Testing 12 Ultra Efficient Electric Boat Propellers

how yall doing welcome to RC test flight propeller design competition episode 2 in this video we're going to be testing eight more propeller designs but wait there's more we actually have a handful of bonus propellers and that's because there were a few resubmissions and a few stragglers that came in late you're not going to want to miss this we had two cfd software companies team up to produce what they think will be the best thidal propeller that I've tested so far and we'll also have a Redemption Run for the patent pending panovic propeller last time NAD panovic submitted his propeller with a 9 out of 10 confidence level that it would win and it got dead last so he resubmitted a new design and I'm going to test it in this video so now let's meet our eight original contestants our first contestant is called RC test swim and it was submitted by Dan edmiston he says that at this scale keeping the Reynolds number high was a priority and that's why he went with two wide blades the tip fences are a result of that looks about right engineering and his confidence level is 5 out of 10 he definitely went all out in making the Hub as streamlined as possible but I'm just hoping it doesn't vibrate because you know this the mass is kind of unconstrained out here next up we have whale otron and it was submitted by slav engineer he says the blade shape is inspired by the pectoral fin on a whale and the diameter is 125 mm which is just 5 mm larger than our Baseline propeller but the blades have a much higher aspect rate ratio so hopefully this reduces drag he says the air foil profiles were carefully crafted with an optimal curve along the cord line and their positions were determined based on velocity triangles in other words he did math and he's very confident that it will pay off because his confidence level is 10 out of 10 congratulations slav engineer you're the first 10 out of 10 confidence level we've seen this is wing tips submitted by Mobi Obi he says that he thinks winglets are a solid Theory but possibly underused due to their extra production costs and his confidence level is 7 out of 10 my thought is that this is going to have more rotational resistance than the Baseline propeller uh the blades are similar in size I guess they are slightly larger but there's also more of them so I don't think this is going to perform that well only because it has too much rotational resistance I think if you went with a two-bladed version of this it would probably do really well I don't know if the winglets are actually going to help or not but the salad maker was submitted by Steven Beckett he says two blades is better than three and this propeller will perform better at higher RPM and higher speed than the Baseline propeller he also said he modified The Hub to be more blunt because there was flow separation shown on the Baseline propeller in my intro video that's counterintuitive to me making it more blunt would make that worse wouldn't it so I don't understand that part but I agree with the two blade concept my guess is that this propeller will outperform the Baseline and do decently well next up we have span maxing and it was submitted by Austin Emmons he's obviously going for the biggest span possible given the 3D printer's build volume and he used open prop to design this he also made the point that we don't know what the efficiency curve looks like for this motor so it's tough to know what the target RPM and torque should be for the design that's a good point Austin's confidence level is 9 out of 10 and my thought is kind of the same for the high aspect ratio prop in the last video as long as it doesn't break or bend too much then this is probably going to perform really well this one is called sleep deprivation version one and it was submitted by tyan schillers he said that he spent more hours than he's willing to admit trying to fit the data from my first video into his mathematical model but then he gave up and just came up with this propeller somehow I don't I don't really know if we compare it to the Baseline propeller it looks like the cord is the cord of the blades is larger especially at the root and it maybe has a slightly higher pitch it also has a slightly larger diameter so I don't think I think this is going to perform worse than this one because I tried variants of this propeller that were more similar to this and they performed worse so his confidence level is 3 out of 10 next up we have ingrina Thor and it was submitted by P Schiller he said he used the Bing B series propeller calculator online to determine the diameter and Pitch ratio then he designed his own blades and added some winglets for fun his confidence level is 8 out of 10 and he also said that he thinks it will beat the Baseline propeller by at least 25% he's probably right I bet he will beat the Baseline propeller although it is it does have like a significantly larger diameter so it might have too much rotational resistance for this motor uh tough to say next we have man winglets and it was submitted by Lo van Bantam he says that manays are legendarily efficient with their little winglets and this is what inspired aircraft designers to try winglets on airplanes so why not boat propellers too he also said that the diameter and Pitch have been slightly optimized from the Baseline propeller and his confidence level is 10 out of 10 so