Hi and question regarding the flywheel and more

[Seeker]

Hello there!
I'm the new guy here, but I believe I might be here for quite some time.

I've just started university, studying mechanical engineering. It just so happens that our first assignment is to develop and build our own stirling engine, so I figured this place might just be the best source out there for tips and tricks.

We're working in groups of four people, which are then split into two more groups of two each. My team mate and I have to do a five minute presentation on the subject (and this is my best translation from Danish - the Danish version is just as vague, which is why I'm a little confused)
"Calculations on the influence of the flywheel"

We're both extremely confused as to what it might be that our teacher is trying to get us to do. We've discussed the following things;
- The impact of the weight/diameter on the acceleration of the engine
- The impact of the weight/diameter on the max rpm of the engine
- The minimum weight/diameter in order to overcome friction

And that's where we're currently at. Our presentation is on the 3rd of Oct, so we're not really stressed yet - we just seem to have hit a dead end, so I was hoping someone in here might know a thing or two and would be willing to share their knowledge. We don't figure that we're supposed to come out with exact results, since we don't have a certain engine to measure the variables on, just the general formula(s).

Thanks in advance!

[NerdyEE]

Welcome Seeker and good luck at your university,

I’m not a ME (and also new like you), but I believe your teacher is asking you how the rotary inertia of the flywheel helps overcome the fact that a typical Stirling engine is only a single cylinder. And depending upon the type of Stirling, will only have a small section of the 360 degree rotation cycle with power applied to the inertia wheel…

Your engine power has to overcome friction, and all other elements of power loss. The wheel can only contribute to the friction/loss…

How about you ask your teacher for clarification?? That’s what I keep asking my children to do with their teachers…
-J

[Ian S C]

I looked up one of my old text books (when I say old I mean 1937), theres about 4 pages of figures, but not much explanation. Basicly the idea is to keep all the weight at the rim, and the greater the diameter, the greater the moment arm, there for the less weight required. Too small, not enough inertia, too big too much friction in the bearings. Look at similar size motors, and get a rough idea of the flywheel size, you can experiment from there once you get the motor running.
The motor in my album listed as my second motor has a 6" flywheel, about 2lb wt, and runs up to a max of about 2000rpm, but if you take the flywheel, and pully off, it will still run, but with very little torque.
If your university has an engineering department, it must have a library, this will have more information than you'll find either here or after a long search on google.
Ian S C

[Jerry]

I believe you can get a general idea of what the instructor is asking by simply googling his question. The results of a search on "Calculations on the influence of the flywheel" shows similar discussions and the calculations required.

https://www.google.com/search?q=Calcula ... tartPage=1

[Seeker]

Thanks for the help people. I think we managed to put together something resembling a presentation, so tomorrow we'll see how it goes