This thread is amazing. It started with Bendigo pointing out the folly of trying to "pick the top". We then really got off topic didn't we. Thanks for all the contributors. Good to see some new names posting. This CFD forum was a bit slow a few months ago. Good to follow now, if you can put up with my rubbish. If you read but have not posted, give it a go! Any topic! Yep I think this open ponderings could be a regular thread. cheers mower