after reading this I looked up pictures of mantta rays and they don't really have winglets so I don't know what he's talking about they do have like floppy narrow tips that can sometimes flop up and look like a winglet but uh I would not call that a winglet it's kind of a stretch so those are all our contestants for this video now it's time to go out and test them first off is RC test swim I was actually very surprised to see that the super long gradual tip didn't really get rid of the stagnation Zone there's still bubbles clinging to the tip but maybe this isn't really stagnation maybe it's just a tornado or a Vortex speaking of bubbles clinging onto things there aren't really any bubbles clinging onto the blades themselves which is a good sign that suggests they're not stalled and it looks like the flow is staying attached over the winglets as well which is kind of surprising to me because the winglets use very thick air foils I am suspicious that the winglets are going to be causing a lot of parasitic drag compared to the amount of induced drag that they may or may not be reducing for the rest of the blade the craziest thing about this propeller is it's making dual vortices one on the upper winglet and one on the lower winglet this is really interesting to me and I would love to know what's really going on here like are they both spinning in the same direction or opposite directions not sure this propeller had a top speed of 3.4 m/s and it scored an average integral efficiency of 23.1 so it beat the Baseline propeller I was actually really surprised by this I thought for sure the winglets were going to have a prohibitive amount of parasitic drag but that may not be the case I was still really curious about the Dual vortices so to find out what's going on I ran the propeller through air shaper to my delight the Dual vortices show up here too but it's not immediately obvious which way they're spinning when I looked closely at the surface friction lines and surface pressure map it started to make me think that they're both spinning clockwise if viewed from behind that makes sense if they were both spinning in opposite directions that would mean the propeller is pushing water either outwards or inwards which from the streamlines it does not look like it's doing if you haven't already noticed propellers get me really excited but I'll admit there's another project that I'm even more excited about this is it I can't tell you what they do yet but I can show you what they are these are some 3D printed enclosures but inside is where the magic happens this is one board and then the other is in here let's take a peek inside voila there it is we have a ESP 32 chip here and an STM 32 chip here so there's a lot going on on this board and if you think I could make this board myself then you're crazy cuz that's where the sponsor of this video comes in PCB way not only is pcba sponsoring this video but they're also sponsoring the prizes for the first second and third place winners of this propeller contest and if you don't design pcbs then this is still relevant to you because they also offer 3D printing injection molding CNC Machining and sheet metal services check out these parts I just had pcbway make these are CNC machined aluminum Servo shafts that go on the end of these giant servos yet another project that I'm super excited to show to you but can't quite give you any details yet the list just keeps going on and on look at this this is some super intricate CNC Machining and PCB way just cranked it out I just uploaded the cad file and said make this and they said here you go like look at that thing that is not an easy design to CN C Machine but they did it they're really good I'm telling you so big thanks to PCB way for being a huge supporter of this channel they're super useful for projects like these go check them out at the link in the description now back to the propeller tests next it's time for wh otron I initially didn't have super high hopes for this propeller but it ended up really surprising me there's nothing too crazy going on in the bubble view but the fact that the camera is coming out of the water is a that it's going pretty fast every now and then you'll see a pocket of air cling to a blade and linger for a bit but it doesn't stick around for too long this could be a sign that the angle of attack on the blades is getting close to the stall point but not too close and the wayron had a top speed of 3.6 m per second with an average integral efficiency of 28.3 that puts it in first place beating the Baseline by about 27% pretty impressive I should note that these graphs are just one test run but the final score is going to be based off of three runs at averaged together so the numbers might jump around a bit now you can't have my food bird next up is the salad maker I was pretty optimistic about this propeller from the bubble view it looks like the blunt tip definitely doesn't prevent or reduce the stagnation Zone at the back there's plenty of bubbles hanging around back there it's got some strong vortices clinging to the tips which usually isn't a good sign but it's not a deal breaker and this propeller had a top speed of 3.51 m/s with an average integral efficiency of 26.5 that's about 19% better than the Baseline but still not as good as wayron this dude just decided to fish right there it's kind of weird what are you catching here fish what is it