exit is that by reducing the area of the exit it increases the velocity of the airflow. This ultimately reduces the static pressure of the airflow coming off the prop reducing the apparent disk loading.
Quick disclaimer I'm only an engineering student so there is a decent chance I'm wrong
In this specific case, what we're running aren't true ducts. Even if the prop tip is scraping the walls. The prop tips would need to sit inside a very closely fit channel in the wall of the duct to actually have true duct performance. This isn't practical for our purposes however. There are some benefits to ducts that can be explained but the end result is that it needs to be tuned right and it flies great when it is
@@Kabab i agree with you that the ducts aren't true ducts, however I'm am if the opinion (note I haven't flown any quad with ducts this is purely from my understanding of the aerodynamics) that whilst many of the benefits of ducts aren't particularly prevalent in the ducts that people are using they are still in effect. furthermore the stanfpv ducts really do seem to have some of the benefits of ducts despite their imperfect fit. all in all I'm still not a huge fan of ducts but I'm curious to see what benefits could be had from making ducts with a better fit and props to match.
@@robinbiskupic2639 if you fly something with ducts that actually work, you can very very easily feel the benefits. Super smooth, slow, controlled flying.
Pretty interesting, Bob! And it makes a lot of sense! 😊
Stay safe there with your family! 🖖😊
Smaller outlet means nozzled, bigger means diffused. Nozzle increase exit speed, diffuse reduce them. Make the bottom bigger and add a fix prop at the exit (act as counter rotating).
So that the driving props lift the drone, the fixed props lift the ducts.
Taller stator motor always better, wider stator reduced props efficiency.
Ducts surface are smooth and glossy, sturdy not flexi. Monocoque is the best.
- 2 cents
The perfect duct/prop combo has not yet been made.
always pushing for innovations :)kudos bob
The theory of lift that Kabab talks about here is based off Bernoulli’s principle using conservation of energy. But there are two other theory’s, the Newtonian theory using conservation of momentum and the coanda effect which basically uses an attached flow to redirect the flow off air to produce lift.
As for the exit hole smaller than the prop you will have an increased air velocity at the point of exit with a lower static air pressure this can be calculated using Bernoulli’s equation
Ironic that we’re back at 2204 but in much smaller weight quads. Granted it’s a premium motor.
Yep. 2204 is a 3" motor now 😅
Wow those intro shots was awesome thanks for sharing..
I like the short ducts that are on my ET Max. You get some of the benefits of the duct with creating drag in flight. I thing that they also make for smoother yaw spins as wind isn't hitting the prop from the side as you rotate. They allow for smooth, fast flight down low and aren't bothered much by side winds. The ducts also come in handy when blasting your way through scraggle.
Nice flying brother 🔥🔥✌️📸
Yoooo you talked to a Northrop Grumman engineer? That’s so cool!!
I'm glued to the info you're throwing out. Great video.
With the stanfpv ducts, the bottom portion having a smaller diameter actually creates a nozzle rather then disrupts the air flow. So the air leaving the duct is actually traveling faster then a duct with a straight wall design. However, that doesn't necessarily add to the benefit of the prop because props pull rather then push. If the thrust was generated by a jet or rocket engine then the nozzle would aid in the thrust, (up to a certain speed cause then a reverse nozzle actually aids in thrust for the rocket.) Since the nozzle isn't really helping the prop what it is doing is causing unnecessary pressure inside the duct, which could affect prop efficiency.
With the short duct height you are really just getting rid of unnecessary friction. Which would effect efficiency probably more then the weight savings. I'm sure you tried multiple different heights but I'm curious how short of a duct you tried. Your final duct was probably the threshold of duct benefit and losses due to friction.
The smaller exist causes obstruction. These aren't jets. They're weak motors spinning props. The motor and prop is still doing 95% of the work. The duct needs to get out of the way.
The intro got me in a weird MIND set and Focus ! Still need to finish this vid ! thanks Kab
Before the weather changed I was flying the 2203 daily never had a issue. Love those motors
The small lip isn’t for lift. It’s for smoothing the airflow by reducing the entry loss.
