Testing 8 Innovative New Boat Propeller Designs

this is episode one of the RC test flight propeller design competition about 6 weeks ago I made a video detailing the rules of the competition and how I went about setting up this drone boat to automatically measure the efficiency of whatever propeller is attached to it since then there have been over 50 submissions and I chose to print 24 of them as of now I've already tested all 24 but 24 is a lot of propellers for a single video so I'm going to split this up into three videos we'll take a look at eight propellers per video at the end of the third video the overall winners will be announced the prizes are store credit to PCB way the first place winner gets $300 the second place gets 200 and the third place 100 so in this video I'm going to be testing these propellers let's meet our first eight contestants the very first submission I got to this competition was from someone who literally just downloaded the Baseline propeller and resubmitted it without making any changes and they said use a super hydrophobic coating on it now I've actually gotten a lot of comments in the past from people telling me I should try super hydrophobic coatings on propellers and boat holes so I figured this competition is the perfect opportunity to try it out I'll test the Baseline propeller before and after the Super hydrophobic coating is applied to see if it does anything for those of you who didn't watch the intro video the Baseline propeller is designed to be like a average kind of middle of the road boat propeller that we can use to compare all the other propellers against I arrived at this design by testing out a ton of different diameter and pitch angle variations and this is what happens to work best with our given motor so the first actual submission is the twin turnup and it was submitted by Josh Fisk he says the idea here is to reduce drag by going down to two blades instead of three and he also made a streamlined tip at the end of The Hub to hopefully get rid of that stagnation area that we were seeing in both the air shaper simulation and the underwater GoPro footage from the Baseline propellers I asked each contestant what their confidence level was that they would win and Josh's was a 5 out of 10 my thought is that it's pretty likely that this propeller will outperform the Baseline it's pretty widely accepted that two blades are more efficient than three because you can make each blade longer um I think most boats just use three-bladed propellers because it reduces the gyroscopic procession wobble that you get with two blades and also they're trying to get more thrust more Peak Thrust out of a smaller diameter because you know you don't want your props hanging down too low and then sticking up out of the water so that's I think that's why three blades are more common our next contestant is the spin doctor and this was submitted by Jacob he says that he actually uses this propeller on his efoil board and it's roughly comparable to a b Ser propeller for those of you who don't know the waging B series propeller wag Engen I don't know how to say it wag uh wag Engen B series design is probably the most popular boat propeller design on the planet it's you know that one that looks like like this you probably seen it on a lot of big ships and boats of all types Jacob's confidence level is 6 out of 10 and this propeller just so Happ happens to look really similar to the toal propeller that Hinrich from Friendship systems made for me and that was shown in the first video that propeller did outperform the Baseline propeller and this propeller looks almost identical so I'm guessing this propeller will also outperform the Baseline next up is the ring Glide propeller and it was submitted by Frank sprit he wants to reduce drag by eliminating the tip vortices and ensuring gradual flow of water into the propeller his confidence level is only four out of 10 though for some of these bigger crazier props I'm just going to impr print them because it would take a ton of resin and I'll be honest I'm not super confident that this will work really well the main reason I'm not super confident is because these blades are like Batman shaped I don't even know how to describe that but but the tip cord is like 180° so this is just going to have way too much rotational resistance to actually work well I'm printing the fdm printed props on the prusa XL and I'm using petg for the actual propeller itself and Pla for the support material and Pla does not stick to petg so that makes removing the support material super easy which is nice another thought I had is that there's a ton of surface area out on the outer diameter of the propeller and that's where things are moving the fastest you know through the water so there's going to be a ton of parasitic drag on this next up we have bigger parentheses diameter is better this was submitted by nerd 1000 he said that instead of studying for his PhD thesis defense he designed this prop using a tool called Java prop basically his goal was to maximize the span given the allowed print volume and and utilize High aspect ratio blades and his confidence level is 6 out of 10 what's with all these low confidence levels people come on have some faith in your design so sail planes use super long narrow blades because they're really efficient they have a good lift to drag ratio so the question