Making a Fast Lego Boat 3/3 - underwater propellers
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- Опубліковано 10 вер 2024
- Building a fast Lego motorboat with two submerged Lego propellers. Only Lego parts are used, except for a BuWizz 3.0 battery box. Enjoy!
Battery box: BuWizz 3.0 Pro buwizz.com/sho...
Motors: 2x Lego Buggy motor 5292c01 www.bricklink....
Propellers: 2x Lego Propeller 2 Blade Twisted 4745 www.bricklink....
Propeller attachment: double-sided tape rolled on a Lego axle
Hull: Lego Hull Giant Bow 4245c01 www.bricklink....
More details in my blog, including a part list and 3D model for the motorboat:
brickexperimen...
You can read more details and download partlists and 3D models for the three boats here:
brickexperimentchannel.wordpress.com/fast-rc-lego-boats-blog-post-series/
Are you going to fix your paddlewheel ship by stopping the splashback slowing the boat down? As in the tubs over the paddles were acting as brakes
You're the same person who runs Brick Bending aren't you? I noticed the two uploads within 10 minutes of each other, this video and the brick bending one.
@@bobstr6224 Not for now. I acknowledge the splash guards could be improved as you said.
@@-_._._- No. This is the only YT channel I have.
I love your videos! Please don't change anything
Would've been interested to see you try out a rudder instead of using engine power to steer!
Loved the video
Definitely would have allowed him to apply some "trim", especially at WOT.
Definitely would be interesting but doesn't using engine power alone for steering across the board make for a fairer test?
@@adamoliver82 I would argue he should have used a rudder across the board at the start. however, that would require him to start everything ALL over again, so for this it's probably okay there's not rudder
@@ProeliatorDeus From experience with LEGO powerboats like this, I can tell you that a rudder would have increased both appendage drag and skin drag, the latter by increasing draft through the addition of non-propulsive weight. And that added drag would have reduced top speed Plus, rudders are poor at steering at low speed and in reverse. Twin-screw steering via differential power to the drive motors is much more effective in LEGO boats.
he's preparing for a naval invasion, quickly! build the lego sea mines
Yeaaaah! Prepare the sea mines. And make them magnetic too.
a man has fallen into the river in Lego City! Build the SEA MINES!
@@Wolang13*HEY!*
@@stevenstice6683 that's what I was going for xD
Build the lego submarine to torpedo the fast lego boat !
Not gonna lie, that was one fast Lego boat
5kmh is slow af for an rc boat 😂
I'm going to lie, that was one slow Lego boat
You record the sound nyyyyyooooommmmmmmm in the boat and go for a ride👍👍👍👍👍👍👍👍👍👍👍👍👍👍
Why would this be something it would cross anyone's mind that it would be lied about?
How about a fastest Lego train?
Similar to RCTestFlight's findings on his fan-made boat propeller challenge: The goal for fastest boat actually ends up finding the correct matching propeller type for your motor and power configuration. Since you have 2A and 12V available for each motor, the propeller must not be more powerful than 24W. Plus the RPM has to match up so the tip speed is not too great. The smaller propeller means a lower tip speed ratio + less energy spent just to rotate the mass vs a larger prop. The greater pitch of C offsets the lower diameter and number of blades, which makes it the best prop for the configuration. Also if you were to use a more powerful motor, there comes a point where a larger diameter at lower RPM is better, but for small scale, what you've found will generally hold true!
He's probably better off 3d printing such propeller given the limitations if Lego parts.
Also rctestflight's series was so interesting to watch!
what you are describing is the mechanical equivalent of impedance matching; you are tuning the load (propeller) to the source (motor) for maximum power transfer at a certain frequency (rpm)
the video was good and that's all that matters so go further to annoy other people
Love the 3-Part Fast Lego Boat series 😯
Would love to see an amphibious Lego build that can seamlessly traverse both land and water.
YES!
ooh he should!
That's a dumb idea.
that's a great idea.
So a hovercraft then?
5:14 the two grey sockets look like totems 😂
OH LOL, I DIDN'T EVEN NOTICE THAT!