Whatever it's for, it needs to be a certain shape and the entire duct produces more thrust at better efficiency than without it
Bernouli principle is not related to the wing lift, but it is a common myth :)
there are numerous demonstrations on youtube. It is more of a reactive thing, you go up about as much as you push air down
yeah I knew it was something about Bernoulli but also not. I left out attack angle here because it doesn't apply but I know attack angle is probably more than half of how a wing works.
@@Kabab In case you wana know a quick rundown
There are two (one) kinds of lift, Newtons and Bernoulis (and Bernoulis one is not really a thing, and that was demonstrated)
Newtons lift is bassically you chosing a optimal shape to push the air down, or to curve the airflow. And then you are taking into consideration all sorts of things like flow separation, drag, lift
Bernouli assumes that two particles that start at the start of the wing reach the end of the wing at the same time. And that was even demonstrated to be false in a wind tunnel. There is a demo and some egeneral lift physics here: ua-cam.com/video/w78JT6azrZU/v-deo.html
Have fun :)
@@Kabab The wind tunnel demonstration in the video from the previous comment is at 6:29
Dayum, all of your vids are very educational.
Thanks for pushing this art forward so diligently! You da man! Everyone go to LA and have him work on your teeth! 😉👍
I loved my 2203 2800kv motors on my 6s taycan dumptruck, but i smoked 3 of them trying to turtle mode when the battery strap let loose. are the 23xx 2350kv motors the only ones that can run 6s or are the 3450's ok to run 6s full crank like the 2800's? or is hte 2350kv verison basically the same thing as the old 2800kv versio? if not do i need to get the 4s version and just run a 33% throttle cut when flying 6s on it?
Thanks for the insights! I am just gonna keep the StanFPV ducts I have on my Cinesplore right now. It has been flying well and it took me a while to get the StanFPV ducts.
they're also on thingiverse if you wanna print yourself.
I bought standfpv ducts long time ago but never installed. accidentally bought 3" that mount 2.5" props. Wanted 4" for 3".. so it worth putting on even if I go down a half a inch
wow This place is so beautiful 🌲
Very interesting video, thank you for sharing the explaining everything. One question I did have around the 18 minute mark you are talking about constricting the air inlet, and I believe you mentioned it reduced noise but you lost the benefit of the added lift from the lip. Have you tried to design a duct that does both? So in the picture in the video keep the inside edge the same but the outside edge get flared out to give you the lip too. Not sure if that makes sense or if it would work/give you the benefit of both or not.
In general, multirotors with these rings around the props that have some duct-like effect benefit most from not being restricted any more than they need to be in order to get that duct-like effect
9:04 i don't think front and back cancel completely
back has a shorter lever to the cg
a large part of the lift generated by a wing comes from deflection, how else would a plane fly upside down?
thats also why props aren't flat airfoils
something interesting to try would be small wings sticking out from the ducts, at the normal cruise angle +3°
another thing would be to make a frame to hold normal edf's, especially the penta props make them seem similar
Both have been tested by Free Zillion. link to his YT in the description but he doesn't make videos about all the things he tests. He's a bit of a madd scientist
Very interesting. Thank you for your commitment, and thanks for sharing.
Just beautiful
We've come full circle with 2204s! It only took 6 years!
Yep and now 2204 is a 3" motor 🙈
@@Kabab you know, far back in 2013-14, i was thinking that quads should be ducted to cruise into environment without breaking props at every shock (props were so brittle at that time). when the FIRST 4in1 esc came out, I built a "tootpick quad" (yes yes) thanks to a toy grade quad and included it in TWO plastic frames. you don't believe me ? here it is ! ua-cam.com/video/nHQEET41fKA/v-deo.html
I think for the notched duct doesn’t work because when the blade comes swinging the air inside the notch (small but significant) has barely any space to go, and the notch creates turbulence due to flow separation and collision. We don’t see our commercial jetliners’ a turbofan engines have those for the same reason I imagine.
The main difference between planes and quads is that quads are always flying in a hover state even at max forward speed. Things work very differently
Good one. Iam just shifting from 1408 to 2205 iflight motors on bumble bee frame. Hope 2205 is not over kill?
