About a third of the way through the film Brains creates his third or fourth 'model', which is a deadringer for Tarheel's Nova III above. The resemblance is striking!
Alas, I have not been able to find a photo of Brains's model anywhere (anyone help here?) The originals most definately won't exist as Brains, highly strung as he is, throws them all on the floor smashing them into pieces! Balsa death dives!
In the UK Thinderbirds 6 is repeated today at 1pm Film4. F.A.B!