I would use the flywheel, just be sure to use some sort of “slip” joint so the handle doesn’t keep flailing around after someone stops turning it.

Also for safety reasons I would shield the flywheel.

Yes! That was the first thing I researched. I'll use a one way clutch bearing to prevent the crank from turning with the flywheel.

 

Yes! That was the first thing I researched. I'll use a one way clutch bearing to prevent the crank from turning with the flywheel.

Also my plan was to have a cage around the flywheel. All the mechanics will be housed in 1/4" steel plate housing with a small 1" thick safety glass viewing window. I'll light up the interior.

All very good advice.

 

All very good information and advice!

I feel very confident about winning this competition. The location is right next to a hydro electric dam so the parallels are good.

 

If sustained human power is about 1/3 HP or 248 W then a one arm hand crank might be about 75 W. If the generator already has a flywheel
then keep it. Gearing might be 1:10.

 

I reassert that a flywheel is unnecessary , it may have 'artistic' appeal , but It will only WASTE power in bearing friction and wind resistance .... The gearing will be driving a motor/generator at 1000's of RMP and at that speed the motor/generator itself will act like a flywheel .... I guarantee the two hand generators pictured have no flywheels inside....

The reason exercise bikes etc have what could be called flywheels is to give a pleasant feel to the machine , no sudden changes of speed .... And to dissipate (waste) , in wind resistance, the energy of the person exercising....

Unless TS is competent at building technical devices , I would recommend he buy the 20W one pictured .... It's quiet a task to build one of these which operates well...

An easy shortcut would be to use an old discarded cordless drill/screwdriver ... ( I have 2 of these in my junk box) .... the power of the motor/generator is about right , and so is the gearing , just put a handle in the chuck and collect the power from the motor....

But I think TS has his heart set on a big flywheel for dramatic effect .. in which case why not put magnets around the circumference of the flywheel and collect the power from coils ... no need for motor/generator or gears.

 

I reassert that a flywheel is unnecessary ...It will only WASTE power in bearing friction and wind resistance .... The gearing will be driving a motor/generator at 1000's of RMP and at that speed the motor/generator itself will act like a flywheel .... I guarantee the two hand generators pictured have no flywheels inside....

In what way will the motor generator act as a flywheel? Will it smooth out the motion? Will it store energy to maintain the electrical output after cranking stops? For how long would a drill motor supply 12W after you stop cranking?

As I envision it, the “wasted” energy is a good thing.

And a delay after cranking stops is a good thing.

This isn’t a flashlight, where weight of the gears is a concern.

It’s a static demonstration display. Where having to work is a good thing. And a delay in the rundown is also a good thing, giving the participants time to observe the effect.

I can understand those who say that a flywheel is unnecessary. But I don’t think the people who made those statements understand the requirements. Sometimes, design feature that doesn’t make sense actually does.

 

As I mentioned in #4, a flywheel will help the feel of it. And that is a very important part of an art installation. Having to work up to speed helps impart the idea of the effort needed to generate the power. I have a hand flashlight and it does work ok. But it feels "tinny and cheap" as there is no need for a flywheen just to make it go. Adding a good hunk of inertia is worth while for the user experiance.

 

In what way will the motor generator act as a flywheel? Will it smooth out the motion? Will it store energy to maintain the electrical output after cranking stops? For how long would a drill motor supply 12W after you stop cranking?.......

Fly wheel effect is about I x omega squared ........... I is the moment of inertia dependent on mass and how far the mass is from the axis Times omega squared ... the rotational speed squared ..... so although the motor has a small mass and inertia (I) , it will be spinning very fast which will give a fairly big flywheel effect .....(but nothing approaching that of a big heavy flywheel)

But I get what people are saying ... this is an art project ... so make a gigantic flywheel ...put neodymium magnets all around the circumference , and stationary coils outside ... this will also visibly demonstrate how electricity is made ...

 

But I get what people are saying ... this is an art project ... so make a gigantic flywheel ...put neodymium magnets all around the circumference , and stationary coils outside ... this will also visibly demonstrate how electricity is made

Then an old bicycle is where I would start. The crank, chain and rear wheel.

The pedals taken off of the crank and handles put in their place.
The chain connecting to the rear wheel, it has the one way bearing in it already, the free wheel.
Then the rim of the rear wheel without the tire, and it would have the magnets epoxied to it, in alternating poles configuration.

That is basically how the first Model T fords generated their electricity. A series of magnets in the flywheel of the engine and coils near it.

 

I retract my 1:10 suggestion. Your motor might be1 to 4 HP @ 130 V DC. I would start by direct hand cranking the motor with a load of about 10 ohms and measuring output Vs. Might find that a step up is not necessary? Any specs on your motor inc. model number?

 

But I get what people are saying ... this is an art project ...

Who said it was an art project?

UPDATE: Oops

 

Fly wheel effect is about I x omega squared ........... I is the moment of inertia dependent on mass and how far the mass is from the axis Times omega squared ... the rotational speed squared ..... so although the motor has a small mass and inertia (I) , it will be spinning very fast which will give a fairly big flywheel effect .....(but nothing approaching that of a big heavy flywheel)

But I get what people are saying ... this is an art project ... so make a gigantic flywheel ...put neodymium magnets all around the circumference , and stationary coils outside ... this will also visibly demonstrate how electricity is made ...

That's is a cool idea but a little too much work for

Who said it was an art project?

Me the Ts

 

I have seen just such a setup at a science museum in Minneapolis. the flywheel was on the motor shaft and the crank had about a 4 inch circle of rotation while the flywheel was several inches larger in diameter. the motor was a brush type, about 4 inches in diameter. The flywheel was needed to keep the speed sort of steady because most humans can not maintain a constant force pushing a crank like that. And there was a switch to engage an incandescent lamp load instead of the LEDs, to show the difference in the power needed. AND there was an analog voltmeter to show the generator voltage. It was a popular item while I was there.

 

I’ve seen a human powered generator with light bulbs at every science or engineering show I’ve ever been to.

 

We have one of the original Edison DC self exited generators in the local Electrical Museum here.
It's a draw with the kids.
Max.