Nope. It'll be excellent
Hey Kabab. I've got a question/Problem I wonder if you can help me with? I've trawled the internet for answers but can't find any. I've printed and added some half ducts/prop guards to go on my 5 inch. But when I arm and then hover, the throttle increases slightly on its own. Which is obviously not ideal. Especially for flying indoors and in tight spaces. It happens with airmode on and off. Any ideas? Prop guards would really help for what I'm using my drone for atm.
This is called air mode. It's normal and is what allows the quad to actually perform well in the air. You're not supposed to sit on the ground armed for long.
I believe the "prop obstruction" you talk about with having the ducts longer at the bottom is essentially a pressure issue. By boxing in the thrust it creates a higher pressure downward of the prop reducing it's efficiency. It's worth noting that whilst you might have an issue with prop obstruction with a properly designed jet (which is where you are headed) the nozzle is what is actually producing the thrust. In a true jet the propeller doesn't really accelerate the air, it creates pressure which is then focused with a nozzle. Our props are bad for static pressure.
The main thing we discovered is that hover state and constant motion state is drastically different with the use of ducts. There's just about nothing a jet duct shares with a quadcopter duct. I do understand what you mean however it doesn't seem to apply here. Regarding the obstruction, jets don't generally change their output several times a second in order to fly. Obstruction there is actually beneficial as you describe but not here.
@@Kabab I'm not suggesting that the prop obstruction is good I'm more just pointing out that you are starting to change the nature of the system. Certain prop designs are much better at static pressure and might improve the effect. I wonder if a computer fan would hold up to cinewhoop rpm.
Man, loved this content!
What happened with GEPRC Cinequeen 3'' ducts? I remeber you mentioned them behaving awesome and wanting to test them? Where do they fit in this story?
We've got them in the store. They fit the 3" tooth fairy 2. I just haven't announced it yet
Chord length and angle of attack.
Have played with them a bit on my own builds between 10deg and 15deg angle of attack. But things were not equal because for one duct setup I had to make a spacer to mount the motor higher to raise the prop line to match the edges of the duct.
My interest is to see how much change in effect there is between a prop pushing air at the top of the duct versus a prop pulling air from the bottom of the duct. Firsy set I ever build had prop line at around the 1/2 way point of the airfoil but the 2nd set(15deg) forced me to have prop line at top of the duct.
Biggest difference I noticed between the two was with first set I could still turtle mode. 2nd set I could no linger turtle.
yeah attack angle is more than half of how a wing works...didn't wanna get too complicated
I already commented this couple of times to other people but you will not see them so check out Jason L. Pereira 2008 study for answers to your questions.
Great explanation thank u
How much more do the 2204s weigh compared to the 2203s? Will I feel a difference on my 5“ ultralight 3/4s)?
About a gram. You won't feel any difference but more power and more control
tilting motor arms + ducts? :)
Prop wash city
Ducted fans in a static condition are extremely inefficient. They are using a lot of energy to squeeze that air through the duct which is why they are so loud. The bell mouth shape with the lip helps smooth the airflow coming into the duct. Maybe a more rounded inlet lip such as on a CF6-80C2 or any modern turbofan engine would help.
Not really sure what the advantage is of a ducted fan on a drone though.
It's not truly a duct in this situation. It does genuinely give more thrust and more importantly, it slows down movement a lot. That's the key. Moving slow.
You said that the most important factor in performance is the motor-prop combination. Ok, but can you get that smooth low-altitude of your intro, without the ducts?
yes I can without ducts but the speed would be higher and less consistent. the quad would also be less efficient
Always learning, thank you!
Hi! Can I ask question? Just got my fpvcycle 2204 2800kv motors and mounted it right away to my cloud149, but my motor jitters while hovering. Im using betaflight 4.1.7 with everything stock, Iflight aio f4 fc, gemfan 76mm 5 blade props. May I know if i'm missing something that causes the jittering? Thank you.
