Lego Propellers in Water (worst to best)

22 Lego propellers are tested in a water-filled container. Which one provides the most thrust? Enjoy!
2 non-Lego propellers are also tested for comparison.
Test method: a Lego Buggy motor (5292c01) and 7V input voltage. A weight scale measures the thrust in grams. Multiple gear ratios (from 1:25 to 5:1) and both directions of rotation are tested for each propeller. The test bench is explained in detail starting at 1:46.
Note: the list of gear ratios shown from 3:22 to 3:50 are incorrectly presented as inverse ratios. Sorry about that.
The results can be read in my blog:
brickexperimentchannel.wordpr...
0:00 propellers worst to best
1:00 RESULTS CHART
1:46 TEST BENCH
4:22 TEST PROCEDURE
5:44 6041 Propeller 3 Blade 3 Diameter with Axle Hole
6:08 4745 Propeller 2 Blade Twisted
6:40 92842 Propeller 3 Blade 5 Diameter
7:12 non-Lego boat propeller - Joysway 2-blade P1.4x40mm 83 series
7:51 30332 Propeller 3 Blade 9 Diameter
8:21 4751c Propeller 4 Blade 13 Diameter without Studs
9:02 2952 Propeller 2 Blade 9 Diameter
9:27 64683 Technic, Panel Fairing 3 Small Smooth Long, Side A
10:10 Lego liftarm propeller 2-blade 14x9 45-deg
11:05 18592 Propeller 3 Blade 13 Diameter (Ninjago Airjitzu)
11:39 41325 Propeller 4 Blade, for Flying Model Helicopter
12:26 2740c01 Technic Propeller 3 Blade with Gear 24 Tooth
13:10 non-Lego drone propeller Diatone Bull Nose 4 x 4.5
13:51 89509 - Propeller 1 Blade 14L with Two Pin Holes and Four Axles
14:41 COMPARISON TEST: 2 vs 4 blades
14:58 COMPARISON TEST: short vs long blades
15:23 COMPARISON TEST: 30 vs 45 vs 60 pitch angle
15:49 COMPARISON TEST: narrow vs wide blades
Music:
Heaven and Hell - Jeremy Blake
• Heaven and Hell - Jere...

[@BeTheGr8]

Just straight into action. No intro, no sponsors, no bs. Love these kinds of channels

[@justinarseneau4450]

Fr

[@nissanoo0393]

can u recommend any other channels like this boss

[@BeTheGr8]

​@@nissanoo0393Primitive Technology, Cutting Edge Engineering Australia, Matthias Wandel, Code Bullet

[@gilangvirgiawan2780]

Yes🎉

[@abdelrahmanmekky7011]

​@@nissanoo0393primitive technology but instead if lego it's nature

[@drake52]

the fact that you are testing propellers makes me wonder if you are planning on revisiting your Lego submarine.

[@rukirgaming]

kinda seems like an anual tradition at this point

[@BenjaminMarshallScienceMan]

It would have been cool to only have the audio from the under water camera, that way you could hear the noise difference between the small and large propellers. In both watecraft and aircraft, small propellers have the trade-off of making more thrust per unit-area, but being significantly louder. That is one of the main reasons that fighter jets are so much louder than giant passenger aircraft despite having a fraction of the engine power, and why nuclear submarines utilize HUGE propellers that spin very slowly.

[@GerinoMorn]

There is a point where cavitation becomes an issue, right? And you get that ultra-loud collapsing bubble thing...

[@BrickExperimentChannel]

I just listened to the pure underwater audio. You're right. Smaller props are louder. :) By the way, that propeller camera was outside the water container. But I had a separate waterproofed Lavalier mic to capture the underwater noises. What you hear on the video is a 50/50 mix of the sound underwater and above it.

[@mikieswart]

@@GerinoMornahead flank; emergency speed. warning! vessel cavitating; excessive noise!

