Students invent quieter leaf blower • Hacker News Board

Re: Students invent quieter leaf blower

#391

Post by sokoloff » Thu, May 16, 2024, 8:55 PM UTC

omgJustTest wrote: post #239

sokoloff wrote: post #38

Earlier quoted context omitted.

> JHU should make these comments!, and also offer their designs for free given these are public orgs using mostly public dollars JHU is private. It seems like this research may have been sponsored by Black & Decker, also private.

"Johns Hopkins researchers' success in winning federal funding—which accounted for close to 87% of its 2022 R&D expenditure—enables them to pursue projects in an array of fields, from human genetics to artificial intelligence." [1] https://hub.jhu.edu/2024/01/05/nsf-higher-education-research... Oh yes... "private" org using public dollars is more appropriate.

It appears as if this specific research was funded by Black & Decker. If they couldn't get the benefits from it, it's not as if they'd pay JHU to do and make public this research, but rather that they'd do the research a different way, likely robbing the JHU students of the real-world problem-solving experience as a capstone project of their engineering curriculum.

How JHU's other, unrelated research is funded doesn't seem terribly relevant to this privately-funded, patent-pending innovation.

Re: Students invent quieter leaf blower

#392

Post by nisse72 » Thu, May 16, 2024, 9:03 PM UTC

hindsightbias wrote: post #313

unsupp0rted wrote: post #297

The first time I woke up in North America to the sound of a neighbor with a leaf blower, I asked myself how this could possibly be legal.

You should go to the beach and relax with a two-stroke jet ski.

or on a hike with a UE Boom

Re: Students invent quieter leaf blower

#393

Post by iwontberude » Thu, May 16, 2024, 9:11 PM UTC

brequinn wrote: post #334

iwontberude wrote: post #85

Earlier quoted context omitted.

Leaf blowers are already mostly electric, and they are annoying as hell. People will take time to replace them, but I assure you they aren’t loved at all.

Curious - why dont people love them? I assume just not as powerful as gas?

They chew through batteries so fast and they have a really high pitched sound ~16kHz that gives me tinnitus when I use it without ear protection. I suppose the same would happen with a gas one, but I was hoping to avoid wearing ear protection.

Re: Students invent quieter leaf blower

#394

Post by cchi_co » Thu, May 16, 2024, 9:32 PM UTC

modeless wrote: post #296

We don't need quieter electric leaf blowers. We need to ban the gas ones, with no grandfather clause. Not just for the noise pollution but the local air pollution. It's crazy the volume of air that can be ruined by a single gas leaf blower, far worse than modern cars, and they are inescapable in cities.

But more sustainable alternatives to gas-powered leaf blowers are needed I think

Re: Students invent quieter leaf blower

#395

Post by ssl-3 » Thu, May 16, 2024, 9:34 PM UTC

WaltPurvis wrote: post #346

SV_BubbleTime wrote: post #233

Earlier quoted context omitted.

But that is NOT the same as human perceived volume. Less 37% energy is not 37% less volume to humans. You won’t be able to tell the difference in volume except for the tone which could be more or less pleasing depending on the frequency they say they got 12db on.

I learned something new today (I didn't know decibels were logarithmic), but I still don't understand how it relates to "human perceived volume" as you put it. If a typical electric leaf blower makes 70 decibels of sound, it seems odd that cutting that to 67 decibels makes it sound 37% less loud. Perhaps it does, but I think I'll have to hear it to believe it. I may have to buy a sound meter and run some experiments.

A reduction of 3dB at any point in space is equivalent to halving the energy at that point.

But we humans don't perceive sound energy linearly, so half of the energy is not equivalent to half of the perceived loudness.

The usual rule of thumb is that it takes a reduction of 10dB (1/10th energy) for a thing to sound about half as loud, or an increase of 10dB (10x energy) for a thing to sound about twice as loud.

