leaf blower propulsion system

[A.K. Boomer]

I don't know AK, sounds to me he hooked another one.

No - that statement stands --- very surprised as in in disbelief,,,

it's too much benefit and im glad I stated that... I knew what was happening from the get go --- But ---

Also glad I did not write it off as total nonsense --- as in your quote and I quote; " May as well use a cordless blower and recover the energy by using a wind powered generator to charge the batteries. Physics be damned."


You do know propulsion can be had this way right? right?

just making sure you, tomato coupe and fasttrack know the basics, no harm done...

[MattiJ]

None. Newton's third law as quoted in Wikipedia:

The third law states that when one object exerts a force on a second object, that second object exerts a force that is equal in magnitude and opposite in direction on the first object.


-js

Now we are jumping to wrong conclusions. Net sum of forces between the umbrella and the blower are zero but we still have to remember the thrust generated with the airflow/air mass.

Bucket thrust reverser is about the same idea:

[wierdscience]

None. Newton's third law as quoted in Wikipedia:

The third law states that when one object exerts a force on a second object, that second object exerts a force that is equal in magnitude and opposite in direction on the first object.


-js

True, but it's not always so cut and dried, recently a $10,000 bet was settled as a result-

https://www.youtube.com/watch?v=yCsgoLc_fzI

[PStechPaul]

It looked like he was able to steer by leaning to the sides, which would work for a skateboard, but not so much for a janitor's mop bucket.

[aostling]

. . . Bucket thrust reverser is about the same idea . . .

That was the train of my thought, too. The aircraft thrust reverser has a net backward pressure differential, with the back side seeing ambient static pressure, but the front side seeing stagnation pressure given by



The high velocity in that last term provides a substantial force acting on the impacted surface. That situation would apply to the leaf blower and umbrella too. I suppose the force is small, though, now that we know the video was trickery.

I would still like to see somebody try it with an unpowered skateboard or wagon, to see if it would attain some modest forward velocity.

[polaraligned]

The bucket he dumps out in the beginning and then jumps in clearly is not the same as the one he is riding in.....just your typical fake news...America has been dumbed down.

[A.K. Boomer]

Now we are jumping to wrong conclusions. Net sum of forces between the umbrella and the blower are zero but we still have to remember the thrust generated with the airflow/air mass.

You are correct - although having the umbrella close to the thrust does indeed create more force on the leaf blower like Jim's example states, its not really where the "Magic" that's eluding many happens... in fact that thrust would be pushing in the opposite direction - so both the umbrella and the leaf blower are in an "initial" balanced"tug of war...

Once again my original statement of "there's allot going on there" is just that - it's not just basics in mechanical physics laws but also basics in fluid dynamics combined...

To some degree "reverse engineering" the experiment does leave you with the final results of more pressure coming off of the man and (modified) cart in one direction more then any other - when you reverse engineer it your left with the conclusion that there is an unbalance in air mass and the only thing creating it has to have opposing force on it in order for this to occur...

this is not "perpetual motion" or a free lunch - the second the battery's drain in the leaf blower all unbalance will cease to exist, this also does not disobey any laws of physics...

I'll explain why in a second...

[A.K. Boomer]

First some pics, I woke up thinking of how I could create an example to prove how something attached to the same unit can create this effect, so a couple minutes later im out in the garage with a simple cone shaped devise gorilla taped to my hanging air hose gun,,, the air gun was gorilla taped in the "on" position and I controlled flow with my compressor tanks valve,,,

first pic is static and how the hose hangs with the weight of the air gun;





second pic is the air gun creating thrust due to pressure - normal simple reaction everyone would expect ;



third pic is cone and hose in static mode;



Last but not least --- creating thrust in the opposite direction in which it came,,, the air gun and the cone are equalizing each other out, but there's an "expansion plume" going on inside the cone after initial thrust is equalized --- the leaf blower and the umbrella have the same effect - the leaf blower is a mild air compressor - the thrust is the result of that compressed air escaping and it's "initially" equalized, but fat lady ain't done singing yet, the air is still expanding after the fact - the cone and umbrella are the perfect shape to catch all that would have normally just vectored off to the sides (90 degree's) and re-harnessed it for actual further work...



Over the years iv taught many of physics majors how physics actually works... it's fun.

No little strings attached guys, no magic - no perpetual motion or hokey pokey lol

[MattiJ]

Exellent work A.K. Boomer!

[Dan Krager]

I still think this is the best illusion! I laughed so hard the first time that I couldn't breathe. I still giggle at it.

[gellfex]

If you want something that really appears to defy physics, try watching the recent America Cup races where the foiling boats can do 50 mph downwind in a 20mph breeze. And they're always close hauled!

[A.K. Boomer]

Thanks Matt, it's not in defense of the guys vid being totally legit, But I could see him choosing prime opportune clips of perhaps mild downhills and such and not having electric assist other than the blower, what I can't see is his dramatization in the entry where he unfolds the umbrella and then his neck snaps back like he's in a hot model tesla lol
but also have to say that he did have to mod out the bucket, there's no way he could have made the vid without doing that regardless - he had to mod it out just in order to steer the damn thing,,, it would have been a real hoot to watch him trying to corner a bucket with 4 individual swivel casters lol

Gelflex sailing always reminds me of speed skating --- harnessing the vector forces to achieve speeds way beyond conventional means ... Id hate to be a tuna and get hit with that boats slicer/dicer...

[BCRider]

If you want something that really appears to defy physics, try watching the recent America Cup races where the foiling boats can do 50 mph downwind in a 20mph breeze. And they're always close hauled!

I think if you can check the wind you'll find that they are not going directly downwind but at some angle in order to keep up their speed. By staying on the foils in this way they cover more distance but the time needed for the straight line "as the crow flies" of the course is covered faster.

With fast sailing craft like this there's a function of "apparent wind direction" that applies. Foiler boats like these along with the faster wind surfers back before kite boards felt this. As the hull speed builds the apparent wind direction shifts towards the nose of the craft and close hauling occurs with the build in speed. Even to directions where you would not expect to run close hauled in slower displacement boats. And by golly it's a LOT of fun ! ! !

Excellent work AK! Any chance of repeating it with just a flat surface? I'm thinking that without the reversal from the cup that we'll see little or no movement.

[Michael Edwards]

I'm waiting for Musk to put some propellers on his cars to generate energy to run the car. The faster you go, the faster the prop turns, so the faster you go. It wouldn't be 0 to 60 in 2 seconds, but it could be LA to New York non-stop.

Reminds me of the Geico commercial...

[tomato coupe]

Having been fooled, I'd like to know by how much. Does anybody have a leaf blower and an unpowered skateboard (or little red wagon)? How much headway, if any, can be obtained by blowing on an umbrella?

A zillion skateboarders have tried it, and there are multiple videos documenting it. To quote one video "That's pretty lame. That is so much lamer than I thought."

If you calculate the thrust produced by a typical cordless electric leaf blower, the results will be obvious.