hamster power

[Nigel Goodwin]

Just an update - the TV series was called "Beat the ancestors" and the specific episode was "Gothic Mega Crane"

https://www.radiotimes.com/tv-programme/e/vgdcs/beat-the-ancestors-episode-guide/

 

[gophert]

The human powered one I showed was EXTREMELY effective, and the donkey powered ones probably even more so (a donkey is heavier and stronger).

There was a TV series on in the UK a couple of years ago, where they were given simple drawings (often very vague and very old drawings), and had to try and build a working replica, improving it if they could. One was a medieval multi barrel cannon (which worked really well) and another was a human powered crane.

They made space for two people in the 'hamster' wheel, and improved the design by having two gears, and a swinging jib - they easily picked up a car with it, and swung it round to drop it elsewhere.

You tend to think that losses would be huge, but such devices work, and work well, as do old water wheels and windmills. When you look at the size and weight of them it's incredible that they can be moved at all, never mind provide power from a relatively small source.

I didn't mean that it doesn't work, I was thinking more in terms of efficiency. With modern bearings light weight materials and efficient motors, can the bucket of water be brought up out of the well with 50%, 25 or even 10% of the joule equivalents of energy (whether it is corn to feed the donkey vs coal used to make electricity as the energy source?).

 

[Tony Stewart]

Thanks Nigel. I have Kodi and StremIO, so I can watch any TV or movie from the past or present on my PC on the big screen.

 

[gophert]

... or better yet, converting incoming sunlight to electricity via solar panels to charge a battery to run a motor to pump the water, vs sunlight to grow the corn, to harvest the corn, to feed the donkey to pump the water.

 

[Nigel Goodwin]

I didn't mean that it doesn't work, I was thinking more in terms of efficiency.

Efficiency doesn't really matter, it does the job, and it saves humans powering it

Likewise with antique water wheels and wind mills, they might be technically inefficient, but they are effective, and that's all that matters.

 

[Nigel Goodwin]

... or better yet, converting incoming sunlight to electricity via solar panels to charge a battery to run a motor to pump the water, vs sunlight to grow the corn, to harvest the corn, to feed the donkey to pump the water.

Where did you get your solar panels and electric pumps, back before the USA was created?

Plus when times are BAD, you can eat the donkey!.

 

[gophert]

Plus when times are BAD, you can eat the donkey!.

You can only do that once - assuming the old fella is not uncooperative and decides to kick the bucket before times are bad.

 

[gophert]

Where did you get your solar panels and electric pumps, back before the USA was created?

Plus when times are BAD, you can eat the donkey!.

From the Ye Old Solar Panel Shoppe.

 

[alec_t]

A decent alternator attached to this system should power the prison lights and heating .

 

[Dr_Doggy]

Where did you get your solar panels and electric pumps, back before the USA was created?

Plus when times are BAD, you can eat the donkey!.

actually for that very reason i initally wanted to use rabbits... but their backs dont like the wheels either.

 

[Dr_Doggy]

ooops .. delete

 

[Dr_Doggy]

so if my 2lbs rat runs the 11 inch wheel at about 60rpm average ... but since I am attaching then generator to the center of the wheel i will want to match my rpms

so maybe this motor?
https://www.robotshop.com/ca/en/dfrobot-6v-180-rpm-micro-dc-geared-motor-with-back-shaft.html

also according to google i use a avg of 12kwh per day ,. which is about 500watts per hour for 24hrs and that motor is about 18watts @180rpm, so 6watts@60rpm
so if my rats ran 24/7 then 90 of those motors would do the trick?

am i correct in my assumptions?

 

[gophert]

also according to google i use a avg of 12kwh per day ,. which is about 500watts per hour for 24hrs...

No, you need 500 watt-hours each hour.

That is 500 watts continuously for an hour.

I did some math because you are limited by the mass of the rat(s) x acceleration of gravity x change in height of the center of mass of the rats divided by the change in time.

This is for a climbing rat - essentially climbing the vertical section of the wheel to achieve maximum torque on the wheel.
At the vertical section of the wheel, the 90 rats (2lbs each (0.9kg)) will need to climb at a rate equivalent to 41 rpm. That is more like climbing than running if they have to stay at the point of the wheel at the same level as the axle.

Now, If we assume the animals are essentially running, and staying about 5° from bottom dead center of the wheel, the 90 rats will need to run about 11mph (470rpm on an 11.5" wheel.

 

[Dr_Doggy]

500 watts continuously .. exactly 90 continuous running wheels
the rats spend alot of the time at the 90deg position and on the YT vids they were clearing 60rpm, so ya 50rpm avg

but how much torque is that on the center point?
i cant have too much resistance on the motor or it will stall the rat.. or not let him stop!

if i could find the perfect little motor for each wheel I think i can get the rest together easy enough, but which motor? ()

in my mind:
i would imagine i want to match the max rpm's best i could but then i need to match the motor power
to keep the wheel loose i will step the weight down 80% , so the wheel can stop easy for him, so 0.2KG * 9.8 = 2newtons of force

the example motor listed above has a stall torque of 11.11 oz-in OR 0.80 kg*cm

so 0.2kg rat * 11cm radius = 2.2kg*cm on the rat side?

so does that mean i would want a motor similar to the example one but with about 3 x the stall torque value?

 

[gophert]

Note that a rat "runs to exhaustion" at about 1 mile at 5 mph. A rat run to exhaustion will need almost a full 24-hours to recover. They sleep almost the whole 24-hours and only wake up enough time to drink for a bit. Note that the run to exhaustion is on a flat surface on a motor-powered treadmill. So less than 15 minutes and not really producing any "work" for 5280 feet. If you make them climb a vertical surface, I suspect they will run to exhaustion in a much shorter period. You'll need a lot of rats.