Afraid I am the old school not so flexable person on this issue Roli is refering to . I know that it looks great being inside the plane but have had first had experience in the past where it did not work on some planes . One of the aircraft belongs to a fellow Jomac ( Johannesburg Aircraft Club ) member , Francois Greber. He has a large ( I think 27%) extra 300S which crashed on flight 3 or 4 due to interference ( radio went into fail safe mode ) . Fortunately not too much damage - happened on the landing . He had the antenna nicely taped to the bottom of the plane ( outside ) . He had the plane repaired and prior to a flight showed me he had range problems - looking at antenna postion I pulled it off against his will made him buy an external whip antenna - problem solved . I am also building an Osmose and it will certainly have an external antenna