[@BenjaminMarshallScienceMan]

​@@GerinoMorn Cavitation is caused by a rapid drop in pressure on the trailing edge of the blades, in aerospace the equivalent phenomenon is called 'boundary layer separation', which is the same thing that causes aircraft to stall and lose lift. As far as I'm aware it's simply an issue of your propeller moving too fast for its given blade pitch, so the only solution is to slow the propeller down or reduce pitch, meaning it needs to be larger to make the same thrust. Of course, the larger your propeller is, the faster the tips of the blades are moving at a given RPM, so scaling the size only goes so far.

[@kennethmoureau5123]

@@mikieswartEject decoy!

[@theo123-cookie]

Helicopter helicopter

[@Nomaditis]

Paaaara kofer paara kofer 🗿

[@unromanoarecareanaveragero8275]

You guys are 3 years late.

[@AGERES_SDF]

​@@Nomaditishelicopter helicopter

[@AlbertaGeek]

Badger badger

[@U014B]

Yes, Papa?

[@koray8820]

top tier data analysis, im fully satisfied

[@Themanhimself000]

Bro's the top lego engineer 🗿

[@OverTheHorizon840]

I wish it had 3d lego propellers

[@muffinconsumer4431]

“Bro-“ Brainrot

[@Malfin_L]

@@muffinconsumer4431 ok bro

[@muffinconsumer4431]

@@Malfin_L Bro said ok bro

[@Malfin_L]

@@muffinconsumer4431 ok bro

[@etepeteseat7424]

While I enjoy your build-up-to-the-best-bit style, I want to commend you for the intellectual honesty in getting directly to the showing off all the variations in this large-dataset case which otherwise might have had a very long build-up; not a second wasted, and once you'd shown the most clickbaity part of the video, you investigated each case further. Very respectful of your audience's time, thank you. 🙂

[@Username-qx9gk]

Gramms per Watt would have been useful, but with the gears you also arrived the sweet spot for that motor. Although "static thrust" numbers could be very different to those when boat and prop are both moving fast through water

[@ionstorm66]

To be fair I doubt a Lego powered boat is going to move fast enough the dynamic thrust will be too different then the static thrust.

[@Elias-eo1vh]

​@@ionstorm66Maybe true, but it would be interesting to see how the different propellers would perform when it comes to top speed and/or efficiency, while the larger props generated a considerable amount of thrust, they also create much more drag and resistance when mounted on a moving boat.

[@ABaumstumpf]

Yeah would be very interesting. But there are the current-numbers and the voltage seems pretty stable. @@ionstorm66 There is no need for high speeds for significant difference to arise.

[@BrickExperimentChannel]

Good idea with the grams per Watt. I added that comparison to the blog. brickexperimentchannel.wordpress.com/2024/04/13/lego-propellers-water-thrust/

[@Papinak2]

Just a little warning, these results are valid at 7V, closest to that is 6x rechargable AA batteries.

[@torpid5092]

Anybody else find this really weirdly relaxing? Just a quiet video with no dialogue and some experimenting

[@papirus00000]

It's just like childhood lego experiments in your room

[@KapitaenAwesome]

Just like Primitive technology. (The OG, not the horrible ones with music and click bait building "underground pools"

[@Psychodog_]

I love these kinds of videos. Good old empirical science. Test a bunch of stuff, note the result, analyse, learn. Great resource when making boats, planes and helicopters.

[@lwpeden5]

I loved the freeze frame on each propeller followed by their dimensions. Made me feel like I was watching a heist flick where all the characters with special abilities are being introduced.

[@rekire___]

My man trying to teach us mechanical engineering and thinking we wouldn't notice

[@j-7005]

He is studying for the next Submarine!

[@Bocchi-the-wide]

Nahh that's wild why😭

[@andrewpinedo1883]

@@Bocchi-the-wideI bet some of the components on that submarine were made of Lego.

[@user-uu8ep1il5w]

⁠​⁠​⁠​⁠@@Bocchi-the-wide He is talking about the Lego submarines BEC has made.