@@evergreengaming2.053 Me neither. OP has good eyesight and hi IQ. I think he may be the chosen one. All hail thegahta!
like lego indiana jhones the original adventure videogame
Twin motor, you can get one to run in reverse so you can use the same prop for rotation and normally better control/no need for corrections. Both spin to the middle or outside, the best variance can depend on hull type... but at the small scale, I am unsure.
I was just gonna say that
That requires an inverted prop, which Lego doesn't make.
@@joneydew4739 An idler gear would have done the job easily enough.
The inverted prop is only if you run the engine in the same direction, as these are electric it is just a wire swap and it doesn't care.
@@wobblysauce No, just reversing the engine would also reverse the thrust. You need to have a mirrored prop *and* spin it the other way around.
I suspect we'll get 4/3 next week for a caterpillar drive. :D
Only one Ping, Vasili.
Oh yes please
I love these videos, my only critique is that picking the best prop for example might be dependent on the gear ratio and not testing the full matrix (as far as I can tell) irks me haha
All props were tested with multiple gear ratios to find the best one. I left those tests out of the video, because they are a bit boring to watch. You can read the results here:
brickexperimentchannel.wordpress.com/2024/08/17/fast-rc-lego-boats-motorboat-with-underwater-propellers-7-8/
@@BrickExperimentChannel Nice!
@@BrickExperimentChannel oh my god this is exactly what I wanted haha thats AWESOME
@@BrickExperimentChannel What about the propeller type selection affecting the optimal vertical position and propeller pitch? Annoyingly, that would have been a nightmare to test.
@@BrickExperimentChannel god I love science
So the 'final' comparison is
top speed: airboat 5.0 km/h, paddle wheel 3.9 km/h, underwater propellers 5.3 km/h
approx. journey time (final time visible before overlay disappears): airboat 04:54, paddle wheels 04:53, underwater propellers 04:29
comparing paddle wheel to airboat is a matter of the compromise between speed and steering (we can basically take them to be identical in journey time), but the advantages of underwater propellers do make a proper improvement against both in real-world tests.
In the experiment, the implementation of the paddle wheel has a fundamental design error, due to which it turned out to be noticeably less efficient than it should have been.
It's surprising how close they all were
Extra challenge: could you get any of the used hulls planing? With any prop tech.
This one is almost there as can be seen in the video. Very close. And when he is testing the RC one (I guess thats what it is) at the end of the video, it looks to be on plane to me.
The only issue I see is the elevated position of the engines. Generally the lower the better for stability. I guess keeping them higher up helps with keeping them dry however.
True. The motors should be in a lower position. I just couldn't find a better build with the gears and all.
@BrickExperimentChannel what about the most elevated vertical position with a -5 degrees kick? I think it could be better
The 1:5 planetary gear hub could possibly help with that, with a slight reduction to make it run at optimal speed
@omridoren I think you're right. Negative trim moves the prop a bit lower, allowing a higher leg position to reduce drag. Kind of micro-optimization, but still better at least in theory.
@Inferno_407 The gear hub (46490c01) is very compact and could help lowering the motor. But it is inefficient. I have a few of those hubs, and when you turn them with your fingers you can feel the resistance. The hub is full of thick grease or something. They are useful for turning truck wheels, but not 2000 RPM propellers.
One of these days I want you to list, 'mechanically accelerating projectile' as one of the builds and then just throw it as hard as you can.
that would be cool - gotta make some constraints on the energy source
2:33 I didn't think it could run that fast without sinking
What is that adorable little camera visible on the boat watching the captain
The best prop I've found is using about 15 lego pieces.
You need 2 of the 4 pegs with perpendicular center cross , 4 of the single pin with pin hole (the black ones from your motor mount.) And 8 1x5 technic beams held together with long pins and tied together with string when built. You can build them mirrored of each other super easy. They work great in reverse too.
are there any photos online? i'm a smoothbrain.
@@acomingextinction Not that I know of. I thought of it for my own boats.
I might do you better than a picture, a little later I might make a quick video just showing my prop motor.
Just have to use my own smooth brain to figure out how to control and film with the same phone. If I can't figure it out I'll make a video without controlling it.
But I just got off work, so I'm going to relax for a little bit first.
@@acomingextinction I couldn't figure out how to control the motor using BrickController 2 and also film with my phone.
I'm posting a 8 second video that shows enough to be able to get ideas, maybe even copy my design. It features a crow calling in the background and my barn cat meowing at the end.
