William Gurstelle
William Gurstelle is a professional engineer who has been researching and building model catapults and ballistic devices for more than 30 years. He is the author of The Art of the Catapult; the bestselling Backyard Ballistics
William Gurstelle is a professional engineer who has been researching and building model catapults and ballistic devices for more than 30 years. He is the author of The Art of the Catapult; the bestselling Backyard Ballistics