Finger engine flywheel weight

[hosinsky]

I have read that the weight of a finger engine is rather important, people adding weight to get the engine to work well. I would like to build a finger engine using some 15 mm alu plate to make the fly wheel, but what size do I need, or really, what  (weight x radius)  do I need for the engine to work well?

Goran
Canary Islands

[NickG]

15mm is quite thick so I'd say something like 100mm diameter should be ok - thin the middle section out to give it a decent moment of inertia but reducing the weight on the bearings. There are so many other factors too though, the geometry and the friction in the joints etc.

[BillTodd]

If you use a heavy flywheel, make sure there's no finger-nip trap under the paddle to crush little fingers 

[black85vette]

If you use a heavy flywheel, make sure there's no finger-nip trap under the paddle to crush little fingers 

I will second this.  Also eliminate things like spokes that little fingers can stick through when it is moving.

I built one for my grandkids and didn't find the flywheel to be all that important.   It has no compression or friction and very little mass to overcome