Finally the upper body (sustainer element) is put together. The cut outs for the flare nozzles are as good as I can get. I just couldnt find any really accurate design info so have done them to the sizes already mentioned in the thread. The BT60 inner core is now glued into place against the already added BT70 to BT60 centering rings. The flare nozzles (once built) wil be glued against the inner BT60 core - the nozzles all seem slightly different on every drawing or pic of this bird I have seen so I am going to go for very shallow cones (maybe).
I cant give any accurate dimensions here other than to say the BT60 core on this sits 79mm higher than the forward edge of the BT70 outer skin while the lower edge sits 1 5/8" below.
The prototype drawing worked from the Fitters mini scale paper model suggested the upper end should be 84mm but by eye I am betting on 79mm - 5mm doesnt seem a lot but it makes a big difference to the eyeballs and affects how the cone at the front end looks by quite a bit. The Fitters paper model was only of very limited use I found in making up plans for this somewhat larger bird.
I lack any lathe type gear - the real thing has more of an ogive shape from forward of the front fins but I couldnt find a nose cone the right size and shape so am going for a gentle cone with an ogive balsa nose. Will it work out ? I havent a clue right now
Oh - final note - the inner BT60 core (assuming anyone wants to clone this) has to be long engough at the lower end to have a usable transition via centreing rings to the BT55 inner core of the booster (lower) stage but not so loing that it fouls the mid stage cone that joins the two stages together.
The recovery gear fits into the upper end of the inner BT60 tube shown here from a point just forward of the front edge of the flare nozzle cut outs. There wont be a baffle in this kit cos I forgot to order one but there will be a kind of baffle plate to stop the chuts and gubbins being forced into the smaller BT55 tube due to acceleration.
I did originally plan this as a two stager - it might still be depending on how the first flight as a single stager works out.