(This leads to all kinds of interesting problems with making things quieter or louder. It seems superficially implicit that moving from a 100-Watt amplifier to a 1,000-Watt amplifier would be strikingly-dramatic difference, but in an ideal world where everything else is the same then that change only makes things about twice as loud -- the same as moving from a 1-Watt amplifier to a 10-Watt amplifier.)

Re: Students invent quieter leaf blower

#396

Post by craigmcnamara » Thu, May 16, 2024, 9:55 PM UTC

cchi_co wrote: post #394

modeless wrote: post #296

We don't need quieter electric leaf blowers. We need to ban the gas ones, with no grandfather clause. Not just for the noise pollution but the local air pollution. It's crazy the volume of air that can be ruined by a single gas leaf blower, far worse than modern cars, and they are inescapable in cities.

But more sustainable alternatives to gas-powered leaf blowers are needed I think

Have you heard of a rake?

Re: Students invent quieter leaf blower

#397

Post by philbin » Thu, May 16, 2024, 10:14 PM UTC

[dead]

Re: Students invent quieter leaf blower

#398

Post by caseyohara » Thu, May 16, 2024, 10:24 PM UTC

odiroot wrote: post #310

modeless wrote: post #296

We don't need quieter electric leaf blowers. We need to ban the gas ones, with no grandfather clause. Not just for the noise pollution but the local air pollution. It's crazy the volume of air that can be ruined by a single gas leaf blower, far worse than modern cars, and they are inescapable in cities.

They have been a bad idea from the start. Who thought an unbalanced, two-stroke internal combustion engine with a minuscule exhaust (and no muffler!) was a good idea for a tool operating in residential areas.

It’s the power-to-weight ratio. Two-stroke engines are used in blowers, chainsaws, trimmers, and edgers because the power:weight ratio is far more practical for handheld tools than a four-stroke engine.

Motorcycles and snowmobiles are mostly four-strokes these days because the increase in weight isn't a big deal compared to a chainsaw or trimmer.

Re: Students invent quieter leaf blower

#399

Post by kbenson » Thu, May 16, 2024, 10:26 PM UTC

xkqd wrote: post #328

kbenson wrote: post #324

Earlier quoted context omitted.

Why? I'm sure they're less practical than the gas powered ones, but every tool system with their own battery standard seems to have one. Even if you had to have a few batteries charged in reserve, that seems more like slightly more expensive and annoying than utterly impractical. Am I missing something?

You basically can run through a high capacity battery in less than 10 minutes, completing a light cleanup of a standard 1/4ac lawn. The battery itself will take 3-4 hours. Running through an entire block would deplete numerous batteries, meaning you’ve got to purchase 2 dozen if your crew is going to do the average 20ish homes a day. The purchase cost is one thing sure, but batteries are a consumable and the logistic…

From a little looking, the Greenworks 82BA26-52DP[1] seems like it might work well. It has a fairly long run time on battery on high (40 minutes), very long on low (2 hours), and has a dual port charging solution that seems to be able to charge batteries in 40-60 minutes depending on battery size. About a hour per tank of gas for a gas powered leaf blower seems to be about average, so I don't think stopping that often is really a problem.

It is more expensive up front, from even the electric blower's own numbers, but they say it's much cheaper over a year if you have a 4 hour daily usage cycle.[2] I don't know enough to know whether the claims make sense or not. Maybe you know more about this, but maybe it's not as clearly one sided as you think?

1: https://www.greenworkscommercial.com/products/82ba26-52dp-82...

2: https://www.greenworkscommercial.com/cdn/shop/files/82BA26-S...

Re: Students invent quieter leaf blower

#400

Post by ElijahLynn » Thu, May 16, 2024, 10:40 PM UTC

modeless wrote: post #296

We don't need quieter electric leaf blowers. We need to ban the gas ones, with no grandfather clause. Not just for the noise pollution but the local air pollution. It's crazy the volume of air that can be ruined by a single gas leaf blower, far worse than modern cars, and they are inescapable in cities.

The video shows the electric leaf blower before, and with their invention after. And it's a big difference, and makes the electric even quieter. I think we definitely need this even for electric!

Yay, for quieter cities!!!