Make sure your using a good capacitor and it is applied correctly. Also, try using emu flight or BF 3.5.7
@@Kabab thanks! Will try your advise today. I really love how these motors look 👍
Trouble with the slotted duct design, is that any efficiency gains have to overcome the loss of efficiency you get by effectively reducing your propeller size. Most of the lift is generated at the tip, and you just hid it. It's worth remembering that some of these ideas work GREAT in the full-scale aviation industry because you can have a 5ft rotor and 3mm slot for the tip, whereas you are working with a 5inch rotor and still using a 1mm slot... same goes for the gap between blade-tip and edge of the duct. It should be 0.1% of the propeller's diameter. The bigger you go, the easier that is to achieve. I also suspect that on this tiny scale, fluid dynamics work differently: Air is effectively thicker on a smaller scale thus it's hard to know how beneficial they will be.
The engineer things it's got a lot to do with the fact that it's not in constant motion with air already being forced into the duct.
You should add horizontal fins to the outside edges of the ducts if you want more lift, lol.
Some have tried that. It actually does work to some extent
@@Kabab I'd be curious to see one, they must have an "organic" look to them.
@@yannickg6904 talk to free zillion on facebook
Good job 🚀🕹🎥💪🤩
the grass in the duct looks kinda cool
Thanks
I love how much you explain yourself. I feel like this is still you trying to keep it short lol. How about iflight making 2203s now?
What can I say? It's the reason why my new motors won't have any sizes on them.
I am curious, why use ducts at all? DJI seems to get away with it, by just using low kv motors.
DJI doesn't make anything in this category. DJI doesn't make any full manual flying quads yet....soon they will have one.
@@Kabab I agree, but wouldnt using low kv motors with the same style props as the DJI drones, make our freestyle drone fly the same as theirs? Cancelling out the need for a duct to make it fly "cinematically"?
Hey kabab do you recommend putting the GoPro 9 on the glide frame for my new build also has is the updated glide on tbs store
I've got new motors coming specificity to carry the hero 8 and 9. They're a pretty nice step up in performance with no weight penalty
@@Kabab sweet, just ordered the glide from the tbs store, can’t wait for it to arrive :))
I have a weird and repeatable thing happen to my Tina Whoop when I put on some ducts I designed for them out of curiosity.
I flew up high, tilted forwards a little to go forwards, then (not fast, not slow) dropped the throttle to 0 and with no throttle it kept its orientation because of airmode, but instead of dropping fast straight down, it carried on gliding forwards and down.
I'm guessing that happens because the ducts trap air under them?
ducts make everything respond a little slower so once you get air rushing into the duct, it doesn't immediately slow down when you cut the throttle.
@@Kabab Thanks, it helps to remember & think about how air is still a fluid.
Do the ducts really help more than the weight savings and flight performance of a 3 inch quad without ducts?
yes definitely. Tuned ducts however. Random whatever designs don't work. The duct needs to be properly designed for the prop height and the quad.
Y'all can take really fine powdered salt and make packed molds with your 3d prints(not tpu) and remedy the plastic into a solid piece. Check out tutorials for better idea of this.
Hopes to work for Northrop Grumman soon!
This makes me curious, what would be the difference between to the iflight ProTek25 ducts in which is half octagons and the circular ducts? I am more confused than ever.
the octagon things are just prop guards. They don't have any duct effect.
@@Kabab then it makes sense, ish
So that means quads like the wingsuit s are just prop guards? I read what you said about narrow lower ducts being in the way cos I just noticed my racewhoop 30 frame has narrower ducts at the bottom.
who else thought the thumbnail was a high up 360 deg shot?
👍
I finally loaded emuflight on my cinesplore and it's a night and day difference from betaflight. Feels like a different quad
Like I've said - if you're going to run defaults or a preset, then Emuflight is arguably the best firmware. For limited tuning, KISS takes the cake, and if you want to spend time dialing in a tune BF still carries a slight edge... but the EMU presets are so good, this makes sense.
@@tehllama42 I even tuned betaflight and it was ok but still had some bobbles. Emuflight took all that away and the quad doesn't feel like it's stuck in place like it did with betaflight. I've tried emuflight on 5" and didn't like it but that was about a year ago now
Man, she's pretty smooth 🤙🏻
Could you do a video for beginners / an intro into fpv (or toothpick quads)? Thank you !
I hope to when I get a chance.
When can we expect to purchase v3 of this duct 5"? Going to make in 6"? 🙏
We're not planning a 5" cinewhoop at the moment
@@Kabab so no more production and sale or CineSplore?