here is will that concept apply to propellers I think it probably will if they don't snap all these propellers are printed on the formlabs form 3 plus with gray Pro resin and this stuff is really strong it's really good for a resin printer but you know there's that's a pretty thin blade and we're going to be putting 400 watts of power into it so if it doesn't break I bet this propeller will be really efficient but we'll see resin printing is also really good for propellers because you don't get all the little layer lines that you get with an fdm printer so it's got a nice smooth surface finish and that should reduce parasitic drag and hopefully be pretty efficient next up we have nodules and feathers and this was submitted by James D who is a product design engineer this propeller is basically identical to the Baseline propeller but it has the Leading Edge of a whale's Fin and the trailing edge of a bird's Wing he thinks these nature inspired features will add vortices which will reduce flow separation and hopefully increase efficiency his confidence level is 7 out of 10 a few months ago I had a ton of people send me a video about bionic propellers and apparently adding uh tubercles like those on a whales fin can delay the onset of flow separation and uh help the blade continue operating at a higher angle of attack and apparently it also makes the blades A lot quieter and at the end of this video series so in the third video I'm going to be using an underwater microphone to measure the noise levels of a few of these propellers so don't forget to subscribe so you don't miss all of the videos my hunch for this propeller is that it's probably not going to be any more efficient than the Baseline but I don't doubt that it could be quieter though that'll be interesting the panovic propeller was submitted by NAD panovic and he says this is a patent pending propeller that uses a new complex blade design and it's proven to be quieter and more efficient than and a regular drone propeller but I emailed him because his original submission had trailing edges that were too thin to print and in that email I also said hey this is just a hunch but I'm pretty sure the angle of attack is way too low for this thing to perform well and he replied saying that he's quite confident in his cfd simulations so his confidence level is N9 out of 10 my hunch is that there's just no way this thing is going to perform well and that's only because of the angle of attack the blade design I I have no idea it might be great at a higher angle of attack but it's the angle of attack is just going to kill it also I think it might break like this thing is super flimsy he said this design is made for metal and we're making it out of plastic so here's a fun one the Fibonacci flippers was submitted by will he says that this design supposedly makes for really good wind turbines so why not reverse it and throw it in the water he hopes that maybe reversing the direction might create a large amount of thrust with a semide decent efficiency and his confidence level is 7 out of 10 I don't think it's going to come anywhere near the performance of the Baseline propeller but if it pushes the boat that'll be pretty cool so I'm excited to see this one last but not least we have the Mars glider and this was submitted by Joker 1 he says that since these propellers are operating at lower Reynolds numbers he's using a low Reynolds number air foil and this specific air foil was developed for the Japanese Mars glider I Googled around for a Japanese Mars glider and I couldn't find anything so I really don't know what he's talking about but right after he submitted this design the company micronics 3D reached out offered to print a propeller so I said sure you can print this one and they did micronics is developing a SLS printer that doesn't cost a bajillion dollars so that would bring SLS technology to the high-end hobbyist Market which would be pretty awesome this prop feels pretty strong it's made out of nylon and it's also lighter than I thought it would be the surface finish is rougher than the SLA printed props but I can probably smooth that out later somehow so those are all our contestants for this first video but this is going to be a pretty boring competition if we can't actually see the propellers doing their thing so I need to devise some sort of a underwater high-speed camera setup to take video of these propellers spinning the first thing I tried was attaching this free fly Ember slow motion camera onto the boat along with a prob blend that will stick through the surface of the water the cylindrical shape of the prob blend is going to have a ton of drag and that'll make it really difficult for the boat to go fast so I 3D printed an air foil shaped sleeve that fits over the end of the probe one of the downsides to probe lenses is that they do not let in very much light this one is F14 for all you camera people out there who know what that means plus high-speed cameras have super fast shutter speeds and also need a ton of light so even direct sunlight is not going to be enough for us but luckily I happened to know a guy who makes these awesome high-powered LED modules that can be powered with LiPO batteries they are typically used on drones to light up things from the sky but they should also be perfect for this application the reason I'm trying to build this camera setup onto the boat