What size (diameter) is your tunnel? and what air speed. We have got a few tunnels here ;-) so I'm happy to help. We / I have made several Pitot-static probes and force sensors for calculating drag etc. ******************************************************************** This email and any attachments are confidential to the intended recipient and may also be privileged. If you are not the intended recipient please delete it from your system and notify the sender. You should not copy it or use it for any purpose nor disclose or distribute its contents to any other person. ******************************************************************** -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics