humming fly wheel

[DaveH]

I would like to make a fly wheel that hums as it goes round. (Or even whistle dixie).

Remember those humming spinning tops? from the 50's - well something that hums like that.

Any sugestions?

Fly wheel diameter approx. 3"

DaveH

[Blade]

Maybe you could look at old siren designs for ideas.

[Bogstandard]

Dave,

Have it ringing a bell each revolution, it will be easier.


John

[j45on]

I cant find any info on the net as to how they work but you can buy them quite cheaply
http://gyroscope.com/d.asp?product=HUMMING
then you could figure out how it works and copy it

[John Hill]

I think you need interrupted air flow to make it hum.  

Perhaps hollow spokes open near the hub end and hollow right through to holes in the outer rim, put something near the flywheel for the air to impinge against.  If you can get your engine up to 10,000 rmp or so you will have a siren!

Thinking further, you might not even need the holes at the hub end, just hollow spokes with holes in the flywheel rim.

[DaveH]

I have also looked, didn't find much - did find some whistling yo yos.

So probabily needs to be hollow - with some holes in it.

Seemed a good idea at first, - now I'm not so sure.

Surely someone must have some thoughts.

DaveH

[John Hill]

Still thinking.......  if it is a solid flywheel just drilling radial holes might be enough but I fear it might be impractical in a small model as to get pleasing audio frequencies it may be necessary for the flywheel to be a foot or so in diameter.

[DaveH]

John,

10000rpm I was thinking in the range 50 - 100rmp.

What about holes drilled radially on the periphery of the flywheel towards the hub, with a small holes near the hub.

Well I know what I mean

DaveH

[DaveH]

                   

Dave,
Have it ringing a bell each revolution, it will be easier.
John

Ring my bell

DaveH

[DaveH]

I can make a hollow fly wheel that's not too difficult - where to drill and what size and number of holes seems tricky  

DaveH

[DaveH]

Kenneth,

Slowish 50 - 100rpm Hub about 1/2 inch or so.

DaveH

[DaveH]

Has anyone seen a whistling yo yo.

Wondering how they work - number of holes ect.

DaveH

[BiggerHammer]

The old Duncan company sold many different whistling
tin yo-yos. These varied in size and had many different
designs on them. Many patterns were very colorful like
the one pictured here, with very detailed logos. Others
were simple one color models with an ink stamped logo.
All of them had one thing in common ... a tin outer shell
with two to four quarter inch holes on the outside edge
of each half. As the yo-yo spins, air is drawn through
these holes, creating a whistling or humming sound.
Each half usually had a different number of holes. This
was clever because each half would make different
sounds at different speeds. I want more tin whistlers.

Found that.

Now a question. Does the flywheel itself have to whistle or could you mount a plate with holes in it or a tube with one closed end in close proximity to the flywheel and let the air being dragged by the flywheel make a whistle? Not sure if the physics would create the desired effect though.

And my idea would be to Drill holes in the flywheel and insert  closed end tubes into it. You could then change the geometry of the tube end until that puppy whistles.

[DaveH]

Thanks BiggerHammer,

Worth a try I'll see what happens

DaveH

[BiggerHammer]

I think you need interrupted air flow to make it hum.  

Perhaps hollow spokes open near the hub end and hollow right through to holes in the outer rim, put something near the flywheel for the air to impinge against.  If you can get your engine up to 10,000 rmp or so you will have a siren!

Thinking further, you might not even need the holes at the hub end, just hollow spokes with holes in the flywheel rim.

Oooooo..... looks like I had the same ideas as you with only minor differences. You were here with the ideas first and a more accurate description. I guess I should have read the responses a bit more thoroughly. My apologies. It was late and a long day at work with a 3 hour commute home. 

[DaveH]

Well drilled two holes in some 3" dia. Ali. Then spun it in the lathe.

I think I get more wind noise from the jaws than from the holes 

Although I am bit wary of placing my ear too close!

I have the feeling more holes, or it might need to be hollow.

What we need here is a musical physicist 

DaveH

[BiggerHammer]

Well, if all else fails you can duct tape some deer whistles to it. 

What size are the holes you drilled in the aluminum? could you stick some drinking straws in them with the ends cut at an angle? Let the straw protrude from the flywheel so it can catch air? Trying various angles to see if any work? There may be a boundary layer of slower moving air near the flywheel. The flywheel may be "dragging" the air with it. Not much on fluid dynamics here, (yes, air is apparently a fluid ) but I know it can happen when an object like an airplane moves through air.

Though I have looked at some whistling arrowheads and deer whistle designs. You may be able to incorporate the arrowhead design into the flywheel.

It might also be cheaper and easier to make the prototypes out of wood instead of metal. Just from looking at the arrowheads you might try drilling the holes at about 45 degrees off center of the flywheel center. 

[BiggerHammer]

Just found this. I think it may solve your problem. The Chinese YO-YO or Diablo.

http://hua.umf.maine.edu/China/ModernBeijing/pages/286_ChineseYoyo.html

[DaveH]

BiggerHammer,

Thanks very much 

Looks very promising - seems my round holes is not the way to go.

Some thin slots and a square hole may well work.

I'll give it a go
 

DaveH

[John Hill]

Well drilled two holes in some 3" dia. Ali. Then spun it in the lathe.

I think I get more wind noise from the jaws than from the holes  

If it was my lathe the box full of straight cut gears would overcome any whistle noise!

I think it might work if there is air flow and something to interrupt it.  The radial holes in the flywheel would give the air flow (I think  ) but they would have to be open at the hub end so air can flow right through then if there was a plate close to the rim at some part of the circle that would interrupt the air as each hole went past.

My feelings are that it will be quite hard  with the low RPM and the small diameter of the typical models we play with.

Does your intended engine have an air exhaust? If so it might be practical to route that near the flywheel and use the exhaust as the source of air flow.

[DaveH]

Hello John,

I think I am battling a bit here 

I've used up all the empty containers I could find. Drilling lots of holes different sizes ect.

The link from BiggerHammer could work, just have to find some more tins/container to mutilate.

I am going to try the slots - might work.

I am making some (4) finger engines for the grand-kids, I just thought I might be nice if they hummed as they went round.

I really must stop this thinking - it's detremental to my health Seemed a good idea at the time.

DaveH

[Bogstandard]

As I said before Dave, stick a one per rev bell on them, much easier. 


John

[foozer]

Just an old baseball card tracked against the spokes ought ta do it

Robert

[DaveH]

Aaaagh I thought this was going to be easy. 

That bell sure looks good John

I'll have one last go with slots, if I can't get it to work, I'll call it a day.

I would like to thank everyone for the help and suggestions.

 

DaveH

[doubletop]

I'm on the same wavelength as Johns simple solution. How about a piece of stiff cardboard held in place with a clothes peg? Used to work great on my bike when I was a kid

Pete