If you plan to build and fly a model aircraft in the UK of any type which weighs over 20kg then it is mandatory (a requirement of the Civil Aviation Authority) that the aircraft is built, inspected and flight proven using the over 20kg scheme operated by the Large Model Association on behalf of the CAA.
Therefore, if you are planning to build or fly such an aircraft you should contact the Chief Examiner for the Over 20kg Scheme Tony Hooper. It is strongly recommended that you do this before you begin building. Please DO NOT contact the CAA (Civil Aviation Authority directly). Registration of such a project can be made using the form found here. If you have an questions for Tony he can be contacted on 01926 641 490 or 07976 691 992.
“Our aim is to help you complete a successful project to produce a structurally sound and safe aircraft to operate.”
Please note that if you are considering building a model that weighs over 150kg you will have to put the model through a full airworthiness certification with the Civil Aviation Authority.
For a detailed explanation of how the over 20kg scheme works please click here