mathematics of a rotary engine
 

Anyone know anywhere (website,etc). that has info on the specific mathematics of the rotary engine, specifically the rotor/housing combo. I know the housing has an epitrochoid shape and i inderstand how an epitrochoid is created, but how do you figure out what radius to use for the circles so you can have a triangles apexes touching the side at all times?

http://www.rotaryrefs.net/

Go to Books & Info and download 'Rotary Engine' by Kenchi Yamamoto, it has everything you need.

The rotors arent exactly triangle.

If you connect the 3 apex seals by a line they are :)

I believe they are a "gothic" triangle, if you draw an arc from one apex seal to another using the third as it's center for all 3 faces, you have a gothic triangle.

-Marques

Nope... having tried a mathematical model doing the gothic triangle idea, they overlap the rotor housings. I came across stuff that does work, but don't remember where.

The book at that link has the exact formulae for the housing and the rotor.

dang! i've been looking for this book for a long time. thanks so much! that site's awesome!

Here's an Excel spreadsheet I started a year or so ago to evaluate port timing on a 13b. I had plans to calculate apex seal velocity/loads/rubbing angle as well, but haven't had a chance to get this calculations added yet.

The link to the Rotary Engine book is awesome! I haven't seen these equations before. No need to derive them now.

Glenn

ALright, how do I upload an Excel file?

Can anyone calculate the chamber volume per degree thru the entire compression phase? It needs to be very accurate and I have NO idea how to do it. I'm a finance major...not engineer haha

www.rotaryengineillustrated is the best site that easily explains the mathematics and physics about the engine

http://www.mikesdriveway.com/misc/rotor.doc

MikeC came up with this. there is an integral for "d', which is the same as piston displavement. Pic starting Theta (crank) and use d value x face area + min volume at tdc to get total vol at ea deg of compr.

SPOautos, PM me an email address and I can send you an Excel file that does what you are looking for.

P.S. Sorry for the slow reply, been a hectic week.

Glenn

It's just a sine wave:

V = Vmin + Vswept * (1 - cos(a / 1.5)) / 2

Vswept can be calculated accurately but you have to measure Vmin.

rotary design math
 

great site, but not much math there

try

http://not2fast.wryday.com/engine/rotary_design.pdf