[smuzz]

Yeh, I looked at the post that the bloke put on the discussion list on the HK website and I'm not sure it really matters to you because you're building the plane as you go and you can accommodate whatever alterations you want. I think he might have had a specific need to use a collet adapter but I've never liked them myself and much prefer the bolt-on adapters which are way more robust.

Notice though, that some (all?) of the NTM Propdrive motors require you to separately order the mounting hardware and bolt-on adapter - but it's only a couple of bucks. I think they call it an "Accessory pack" which makes it sound optional, but it ain't Check up on that Mick, because I can't see the bolt-on adapter in the accessories list on that page - but there should be a pack available for all the NTM motors of that size.

Correction: the short-shaft page does show the bolt-on adapter