@@GeordieMilne cinesplore is a 3" :)
I say try a half round lip.so it would be more like a wing
Is the duct even useful?
I find I flights protek 35 interesting, where its just a guard not a duct, also 3.5 inch props feels like a better idea that trying to hail a hero 9 on a 3 inch ducted whoop.
I see they're using the short wide motors also!
the protek 35 doesn't have ducts. Those are just prop guards. Actual ducts that have been tuned are very very good. If they're not tuned or poorly designed they're awful.
I really love your testing approach! Do you have any info on the curvatures? What’s the most efficient? Like what if one makes the lip more like the edge of a wing and the rear piece thinner... like a wing?
you can't make it a 90deg joint but also making it too gentle of a curve won't do anything. It doesn't need to be a huge saucer. Anything in between those two seems to work similarly.
@@Kabab can 3.5" props be used on 23mm short 3450kv motor?
@@AfafPrinceOSH yeah or you can go with the 16mm motor which is fantastic for med to light crafts and 3.5" with 4S. Really golden performance
Check out Jason L. Pereira 2008 study. They give you the optimal duct design. It covers all your questions.
I so want to build a cine quad but I’m so damn broke right now it’s pitiful. The bs lockdown straight up murdered my bank Accts this year 😢. I’m lucky tho that I do still have a couple 30x30 and a couple 20x20 escs and 5-6 revoltosd’s and a few sets of 2207’s for repairs on my race rigs or even my 2 freestyle rigs. But till about 3 weeks ago haven’t flown much at all the last 6 months. The one time I did fly during the last 6 mths I blew up my Falcox gtb339(from the first batch Fl1 sent out and it last me much longer than I expected) lol, but it went thru 4 races and tons and tons of practice. If my notes are right I got 150+ 525mah 3s and 300+ 525mah 2s packs thru it(left a 85% throttle cap and never changed it). But I found it weird that out of all of the crashes and hitting race gates and trees head on at full clip, it was clipping a tiny branch that took out either the motor or esc, haven’t had time to put another motor on and see which is dead(betting the esc). But I’m back to flying 5” and posting on here and Instagram 👍. Kinda wanna get some ducts for my dolphin1 and use it for some cine.
it's always the stray that breaks the camels back
@@Kabab I’ve always said at least since my wreck in 2001 that left me in a coma for 3 months that it would be the slow crash that kills me. Funny but not funny. I used to race with the uscca and got into a wreck at the road course in Atlanta, got pushed into a wall doing 140mph... fractured c6, tiny crack in my skull, and then had an extreme fear of driving for 3 years. Not fun especially being a car guy. But I can say that was the one and only wreck I’ve ever been in and no speeding tickets in 20 years. Lol.
@@archer4922 I had a similar wreck that wasn't even my fault. I was stopped and someone decided to drive on the wrong side of the road. Barely recovered from that one. Cheers 🍻
Pretty impress how ducted drone fly now,
Nice intro
I honestly thought ducts were really good vortex management and made it so that more air can get sucked into the props
Can you share you gopro8 setting for video opening? Thanks
It's in the description. I use default gopro settings with shutter at 1/60 and am ND filter. That's it. 100% default 4k/30 setting otherwise
@@Kabab thanks for replying ^^
best optimization you can get with ducts is removal. the only benefit ducts have is the subjective perception of enhanced safety.
This is what I used to believe as well until I flew a duct that actually performed right. Without ducts, cinewhoops fly poorly for their intended use and I might as well just use a 5" quad. I understand completely what you're saying but I would bet your mind will change if you flew one that worked right just like my mind did.
@@Kabab your good looking footage doesnt have the audible noise.. am happy with my "cinema" rigs but the environments where i can and like to fly are just not going to take it - people will apporach and complain. all the things i did to reduce the noise were like 10% in the end. this is not going to change significantly except by magic. noise level is a very important part for my expectations in terms of performance.
Na, noise doesn't change. Unless you drastically increase the prop size and keep the weight the same, you get the same noise output for any given AUW within an inch or two prop size change.
