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# Birdmill

Because birds want to play chicken.
 (+2, -1) [vote for, against]

**Improved, order of magnitude more accurate**

Unabubba recently said: "I read recently that clear and mirrored glass on buildings in the US may be responsible for up to 1 billion bird deaths per year."

It has also been noted that birds don't actually die of the collision all that often.
My suspicion is that flying into plate glass is a daredevil extreme bird-sport.

I propose that instead of trying to dissuade the birds using kestril laminates, we should be encouraging them to lark about in a safe manner. And generate energy in the process.

The birdmill would be constructed of a rotating set of stiffly hinged glass plates for the birds to bounce off. This impulse would be used to generate energy with a motor.

Energy per bird impact:
ke=1/2 m v^2
where I assume that on average:
m=mass=50g=0.05 kg
v=20 m/s

therefore energy=10 joules per impact.

If we could persuade the otherwise doomed birds to have one go a day on average, we would have 1,000,000,000/24*60*60=11574 strikes per second.

If the generator were 50% efficient, we would get an output of 11574*10/2=57870 J, or 0.058 MJ per second.

So we could gain about 0.058 megawatts of power from our avian friends.

 — Loris, Jul 20 2004

Put Window Tints Of Birds Of Prey In Windows Of High Rise Buildings http://www.halfbake..._20Rise_20Buildings
Doesn't fully exploit resources [Loris, Oct 04 2004, last modified Oct 05 2004]

Large numbers http://www.unc.edu/...tt/units/large.html
quite how the American system got quite so <mess>ed up I don't know. [Loris, Oct 04 2004, last modified Oct 05 2004]

Bird speed http://www.bbc.co.u...ature/speedofbirds/

Bird weights http://www.upatsix.com/faq/weights.htm

 I've recently been informed that a billion is a different quantity in the states than it is overseas. That said, I'm not sure which one you're using.

 Also, why are you calculating on a daily basis? You need to divide by 365.25*24*60*60 = 321.8 strikes per second. I think.

Funny idea, though.
 — yabba do yabba dabba, Jul 20 2004

 I used the american billion since it was about american birds. A proper billion is a thousand times larger.

Also I figured that if the birds didn't die they could do it every day, rather than just once in a lifetime.
 — Loris, Jul 21 2004

An American billion is 1,000,000,000.
 — yabba do yabba dabba, Jul 21 2004

Or, burn the dead birds! Should get more energy like that!
 — my-nep, Jul 21 2004

Awwwww fwancey pudin de wittle birdies to work makin eletwicity. Shame on u. Make da fwiggin stuff yerself
 — tasman, Jul 22 2004

 Tabs, I can't see any error in my arithmetic.

 1 (american) billion * 10 joules = 10,000,000,000 joules

 Birds survive impact and therefore can have one impact per day (on average).

 — Loris, Jul 22 2004

 I love the halfbakery. Birdstrike-generated electricity leads to knowledge of how the two systems of numerology originated.

If only I could remember what I was looking for when I first surfed in here last year.......
 — normzone, Jul 22 2004

You're right about the 10,000,000, Loris. Sorry 'bout that.
But "if the birds didn't die they could do it every day..."
...until they do die.
 — yabba do yabba dabba, Jul 22 2004

 I see... I made several mistakes, all of which I hope are corrected. 1) transcription : 117540 > 115740 (negligable) 2) description. Not a mathmatical error, but of associated text. 10^9 birds, 10 joules per impact = 10^10 joules, not impacts. It was right until I edited it, honest. 3) I think I multiplied by 10 joules twice; probably because of (2). _This_ is why the power output has gone down.

 I'm not going to divide by 365.25, because I still hold that a bird could collide with my machine every day, but can only die once.

 I'm a bit sad about the power reduction, too be honest. Also, I assume that everything not mentioned so far must be correct. I did think perhaps I could increase the birds speed to make up for it, but on googling I found link 3.

 Taking a high fraction of the fastest bird speed (I used 45mph) and converting it to m/s, I got 20.1168 meter/second.

So I think my initial estimate was bang on.
 — Loris, Jul 22 2004

 We may need to work on your 50g weight assumption.

 Skyscrapers in cities attract predominantly sparrows, warblers, and other small passerines. A sparrow weighs about 1/2 ounce (14 g); a warbler somewhat less. An average duck may weigh 3.5 pounds (1568 g), but you won't get too many ducks crashing into skyscrapers.

Ignoring the warblers, as they are offset by medium-sized birds whose weight is greater than 50 g, you will need approximately 0.024 dps (ducks per sparrow -- note: first use EVER of that unit!!!) in order to meet your 50 g assumption. It's unlikely you will see 1 duck for every 40 sparrows crashing into buildings.
 — phundug, Jul 22 2004

 Funny you should say that, that was my next attempt to increase the output. Googling for "bird average weight" gave the highly enlightening link 4. A bit of Excel trickery later, and we have an average weight of... 314g

 First I excluded xanthopterys, and deleted text from the column. I then split the ranged values into 2 columns, and took the average. The average of these all gave the result.

 This would mean a new power output of 0.36 MW.

 Now the only problem I can see is that people might complain that the average pet parrot might not be the same weight as the average american window-barging bird.

But on the other hand, maybe it is on the low side. Particularly if we could persuade ostriches to charge the bottom part of the birdmill.
 — Loris, Jul 22 2004

European or Asian ?
 — normzone, Jul 22 2004

(Thank-you, Tabs)
 — Loris, Jul 22 2004

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