Hi Pieter, Thanks for the 4 .jpegs. That is a colossal sculpture! I'm not sure that I understand the function of the variety of "gnomons", spheres, and suspended planar surfaces. It appears quite complex at first sight. Perhaps you could elaborate.
The first challenge that springs to mind is the type of shadow that is cast by a slender gnomon upon a plane surface a long ways away. I assume that you will want to use the tip of the gnomon as a seasonal marker in some way. I suggest that you use a dimensioned "pole" cantilevered from a high roof-top to look at the shadow carefully. You will also be able to experiment with the surface colour and texture of the dial face using the shadow of this set-up. You are going to have significant aerodynamic forces due to lift, drag and, interestingly, the shedding of vortices from all of the shapes. The shedding of the vortices off of the struts, cables, and the planar surfaces will cause vibrations which can lead to enormous resonance loads, large enough to destroy the structures. There is no question that you MUST consider aerodynamic loads in this project. At the Science North "Celeste", http://sciencenorth.on.ca/AboutSN/polaris/index.html , I had to decouple the various sections of the semicircles to prevent the thing from shaking itself apart in a 50 km/hr wind. Here is a good URL to look at some of the aerodynamic (q) loads: http://www.lerc.nasa.gov/WWW/IFMD/airplane/short.html I trust that this is a helpful start. Cheers, Tom Pieter M DeKock wrote: > We are in the process of designing a horisontal sundial for the southern > hemisphere with a gnomon height of over 40m. We would be grateful to receive > any response with regard to any of the following: > > -common errors to avoid during concept, detail drawing and construction > stages; > > -flagging of any issues concerning the size & shape & material of the > gnomon/style; > > -any other information that would help ensure that the practicalities of > designing a sundial on this scale are met. > > Pictures of the proposal are available as jpeg files. > > Pieter. -- Tom Semadeni O [EMAIL PROTECTED] o aka I (Ned) Ames . Britthome Bounty ><<((((*> Box 176 Britt ON P0G 1A0 'Phone 705 383 0195 fax 2920 45.768* North 80.600* West