I even show my gear ratio to make it have a nice turning angle, going full 90 degree makes it not turn very good, this turn angle lets the boat spin in circles.
When you have more than one prop, not even motor, you always want them to spin in opposite directions to cancel out gyroscopic processions... With the smaller props it's not as noticeable but having them spin the same direction will always introduce a little bit of side drift and roll force on the boat
(had to learn that for my sport boating license)
Ideally, sure, but if you have them spin the same direction, you can have identical engines, gearboxes, and props on both, and the part commonality often wins over the slight performance benefit in real designs.
i think that turned out to be the case with prop E when they were both spinning in the same direction and messed things up
His controller is probably better than the one used in that submersible. 😂
Guess they should have used a Playstation controller instead. 😂
Wasnt the controllers fault that it imploded
saying it was the controller is like saying it was because of the t-shirt one of the guys were wearing
@@MrTefelol great analogy.
@@MrTefe but the controller did die
@@leboxdude1252 Yea no fucking shit take a controller to the titanic and make it explode with the sub its in. Did you think it would survive that?
Never have I ever clicked on a video so fast. Friggen love this channel
Bravo! It's crazy how fast the motors drain that battery pack
watching that boat scoot was the funniest thing I've seen all day thank you
you’re the best lego youtubeur of the time ❤
Cool. On the river clip I expected turning the engine sound into a melody, sort of the water pumps video ending. But this epilogue was a surprise as well.
Propeller A brings so much nostalgia, all the cool underwater themed sets had it
These videos are satisfying
Is it possible to make it air piston powered?
Go to his Chanel
Interesting that the best trim level was a minus? Which unless I'm very much mistaken, is the opposite to real planing hull boats which run a positive trim angle. I wonder why? Maybe the lego hull becomes unstable because it's so light, therefore it being advantageous to keep the nose down? Likewise with the battery position. Intriguing
I wondered that too. My guess is that the boat is too back-heavy. Negative trim makes is more level. If the motors were located at the front, making the boat front-heavy, then a positive trim would have been the fastest option, I think.
@@BrickExperimentChannelhai
Next video: Can I make a lego hydrofoil?
The long awaited trilogy is complete
Can we give this channel the best lego channel award already.
Also, if anyone asks why we use underwater props instead of air props or paddles, show them these last three videos. Higher speed as well as higher maneuverablility while reducing risk of unnecessary injuries to the users.
I love the building sound ASMR
This series is so good! Always stoked for the long journey.
compared with the previous version, which one is the best propulsion?
As great as the recent videos are, I have to say I miss the music during the field tests. You always had a good choice of relaxing music for them.
I notice that for the sea trials the battery was moved aft slightly from the position picked as best in the pool, I wonder if that was a trade-off to reduce the chance of it taking a wave or getting knocked off in a collision with an obstacle, or if there was some off-camera fiddling that found that was actually better after the changes to other factors like prop depth and trim, or if it was to compensate for how the cameras affected the weight and balance, or some combination of factors?
Also wonder if additional ballast besides the motors and batteries could further optimize some of these designs? Though at that point might need to start from theory rather than just exhaustively testing, since the options for both amount and position of the ballast opens up a LOT of possibility space...
Just because the battery blocks the view for the onboard camera. The video footage looks nicer this way IMO, even though the boat is a bit slower. The two onboard-cameras and minifig slow down the boat further and make it too back-heavy.
@@BrickExperimentChannel Ahh that makes sense. I've loved this series, by the way, thanks!
I would've liked to see a remake of Propeller E with either an inverted version of Prop E or some kinda different propeller arrangement, to allow use of two Prop Es without the rolling issue.
You should try putting two hull G’s tail to tail or even farther apart with tape if you feel that it’s allowed because the top speed of a non-planing boat is a function of its waterline length.
cool as always
This is probably the quickest but is clearly the less stable and constantly needs direction tweaking:)
But maybe with a rudder or something similar would be more stable.
This has been a great little series. Genuinely excited to see what happens here.
Nice to see this actually be faster than part 1, unlike part 2
For a 4th boat, you could try making one that has a single motor and uses a rudder to steer. Hull C with the cutout could work for that rather well.