baby fish next up is Spam maxing will the large diameter pay off let's find out and oops there it goes as the boat tests each prop I can look at the battery current and the speed here and kind of get an idea for what's going on and it is pretty clear how these like long narrow aspect ratio two bladed props just pull less current on the bubble view we can see just pure beauty that last line of bubbles gets perfectly wrapped around the vortex core and it's just magnificent I could watch this crap all day I mean look at it how cool is that it's really cool as with the large diameter prop from the last video the vortices are looking pretty thin and at higher speeds they seem to not originate from the blade itself but rather just start a few inches behind it span maxing had a top speed of 3.6 6 m/s and an integral efficiency of 37 which puts it in the lead by a long shot that's 66% better than the Baseline propeller this one's going to be tough to beat next up is sleep deprivation nothing too out of the ordinary to see here it looks very similar to the Baseline propeller while underway this one came in with a lower top speed of 3.3 m/s and an integral efficiency of 16.2 that's 27% worse than the Baseline propeller I think the reason why this one did so poorly is just that the blades are slightly too large in every Dimension and the pitch is slightly too steep that means it needs to be paired with a motor that has more torque and a faster boat hole in order to reach its full potential perfect testing conditions next we have integral line of Thor nothing too crazy to see here the vortices are nice and thin which seems to be a good sign I didn't notice any air clinging to the blades which is also a good sign and this propeller propelled the boat up to a max speed of 3.56 m/s and it scored an integral efficiency of 27 that puts it roughly neck and neck with whon it was just slightly worse than wayron at higher speeds now for mantel winglets this propeller had thick vortices in a ton of flow separation of the tips definitely more than we were seeing with the Baseline propeller this leads me to believe the wing tips are really hurting its performance rather than helping it the top speed was 3.3 m/s and the average integral efficiency was 19.7 that puts it in second to last place it did 10% worse than the Baseline next up is wing tips at first glance this propeller looks pretty normal but if we look more closely we can see some interesting stuff first it looks like the vortex is originating at the tip of the winglet this does seem to suggest that the winglet is doing something for better or worse it's not just perfectly aligned with the flow and not generating any Force the top speed of this propeller came out at 3.16 m/s with an integral efficiency of 16.6 that puts it in dead last I think this is likely due to the fact that the diameter is larger than the Baseline and there are more blades all that means more rotation drag more rotational drag means this propeller demands more torque from the motor and remember torque is basically proportional to phase current we do have some wiggle room within our torque and RPM limits to maintain the max power of 400 watts however there is an optimal point on the motor efficiency curve and if a propeller needs more torque than this optimal point the efficiency of the motor is going to drop that's probably what's happening for some of the props we've seen like sleep deprivation and wing tips it's not that these props wouldn't perform well with the right motor it's just that my motor is not the right motor for them as Austin emmans the creator of span maxing pointed out we don't know what the efficiency curve looks like for this motor so that makes it really difficult to use math to arrive at an optimal design if I do another propeller design competition in the future I'll try and get a motor efficiency curve beforehand so span maxing is our winner for this episode let's see how it compares to the bigger diameter is better which is the winner from last episode bigger diameter is better is shown in green here on average it's about 4.6% less less efficient than our new winner span maxing if you want to use any of these propeller designs for your own watercraft projects you're in luck because every single one of them is in this single on shape document many of these propellers were even designed natively in onshape on shape is free for hobbyists and it runs entirely in your web browser So within a few minutes you could be using it to design your own propellers or modifying these existing designs click on the link in the description to sign up for on shape Here's the final results for episode 2 using data from multiple test runs that's averaged together and here's the results from episode 1 and two merged together now it's time for our bonus propellers first we have this one that snuck in late it's called dual Harmony and it was submitted by black turbine this prop caught my attention because it has these little blades on the back of the Hub it turns out that these are called boss cap fins and they're used on big ships to reduce the stagnation Zone behind the Hub so in the bubble view it looks like there's definitely still a Vortex originating from The Hub but it's not fully attached like some of the other propellers here's a comparison so that could be a sign that the boss cap fin is actually working but I also see some flow Separation