Cart Shopping Cart My Store Account Orders Downloads Shopping Cart Remove item Thumbnail image Product Price Quantity Subtotal × 13. Will Accessories Impede Our Payload? $20.00 13. Will Accessories Impede Our Payload? quantity $20.00 × 4. The Weight Engineer and the Flutter Problem $20.00 4. The Weight Engineer and the Flutter Problem quantity $20.00 × 9. Aircraft Balancing and Center of Gravity Control $20.00 9. Aircraft Balancing and Center of Gravity Control quantity $20.00 Coupon: Apply coupon Update cart Available coupons (Click to apply). Cart totals Subtotal $60.00 Tax $0.00 Total $60.00 Proceed to checkout