Testing 15 Lego Propellers - Lego Technic #lego #legotechnic

I have been curious about how the size and shape of a propeller affect its efficiency for a long time. I tested some propellers that I found in my drawer. I hope you find my experiment interesting!

You have been running some props in the wrong direction. Best test them in both directions

The wind detector falling over was a task failed successfully

4:21 THAT COUNTS???? hahahha aah omg you got me good

+1 for the Hot Wheels track! Such a bummer to spend the time build up something like the 'wheel' only to find it completely ineffective. All AFOLs know this pain. Thank you!

You have to tilt the rotor as much as the slope to keep the force and it's vector constant

I see several ways this test can be improved. 1) The tilted track means that at the higher levels, the propeller is no longer blowing along the axis of travel. A better setup would be if the track was attached directly to the motor frame, and the entire assembly was tilted. 2) Not all of the tests were at the same distance from the axis of rotation. A better setup would be three tracks, one at the bottom edge of the propeller, one at the center, and one at the top. The bottom one would trap air against the track, while the top would not, allowing comparison. 3) There are no really useful metrics. For an apples to apples comparison, make the track(s) longer, tilt them at 30 or 45 degrees, and attach a scale to the tracks. The propeller pushes the balls up the track, but it is long enough that the ball(s) 7:43 eventually stalls before reaching the end of the track. Measure the distance to get a comparable metric.

Your design choice to put the 3 flags along the ramp really drew me in: Flag 1, Flag 2, Flag 3, The Box!!! Loved it ~ thank you 😊

Man I love seeing propeller pieces when I was a child

I heard somewhere that propellers with more blades can apply more force per RPM but can't be spun as quickly. looking at the chart, the 2B9D and the 3B9D produce the same amount of wind, with the 3B9D being slightly slower. I think this is true, but there might be inefficiencies which causes the level to not coincide.

Putting in the propellers it just so satisfying

Another amazing feat of LEGO engineering!

It’d be cool to compare ducted designs! Or maybe even multi-stage setups with progressive RPM on the addition fan stages? Or additional vanes after the fan to create laminar flow, which would increase the distance the air travels?

the effort put into these videos is amazing

Absolutely loved this video since I always wanted to know which propeller worked best

More blades doesn't equal more wind. It's actually negatively affecting the amount of moved air by decreasing the efficiency of the vortex. Same reason boats or wind turbines usually only have 3 blades on a propeller. It's a fascinating science actually. I recommend looking it up.

For some runs with small propellers, especially where they do not hit ~70% of max RPM, it would be good to test to remove the last reductor stage, for more torque & less friction

Maybe try to make a cilinder around some of them to funnel the wind?

love your channel

The wheel is pretty much just a large centrifugal fan which pulls air through the middle and flings it to the outside. You usually see them inside a cowling with one outlet for directing all that airflow to one area (usually inside someplace that needs cooling)