ORIGINAL: AndyAndrews
ORIGINAL: R_Belluomini
We use a rolled mylar sheet for the thrust tube.
I am assuming that BVM sells the mylar correct?
BVM does sell precutmylar exhaust tubes for their jets. You could get the one for the electra. You'd have to cut off some of the length and overlap it in such a way that the rear of the opening is 3.5 inches.
Or, you could get a roll of mylar from Taps Plastic and make your own.
http://www.tapplastics.com/shop/product.php?pid=255
Kirk