I wan't happy with the weight of the components suggested in the manual. I see no point in useing standard sized servos when you can get the same performance from a much smaller unit now days. I remade my calculations with lighter yet good parts. The electric retracts had to go.
New calculation based on Futaba BLS servos, Jet 1A retracts from Savex L39, Break only on the front wheel and the engines mounted in the back(!)