on the main blades which is a bad sign that could mean they are close to a stall this propeller had a top speed of 3.3 m/s and an integral efficiency of 18.6 which is about 8.8% worse than the Baseline I should note that all these bonus propellers were tested at a later date and after I had made some tweaks and improvements to the setup so don't compare these numbers to the previous tests however I also reran the Baseline propeller and span maxing along with the bonus propellers to give us a reference point so yeah dual Harmony didn't do so hot next up is forever alone submitted by Aeron nerd this is a one bladed propeller and in theory one blade should be more efficient than two if it doesn't destroy my boat the mass distribution of this propeller is balanced but the thrust load is obviously going to be very imbalanced the tip was also pretty thin and I was worried that it would break let's see if it feels balanced in the air definitely vibrating but I don't know that it's vibrating any more of the other propellers oh that's really bad yep yep yep nope I'm not doing that so it was fine in the air but once underwater it was no chill I guess the vibration is just from the imbalance and thrust so then Aeron nerd made a two-bladed version but this version is kind of cheating because the span exceeds the maximum allowed diameter I had to print it at a bit of an angle which worked but isn't optimal anyhow in the bubble view we see no Hollow vortices which is a good sign also no flow Separation on the blades themselves we do have our little waves visible down here on the bottom which shows there are indeed vortices they just aren't strong enough to rip up the bubbles and propagate around or cavitate whatever you want to call it so forever alone came in with a higher top speed than span maxing at 3.62 m/s but the integral efficiency was about 1.5% worse also I have a hunch that these super high performing propellers are starting to really push the limits of this boat and the results start to get a little fishy for example the holes could be briefly jumping out of the water or the propellers could be breaching the surface I'm not sure if stuff like that is actually happening but I have a hunch it could be anyways this propeller could have surpassed the point where increasing span increases efficiency if you go too big it's going to need more torque and less RPM and that moves you away from the optimal point on the motor's efficiency curve next up we have the air shaper and friendship systems collaboration propeller friendship systems makes a cad model software called cases and it's designed specifically for fluid mechanics applications such as boat holes propellers hydraulic systems and stuff like that what makes this CAD program special is that you can turn different design variables into parameters here's some examples you have your span and since this is a pidal propeller you have your upper blade pitch and your lower blade pitch the tip angle and so on I'm going to do my best to explain this even though I don't fully understand it myself but basically what they did is they took that parameterized CAD model and then they used airshaper to run 72 different simulations of different variations of all those parameters so that gave them a huge three-dimensional data set of a crapload of different data points they had much more than three but basically then what they do is they interpolate between data points and that allows them to find the optimal efficiency even if they didn't simulate that in the first place that's called interpolation I guess I don't really know I I didn't go to school this whole process is called a surrogate based machine learning genetic algorithm and probably hundreds and hundreds of hours of computer processing time later this is what you get this little propeller right here it's pretty cool to think that this is the result of all that work way back before I even made the propeller test competition intro video Hinrich from Friendship systems came up with this design for me and this is basically just a three-bladed tootal propeller that he didn't use any machine learning algorithms or cfd optimization to make but their goal with this new propeller was to optimize it enough to beat this original tootal propeller now we both agreed that it would be very difficult to design a teral propeller that can beat these high aspect ratio two-bladed propellers so their goal with this one was not to win the competition but rather just to beat this original teral propeller let's see if they can do it and big thanks to airshaper for generously giving all the simulation time to Friendship systems so that they could design this the thing that makes airshaper different from other cfd programs is it's all web based and it's really easy to use all you have to do is upload your CAD model set up some parameters like speed and fluid density and if it's a propeller you can select the part that spins and enter in the RPM then from that you can start the simulation and once it's finished you get to see the results it's very visual which makes it fun to look at if you want to take a closer look at any of these simulations yourself you can check them out at the link in the video description here we go the vortices look relatively weak so that's good I don't see any flow Separation on the blades so that's also good and here are the results it came in with a top speed