I flights protek 35 does basically this, it has solid injection moulded skinny prop guards, but no ducts. Looks like its a great evolution on the cine whoop platform
@@cinialvespow1054 prop gards are not much use in flight performance. They actually make performance worse. Actual ducts are a very notable improvement in performance
Could this be comparable to tiny whoop ducts? Very interesting!
Well yeah but tiny whoops are wayyy smaller. A tiny whoop can fit inside just one of this things ducts
@@Kabab of course. I bet some of the benefits on a cinewhoop duct are very minimal/not as noticable in a tinywhoop duct. But I could be wrong
👏best 👏cinewhoop👏evaaar
Why havent any of the prop makers given us the absolute perfect fit prop for ducts?
Gemfan has. Their 3 blade 75mm and 5 blade 76mm. Ducts come in all shapes and sizes and you also don't want a perfect fit prop or as soon as you touch something it could bind and you'll fall out the sky
Can we just get over ducts already and gemfan or hq start making ducted props? :D
If you mean props that have ducts built into them, I think that would be a good way to go too. Sure the wright is gonna be annoying to have spinning but with a 2305 motor or something it won't be an issue and the whole system will be lighter despite the bigger motors
@@Kabab That's exactly what i meant. Question would be how the spinning duct would affect the aerodynamics, yet still, while they would be safer than regular props, they might cause some trouble when bumping into things, not to mention people. Guess when it comes to safety the basic cinewhoop design is still unbeatable.
So you basically reinvented original tiny whoop ducts, just for 3" props xd
That final design is basically it www.rcgroups.com/forums/showatt.php?attachmentid=10048654
sort of. Tinywhoop ducts should actually be shorter for improved performance or should have an expansion on exit.
@@Kabab Yea, some people do mods to these ducts, when they cut off pieces of duct's bottom part but I noticed worse performance after doing this, even when the whoop was a touch lighter than before
@@flowrfpv could mean the air flow is mixing then. Maybe an expanded exit will be better. 🤷🏻♂️
The intro had reelsteady right. Can't tell really. I saw some warping and made me think of reelsteady.
Reels ready does warping? I thought it was pure gyro based reframing. I wonder if there's any app that does only the gyro reframe and not warm
Without RSGo the quad flies like it has RSGo applied. You can see my previous videos at the link in the description about the build. I use RSGo to change the file from 4:3 how I shoot to 16:9 with the lens distortion improved. The warping is from that lens distortion adjustment. This video has RSGo applied at the lowest setting which is almost off but it still does a very little bit.
@@Kabab oh ok . I actually like that look that rsgo does. That why I'm about to have to buy a new computer to use 64bit programs like rsgo. It wout help my vids so much. I already got it locked In with your 2203 motors, just need that last little bit out of it lol.
@@cinialvespow1054 not really warping like alot of other stabilizer apps but it does make for a slightly different looking video. And the lens distortion fix adds to that look.
There is a complete research paper on the Drone duct design. I guess you would find this extremely helpful.
ninum.uit.no/bitstream/handle/10037/9982/thesis.pdf?sequence=2&isAllowed=y
The research paper that you linked to provided only measurements from static testing which may give us a good idea of how these duct designs perform in hover mode, but I did not read anything that might simulate flight tests at various flight speeds. Motor efficiency while hovering may be much higher than it would be in the typical flight plan of these small FPV quads. I have never seen any wind tunnel testing of ducted propellers in the 4 inch or 5 inch range. I think the best tests for efficiency would factor in the full range of flight speeds and the angle of flight incidence of the quadcopter to evaluate the air resistance of the duct while in typical flight. a wide range of various flight maneuvers that are the core flight regime of these small FPV quads may also not be significantly more efficient with the duct.
There are a number of papers that have been written about the improved overall efficiency that can be high enough to offset the added weight of the duct. That improved efficiency in hover mode would definitely lend itself to slow flying multi-rotors where extended battery life would prove beneficial to the flight plan. But more research in high speed FPV flight is needed.
I thought the Duct was just too be able to fly close proxy and around people, but that overall a ducted prop performs worse as a nonducted one.
Random ducts or cylinders or prop guard designs will hurt flight performance quite a bit. A duct design tuned for the prop and frame can significantly improve the ability to fly smoothly and slowly as well as increase the efficiency of the quad because of the lift effect.
