Might want to check with mr webster but as I recall math people like to use ellipse and most people use oval and they both are for the same "egg shape" to add another name for it.garys said:
Now on to the problem...... I don't know of a good way to figure it out sounds like it might have to be a bit of luck and trying different sizes/shapes.
If you had a digital camera and could center yourself then shoot a picture and post it I could try and get something close in my cad package????
Maybe someone else has a better idea??
Ed