[@hermaeusmora4874]

Gotta go tell my gf that 15cm is indeed considered huge

[@KiriMantiss]

Had to stop and re-watch at 0:20 . I legit had thought it was a comically edited failure because of how smooth that piece just gently sank down. Love watching allt he test and trials you come up with. Keep up the awesome work!

[@IdealIdeas100]

its crazy how much more power some of the much smaller ones put out in comparison to the larger ones

[@KingOfDams]

Really educational!

[@peacekeepers_error]

Wake up BEC uploaded a new video

[@duncanfreeman5436]

THIS is peak content. Densely packed with information. Good testing procedures. Great usage of graphics. Legos!

[@JushuaAbraham-sj2xl]

As propellers are tested at zero forward speed it is more useful to be compared in term of "figure of merit"(thrust/shaft power)

[@JoXDDFive]

your videos are fantastic, from the editing, building puzzles solved to the top tier data analysis all in an easy to understand presentation WITHOUT saying a word!!!

[@ResidentIT_]

i cant describe how much i love this channel. good, interesting test with good usable results. nothing is over the top and is a very relaxing watch. cant wait for the next sub video!

[@rumblehansi]

props for this test and the editing

[@e1woqf]

Next we need to know which design is the most efficient: thrust vs. power draw BTW: good work!

[@BrickExperimentChannel]

The non-Lego drone propeller wins that comparison. It gets 60 grams per Watt. From Lego propellers the white long panel 64681 wins it. :) brickexperimentchannel.wordpress.com/2024/04/13/lego-propellers-water-thrust/

[@sage5296]

Man the editing here is hella clean, very nice video, and the processes were very clearly laid out which is fantastic

[@Maccaroney]

Great video and i love the editing. Makes it really easy to watch. Would love to see these blades spun up really fast underwater for fun and maybe to find the failure modes.

[@compi3882]

TBH I love how you just got straight to the point, and saved the details for later. Everything you needed to know, followed by everything you want to know.

[@lerikhkl]

This is so thorough that I can't even think of something to add! Great job!

[@puddinhead99]

this is incredibly in-depth and i appreciate your deligence

[@motorhorn]

Fascinating as always

[@The-creator-of-good-videos-15]

Cool Lego experiments, man! I hope they get better and better every day with each and every video you make. Awesome job, man! 👏🏻 👏🏻

[@lincolngolladay]

Thanks for all the time and effort for great data!

[@phillipbuck6104]

I appreciate how scientifically rigorous and well documented this is. Good experiment 👏

[@hedix13]

This is some incredible editing! Plus the effort in collecting the data itself! I know it's just Lego propellers, but I enjoyed watching the video. Thanks!

[@dogvetusa]

Thank you for going over the set up for testing too.

[@catmage]

Wow, that is incredibly thorough testing. Well done!

[@TheElMexicano]

Never a dull upload with this channel that’s for sure 👍

[@Zero-ry2rc]

This was absolutely fascinating

[@JosephsDesign]

Very cool results and very thorough test procedure!

[@goobydoo9278]

Everything about your videos are so efficient and informative

[@breakfingers]

Captivating video. Love all the graphics you showed

[@doubledarefan]

Props to you for doing these experiments.

[@user-uu8ep1il5w]

Hehe

[@greatraven3839]

This feels like a college project for a fluid dynamics class. Well done!

[@jackmalcolm]

This is amazing data collection/analysis

[@edcramer6475]

The instrumentation an attention to detail is great, data can be fascinating stuff.

[@r4ryder388]

How does one acquire so much red technic pieces?

[@inkyencore0429]

eBay.

[@M0torsagmannen]

now this is the answer thati never thought to question, very interesting results.

[@DonVigaDeFierro]

Huge props to this channel!

[@mhas9110]

This is lovely research ❤

[@DonLuca27]

Fantastic video, as always. I would have loved to see some efficiency comparison as well (power/thrust), maybe next time :P

[@Jamesonfp]

id love to read the research paper you make from this

[@Bayoll]

Surprisingly advanced methodology

[@Irskin]

You can *really* see the difference in directional thrust from the ones with an actual aero/hydrofoil shape to the blades, wow.