is so that we can actually see what's happening with the propeller at speed it would be much easier to film while the boat is just tied up at the dock but then we'd only be seeing what happens during St thrust Which is far from the optimal condition for these propellers they're optimized for speeds between 2 and 3.8 is m/s or at least they should be if they're going to have any chance at winning when I'm testing propellers at the lake I need a way to keep my computer and camera batteries charged and for that I'm using the Opus Exodus 600 it's a portable power station that has 256 wat hours of battery capacity that's enough energy to push this boat for 22 Mi at a speed of 2 m/s it features dual 600 W AC Outlets USB a and C ports a 12volt DC output and inputs to connect solar panels it can charge it up to 240 WTS from solar alone and when charging it with AC it can fast charge in just over 30 minutes when I say I use this thing a lot I'm not kidding I've just started keeping it in my car because it seems like I need it every time I leave home I've used it to power all my devices during countless autonomous boat missions and when I need more power to charge big drone batteries I bring the Opus Mega 5 that can do up to 4,000 watts but the Exodus 600 is even powerful enough to run smaller power tools which is great for fixing Colin's car Opus is running a program called Opus help where 5% of their sales go towards providing power banks for those in need this helps keep the lights on for hundreds of recipients who live in places with unreliable power or who struggle to pay the power bill if you're interested in the Opus Exodus 600 it's available now on Amazon or from opus.one frames per second is borderline too slow for looking at these propellers they're spinning at around 1,700 RPM which is 28 revolutions per second that means the camera is only capturing 20 frames per rotation it's not terrible but it's maybe not the best way to see what's going on with the flow here I put some food coloring in the water it looks pretty cool but this also is just a static shot the boat isn't actually moving so the flow isn't really representative of the real operating conditions in one of my propeller test videos from last summer I realized that if I can get the RPM of the propeller and the camera's frame rate to line up you kind of get this effect where it looks like the propeller isn't spinning at all this is great for observing the flow and we can use a GoPro which can go underwater so we don't need the prob Blends I hopped into on shape and designed this symmetrical hydrofoil that the GoPro fits inside of by the way all the 3D models from this video including the propellers themselves are available from the on shape links in the description on shape is free for hobbyists so all you have to do is sign up for an account and you'll have access to everything including the native design history of all the parts like this one I 3D printed the GoPro foil on my prusa XL it took a few iterations to get the design right but eventually everything fit together that whole thing attaches to the side of the boat again it took a few tries to get it right but now the GoPro can stare directly at the propeller and get awesome shots like this one oops the footage looks good but it would be better if there was something in the water that would allow us to see the flow better for that I designed this crazy looking symmetrical hydrofoil thing that attaches to the front of the Drive Unit the goal here is to inject little air bubbles into the water while creating as little turbulence as possible I 3D printed it on the form 3 plus and the cool thing about this part is that it has little channels in it for the air to flow through the upper section gets a tube routed through it and that goes down into the lower foil section then the other side of the tube is connected to some little air pumps the whole assembly is just held on with a velcro strap and it looks like this when it's finally installed in order to get the highest possible shutter speed for the GoPro I'm using one of the stratus LEDs air modules again and the bubbler works so now we can finally start testing propellers as a quick recap from the first video what I'm doing here is having the boat run a waypoint Mission and at each Waypoint the speed is increased by 0.1 m/s excuse me it starts at 2 m per second and then tries to get all the way up to 4 m/ second but most props can't actually push the boat that fast then it turns around and comes home so I can swap props out and do it all over again 24 times for 24 propellers I should note that I'm not actually running the efficiency tests with any cameras on board all the underwater or onboard footage you see is captured separately so let's start off with our Baseline propeller from looking at the underwater footage we can see that there are some pretty serious bubble vortices coming off the tips a lot of people will probably think this is cavitation but I kind of half disagree reason being is that when we don't blow bubbles into the propellers these vortices are much smaller if not entirely absent they do show up sometimes but it's really hard to tell if a stray bubble hitting the blade is what instigates the visible spiral a true cavitation pocket occurs when the pressure drops so low that the water turns into vapor but I think the spirals we're seeing is a mixture