of 3.47 m/s in an integral efficiency of 25.6 5 that puts it right in the middle of all the other propellers it beat the Baseline by about 26% in the previous testing sessions hinr original toal propeller beat the Baseline by 5% so from this we can assume that this new propeller would beat hinr original propeller by 21% so that's a really good Improvement later on I measured the phase current and RPM for this propeller versus span maxing which is the first place winner winner chicken dinner and this propeller did 1,430 RPMs at 43 amps and span maxing did 1857 RPMs at 39 amps so this propeller is spinning significantly slower and demanding more torque than span maxing this places it on a different point on the motor efficiency curve but again we unfortunately don't really know what that looks like so we don't know how that affects the efficiency but my hunch is that this propeller is demanding a bit too much current and it would perform even better if it were paired with a torqu or motor or if the blade diameter was slightly reduced would be fun to try out our next bonus propeller is called propell dirt and it was submitted by eldert zra he says this design is used on solar powerered race boats in the Netherlands so I think this propeller is in a similar situation as some of the other ones that just require too much torque from the motor it's probably even hitting the current limit on the motor driver which would prevent it from reaching the full 400 watts if I raised to the current limit it would score a higher top speed which would increase the integral efficiency score but I don't think that would improve its efficiency at the lower speeds here so ultimately what this all boils down to is that these blades are just too big if you shrank them down a bit I bet this propeller would have a chance of Performing really well with this motor so these last two propellers were printed on the brand new formlabs form 4 the benefit to the form 4 over the form 3 plus that I used for all the previous propellers is that the form 4 prints way faster these propellers only took about 2 hours each and it also has a larger build volume which will allow me to print larger propellers in the future now it's finally time for the panovic Redemption in the first episode NAD panovic submitted this patent pending propeller design with a 9 out of 10 confidence level but then it got dead last so if we look at the underwater video from the first P noic propeller you'll notice the blades are flexing a lot and that's probably one of the reasons why it did so poorly I don't think it's the only reason why I think the blade pitch was also just way too low that's just my hunch could be true could be not so for version two NAD made much thicker blades so if I feel this one the blades are very stiff uh especially compared to some of the high aspect ratio propellers where the blades get really narrow at the tips so I don't think this one is going to have any deflection issues and the blade pitch seems a lot more in line with what I would expect to perform well maybe still a little bit too shallow but definitely closer so I'm excited to see how this one does Let's test it so the bubble view looks clean I don't see any significant flow separation there are a few bubble packets that cling to the blades but not too bad the vortices aren't super thick looking so that's probably good and most importantly I don't see any deflection happening with this new version the panovic V2 scored a top speed of 3.3 m/s and an integral efficiency of 21 so it beat the Baseline by 5% not bad it also looks like it mostly did better at lower speeds so that leads me to believe the blade pitch is still a bit too low my hunch is that a two-bladed version of this with a slightly higher pitch would perform even better so that's it for our bonus propellers now back to a few of the propellers from the main round I thought it would be fun to see if the airshaper simulation results line up with the real world results that I was getting so I ran simulations on three of the propellers each at their actual measured speed and I adjusted the RPM until the power consumption numbers were roughly the same and then if we compare the calculated thrust sure enough the Baseline was the worst the wayron came in second and span maxing one so these results are in line with my real world results it was also cool to see that the simulated thrust of these propellers was roughly in the ballpark of the real measurements it was only off by about 15% which actually surprised me considering how many additional factors are in real life that aren't accounted for in the simulation these simulations are all public so you can check them out in the links in the description in the next propeller Test episode we'll be testing eight more propellers and announcing the winner for round one or season 1 or whatever you want to call it and we'll also be measuring the noise levels of a few of the propellers to see which types of designs are quietest don't forget to subscribe and click the notification Bell so you never miss an episode and you can also support me on patreon if you want to help me make these videos in the future that's all for now thanks for watching bye oh [Music]

Channel: rctestflight

Views: 495,711

Keywords: propeller, design, competition, boat, ship, toroidal

Id: iMkfGEjstXU

Length: 24min 13sec (1453 seconds)

Published: Thu Jun 13 2024