Nice. ;-)
nice vid love youre work do watch RCmodel reviews?
Of course. I love bruce
Great
But this is 30fps. I don't record in 60 😅
@@Kabab you should ! :D
@@Unnaymed I like the blur that comes with 30fps. When you go to 60 it completely changed the way the shutter speed works
@@Kabab 60fps with shutter speed @1/60s are great no? With my phone it's great.
At 30fps everything is blurry.
@@Unnaymed this video is 30fps. The blur is intentional. The frame rate doesn't really have much to do with the blur but it does have a lot to do with the iso and the way the aperture works.
Coming from a life long RC "everything" guy. For God Sake man! Get yourself some MIP drivers and be gone with that knock off hex driver that looks like the tip got ran over!
amzn.to/3oEkQoi
But in all seriousness. If you've never used MIP stuff, you're missing out. Get them and you'll understand immediately what I mean. They are that good. Worth every cent
I've got some but also have those
CineSplore Parts, build, Recommendations: bit.ly/31Wv3Ts
The motors that will make any cinewhoop fly way better: bit.ly/2JI2R1k
Table of Contents:
00:00 - Intro
01:46 - Motor update
04:54 - Hover vs constant motion
05:30 - How a wing works
06:09 - How a duct is like a wing
08:05 - The drive train is more important
08:31 - How ducts help fly slow maybe
09:49 - Thrust obstruction effects
11:13 - Ways to optimize
16:16 - Effects of hiding the blade tip
17:55 - Design that reduced noise but performs bad
Music: UA-cam.com/UDACHINYC
Specific song: Udachi - Sky Limit
This was a super duper basic duct discussion. For much more insane and amazing duct design and testing, check out and talk to this guy: ua-cam.com/channels/xOnKMnYqgzDE8A_LQIKRFQ.html
Camera is a Hero 8 with this ND filter: bit.ly/36IjSkN
Stay tuned to www.FPVCycle.com. We've been working extremely hard on a bunch of new things.
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facebook.com/groups/379155946182689/
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Pin this one, then delete my reply plz.
If you want to brush up on how wings work: here is a short paper: www.longdom.org/open-access/calculation-of-the-air-displaced-by-a-wing-2168-9792-1000204.pdf
Hint: fighter jets can easy fly upside down ;)
Here's some research that has been done, and gives a solution capolight.wordpress.com/2015/01/14/quadcopter-rotor-duct/
what this does NOT take into account however, is the weight of the material used. So the ideal duct design on paper might actually add more weight than thrust in the real world which is what I think you are finding with shorter duct height and a smaller lip proving to be the most practical.
I've read this and the papers it's based off of. They almost totally negate the motor and prop entirely. They exclusively look at the duct when 90% of the work and 100% of the control performance is being done by the motor and prop
@@Kabab well thanks for doing all these practical tests so we don't have-to.
@@TheBaconWizard I am positive I haven't covered all the bases but I've tried to be as practical as possible
No ducts probably perform best so why not just scrap ducts and just make them as propguards which is what they are really for.
This is what I used to believe as well until I flew a duct that actually performed right. Without ducts, cinewhoops fly poorly for their intended use and I might as well just use a 5" quad. I understand completely what you're saying but I would bet your mind will change if you flew one that worked right just like my mind did.
Iflight protek 35 looks very interesting. I'd love to try it. From videos it seems to fly way better than any ducted cinewhoop, including the cinesplore. Just solid injection moulded prop guards
@@cinialvespow1054 please stop steaming comments and marketing for iflight. Prop guards actually hurt flight performance. Actual tuned ducts improve flight performance quite a bit.
@@Kabab Cool maybe some day.... Was told the drag from the radiator scoop/duct thing on a P-51 is cancelled out by it's design. Smaller opening in front larger in the rear.
@@fubar4fpv what you're thinking of is the Meredith effect (which works because the radiator heats the air and the duct converts the heat into thrust). Nothing to do with quad ducts.
It's ALL Bournulis principle. Come on dude!
Yeah I know I just need to talk with constant disclaimers to ward off the smart asses
🦆🦆🦆
a little bit too scientific for a lazy viewer