of water vapor and air from the bubbles I think more likely than not it's a combination of cavitation and ventilation ventilation is where air clings to a surface and in this case that air would be coming from stray bubbles regardless of what's causing the spirals I think it's safe to say there's a strong tip Vortex here so let's keep that in mind as we look at other propellers the strength of the tip Vortex could be one of the things that has a correlation with efficiency I ran each propeller multiple times on multiple different days to get a more accurate measurement of the efficiency and here are the numbers for the Baseline propeller it's currently in first place because it's the only propeller we've tested so far the integral efficiency is the number we're using to rank each propeller and a bigger number means more efficient the intro video talked more about this but the integral efficiency is basically just the area under the curve when we plot efficiency versus speed now let's talk about what this graph actually shows here we can see the propeller starts off really efficient it's making 26 G of thrust per watt and by the time the motor gets up to its Full Throttle power cap of 400 watts the efficiency is down to 10 G of thrust per watt so let's pull our head out of the technical detail bucket and get back to the contest and auto mode there is zero wind it is so nice right now so I took the Baseline propeller and applied a few coats of this nanoceramic super hydrophobic coating and then let it drive before running the next test looks pretty hydrophobic to me not quite as hydrophobic as a duck but it is hard to beat nature this is an insane New Concept will revolutionize Transportation forever just kidding it's pretty average so the efficiency curves pretty much look identical and as for the numbers the super hydrophobic coating actually did slightly worse but that amount is in the noise I think it's safe to assume the coating made no difference next up is the twin turnup at higher throttle levels the tip vorticy spirals become visible even with no bubbles being pumped into the flow with the bubbles turned on I was really surprised that there still appears to be a stagnation Point behind the Hub even though it tapers off much more gradually than the Baseline propeller I guess the angle back there is still too [Music] steep here's our efficiency curves the Baseline propeller is on the top for comparison the average integral efficiency over the course of three test runs is 26.9 and that puts it in first place a the baby ducks hatched they are adorable little balls of fluff wow now it's time for the spin doctor is this pidal propeller the miracle invent mention that all those YouTube videos said it would be let's find out on the underwater view I don't see any tip vortices with the bubbles turned on there is some sort of a spiral coming out of the back but it doesn't look like it's originating from the tip which is really interesting here's the efficiency curve compared to the Baseline propeller looks pretty similar and the average integral efficiency over a few runs is 23.3 which puts it in second place we'll have to wait until the third video to see if it's any quieter than the others holy I left half of a power bar here for like 60 seconds and a bird just swooped in and ate it damn it next we have the ring Glide propeller I know a lot of people are going to say that I didn't give this propeller a fair chance because it's fdm printed but in the intro video I tested the difference between an fdm propeller and an identical SLA propeller and the fdm version was about 15% worse so if this propeller ends up being even like 30% away from the Baseline propeller I'll reprint it with SLA and test it again doesn't even fit there we go oh God God it's so bad it's already doing 16 amps at only 1.6 m/s that's terrible from the underwater video I don't see any vortices which is good I guess but this is proof that the vortices aren't everything because the efficiency was terrible the integral efficiency is only 0.46 which puts it in dead last by a long shot but I should mention this system of measurement kind of falls apart with props that can't go very fast because a big component of the integral is the max speed since this propeller has a max speed that it was relatively low the integral efficiency number we're looking at is going to be disproportionately low so for cases like this we should just look at the actual grams of thrust per watt at 2 m/s which is about 4.83 this number can't be used in comparison with the integral efficiency but at least it will allow us to still rank the really bad propellers our sixth contestant is bigger diameter is better will the high aspect ratio efficiency promises hold true let's find out I'm just I'm just dying over here it is the nicest day ever look how calm it is it's just dead flat wow if anyone's trying to get rid of their Lake housee for cheap let me know so without bubbles the prop looks like this I don't see anything sticking to the blades no cavitation no ventilation no nothing seems promising for high efficiency when we turn on the bubbles is when things start to get crazy I can see vortices but they don't originate at the tips they only start to become visible a few inches behind the propeller I'm still not entirely convinced this is pure cavitation I think what's happening is when a bubble hits