[@OcelotTheGreat]

Very nicely done!❤

[@rhgamehamel6350]

Make working replica of engine using vacuum

[@jarrettbellboy]

Something about the #6041 fan that is so nostalgic. It was used in so many early 2000s wacky sets in underwater, space and plane sets in both earth tones and wild highlighter transparent colors.

[@timehunter9467]

Nice to see the old ZNAP wheels being given a chance! I still have a lot of that stuff somewhere.

[@Matthias-499]

Nice video, like your Lego techniques a lot

[@coltonverrier4976]

you have not even finished the vid yet

[@koosnaamloos4291]

I love that somewhere, someone is going to find this incredibly useful for their own project

[@peterrogulla7726]

At first i thought it was just like any good LEGO channel. Then i saw the "Biltema" tachometer, that confirmed my thoughts. Jokes aside, this is great content and i absolutely love the seriousness!

[@BenjaminGoldberg1]

Awesome. I would love to see some lego impellers. Or, better yet VSP-style cyclorotors.

[@shivajoshi9068]

it was fascinating to see the difference between CW and CCW thrust may be sorta dependent on the difference of the pitch angles of the 2 sides of the propellers!! thank you for making such amazing videos! love the whole thing!

[@nastyevilbunny]

Loving the data comparison.

[@MrGustavier]

Fascinating.

[@silverground3670]

There are too many variables, but it's very nice and detailed and arranged very neatly and meticulously making it easy to understand

[@LutraLovegood]

This is gonna be very useful on my cars!

[@HigginsObvious]

Woah awesome results! Its been a while since I did any fluid mechanics, but I wonder if the biggest propeller wouldn't get better results in a larger test container? 1cm clearance seems like it could cause drag issues that might be making it look worse than it is.

[@Nikolai_The_Crazed]

This gives you a great idea of how well each propeller does under their respective optimal conditions, but what I’d like to see is a data set where all the propellers use the same rpm and gear ratio. That way we can see how the variation of those two factors changes the results. If they’re all taken from the same baseline first, then it gives a frame of reference for their performance under optimal gearing and rpm. It highlights what effects small compromises can have on performance. Someone might use more compact gearing for a smaller project, and get different results because of it.

[@Atilolzz]

Crazy cool research!

[@JeremyMcCrearyTechnicalLEGO]

Excellent static thrust tests! Hoping you have some working LEGO powerboats in the works. During my LEGO powerboat heyday (see channel), tested all existing LEGO props and several easily adaptable non-LEGO props with methods much cruder than yours. The 2-blade 4745 turned out to be the best performer in speed trials, where many factors other than static thrust also come into play. Longer hulls with twin outdrives powered by their own L or XL motors were nearly always fastest. Buddies and I handily won the 2015 Brickworld boat drag race with such a boat fitted with 4745 props. If race rules had allowed us to sand the 4745's slab blades into airfoils, we'd have won by a much bigger margin. Real marine prop blades have airfoil profiles to add forward lift to the thrust generated by simply deflecting water aft. No LEGO prop blades had such profiles at the time. Also no LEGO counter-rotating pairs, which meant lots of propwalk. When not restricted by race rules, we always used 52-55 mm 3-blade counter-rotating props made for hobby-shop RC boats. No LEGO prop could come close in speed trials, with or without blade shaping. Naval architects consider the matching of hulls to powerplants to props something of a black art. Ditto for LEGO powerboats. The key is to arrange for the boat to come to max speed just as the motor's hitting peak mechanical power near 50% no-load shaft speed. That's where gearing becomes critical. Lots of guess-and-check involved.

[@WoLpH]

For the 64683 Technic, Panel Fairing, you could try variable pitch and see what pitch works best. The tests are absolutely awesome in any case! I love it :)

[@RedShift5]

This is like Project Farm but for Lego. This man must also be protected at all costs.