Theres also gonna be a lot of variation of the speeds and props based on rpm. Try all the props again at like 5 different rpms.
I learn so much from this channel! 🙏🙏🙏
That's the most stable one I've seen you do yet
I’ve seen some fast Lego boats in my life, this is certainly one of them
all the propellers look so cute!
It even gets up on plane! Sweet
youre so enthusiastic with lego, love your video
Great use of the scientific method, kids- this is how discovery is achieved!
best series on youtube so far
This is so much faster, wow!
Wow! Way better format than the first two of this series in my opinion. Amazing work as always!
Wasn't expecting the boatcam... that was awesome.
Lego really should make opposite handed versions for the propellers.
I feel like Hull B got sold short, as it's practically begging to be made into a catamaran. I'd love to see it re-tested with the middle segments removed and the outer ones bridged over the waterline. Unless that configuration isn't buoyant enough to support the weight of the powertrain?
I really do appreciate your content, i would like to see you try to make a siren out of lego
it would be super cool if you could mess around with doing some sort of impeler jet drive
Wow dude that's SO manoeuvrable too!! 👌🏼
Your videos always kinda make me want to buy a bunch of lego and iterate on your findings...
Very impressive test matrix and result! Keep up the great work!
Made a lot of twin-screw LEGO powerboats ca. 2013-2015 - one of which won the BrickWorld boat drag race using a City Lines hull and your chosen 2-blade prop.
Since you've already strayed from LEGO "purity" with the double-stick tape and lube, may I suggest for future testing:
1. Sand the prop's slab blades into airfoll profiles with coarse to fine emery boards. Exact profile doesn't matter. HUGE boost in thrust! (Eventually went to counter-rotating hobby-shop RC boat props for another huge thrust boost with no prop walk.)
2. Give the City Lines hull another try after fairing the keel recess with smooth tape. Much more favorable length/breadth ratio at the waterline.
Hey, that's so cool. I found your boat in the drag race video here ua-cam.com/video/Sxtq_2ZR9Wo/v-deo.html
Thanks for the suggestions. Both are easy modifications to try out. Could you expand on the "favorable length/breadth ratio"? I understand the tape modification will raise the hull higher and reduce drag, but the length/width ratio is a new idea to me.
@@BrickExperimentChannel What a blast from the past! If we'd been allowed to sand the prop blades into airfoils, we'd have left everyone else in the drag race far behind. We won partly on our ability to hold a straight course, but that worked against us in the slalom.
Lenght/breadth (L/B) ratio at the waterline is the single most important hull metric when it comes to speed. The greater the L/B, the faster the boat for a given propulsion system. At the time, the City Lines hull had the highest L/B of any LEGO unitary hull capable of carrying 2 L or XL motors safely.
Waterline lenth by itself is also important, and the longer the faster. City Lines hull was the longest then, too.
You also want to minimize draft, and that means minimizing weight. That's why we kept coming back to rudderless twin-screw designs.
You also want to minimize appendage drag, which means having the least possible plastic in the water besides the hull itself.
The tape trick just covers up the recess in the bottom of the City Lines hull. Just a streamlining measure, but it makes a difference.
That makes sense. High L/B explains why the City Lines hull is so fast. It also explains why tankers and other ships in real life are made long and narrow to increase efficiency and save fuel.
The Giant Lego hull, that I used in this last boat, was wider and shorter but still very fast. Maybe that is because the boat is starting to plane? As I understand it, the factors that affect speed change when the boat goes from displacement to planing mode.
I put a link to your speedboat in my blog. That's an achievement to go 4.0 km/h with regular Lego rechargeable battery boxes.
brickexperimentchannel.wordpress.com/2024/08/03/fast-rc-lego-boats-background-1-8/
@@BrickExperimentChannel Yes, everything changes when a boat gets up on plane - and none of my boats ever got close with LEGO motors and batteries. In the displacement regime, waterline length determine "hull speed", beyond which the resistance/kg vs. speed curve turns sharply upward. Got some of my boats past this inflection, but never by much.
@@BrickExperimentChannel Will check out your blog tonight. Thanks for linking my winning boat.
Hull B withouth the two middle ones would be interesting. A real catamaran.