the core of the vortex it instantly propagates through it almost like a crack propagating through breaking glass but that's not even the crazy part look at these wave-shaped bubbles down here they're incredible you can see the stream of Bubbles getting rolled around the vortex it's so cool I think this formation would probably be visible for most props but this prop just so happens to be the perfect diameter as to where that last line of bubbles just flows in at the right spot pretty sweet so our efficiency curve looks like this and we have ourselves a new winner the integral efficiency is 35.3 and the max speed is 3.7 m/s incredible the wind is coming do you see it do you see the wind it's right there maybe wind is an overstatement the breeze is coming oh well at least I've gotten a lot of tests in so far next up is nodules and Feathers the real question is whether or not this one will outperform the Baseline propeller in the underwater view I really don't see any differences from the Baseline propeller here's the efficiency graph it also looks very similar to the Baseline and the integral efficiency is 22.11 which is basically the same as the Baseline propeller but slightly lower putting it in sixth place now it's time for the patent pending panovic propeller will nad's cfd simulation match real life I'll give this thing a near zero chance of not breaking it's pretty flimsy but on the other hand it does have a super low pitch so maybe the low pitch will keep it from getting too much force on the blades will it break will it break will it break it's not breaking amazing in the bubble cam it looks like the only part of the propeller pushing water backwards is the root of the blades out by the tips you can see flow circulating in from the oncoming water probably because the pitch of the tip is too low to make any thrust so it's just making a bunch of drag it sounds like it's vibrating so that propeller might have broken going break the efficiency curve is opposite for some reason I can't quite figure that one out and notice that it couldn't even get up to the 2 M perss starting speed so we'll say this one did 3.5 G per watt at 1.6 m/s which is even worse than the ring Glide propeller at a faster 2 m/s this puts it in last place I would really love to see what this blade design is capable of if the pitch were correct but today is not the day for that next up is Fibonacci flippers I did a quick preliminary test to see if this thing would push the road at all and was pleasantly surprised it's impressive it actually produced way more thrust than I thought it would so then I ran it through the Waypoint Mission from the underwater view we can see that the flow kind of seems to converge inwards and it comes out closer to the tip at the back it looks like there are very few bubbles exiting through the outer diameter surely this propeller is not optimized for this motor so it would be interesting to see just how much efficiency you could get out of a Fibonacci spiral if you spent a lot of time optimizing it the integral efficiency is nine and the top speed was 2.9 m/ second so it beat the ring Glide propped by a long shot I'll give it first place in the novelty category but it comes in at Seventh Place overall last but hopefully not least we have the Mars glider selective laser centering it should be similar in strength to an injection molded propeller I didn't have high hopes for this one because the pitch and cord length at the tip are both so big that it's bound to have a ton of rotational resistance this could cause the phase current to max out at a low RPM which would result in the propeller not getting the full 400 WTS what you building uh boat for testing propellers oh you testing propeller all style of different style yeah very many so cool yeah thank you so I ran this propeller for the first time and it got an integral efficiency of 14 which is pretty bad so that night I rubbed wax all over it and then melted it with the heat gun My Hope was that this would smooth out the surface finish and it also turned out to be quite hydrophobic then I reran the test the a ended up improving the integral efficiency by 0.5 so that's good from the bubble view we can see that there are occasional patches of cavitation that stick to the backs side of the blades or it could be ventilation from the incoming bubble stream probably a mixture of both so the Mars glider had an integral efficiency of 14.55 which puts it in seventh place and its top speed was 3 m/s I don't think that low Reynolds number air foil does much when the rest of the blade design is far from optimal so that's it for episode one of three tune in next time to see if anyone can steal first place from bigger diameter is better and don't forget to subscribe and click the notification Bell to never miss an episode big thanks to everyone who submitted a propeller and also big thanks to formlabs for supplying all the resin for these propellers PCB way for supplying the prizes Mitch for helping me with the data collection system Holbrook Aerospace for the Baseline propeller template and Sebastian for helping me with the mavlink data stuff that's all for this video thanks for watching bye all

Channel: rctestflight

Views: 1,085,708

Keywords: propeller, design, toroidal, fibonacci, spiral, test, boat, competition

Id: KeTh-TIhL9M

Length: 24min 8sec (1448 seconds)

Published: Tue May 14 2024