ORIGINAL: Dave trimmer
...I learned about this at the field and they said that it wouldn't make a difference on my trainer is this true?.......
I might have agreed with them until I recovered my own trainer. Sealing the gaps took the plane from "flopping" over in a roll to doing a crisp clean roll that was easy to perform. Trust me here, just try it and you won't listen to those guys at the field any longer.
p.s. i still dont understand the folding part of the covering before putting it on.
By folding the covering in half you make a sharp "point" of the covering that lets it sit directly at the bottom of the gap.
Ken