Hi I been designing a small electric trike, made a model (Hard copy) and am on the stressing of the tub. Body panels anybody in the industry will tell you how many layers but not structural. I did use an online calculator for a beam 120" long and 63 " wide gave me 8 layers of S glass. the construction of the tub will resemble the Maclaren / Lotus style and probably have conventional enclosed sill structure and may have a transmission tunnel but this will not be used for transmission uses. I have been told that this structure is "in the ball park" and I am wondering If any one knows of an online easy to use calculator for fiber glass structure. Or can confirm that I am "In the ball park" I am hoping to keep the car as light as possible with a laden-ed wt of 450kgs or under and a top speed of 50 to 60 mph in the final model. Can anyone help.