Interesting that none of these hulls had issues with spinning out of control, underwater propellers seem to be very stable.
your underwater series are always the best
This was a great series, would love to see more.
The prop walk issue may only be a problem in static tests. It would be interesting to see those props with the walk issue tested in motion.
I would like the full river trips as a separate video without being sped up.
Here you go ua-cam.com/video/owTkjRK77q0/v-deo.html
@@BrickExperimentChannel Thank you!
It actually almost/sort of gets up on plane. Not bad!
I love for when he gives it full throttle
Very cool. You should put a nug wrapped in plastic on the boat so the Lego man can live life on the edge.
Amazing as always!
OMG I need LEGO boats now!!!
😅
Ok I didn't expect that 4:39
now i dare you to make a lego fast boat only powered by the inertia of a flywheel, no paddling, just pure inertia
This channel is recording my dreams and posting them on youtube
3:50 i would put it back to 0 degrees because ive had boats and the higher the rpm the closer you want to be to 0 degrees for speed
*I have an idea : if you make the hull waterproof, it will have less resistance !*
Very cool video! Nice work.
By the way, which one of your three boats you tested recently was the easiest to control? It's quite hard to feel how controllable boats actually are through video.
The paddlewheel boat was the easiest because it goes straight at full speed and also turns quickly and accurately (stops when you want to) at slow speeds.
The motorboat with underwater propellers was also easy to control at slow speeds but at full throttle, it veers right because the two CCW propellers tilt the hull. That makes it a bit more challenging.
The airboat was the most difficult to control. It oversteers at turns and doesn't go straight easily. The controls are delayed, because you need to build RPM to get thrust. It feels like driving a car on ice.
@@BrickExperimentChannelcould you put different trim angles on the left and right sides to counteract the tilt effect?
@BenAlternate-zf9nr Yeah, I think you could. That is a nice way to fix it. Another way to straighten the steering is 1) moving the propellers to the right or 2) limiting the max output to less than 100% on the left motor. I haven't tested anyone of those, so don't know which one is the most accurate, and works on both slow and fast speed.
@@BrickExperimentChannel Have you considered adding a skeg to the keel? It's what greatly helps with steering stability in a real world applications. It won't necessarily add to the boat's draft, as it can compensate its height with more length. I understand why the keel shouldn't be added to an airboat but here it seams like a no-brainer for me.
Maybe try a hydrofoil for more speed.
The 'Zisch' boats from Felix Wankel could also be interesting.
Большое спасибо за ваше творчество!
Всем мир)
At full throttle, the boat seems to drift toward the starboard side. The weight of the camera might be causing this. A counterweight may prevent this starboard drift.
I was thinking that it might be the same torquing we saw from Prop E, the big yellow ones, but at smaller scale. So we see it add up over long distances. It was a little noticeable in the pool tests.
@@Henchman_Holding_Wrench That's a good point!
Very stable!
without doing a full test matrix / DOE, how do you know you ended up with the optimal config? A previous hull might have been better with a different weight distribution, etc.
real world test location seems very close to home :P
I always wonder if different propulsion and hull combinations would turn out to be faster. After all, its not a given that the best screw for one boat is the best screw for another.
Now that you have some props, you can make some impellers and build some jets!
On the other hand, I can see you have some extra room there, why not more motors?
Surprisingly that boat is faster than the Mayflower
This was great, thank you!
5:26 and 6:00 It looked very much like real Yamaha engines.😊
Contra-rotating propellers with fewer wide-flat blades are almost always better in the water
Now a rocket powered Lego boat!
who'd have thought that the OG lego prop would be the most effective?!
You're always optimizing for the current configuration. You might have skipped some part combinations that would have performed a lot better with different configurations.
Now that you built a working boat, would it be possible to load it with accesories to make it even more functional? Like a weapon (a controllable cannon, perhaps?), or a crane to fish treasure and salvage from the depts. Could the boat stay afloat while hauling cargo up? So many questions!
I love this channel
Thats fun bro. Enjoyed this one. Like all the problem solving
What a speedy Lego boat! I guess. Nice. I guess.
Imagine walking through a forest and all of a sudden a (perfectly working) fast moving , selfmade Lego RC boat sailing by and nobody is to be seen 😂
(PS: isn’t the non-lego propellor 40% faster than the lego version , not30%?)