Of Collars, Latches, and Ebay Items

Three hitherto unsolved problems have been solved since the last post:
* Collar Mechanism
* Airspeed Measurement
* Screen Attachment

Collar Mechanism:
It's pretty easy to find relatively cheap latches with ~1/4 in. of travel (despite the calculations all being done in metric, much of what I work with is in English units), which can be used for compression-purposes. Nails and drilled holes do a pretty decent job as dowels and guides, and surgical tubing provides both the seal, and the resistance to the tension provided by the latches. The end-result is a simple-to-manufacture, interchangeable, quick-release collar. The
specific mechanism will be described in more detail on the website.

Airspeed Measurement:
Finding a pitot-tube anemometer is pretty simple, but finding one that fits in my budget is not so simple. Thankfully, the design airspeeds for the tunnel are known, and good Pitot Tubes are reasonably priced (~$175 for a pitot+static tube with pressure outlets), and ~$150 for a decent differential pressure gauge. From there, using a local machine-shop (or one that a friend of mine has access to), and suddenly you have a differential pressure gauge that shows the dynamic pressure. Combined with absolute pressure (from a barometer) and absolute temperature (from a thermometer), and dynamic pressure can be turned into airspeed.

Screen Attachment:
As Barlow et. al. put it, screens have an uncanny ability to collect dust, and will need to be cleaned, frequently. Given that stipulation, it seemed a bit daft to place the screens in positions that would preclude easy access. It was suggested that I make the screens removable, like a lint-trap in a dryer, but even that seemed like a bit too much work, because then the screens must be securely mounted on something that can be readily removed and reinserted, and seal properly -- even then, the number and position of the screens is variable enough at this stage to warrant a different approach. The collar requires ~3cm per section to operate properly -- I've been using 5cm for good measure (and round numbers). With Sections that small, I've simply decided to make each screen its own section.

Unrelated Comment:
Working with a battery-operated circular-saw on a deck can be quite obnoxious, I'm considering upgrading to a chop saw and a table saw...In the purchase queue they go...