[@STA-3]

Babe, wake up. Brick Experiment Channel just posted a new video.

[@idowedo]

I'm going to sit here in almost silence admiring the time and effort this took you to make, this is incredible.

[@theoozmachine]

It would be nice if you could make explained videos for some concepts you usually use like gear ratios, torque, and other such engineering concepts for us non engineers to understand

[@SeresHotes25]

That's cool! It's interesting to see, what's RPM that will make make the motor to generate the most power. And then it's interesting to know, what's the RPM, that will make each propeller to generate the most force/power. We can then see the efficiencies in percents of each propeller.

[@commelinales]

So detailed.

[@landfillbaby]

good video! very thorough! i'm glad the classics work so well! do you think the ninjago ones would work better with the nosecone?

[@TheWinjin]

That level of comparison and analysis is heads and shoulders above all these KZbin "engineers" that just eyeball the propellers. Looking at you, everyone with 3d-printer who just made something that looks a bit like the MIT toroidal propeller and tried to make comparison videos out of it. There's content and there's scientific content and I think we can see the difference

[@sylphvivie]

Wake up son, Brick Experiment Channel uploaded new video to watch

[@mrcool7140]

F*ing hate that meme

[@Eequality72521]

I really would like to see the input power that each was driven at

[@NeinStein]

The data is there: power is voltage times current. So e.g. at 12:10 it's: 7 V × 0.78 A = 5.46 W

[@bbbenj]

Amazing!

[@3_Bricks.]

It is clear that difficult work has been done. Like. 👍

[@QtreadzSD]

Came for the results. Stayed for the engineering.

[@pigletshut]

That 2740c01 brings back memories. It was "the only prop" on the Technic 8855 prop plane set which I still have stowed away in a closet. How to drive it can be a challenge though.

[@Creativity_Sparks]

0:19 the trust in that was so good, it literally made the piece come off.. 😂

[@CaptainWizard3000]

For the slippery one that required tape to be solid, you could’ve marked it (with a line on tape and prop) to see how much it rotated (if at all) after spinning.

[@matthew.wilson]

Bravo! Next step: A marine "wind" tunnel where you can test variable pitch against flow rate and give us some sweet 3D plots :)

[@Gameplayer55055]

Now do some Lego Ocean Gate pressure testing lmao

[@cyphre]

Crazy how well the super old school lego props did!

[@RandomBogey]

I don’t know what I personally will ever do with any of this information. But, as someone who loves running numbers/data and Lego, I’m down for it

[@clssgn]

With those data, I think you could publish high quality lego engineering scientific article. It should be a thing, lol, getting it peer reviewed would be amazing. 😂😂 but always, so great to see your vids as always.

[@monomomonononono]

BEC IS BACK 🔥🔥🔥

[@rthomp03]

Wow, quite the deep dive (no pun intended). I had no idea there were so many different propeller options. I assume this is part of a larger series of experiments to optimize a Lego boat or submarine? My only disappointment is you didn't make a 10-speed transmission, to avoid having to change out the propeller so often. Or even a CVT to optimize the RPMs even more.

[@atmhso]

Such a good video. My only scientific thought is the size of the container is limiting, in that it bounces the water back towards the propeller and alters the result. Still, minor quibble and probably wouldn't make a significant difference!

[@erinkarp]

Impressive!

[@TheGlitch93]

Can you try to form supercavitation on some props? Would be interesting to see how much RPM each small/medium prop can handle before it starts to form supercavitation...

[@norbert.kiszka]

4:16 small clearance will cause propeller to generate less drag - similar thing we can observe with ducted fans like in turbofans, winglets in planes and with ground effect in low flying planes.

[@zett5729]

Great Video. Would be Interesting to see the different performance patterns in active flow. A lot of Props can create really unintuitive thrust when measured in an active flow scenario.

[@zett5729]

But no clue how you can create such a test structure.

[@Spyzilla1850]

Would have loved to see a toroidal propeller in here! Very nice video.