How much effort would the ducting modification be to do on a finished model? I'm going to be glassing everything so I guess the hard part is going to be getting the ducting to stick to the side of the fuse? I have a P60 and I'll be flying from a mown glass strip (~200m/650ft long with a decent hedge at one end and a maze field at the other). I'm just worried that my auw is going to be too high so I'm wondering if I should leave it off at this stage with the possibility of adding it at a later stage if it is possible.
The bare finished airframe currently weighs 3.45kg/7lb-10oz. I have estimated all the installed equipment plus fuel will be another 4.8kg/10lb-9oz and then the glass and paint finish is likely to add another 0.5kg/1lb to this at least. So I'm looking at 8.75kg/19lb-5oz take off weight. I have estimated that the ducting is likely to tip me over the 20lb mark. I realise people have flown this jet at 20lb+ no problem but I don't know what turbine they were using and if they were flying from a long sealed strip or not.