The idea of Rotorheads sub-forums has been discussed a few times over the years (search Forum in thread titles) and has taken a number of variations. Through the PPRuNe Forums that we have now (I know that Fora is technically correct, but we tend to use Forums by default these days!) there are few aviation topics/specialisations that aren't covered already.
While I understand the desires expressed here, we have found that Rotorheads generally is more of a community than other sections of PPRuNe and as such gets a great deal more latitude than elsewhere. Creating sub forums is fraught with problems: what topics would be appropriate in which sub forum, how do we decide what sub forums should be created, and how do we resolve cross-posting? As mentioned, how do we keep up interest in small specialised sub forums? How do you find a topic that has been previously discussed, in which sub forum?
The Mil Forum is a single forum and covers FW, helicopters, instructing, etc etc, without sub forums.
Even more important, how do I moderate it all and make choices of where to direct threads/posts without upsetting the OP?
Please keep discussing the idea, as I don't have a definitive answer: these are just issues that need consideration from my point of view. In defence of Geoff's concern that the plank posters don't respond to FI issues on the other Forum: that's why we have FI threads here on Rotorheads
